U.S. patent application number 16/229445 was filed with the patent office on 2019-11-07 for webrtc api redirection with interception techniques.
The applicant listed for this patent is CITRIX SYSTEMS, INC.. Invention is credited to TODD GIEBLER, GEORGY MOMCHILOV, JAMES PAGE, VLADIMIR VYSOTSKY.
Application Number | 20190342378 16/229445 |
Document ID | / |
Family ID | 66542551 |
Filed Date | 2019-11-07 |
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United States Patent
Application |
20190342378 |
Kind Code |
A1 |
VYSOTSKY; VLADIMIR ; et
al. |
November 7, 2019 |
WEBRTC API REDIRECTION WITH INTERCEPTION TECHNIQUES
Abstract
A computing system includes a virtual desktop server and a
client computing device. The virtual desktop server includes an
application framework comprising a real-time media application to
provide real-time communications (RTC), a native RTC engine to
execute a portion of the real-time media application when received
by the native RTC engine, and an API code redirection module. The
API code redirection module redirects intercepted APIs of the
real-time media application intended for the native RTC engine
based on redirection code injected into the real-time media
application so that the portion of the real-time media application
is redirected. The client computing device includes a client RTC
API engine communicating with the API code redirection module
through a virtual channel to execute the redirected portion of the
real-time media application.
Inventors: |
VYSOTSKY; VLADIMIR;
(FREMONT, CA) ; GIEBLER; TODD; (POMPANO BEACH,
FL) ; MOMCHILOV; GEORGY; (PARKLAND, FL) ;
PAGE; JAMES; (POMPANO BEACH, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CITRIX SYSTEMS, INC. |
FORT LAUDERDALE |
FL |
US |
|
|
Family ID: |
66542551 |
Appl. No.: |
16/229445 |
Filed: |
December 21, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62667013 |
May 4, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06T 7/90 20170101; H04L
67/1091 20130101; H04L 61/2514 20130101; H04L 65/4069 20130101;
H04L 67/2804 20130101; H04L 61/2575 20130101; H04L 61/2589
20130101; H04L 67/2814 20130101; G06K 19/06028 20130101; H04L
61/256 20130101; G06F 9/452 20180201; G06F 9/45529 20130101; G06F
9/45533 20130101; H04L 67/42 20130101; G06F 9/547 20130101; H04L
67/2861 20130101; H04L 61/2564 20130101; H04L 65/608 20130101; H04L
65/4015 20130101; H04L 67/08 20130101; G06F 2009/45562 20130101;
H04L 65/1069 20130101; G06F 9/45545 20130101; H04L 65/1063
20130101; H04L 65/403 20130101; H04L 67/02 20130101; H04L 43/12
20130101; G06F 2009/45595 20130101; H04N 5/272 20130101; G06F
9/45558 20130101; G06F 2203/04804 20130101; H04L 65/80 20130101;
H04L 67/2819 20130101; H04L 67/34 20130101; H04L 65/1059 20130101;
H04L 63/20 20130101; H04L 65/601 20130101; G06F 3/1454 20130101;
G06F 9/455 20130101; H04L 65/60 20130101; H04N 7/147 20130101; H04L
67/104 20130101; H04L 65/605 20130101; G06F 2209/509 20130101; G06F
3/0481 20130101 |
International
Class: |
H04L 29/08 20060101
H04L029/08; H04L 29/06 20060101 H04L029/06; G06F 9/451 20060101
G06F009/451; G06F 9/455 20060101 G06F009/455 |
Claims
1. A computing system comprising: a virtual desktop server
comprising: a desktop and a desktop application framework
associated therewith and a real-time media application to provide
real-time communications (RTC), and a native RTC engine to execute
a first portion of the real-time media application so as to
integrate with other desktop applications and other operating
system functionality, and an API code redirection module to
redirect intercepted APIs of the real-time media application
intended for the native RTC engine based on redirection code
injected into the real-time media application so that a second
portion of the real-time media application is redirected; and a
client computing device comprising a client RTC API engine
communicating with the API code redirection module through a
virtual channel to execute the redirected second portion of the
real-time media application, with the redirected second portion of
the real-time media application corresponding to real-time media
processing and networking being off-loaded to said client computing
device.
2. The computing system according to claim 1 wherein the redirected
APIs correspond to real-time media processing.
3. The computing system according to claim 1 wherein the redirected
APIs correspond to peer-to-peer networking with another client
computing device.
4. The computing system according to claim 1 wherein said API code
redirection module further comprises a hooking module configured to
perform the following: intercept the APIs of the real-time media
application based on hooking; and inject the redirection code into
the real-time media application based on the intercepted APIs.
5. The computing system according to claim 1 wherein said virtual
desktop server comprises a browser including at least one of hooks
and plug-ins configured to perform the following: intercept the
APIs of the real-time media application based on at least one of
the hooks and plug-ins; and inject the redirection code into the
real-time media application based on the intercepted APIs.
6. The computing system according to claim 1 further comprising a
proxy server configured to perform the following: intercept HTML
content from a web server to be retrieved by the real-time media
application; and re-write the intercepted HTML content so that
execution of the re-written HTML content causes the APIs of the
real-time media application to be intercepted, and the redirection
code to be then injected into the real-time media application based
on the intercepted APIs.
7. The computing system according to claim 1 further comprising a
proxy server configured to perform the following: intercept HTML
content from a web server to be retrieved by the real-time media
application; and inject code into pages of the intercepted HTML
content, with execution of the pages with the injected code causing
the following: intercept the APIs of the real-time media
application, and inject the redirection code into the real-time
media application based on the intercepted APIs.
8. The computing system according to claim 1 wherein said virtual
desktop server comprises a browser including at least one of a
Browser Helper Object (BHO) and a Browser Extension configured to
perform the following: intercept the APIs of the real-time media
application based on at least one of the BHO and Browser Extension;
and inject the redirection code into the real-time media
application based on the intercepted APIs.
9. The computing system according to claim 1 further comprising a
micro-virtual private network (VPN) plug-in configured to perform
the following: intercept HTML content from a web server to be
retrieved by the real-time media application; and re-write the
intercepted HTML content so that execution of the re-written HTML
content causes the APIs of the real-time media application to be
intercepted, and the redirection code to be then injected into the
real-time media application based on the intercepted APIs.
10. The computing system according to claim 1 further comprising a
micro-virtual private network (VPN) plug-in configured to perform
the following: intercept HTML content from a web server to be
retrieved by the real-time media application; and inject code into
pages of the intercepted HTML content, with execution of the pages
with the injected code causing the following: intercept the APIs of
the real-time media application, and inject the redirection code
into the real-time media application based on the intercepted
APIs.
11. The computing system according to claim 1 wherein the virtual
desktop server further comprises a modified electron application,
with the modification based on decomposing binaries of the electron
application to access the APIs of the real-time media application,
adding hooks to inject the redirection code into the real-time
media application based on the intercepted APIs, repackaging the
electron application binaries, and resigning the electron
application, with the modified electron application configured to
perform the following: intercept the APIs of the real-time media
application based on hooking; and inject the redirection code into
the real-time media application based on the intercepted APIs.
12. The computing system according to claim 1 wherein the real-time
media application is active in a plurality of browser tabs, and
wherein said client computing device suspends video playback in an
inactive browser tab.
13. The computing system according to claim 1 wherein the real-time
media application is active in a plurality of browser tabs, and
wherein said client computing device stops rendering in a
non-visible area.
14. The computing system according to claim 1 wherein said virtual
desktop server includes at least one security policy, and execution
by said client RTC API engine of at least part of the redirected
portion of the real-time media application is based on the at least
one security policy.
15. A method for operating a computing system comprising a virtual
desktop server and a client computing device comprising a client
RTC API engine, with the virtual desktop server comprising a
desktop and a desktop application framework associated therewith
and an API code redirection module, and with the application
framework comprising a real-time media application and a native RTC
engine, the method comprising: providing real-time communications
(RTC) based on operation of the real-time media application, with a
first portion of the real-time media application to be executed by
the native RTC engine so as to integrate with other desktop
applications and other operating system functionality; redirecting
by the API code redirection module intercepted APIs of the
real-time media application intended for the native RTC engine
based on redirection code injected into the real-time media
application so that a second portion of the real-time media
application is redirected; and operating the client RTC API engine
communicating with the API code redirection module through a
virtual channel to execute the redirected second portion of the
real-time media application, with the redirected second portion of
the real-time media application corresponding to real-time media
processing and networking being off-loaded to said client computing
device.
16. The method according to claim 15 wherein the redirected APIs
correspond to real-time media processing.
17. The method according to claim 15 wherein the redirected APIs
correspond to peer-to-peer networking with another client computing
device.
18. The method according to claim 15 wherein the API code
redirection module further comprises a hooking module to perform
the following: intercept the APIs of the real-time media
application based on hooking; and inject the redirection code into
the real-time media application based on the intercepted APIs.
19. The method according to claim 15 wherein the virtual desktop
server comprises a browser including at least one of hooks and
plug-ins configured to perform the following: intercept the APIs of
the real-time media application based on at least one of the hooks
and plug-ins; and inject the redirection code into the real-time
media application based on the intercepted APIs.
20. A non-transitory computer readable medium for operating a
virtual desktop server within a computing system comprising a
client computing device comprising a client RTC API engine, with
the virtual desktop server comprising a desktop and a desktop
application framework associated therewith and an API code
redirection module, with the application framework comprising a
real-time media application and a native RTC engine, and with the
non-transitory computer readable medium having a plurality of
computer executable instructions for causing the virtual desktop
server to perform steps comprising: providing real-time
communications (RTC) based on operation of the real-time media
application, with a first portion of the real-time media
application to be executed by the native RTC engine so as to
integrate with other desktop applications and other operating
system functionality; and redirecting by the API code redirection
module intercepted APIs of the real-time media application intended
for the native RTC engine based on redirection code injected into
the real-time media application so that a second portion of the
real-time media application is redirected; and operating the client
RTC API engine communicating with the API code redirection module
through a virtual channel to execute the redirected second portion
of the real-time media application, with the redirected second
portion of the real-time media application corresponding to
real-time media processing and networking being off-loaded to said
client computing device.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of provisional
application Ser. No. 62/667,013 filed May 4, 2018, which is hereby
incorporated herein in its entirety by reference.
TECHNICAL FIELD
[0002] The present disclosure generally relates to an application
virtualization platform allowing virtualized browser and desktop
applications to deliver optimized real time communications using a
standard Web Real-Time Communication (WebRTC) API.
BACKGROUND
[0003] Traditionally, personal computers include combinations of
operating systems, applications, and user settings, which are each
managed individually by owners or administrators on an ongoing
basis. However, many organizations are now using desktop
virtualization to provide a more flexible option to address the
varying needs of their users. In desktop virtualization, a user's
computing environment (e.g., operating system, applications, and/or
user settings) may be separated from the user's physical computing
device (e.g., smartphone, laptop, desktop computer). Using
client-server technology, a "virtualized desktop" may be stored in
and administered by a remote server, rather than in the local
storage of the client computing device.
[0004] There are several different types of desktop virtualization
systems. As an example, Virtual Desktop Infrastructure (VDI) refers
to the process of running a user desktop inside a virtual machine
that resides on a server. VDI and other server-based desktop
virtualization systems may provide personalized desktops for each
user, while allowing for centralized management and security.
Servers in such systems may include storage for virtual desktop
images and system configuration information, as well as software
components to provide the virtual desktops and allow users to
interconnect to them. For example, a VDI server may include one or
more hypervisors (virtual machine managers) to create and maintain
multiple virtual machines, software to manage the hypervisor(s), a
connection broker, and software to provision and manage the virtual
desktops.
[0005] Desktop virtualization systems may be implemented using a
single virtualization server or a combination of servers
interconnected as a server grid. For example, a cloud computing
environment, or cloud system, may include a pool of computing
resources (e.g., desktop virtualization servers), storage disks,
networking hardware, and other physical resources that may be used
to provision virtual desktops, along with additional computing
devices to provide management and customer portals for the cloud
system.
[0006] Cloud systems may dynamically create and manage virtual
machines for customers over a network, providing remote customers
with computational resources, data storage services, networking
capabilities, and computer platform and application support. For
example, a customer in a cloud system may request a new virtual
machine having a specified processor speed and memory, and a
specified amount of disk storage. Within the cloud system, a
resource manager may select a set of available physical resources
from the cloud resource pool (e.g., servers, storage disks) and may
provision and create a new virtual machine in accordance with the
customer's specified computing parameters. Cloud computing services
may service multiple customers with private and/or public
components, and may be configured to provide various specific
services, including web servers, security systems, development
environments, user interfaces, and the like.
SUMMARY
[0007] A computing system includes a virtual desktop server and a
client computing device. The virtual desktop server includes an
application framework comprising a real-time media application to
provide real-time communications (RTC), a native RTC engine to
execute a portion of the real-time media application when received
by the native RTC engine, and an API code redirection module. The
API code redirection module is to redirect intercepted APIs of the
real-time media application intended for the native RTC engine
based on redirection code injected into the real-time media
application so that the portion of the real-time media application
is redirected. The client computing device comprises a client RTC
API engine communicating with the API code redirection module
through a virtual channel to execute the redirected portion of the
real-time media application.
[0008] Execution of real-time functionality by the client RTC API
engine on the client computing device addresses high latency and
low media quality issues typically introduced by virtualization of
audio and video devices, which involves several rounds of media
compression/decompression and extra network hops. Specific
functions and interactions of the injected code, the API code
redirection module, and the client RTC API engine are designed to
optimize WebRTC.
[0009] It is still advantageous to run part of the real-time media
application code on the virtual desktop server using a native RTC
engine where it can integrate with other desktop applications and
other desktop OS functionality. Redirection of WebRTC APIs provides
a way for the real-time media application code to continue
executing on the virtual desktop server while offloading real-time
media processing and networking to the client computing device. The
real-time media application code can be largely unaware of the fact
that WebRTC APIs are being redirected, resulting in out of the box
real-time media optimization for many if not all virtualized
applications.
[0010] There are a number of API interception techniques for WebRTC
redirection. These techniques include: hooking; use of a custom
browser; JavaScript injection via proxy; JavaScript injection via a
browser helper object (BHO) or browser extension; JavaScript
injection via micro-VPN plugin; and use of an electron app
decomposition.
[0011] Another aspect is directed to a method for operating a
computing system as described above. The method comprises providing
real-time communications (RTC) based on operation of the real-time
media application, with a portion of the real-time media
application to be executed by the native RTC engine when received
by the native RTC engine. The API code redirection module redirects
intercepted APIs of the real-time media application intended for
the native RTC engine based on redirection code injected into the
real-time media application so that the portion of the real-time
media application is redirected. The client RTC API engine is
operated to communicate with the API code redirection module
through a virtual channel to execute the redirected portion of the
real-time media application.
[0012] Yet another aspect is directed to a non-transitory computer
readable medium for operating a virtual desktop server within a
computing system as described above. The non-transitory computer
readable medium has a plurality of computer executable instructions
for causing the virtual desktop server to perform steps as also
described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a block diagram of a network environment of
computing devices in which various aspects of the disclosure may be
implemented.
[0014] FIG. 2 is a block diagram of a computing device useful for
practicing an embodiment of the client machines or the remote
machines illustrated in FIG. 1.
[0015] FIG. 3 is a block diagram of an architecture illustrating an
application virtualization platform that provides WebRTC API on the
virtual desktop server and executes the WebRTC API functionality on
the client computing device in which various aspects of the
disclosure may be implemented.
[0016] FIGS. 4-7 are various windows illustrating an example window
monitoring/overlay detection scenario with the architecture
illustrated in FIG. 3.
[0017] FIGS. 8-9 are updates to the window illustrated in FIG. 7
based on movement of the server-side window.
[0018] FIGS. 10-11 are updates to the window illustrated in FIG. 9
based on a rendered server-side application clipping a video
stream.
[0019] FIG. 12 is a simplified block diagram of the architecture
illustrated in FIG. 3 illustrating screen sharing with WebRTC API
redirection.
[0020] FIG. 13 is a table diagram illustrating a method of
detecting semi-transparent overlays that can be used with the
architecture illustrated in FIG. 3.
[0021] FIGS. 14-17 are sample images illustrating a test run of a
method of detecting semi-transparent overlays that can be used with
the architecture illustrated in FIG. 3.
[0022] FIG. 18 is a block diagram of the architecture illustrated
in FIG. 3 modified to support any accelerated graphics media that
includes a semi-transparent overlay.
DETAILED DESCRIPTION
[0023] The present description is made with reference to the
accompanying drawings, in which exemplary embodiments are shown.
However, many different embodiments may be used, and thus the
description should not be construed as limited to the particular
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete.
Like numbers refer to like elements throughout, and prime notations
are used to indicate similar elements in alternative
embodiments.
[0024] As will be appreciated by one of skill in the art upon
reading the following disclosure, various aspects described herein
may be embodied as a device, a method or a computer program product
(e.g., a non-transitory computer-readable medium having computer
executable instruction for performing the noted operations or
steps). Accordingly, those aspects may take the form of an entirely
hardware embodiment, an entirely software embodiment or an
embodiment combining software and hardware aspects.
[0025] Furthermore, such aspects may take the form of a computer
program product stored by one or more computer-readable storage
media having computer-readable program code, or instructions,
embodied in or on the storage media. Any suitable computer readable
storage media may be utilized, including hard disks, CD-ROMs,
optical storage devices, magnetic storage devices, and/or any
combination thereof.
[0026] Referring initially to FIG. 1, a non-limiting network
environment 101 in which various aspects of the disclosure may be
implemented includes one or more client machines 102A-102N, one or
more remote machines 106A-106N, one or more networks 104, 104', and
one or more appliances 108 installed within the computing
environment 101. The client machines 102A-102N communicate with the
remote machines 106A-106N via the networks 104, 104'.
[0027] In some embodiments, the client machines 102A-102N
communicate with the remote machines 106A-106N via an intermediary
appliance 108. The illustrated appliance 108 is positioned between
the networks 104, 104' and may be referred to as a network
interface or gateway. In some embodiments, the appliance 108 may
operate as an application delivery controller (ADC) to provide
clients with access to business applications and other data
deployed in a datacenter, the cloud, or delivered as Software as a
Service (SaaS) across a range of client devices, and/or provide
other functionality such as load balancing, etc. In some
embodiments, multiple appliances 108 may be used, and the
appliance(s) 108 may be deployed as part of the network 104 and/or
104'.
[0028] The client machines 102A-102N may be generally referred to
as client machines 102, local machines 102, clients 102, client
nodes 102, client computers 102, client devices 102, computing
devices 102, endpoints 102, or endpoint nodes 102. The remote
machines 106A-106N may be generally referred to as servers 106 or a
server farm 106. In some embodiments, a client device 102 may have
the capacity to function as both a client node seeking access to
resources provided by a server 106 and as a server 106 providing
access to hosted resources for other client devices 102A-102N. The
networks 104, 104' may be generally referred to as a network 104.
The networks 104 may be configured in any combination of wired and
wireless networks.
[0029] A server 106 may be any server type such as, for example: a
file server; an application server; a web server; a proxy server;
an appliance; a network appliance; a gateway; an application
gateway; a gateway server; a virtualization server; a deployment
server; a Secure Sockets Layer Virtual Private Network (SSL VPN)
server; a firewall; a web server; a server executing an active
directory; or a server executing an application acceleration
program that provides firewall functionality, application
functionality, or load balancing functionality.
[0030] A server 106 may execute, operate or otherwise provide an
application that may be any one of the following: software; a
program; executable instructions; a virtual machine; a hypervisor;
a web browser; a web-based client; a client-server application; a
thin-client computing client; an ActiveX control; a Java applet;
software related to voice over internet protocol (VoIP)
communications like a soft IP telephone; an application for
streaming video and/or audio; an application for facilitating
real-time-data communications; a HTTP client; a FTP client; an
Oscar client; a Telnet client; or any other set of executable
instructions.
[0031] In some embodiments, a server 106 may execute a remote
presentation services program or other program that uses a
thin-client or a remote-display protocol to capture display output
generated by an application executing on a server 106 and transmit
the application display output to a client device 102.
[0032] In yet other embodiments, a server 106 may execute a virtual
machine providing, to a user of a client device 102, access to a
computing environment. The client device 102 may be a virtual
machine. The virtual machine may be managed by, for example, a
hypervisor, a virtual machine manager (VMM), or any other hardware
virtualization technique within the server 106.
[0033] In some embodiments, the network 104 may be: a local-area
network (LAN); a metropolitan area network (MAN); a wide area
network (WAN); a primary public network 104; and a primary private
network 104. Additional embodiments may include a network 104 of
mobile telephone networks that use various protocols to communicate
among mobile devices. For short range communications within a
wireless local area network (WLAN), the protocols may include
802.11, Bluetooth, and Near Field Communication (NFC).
[0034] FIG. 2 depicts a block diagram of a computing device 100
useful for practicing an embodiment of client devices 102 or
servers 106. The computing device 100 includes one or more
processors 103, volatile memory 122 (e.g., random access memory
(RAM)), non-volatile memory 128, user interface (UI) 123, one or
more communications interfaces 118, and a communications bus
150.
[0035] The non-volatile memory 128 may include: one or more hard
disk drives (HDDs) or other magnetic or optical storage media; one
or more solid state drives (SSDs), such as a flash drive or other
solid state storage media; one or more hybrid magnetic and solid
state drives; and/or one or more virtual storage volumes, such as a
cloud storage, or a combination of such physical storage volumes
and virtual storage volumes or arrays thereof.
[0036] The user interface 123 may include a graphical user
interface (GUI) 124 (e.g., a touchscreen, a display, etc.) and one
or more input/output (I/O) devices 126 (e.g., a mouse, a keyboard,
a microphone, one or more speakers, one or more cameras, one or
more biometric scanners, one or more environmental sensors, and one
or more accelerometers, etc.).
[0037] The non-volatile memory 128 stores an operating system 115,
one or more applications 116, and data 117 such that, for example,
computer instructions of the operating system 115 and/or the
applications 116 are executed by processor(s) 103 out of the
volatile memory 122. In some embodiments, the volatile memory 122
may include one or more types of RAM and/or a cache memory that may
offer a faster response time than a main memory. Data may be
entered using an input device of the GUI 124 or received from the
I/O device(s) 126. Various elements of the computer 100 may
communicate via the communications bus 150.
[0038] The illustrated computing device 100 is shown merely as an
example client device or server, and may be implemented by any
computing or processing environment with any type of machine or set
of machines that may have suitable hardware and/or software capable
of operating as described herein.
[0039] The processor(s) 103 may be implemented by one or more
programmable processors to execute one or more executable
instructions, such as a computer program, to perform the functions
of the system. As used herein, the term "processor" describes
circuitry that performs a function, an operation, or a sequence of
operations. The function, operation, or sequence of operations may
be hard coded into the circuitry or soft coded by way of
instructions held in a memory device and executed by the circuitry.
A processor may perform the function, operation, or sequence of
operations using digital values and/or using analog signals.
[0040] In some embodiments, the processor can be embodied in one or
more application specific integrated circuits (ASICs),
microprocessors, digital signal processors (DSPs), graphics
processing units (GPUs), microcontrollers, field programmable gate
arrays (FPGAs), programmable logic arrays (PLAs), multi-core
processors, or general-purpose computers with associated
memory.
[0041] The processor may be analog, digital or mixed-signal. In
some embodiments, the processor may be one or more physical
processors, or one or more virtual (e.g., remotely located or
cloud) processors. A processor including multiple processor cores
and/or multiple processors may provide functionality for parallel,
simultaneous execution of instructions or for parallel,
simultaneous execution of one instruction on more than one piece of
data.
[0042] The communications interfaces 118 may include one or more
interfaces to enable the computing device 100 to access a computer
network such as a Local Area Network (LAN), a Wide Area Network
(WAN), a Personal Area Network (PAN), or the Internet through a
variety of wired and/or wireless connections, including cellular
connections.
[0043] In described embodiments, the computing device 100 may
execute an application on behalf of a user of a client device. For
example, the computing device 100 may execute one or more virtual
machines managed by a hypervisor. Each virtual machine may provide
an execution session within which applications execute on behalf of
a user or a client device, such as a hosted desktop session. The
computing device 100 may also execute a terminal services session
to provide a hosted desktop environment. The computing device 100
may provide access to a remote computing environment including one
or more applications, one or more desktop applications, and one or
more desktop sessions in which one or more applications may
execute.
[0044] Additional descriptions of a computing device 100 configured
as a client device 102 or as a server 106, or as an appliance
intermediary to a client device 102 and a server 106, and
operations thereof, may be found in U.S. Pat. Nos. 9,176,744 and
9,538,345, which are incorporated herein by reference in their
entirety. The '744 and '345 patents are both assigned to the
current assignee of the present disclosure.
[0045] Turning now to FIG. 3, the illustrated architecture 300 will
be discussed in terms of WebRTC redirection with interception
techniques. The architecture 300 allows virtualized browser and
desktop applications to deliver optimized real time communications
(RTC) using a standard WebRTC API. Real time communications
includes voice, video and data collaboration. An application
framework 312 provides the WebRTC API on the application server
302, and provides execution of the WebRTC API functionality on the
remote client 304. Various techniques are used to make this
functionality feasible and transparent to the real-time media
application 310, and achieve high quality user experience and other
desirable features.
[0046] The application framework 312 includes a web browser or a
desktop application to provide the real-time media application 310
that provides the real time communications. The real-time media
application 310 is supported by a real-time media application
server 320. The architecture 300 may be referred to as a computing
system 300, the application server 302 may be referred to as a
virtual desktop server 302, and the remote client 304 may be
referred to as a client computing device 304 or as a virtual
desktop client 304. The client computing device 304 is in
peer-to-peer communications with at least one other client
computing device 305.
[0047] WebRTC is a collection of APIs and an open source project
enabling real-time communications (VoIP, video over IP, and other
types of real-time collaboration) in browser and desktop
applications. Since its introduction to the industry by Google in
2011, and adoption by several standards bodies (W3C and IETF),
WebRTC has been included in most popular web browsers, as well as
made available in desktop application platforms such as Electron.
Application and service vendors as well as enterprise IT
departments are increasingly making use of WebRTC for adding voice
and video functionality to existing and new HTML5 applications.
[0048] Electron is an open source framework for building desktop
applications (running outside of a browser) using technologies
originally defined for the Web, including HTML5 and WebRTC.
Electron is also seeing increased adoption in the industry by
leading application vendors.
[0049] Under desktop virtualization, execution of WebRTC
functionality on the virtual desktop server 302 has a number of
well-known disadvantages. One disadvantage is the high latency and
low media quality introduced by virtualization of audio and video
devices, which involves several rounds of media
compression/decompression and extra network hops. Another
disadvantage is network and server scalability concerns caused by
mandatory tunneling of peer-to-peer media through the data center
or the cloud infrastructure, and running high CPU cost audio and
video codecs on the virtual desktop server 302.
[0050] Execution of real-time functionality, including both the
media processing pipelines and the networking code, by a client RTC
API engine 308 on the client computing device 304 addresses these
problems. It is still advantageous to run the rest of the real-time
media application code on the virtual desktop server 302, using a
native RTC engine 316 where it can integrate with other desktop
applications and other desktop OS functionality. Redirection of
WebRTC APIs provides a way for the real-time media application code
to continue executing on the virtual desktop server 302, while
offloading only real-time media processing and networking to the
client computing device 304. Further, the real-time media
application code can be largely unaware of the fact that WebRTC
APIs are being redirected. This results in out of the box real-time
media optimization for many if not all virtualized
applications.
[0051] Redirection, or remoting, of parts of application
functionality from the virtual desktop server 302 to the client
computing device 304 is not new by itself, and has been implemented
in a number of technologies (including such Citrix technologies as
Remoting Audio and Video Extensions (RAVE), Flash Redirection,
Browser Content Redirection, and Real-time Optimization Pack).
However, what is new is using WebRTC redirection techniques to
deliver real-time media optimization for HTML 5/JavaScript
applications.
[0052] WebRTC redirection techniques include a number of unique
features such as: new methods of API interception for browser and
desktop applications; new techniques for providing fallback
functionality; new techniques for video area identification and
geometry tracking; new techniques for window monitoring/overlay
detection; new techniques for selecting and capturing screen
content for content sharing sessions; new types and applications of
policies to control application access to endpoint media sources;
and new techniques for managing network connectivity for real time
media in virtualization application environments. These techniques
are discussed in more detail below.
[0053] As a general overview, WebRTC comprises a set of API
specifications maintained by the Web Real-Time Communications
Working Group (part of W3C), as well as implementations of these
APIs in web browsers and HTML5/JavaScript desktop application
platforms such as Electron. The most relevant specifications for
this architecture include WebRTC 1.0: Real-time Communication
Between Browsers (further referenced as [webrtc]), Media Capture
and Streams ([mediacapture-streams]), and Screen Capture
([screen-capture]). The following description references
definitions and API elements from relevant W3C specifications
without repeating them here.
[0054] The general idea of the illustrated architecture 300 in FIG.
3 is to redirect underlying functionality of WebRTC APIs from the
virtual desktop server 302 to the client computing device 304 by
intercepting calls to the API made by the real-time media
application 310. The intercepted APIs are executed either remotely
on the client computing device 304 via the client RTC API engine
308, or locally on the virtual desktop server 302 as appropriate
via the native RTC engine 316. API callbacks are invoked or
asynchronous API events are generated to the real-time media
application 310.
[0055] Acronyms and definitions in this field include XenApp (XA),
XenDesktop (XD), and Virtual Desktop Infrastructure (VDI). VDI is
virtualization technology that hosts a desktop operating system on
a centralized server in a data center, and provides remote access
to virtual hosted applications and desktops. Citrix Receiver and
Citrix Workspace App are virtual desktop clients providing remote
access to virtual hosted applications and desktops.
[0056] The following major elements comprise the system
architecture 300 for WebRTC redirection. A virtual desktop server
302 provides server-side virtual channel functionality and hosts
virtual applications. For example, these may be implemented in
Citrix XenApp/XenDesktop. A virtual desktop client 304 provides
client-side virtual channel functionality. For example, this may be
implemented in Citrix Receiver and Citrix Workspace App. A
virtualized application (or virtual application) is a third party
application implemented in HTML 5 and JavaScript and uses WebRTC to
deliver real-time voice, video and data functionality. The
virtualized application, such as the real-time media application
310, is hosted on the virtual desktop server 302.
[0057] A server-side API code redirection module 306 includes code
libraries and applications running on the virtual desktop server
302, and interacts with the real-time media application 310 to
achieve WebRTC API redirection. The API code redirection module 306
may be referred to as a WebRTC API connector 306. The API code
redirection module 306 may be considered as a single system
component, or may be split into two subcomponents: injected and
non-injected code, for some of the techniques described below.
[0058] Injected server-side WebRTC connector code 314 (injected API
code) includes portions of connector code that may be either
implemented in JavaScript, or implemented in a different computer
language but providing a JavaScript-compatible API. The injected
API code 314 is injected into the real-time media application 310,
and modifies the HTML5/JavaScript execution environment within the
application process. If implemented in JavaScript, the injected
code 314 would communicate with non-injected connector code
libraries directly using WebSockets or another suitable
inter-process communication mechanism, and indirectly through
rendered screen contents as described below in the window tracking
section.
[0059] Other server-side connector code includes code libraries
implemented in any suitable programming language and running either
within or outside of the application process. The API code
redirection module 306 communicates with the injected code 314
through WebSockets or another suitable mechanism, and indirectly
through screen capture, and with the client RTC API engine 308
through a virtual channel 318.
[0060] The client RTC API engine 308 includes code libraries
running on the client computing device 304. The client RTC API
engine 308 communicates with the API code redirection module 306
through a virtual channel 318 hosted by the virtual desktop server
302.
[0061] The illustrated architecture 300, and the general idea of
optimizing application virtualization by offloading parts of the
real-time media application RTC functionality from the virtual
desktop server 302 to the client computing device 304, are fairly
generic and widely used in systems implementing application or
desktop virtualization. The distinction hereinlies in specific
functions and interactions of the injected code 314, the API code
redirection module 306, and the client RTC API engine 308 that are
designed to optimize real time media APIs. In particular, WebRTC is
optimized.
[0062] As noted above, the computing system 300 includes the
virtual desktop server 302 and the client computing device 304 in
peer-to-peer communications with another endpoint device 305. The
virtual desktop server 302 includes the application framework 312
that includes the real-time media application 310 to provide
real-time communications (RTC), and the native RTC engine 316 to
execute a portion of the real-time media application 310 when
received by the native RTC engine 316. The API code redirection
module 306 redirects intercepted APIs of the real-time media
application 310 intended for the native RTC engine 316 based on
redirection code 314 injected into the real-time media application
310 so that the portion of the real-time media application 310 is
redirected. The client RTC API engine 308 in the client computing
device 304 communicates with the API code redirection module 306
through a virtual channel 318 to execute the redirected portion of
the real-time media application 310.
[0063] The application framework 312 may be a web browser or a
desktop application framework. The redirected APIs correspond to
real-time media processing and/or peer-to-peer networking with
another client computing device 305.
[0064] Various API interception techniques will now be discussed.
WebRTC APIs are defined as Java Script APIs available to HTML
5/Java Script applications within a web browser or within an
application development platform such as Electron. Electron
combines an HTML 5/Java Script application engine with additional
desktop-specific platform functionality. Interception of WebRTC
APIs by a desktop virtualization platform requires additional novel
techniques.
[0065] The following API interception techniques will be discussed
below: hooking; use of a custom browser; JavaScript injection via
proxy; JavaScript injection via a browser helper object (MO) or
browser extension, JavaScript injection via micro-VPN plugin; and
use of an electron app decomposition.
[0066] For hooking, the API code redirection module 306 may include
a hooking module configured to intercept the APIs of the real-time
media application 310 based on hooking, and inject the redirection
code 314 into the real-time media application 310 based on the
intercepted APIs.
[0067] JavaScript rendered DLL APIs are hooked and custom JS is
inserted. For IS, the JavaScript engine DLL is jscript.dll and is a
(in process) COM object server. Hence, the idea would be to employ
standard COM shimming techniques to operate as a "man in the
middle" (MITM) in order to insert custom JavaScript. In the IE
JavaScript engine, all JavaScript objects implement the IDispatchEx
interface. Alternatively, one could hook OS socket APIs, e.g.
WinSock APIs, parse HTTP traffic and HTML content and then insert
JS.
[0068] For a custom browser, a custom Chromium-based browser engine
may be used and a custom Secure Browser published, e.g., as part of
the Citrix Secure Browser Cloud Service. Hooks or plugins are used
within the Chromium engine to inject custom JS. Alternatively, a
custom browser engine may implement some or all of the WebRTC
redirection functionality in native code, limiting or removing the
need to inject custom JavaScript code. The virtual desktop server
302 includes a browser that includes hooks or plug-ins configured
to intercept the APIs of the real-time media application 310, and
inject the redirection code 314 into the real-time media
application 310 based on the intercepted APIs.
[0069] For JavaScript injection via proxy, a proxy is used to
intercept HTML content. The proxy would add additional JS via
content rewriting. The proxy could be a separate appliance on the
network, or reside on the virtual desktop server 302. The proxy
could be configured explicitly (using browser settings) or operate
as a transparent proxy.
[0070] In one approach, the computing system 300 further includes a
proxy server configured to intercept HTML content from a web server
to be retrieved by the real-time media application 310, and
re-write the intercepted HTML content so that execution of the
re-written HTML content causes the APIs of the real-time media
application 310 to be intercepted. The redirection code 314 is then
injected into the real-time media application 310 based on the
intercepted APIs.
[0071] In another approach, the proxy server may be configured to
intercept HTML content from a web server to be retrieved by the
real-time media application 310, and inject code into pages of the
intercepted HTML content. Execution of the pages with the injected
code causes the APIs of the real-time media application 310 to be
intercepted. The redirection code 314 is then injected into the
real-time media application 310 based on the intercepted APIs.
[0072] For JavaScript injection via Browser Helper Object (BHO) or
browser extension, JavaScript code to implement WebRTC API
redirection could be injected into a browser-based application
using the BHO or the Browser Extension for web browsers that
implement BHO or browser extension mechanisms. The virtual desktop
server 302 thus includes a browser including a BHO or a Browser
Extension to intercept the APIs of the real-time media application
310, and inject the redirection 314 code into the real-time media
application 310 based on the intercepted APIs.
[0073] For JavaScript injection via micro-VPN plugin, a universal
windows platform (UWP) App is used to implement a virtual private
network (VPN) app plugin. The UWP VPN plugin app will handle the
declaration of the VPN client plug-in capability in the AppX
manifest and provide reference to the VPN plug-in app handler.
Running the plugin within a sandbox (app container) allows for
greater security and reduced complexity of the implementation.
[0074] The VPN app plugin is able to control VPN connections in
conjunction with the OS VPN platform. In addition, the VPN app
plugin could be configured as a micro-VPN, i.e., it can be applied
on a per-application basis. For example, the configuration could be
achieved via mobile device management (MDM) or mobile application
management (MDM) policies.
[0075] Alternatively, a custom profile may be created using
PowerShell scripts. The configuration could specify apps whose
traffic is to be managed by the micro-VPN plugin. In particular,
the micro-VPN plugin could be configured for browser applications
and Electron based apps. The micro-VPN plugin could be enabled to
intercept network traffic for all or specific apps, decrypt TLS
using local certificate store, parse HTTP traffic and HTML content
and then insert custom JavaScript.
[0076] In one approach, the computing system further includes a
micro-virtual private network (VPN) plug-in configured to intercept
HTML content from a web server to be retrieved by the real-time
media application 310, and re-write the intercepted HTML content so
that execution of the re-written HTML content causes the APIs of
the real-time media application 310 to be intercepted. Then the
redirection code 314 is to be injected into the real-time media
application 310 based on the intercepted APIs.
[0077] In another approach, the micro-virtual private network (VPN)
plug-in may be configured to intercept HTML content from a web
server to be retrieved by the real-time media application 310, and
inject code into pages of the intercepted HTML content. Execution
of the pages with the injected code causes the APIs of the
real-time media application 310 to be intercepted. The redirection
code 314 is then injected into the real-time media application 310
based on the intercepted APIs.
[0078] For electron app decomposition, the electron app is first
run through a tool that modifies the electron app. The modification
is based on decomposing binaries of the electron application to
access the APIs of the real-time media application 310, add hooks
to inject the redirection code into the real-time media application
310 based on the intercepted APIs, repackage the electron
application binaries, and resign the electron application. The
modified electron application is then configured to intercept the
APIs of the real-time media application 310 based on hooking, and
inject the redirection code 314 into the real-time media
application 310 based on the intercepted APIs. Stated another way,
the electron app is detected during virtual app publishing.
[0079] Electron app binaries are then decomposed. App content is
usually located within an .asar archive located within a subfolder
corresponding to the electron application. It is possible to unpack
this archive using asar.exe (available as a node.js package) to
access the JavaScript code for the application. Then hooks are
added where the hooks comprise DLLs or other modules are to be
loaded at runtime and to inject custom JS. The import address table
of the main executable is modified to load the hooks when a process
runs. The application binaries are repackaged, and the electron
application package is then resigned.
[0080] Another aspect of delivering optimized real time
communications (RTC) using a standard WebRTC API is directed to a
method for operating a computing system 300 comprising a virtual
desktop server 302 and a client computing device 304 comprising a
client RTC API engine 308. The virtual desktop server 302 includes
an application framework 312 and an API code redirection module
306. The application framework 312 includes a real-time media
application 310 and a native RTC engine 316.
[0081] The method includes providing real-time communications based
on operation of the real-time media application 310, with a portion
of the real-time media application 310 to be executed by the native
RTC engine 316 when received by the native RTC engine 316, The
method further includes redirecting by the API code redirection
module 306 intercepted APIs of the real-time media application 310
intended for the native RTC engine 316 based on redirection code
314 injected into the real-time media application 310 so that the
portion of the real-time media application 310 is redirected. The
client RTC API engine 308 communicates with the API code
redirection module 306 through a virtual channel 318 to execute the
redirected portion of the real-time media application 310.
[0082] Yet another aspect is directed to a non-transitory computer
readable medium for operating a virtual desktop server 302 within a
computing system 300 as described above. The non-transitory
computer readable medium has a plurality of computer executable
instructions for causing the virtual desktop server 302 to provide
real-time communications (RTC) based on operation of the real-time
media application 310, with a portion of the real-time media
application 310 to be executed by the native RTC engine 316 when
received by the native RTC engine 316. The instructions further
cause the virtual desktop server 302 to redirect by the API code
redirection module 306 intercepted APIs of the real-time media
application 310 intended for the native RTC engine 316 based on
redirection code 314 injected into the real-time media application
310 so that the client RTC API engine 308 communicates with the API
code redirection module 306 through a virtual channel 318 to
execute the redirected portion of the real-time media application
310.
[0083] Still referring to FIG. 3, the illustrated computing system
300 will now be discussed in terms of WebRTC redirection with
fallback. General fallback techniques will now be discussed where
in some cases the necessary functionality will be missing so a
graceful fallback functionality to use less optimized mechanisms is
needed for handling real time media when full optimization is not
available.
[0084] The virtual desktop server 302 and the at least one client
computing device 304 are as discussed above. The application
framework 312 includes the real-time media application 310 to
provide real-time communications (RTC), and the native RTC engine
316 executes a portion of the real-time media application 310 when
received by the native RTC engine 306. The virtual desktop server
302 further includes an API code redirection module 306 to redirect
original APIs of the real-time media application 310 intended for
the native RTC engine 316 based on redirection code 314 injected
into the real-time media application 310 so that the portion of the
real-time media application 310 is to be redirected.
[0085] In particular, the client computing device 304 includes the
client RTC API engine 308 reporting to the API code redirection
module 306 through a virtual channel 318 on capabilities of the
client computing device 304 to execute the redirected portion of
the real-time media application 310. The API code redirection
module 306 switches to a fallback mode if the client computing
device 304 has limited capabilities. In the fallback mode at least
part of the original APIs are used so that the native RTC engine
316 executes at least part of the portion of the real-time media
application 310.
[0086] Real time media functionality enabled by WebRTC redirection
described here will result in optimized user experience and system
scalability when all system components include the necessary
functionality. In particular, when virtual desktop clients and
servers include compatible software and hardware modules that have
the necessary capabilities cooperate to deliver the functionality
as designed.
[0087] If the client computing device 304 has full capabilities
fallback is not needed. In this case, the API code redirection
module 306 does not switch to the fallback mode so that the client
RTC API engine 308 executes all of the redirected portion of the
real-time media application 310.
[0088] However, in real world deployments, it is inevitable that in
some cases the necessary functionality will be missing. A WebRTC
remoting solution must provide graceful fallback functionality to
use other, less optimized mechanisms for handling real time media
when full optimization is not available. Ideally, this fallback
functionality (as well as the optimization itself) should be
transparent to the application, i.e., handled by the application
framework 312 without requiring application changes, and provide a
friendly user experience.
[0089] To provide fallback functionality, a virtual application
solution needs to include some or all of session state tracking and
capability detection and negotiation. In session state tracking,
application process lifetime may overlap with one or more user
connections to a virtual access session, and the process of
enabling optimized functionality or providing a fallback may happen
multiple times as session state changes.
[0090] In capability detection and negotiation, client-server
protocols used for providing optimized functionality need to
support detection or negotiation of the virtual desktop server 302
and client computing device 304 capabilities, which enables the
corresponding code to switch between optimized and fallback modes
of operation.
[0091] When fallback is needed, then the following techniques are
specific to providing fallback functionality for WebRTC
redirection. These techniques include 1) fallback to the built-in
native RTC engine 316; 2) per-modality fallback; 3) partial
fallback; and 4) mapping of session connect/disconnect events to
device availability events.
[0092] In fallback to the built-in native RTC engine 316, the
client computing device 304 has no capabilities to execute the
redirected portion of the real-time media application 310. In the
fallback mode all of the original APIs are used so that the native
RTC engine 316 executes all of the portion of the real-time media
application 310 instead of the client RTC API engine 308.
[0093] When remote execution of WebRTC is not possible (e.g., when
no client RTC API engine 308 is present), injected code can
dynamically dispatch application API calls to the built-in native
RTC engine 316 that is included as part of the application
framework 312. Injected code 314 can use itself as a shim to
monitor these calls and resulting built-in WebRTC objects are used
to enable an eventual switch to remote (optimized) functionality as
well as ongoing monitoring of application WebRTC usage and
quality.
[0094] In the per-modality fallback, depending on client computing
device 304 capabilities and policies, the application framework 312
may implement per-modality fallback functionality when a remaining
part of the portion of the real-time media application 310 that is
not executed by the native RTC engine 316 is redirected to the
client RTC API engine 308 for execution.
[0095] For example, when a client computing device 304 can only
handle the audio portion of a real-time media session, the
application framework 312 may implement optimized functionality for
audio and fallback functionality for video. To do this, injected
code 314 can remote API calls for audio streams to the client
computing device 304 and redirect API calls for video streams to
the local built-in RTC engine 316, merging the results together.
The at least part of the portion of the real-time media application
310 executed by the native RTC engine 316 corresponds to video, and
the remaining part of the portion of the real-time media
application 310 executed by the client RTC API engine 308
corresponds to audio.
[0096] Alternatively, the at least part of the portion of the
real-time media application 310 executed by the native RTC engine
316 corresponds to audio, and the remaining part of the portion of
the real-time media application 310 executed by the client RTC API
engine 308 corresponds to video.
[0097] In the partial fallback, depending on the virtual desktop
server 302 capabilities and policies, injected and server-side code
can implement partial fallback. Partial fallback does not involve
redirection to the client computing device 304. Instead, the
capabilities of the virtual desktop server 302 are reduced.
[0098] In an optimized mode the WebRTC redirection framework may
support audio, video, and data communications. In the partial
fallback mode the framework may only provide audio and video if the
server-side CPU utilization on a multi-user server does not exceed
a certain value. If the certain value is exceeded, then video
support is automatically turned off under high CPU load to avoid
quality problems. Similar fallback restrictions can be implemented
by monitoring media quality for fallback sessions, and disabling
some functionality if quality stays or falls below a defined
threshold.
[0099] In other words, if the client computing device 304 has
limited capabilities and the API code redirection module 306
determines that the virtual desktop sever 302 also has limited
capabilities, then the API code redirection module 306 does not
switch to the fallback mode for at least a part of the portion of
the real-time media application 310, and the at least part of the
portion of the real-time media application 310 is not executed by
neither the client RTC API engine 308 nor the native RTC engine
316.
[0100] For example, the at least part of the portion of the
real-time media application 310 that is not executed by neither the
client RTC API engine 308 nor the native RTC engine 316 may
correspond to video, while the remaining part of the portion of the
real-time media application 310 is executed by either the client
RTC API engine 308 or the native RTC engine 316 in fallback mode
and may correspond to at least one of audio and data
communications.
[0101] As another example, the API code redirection module 306 may
determine that the virtual desktop sever 302 also has limited
capabilities based on at least one of client computing device 304
policies, virtual desktop sever 302 policies, virtual desktop sever
302 CPU load, and media quality.
[0102] In this case, if the client computing device 304 has limited
capabilities and the API code redirection module 306 determines
that the virtual desktop sever 302 also has limited capabilities,
then the API code redirection module 306 does not switch to the
fallback mode for at least a part of the portion of the real-time
media application 310. The at least part of the portion of the
real-time media application 310 is not executed by neither the
client RTC API engine 308 nor the native RTC engine 316.
[0103] The at least part of the portion of the real-time media
application 310 that is not executed by neither the client RTC API
engine 308 nor the native RTC engine 316 corresponds to video, and
the remaining part of the portion of the real-time media
application 310 is executed by either the client RTC API engine 308
or the native RTC engine 316 in fallback mode and corresponds to at
least one of audio and data communications.
[0104] The API code redirection module 306 determines that the
virtual desktop sever 302 also has limited capabilities based on at
least one of client computing device policies, virtual desktop
sever policies, virtual desktop sever CPU load, and media
quality.
[0105] In the mapping of session connect/disconnect events to
device availability events, WebRTC includes a subset of APIs
(NavigatorUserMedia, getUserMedia) enabling applications to
enumerate local media devices, request access to a local media
device (such as a microphone or a camera), and use it for a
real-time media session. Under WebRTC redirection, the
corresponding APIs will respectively enumerate, obtain access to,
and request usage of, devices physically attached to the client
computer.
[0106] To handle fallback scenarios, upon session disconnection,
injected code will update internal data structures and generate
events indicating to the application that all devices have been
physically disconnected. Upon session reconnection and after
successful capability negotiation, this code will indicate to the
real-time media application 310 that new devices are now
available.
[0107] Upon fallback, injected code will defer to the built-in
WebRTC engine 316 to enumerate local devices, which may in turn
invoke other virtual channel functionality to enumerate client
devices and perform non-optimized redirection. For example, this
may be via generic audio redirection or graphics remoting virtual
channels. With this approach, the application designed properly to
handle local media device availability will not require any special
logic to process session connect/disconnect and fallback
events.
[0108] In one aspect, the virtual desktop server 302 enumerates
devices physically connected to the client computing device 304
when the client computing device 304 is connected to the virtual
desktop server 302. When the client computing device 304 is
disconnected from the virtual desktop server 302, then the injected
code 314 generates events indicating to the real-time media
application 310 that all devices have been physically
disconnected.
[0109] Upon reconnection of the client computing device 304 to the
virtual desktop server 302, the injected code 314 indicates to the
real-time media application 310 that new devices are now available.
Upon fallback, the injected code 314 defers to the native RTC
engine 316 to enumerate the devices physically connected to the
client computing device 304.
[0110] Another aspect of providing fallback functionality to use
less optimized mechanisms for handling real time media when full
optimization is not available is directed to a method for operating
a computing system 300 comprising a virtual desktop server 302 and
a client computing device 304 that includes a client RTC API engine
308. The virtual desktop server 302 includes an application
framework 312 and an API code redirection module 306. The
application framework 312 includes a real-time media application
310 and a native RTC engine 316.
[0111] The method includes providing real-time communications (RTC)
based on operation of the real-time media application 310, with a
portion of the real-time media application to be executed by the
native RTC engine when received by the native RTC engine, and
redirecting by the API code redirection module 306 original APIs of
the real-time media application 310 intended for the native RTC
engine 316 based on redirection code 314 injected into the
real-time media application 310 so that the portion of the
real-time media application 310 is to be redirected.
[0112] The method further includes reporting by the client RTC API
engine 308 to the API code redirection module 306 through a virtual
channel 318 on capabilities of the client computing device 304 to
execute the redirected portion of the real-time media application
310. The API code redirection module 306 is operated to switch to a
fallback mode if the client computing device 304 has limited
capabilities, where in the fallback mode at least part of the
original APIs are used so that the native RTC engine 316 executes
at least part of the portion of the real-time media application
310.
[0113] Yet another aspect is directed to a non-transitory computer
readable medium for operating a virtual desktop server 302 within a
computing system 300 as described above. The non-transitory
computer readable medium has a plurality of computer executable
instructions for causing the virtual desktop server 302 to provide
real-time communications (RTC) based on operation of the real-time
media application 310, with a portion of the real-time media
application 310 to be executed by the native RTC engine 316 when
received by the native RTC engine 316. The instructions further
cause the virtual desktop server 302 to redirect by the API code
redirection module 306 intercepted APIs of the real-time media
application 310 intended for the native RTC engine 316 based on
redirection code 314 so that the portion of the real-time media
application 310 is to be redirected. The API code redirection
module 306 receives from the client RTC API engine 308 through a
virtual channel 318 capabilities of the client computing device to
execute the redirected portion of the real-time media application
310. The API code redirection module 306 is operated to switch to a
fallback mode if the client computing device 304 has limited
capabilities, where in the fallback mode at least part of the
original APIs are used so that the native RTC engine 316 executes
at least part of the portion of the real-time media application
310.
[0114] Still referring to FIG. 3, the illustrated computing system
300 will be now discussed in terms of WebRTC redirection with
window monitoring/overlay detection. As will be discussed in detail
below, geometry tracking is used to seamlessly provide redirection
of WebRTC functionality. Applications using WebRTC typically render
received video streams by connecting a MediaStream object to an
HTML5 video element. Visibility and geometry of this element is
usually managed by the application directly or using CSS style
information.
[0115] Applications often create and position other UI elements
(e.g., labels or control buttons) so that they visually overlap
with the video, and may use transparency to blend rendered video
with application UI content. The UI elements may be referred to as
non-accelerated graphics, and the video may be referred to as
accelerated graphics. An application, such as the real-time media
application 310, may have more than one active video element
rendering real-time video at the same time (e.g., one or more
remote video feeds from video conference participants and a
self-view from a local camera 330).
[0116] To achieve seamless redirection of WebRTC functionality, the
application virtualization framework on the virtual desktop server
302 needs to identify and keep track of visibility and geometry of
several video elements, as well as any other elements that overlay
live video. When this information is available, WebRTC redirection
code on the client computing device 304 will use it to create,
position and clip local video rendering windows, and possibly
render opaque or transparent overlays on top of these windows to
represent corresponding application UI elements.
[0117] Geometry tracking for HTML5 video elements may be via color
or pattern detection. Positioning and rendering of video and other
UI elements in WebRTC applications is handled by the HTML rendering
engine embedded in the browser or application framework, and is
typically not readily available through an API or other means of
introspection outside of the HTML renderer.
[0118] One possible way to overcome this limitation and identify
multiple HTML5 video areas and track their geometry includes the
following steps. One step is to use injected code 314 to assign
each video element a unique ID at the point when the real-time
media application 310 makes an API call to connect a redirected
Media Stream with a particular video element. Also, the injected
code 314 causes each video area to be painted with a color or a
pattern derived from the video element ID. For example, this may
include encoding bits of the element ID in bits of video area color
for uniform painting, or in colors of adjacent pixels for pattern
painting.
[0119] Another possibility is to paint the video area using a 1-D
or 2-D bar code encoding the video element ID. In the graphics
capture and remoting code (part of the application virtualization
code), video overlay areas are detected by color, pattern, or bar
code using any of the available techniques for pixel color or area
pattern matching or bar code scanning.
[0120] Detected areas may be non-rectangular or may be partially
clipped. To achieve correct geometry tracking, it will be necessary
to combine the information retrieved from injected code (video
element ID and size in pixels) with results of colored or patterned
area detection to determine the size and clipping geometry of each
individual video element. To improve performance, results of video
area detection can be cached and only partially recalculated for
subsequent frames.
[0121] The illustrated computing system 300 includes at least one
video source 330 to provide at least one video stream, the virtual
desktop server 302 and the at least one client computing device 304
as discussed above. The virtual desktop server 302 includes the
application framework 312 that includes the real-time media
application 310 to provide real-time communications (RTC), and the
native RTC engine 316 to execute a portion of the real-time media
application 310 when received by the native RTC engine 316.
[0122] The API code redirection module 306 redirects intercepted
APIs of the real-time media application 310 intended for the native
RTC engine 316 based on redirection code 314 injected into the
real-time media application 310 so that the portion of the
real-time media application 310 is redirected. In particular, the
injected redirection code 314 defines at least one placeholder to
indicate positioning geometry of the at least one video stream
within an RTC window. A geometry tracking module 332 detects the at
least one placeholder within the injected redirection code 314, and
provides the positioning geometry associated therewith.
[0123] The client computing device 304 includes a display 334 to
display the RTC window. The client RTC API engine 308 communicates
with the API code redirection module 306 through the virtual
channel 318 to execute the redirected portion of the real-time
media application 310. This virtual channel 318 provides
accelerated graphics.
[0124] In particular, the client computing device 304 further
includes a display composition module 336 to receive the at least
one video stream and the positioning geometry of the at least one
placeholder, and to overlay the at least one video stream over the
at least one placeholder within the displayed RTC window based on
the positioning geometry.
[0125] The positioning data from the geometry tracking module 332
may be provided to the display composition module 336 over two
different paths. In a first path, the geometry tracking module 332
provides the positioning geometry to the API code redirection
module 306 so as to be included in the redirected portion of the
real-time media application 310 to the client RTC API engine 308.
The client RTC API engine 308 then provides the positioning data to
the display composition module 336. In a second path, the geometry
tracking module 332 provides the positioning geometry directly to
the display composition module 336 over a different virtual channel
319. This virtual channel 319 is for non-accelerated graphics.
[0126] The RTC window as provided by the display 334 is a
composited display that includes non-accelerated graphics and
accelerated graphics. Non-accelerated graphics include UI elements,
labels and control buttons, for example. Accelerated graphics in
the illustrated embodiment is defined by the video stream provided
by the local webcam feed 330. The display composition module 336
may receive additional video streams, such as from another end
point device, such as client computing device 305.
[0127] The injected redirection code 314 generates the
non-accelerated graphics but does not generate the accelerated
graphics. This means that the geometry tracking module 332 analyzes
the non-accelerated graphics for the at least one placeholder. The
virtual desktop server 302 also includes a non-accelerated graphics
producer 340 that provides non-accelerated graphics over the
virtual channel 319 to a non-accelerated graphics module 342 in the
client computing device 304.
[0128] Referring now to FIGS. 4-7, an example window
monitoring/overlay detection scenario will be discussed. In this
scenario, there are two video stream sources. One video stream
source is from the local webcam feed 330 on the first client
computing device 304, and the other video stream source is from a
second client computing device 305 in peer-to-peer communications
with the first client computing device 304.
[0129] When the APIs are intercepted, the two video stream sources
are enumerated by the virtual desktop server 302. When a call is
started, the client computing device 304 reports to the real-time
media application 310 that there is a first video stream from the
local webcam feed 330. Similarly, the second client computing
device 305 reports to the real-time media application 310 via the
real-time media application server 320 that it has a camera
providing the second video stream.
[0130] The real-time media application 310 gets notification that
the two video streams have arrived, as reflected by events detected
within the intercepted APIs. Since the real-time media application
310 does not receive the actual video streams, it creates a
placeholder for each event. Each placeholder is drawn where the
corresponding video stream is to be placed when displayed on the
client computing device 304.
[0131] Referring now to FIGS. 4-7, various displays illustrating an
example window monitoring/overlay detection scenario with the
architecture illustrated in FIG. 3 will be discussed. As shown in
window 400, the injected redirection code 314 in the virtual
desktop server 302 renders a green rectangle 402 on where the peer
video from the second client computing device 305 is to be placed
and a red rectangle 404 on where the picture-in-picture preview
video from the local webcam feed 330 is to be placed.
[0132] The injected redirection code 314 draws with different
colors, with each color assigned to a respective video stream. An
ID may also be associated with each color to identify the
respective video streams. The controls 406 overlaid on the window
400 are rendered normally.
[0133] Since the window 400 is part of a WebRTC application
framework, the real-time media application 310 needs to know where
the video streams are to be rendered. The geometry tracking module
332 advantageously detects the different placeholders within the
injected redirection code 314, and provides the positioning
geometry associated with each placeholder to the display
composition module 336. The positioning geometry provides x-y
coordinates on where the video streams are to be placed, along with
resolution.
[0134] The geometry tracking module 332 detects the different
placeholders based on color, such as green and red, for example. In
other embodiments, the different placeholders may be detected with
patterns or bar codes. In addition, the different colors, patterns
and bar codes may each have an ID associated therewith that
corresponds to a respective video stream. In addition, the
placeholder colors may change after being detected by the geometry
tracking module to a more neutral color that blends in with the
windows that are presented on the client computing device 304.
[0135] The window 400 is sent to the client computing device 304.
The display composition module 336 within the client computing
device 304 renders the video stream 412 from the second client
computing device 305 based on the specified position geometry
associated therewith, as shown in window 410 in FIG. 5. The
rendered video stream 412 includes a cutout 414 for the controls
406 and a cutout 416 for the video stream from the local webcam
feed 330.
[0136] The display composition module 336 within the client
computing device 304 also renders the video stream 422 from the
local webcam feed 330 based on the specified position geometry
associated therewith, as shown in window 420 in FIG. 6. The
rendered video stream 422 does not need any cutouts as with
rendered video stream 412.
[0137] After compositing by the display composition module 336, the
video streams appear in the correct location with the correct
shape. The window 410 in FIG. 7 includes the video stream 412 from
the second client computing device 305 positioned over the green
placeholder 402, the video stream 422 from the local webcam feed
330 positioned over the red placeholder 404, and the controls 406
as provided by the virtual desktop server 302.
[0138] The virtual desktop along with the hosted real-time media
application's non-accelerated content 406 (controls), and other
hosted application windows, are drawn on the display 334 of the
client computing device 304 using graphics sent by the virtual
desktop server 302. The screen areas behind the accelerated
content, such as the green rectangle 402 and the red rectangles 404
in this example, are also rendered on the display 334 of the client
computing device 304 but they are not visible to the user because
they are overlaid by the accelerated locally rendered content of
the peer video 412 from the second client computing deice 305 and
the picture-in-picture preview video 422 from the local webcam feed
330, respectively.
[0139] Referring now to windows 410 and 420 in FIG. 8, the
underlying server-side window 400 has been moved to a different
position. The injected redirection code 314 in the virtual desktop
server 302 renders the placeholders in a new location. In
particular, the green rectangle 402 is rendered where the peer
video from the second client computing device 305 is to be placed,
and the red rectangle 404 is rendered where the picture-in-picture
preview video from the local webcam feed 330 is to be placed. The
non-accelerated graphics, for example controls 406, are rendered
normally in a new location by the non-accelerated graphics producer
340.
[0140] As a result of the video, the geometry and the
non-accelerated graphics being updated asynchronously, whichever is
received first is updated before the other. As a result, the video
overlays 412, 422 may seem disconnected from the underling
placeholders. This may be viewed as a temporary artifact.
[0141] In this example, positioning and the non-accelerated
graphics of the server-side window 400 are updated first. The
client computing device 304 then receives the updated positioning
geometry of the placeholders from the virtual desktop server 302,
and then renders the respective video streams 412, 422 with the
updated positioning geometry. After compositing, the windows 410
and 420 are in the new location as illustrated in FIG. 9.
[0142] Referring now to window 410 in FIG. 10, an overlapping
application 430 is rendered by the virtual desktop server 302 over
window 400 which in turn clips video stream 412 on the client
computing device 304. Though the position of the video stream 412
will not change, the shape of the video stream 412 will.
Consequently, the geometry tracking module 332 in the virtual
desktop server 302 provides positioning geometry updates to the
display composition module 336 in the client computing device
304.
[0143] Since the video streams 412 and 422, the geometry and the
non-accelerated graphics 406 are updated asynchronously, the
geometry may be altered to accommodate the overlay window 430 early
or late. In this example, the video streams 412 and 422, and the
non-accelerated graphics 406 are updated first, and the bottom part
of the application is not visible until the geometry update is
processed by the client computing device 304.
[0144] The client computing device 304 receives the updated
positioning geometry of the placeholders from the virtual desktop
server 302, and then renders the respective video streams 412, 422
with the updated positioning geometry while window 430 appears
unobstructed. After compositing, the video stream 412 appears in
the same location but with the correct shape, revealing the
non-accelerated graphics of the overlay window 430, as illustrated
in FIG. 11.
[0145] Another aspect of WebRTC redirection with window
monitoring/overlay detection is directed to a method for operating
a computing system 300 comprising at least one video source 330, a
virtual desktop server 302 and a client computing device 304
comprising a client RTC API engine 308, a display 334 and a display
composition module 336. The virtual desktop server 302 comprises a
geometry tracking module 332, an application framework 312 and an
API code redirection module 306. The application framework 312
includes a real-time media application 310 and a native RTC engine
316.
[0146] The method includes providing at least one video stream 412
from the at least one video source 330, and providing real-time
communications (RTC) based on operation of the real-time media
application 310, with a portion of the real-time media application
310 to be executed by the native RTC engine 316 when received by
the native RTC engine 316.
[0147] The method further includes redirecting by the API code
redirection module 306 intercepted APIs of the real-time media
application 310 intended for the native RTC engine based on
redirection code 314 injected into the real-time media application
310 so that the portion of the real-time media application 310 is
redirected. The injected redirection code 314 defines at least one
placeholder 402 to indicate positioning geometry of the at least
one video stream 412 within an RTC window 410.
[0148] The geometry tracking module 332 is operated to detect the
at least one placeholder 402 within the injected redirection code
314, and to provide the positioning geometry associated therewith.
The RTC window is displayed on the display 334. The client RTC API
engine 308 is operated to communicate with the API code redirection
module 306 through a virtual channel 318 to execute the redirected
portion of the real-time media application 310.
[0149] The display composition module 336 is operated to receive
the at least one video stream 412 and the positioning geometry of
the at least one placeholder 402, and to overlay the at least one
video stream 412 over the at least one placeholder 402 within the
displayed RTC window 410 based on the positioning geometry.
[0150] Yet another aspect is directed to a non-transitory computer
readable medium for operating a virtual desktop server 302 within a
computing system 300 as described above. The non-transitory
computer readable medium has a plurality of computer executable
instructions for causing the virtual desktop server 302 to provide
real-time communications (RTC) based on operation of the real-time
media application 310, with a portion of the real-time media
application 310 to be executed by the native RTC engine 316 when
received by the native RTC engine 316.
[0151] The steps further include redirecting by the API code
redirection module 306 intercepted APIs of the real-time media
application 310 intended for the native RTC engine 316 based on
redirection code 314 injected into the real-time media application
310 so that the client RTC API engine 308 communicates with the API
code redirection module 306 through a virtual channel 318 and
executes the redirected portion of the real-time media application
310. The injected redirection code 314 defines at least one
placeholder 402 to indicate positioning geometry of the at least
one video stream 412 within an RTC window 410.
[0152] The geometry tracking module 332 is operated to detect the
at least one placeholder 402 within the injected redirection code
314, and to provide the positioning geometry associated therewith
so that the client computing device 304 operates the client RTC API
engine 308 to communicate with the API code redirection module 306
through a virtual channel 318 to execute the redirected portion of
the real-time media application 310. The display composition module
336 is operated to receive the at least one video stream 412 and
the positioning geometry of the at least one placeholder 402, and
to overlay the at least one video stream 412 over the at least one
placeholder 402 within the displayed RTC window 410 based on the
positioning geometry.
[0153] Geometry tracking includes detection and repainting of
semi-transparent overlays. The technique described above can work
for applications that use arbitrary opaque UT overlays on top of
video elements. To address semi-transparent overlays, the same
approach can be extended as follows.
[0154] Painting of video areas by injected code can be designed in
a way that would allow robust pattern detection even after color
transformation due to semi-transparent overlays. For example,
element ID can be encoded using pixels with highly distinct colors,
while detection code could be designed to accept much smaller or
shifted differences in pixel colors (due to color blending).
Predefined image patterns and information redundancy techniques
such as various checksums used in bar codes can be used to improve
detectability of video areas.
[0155] Further, painting of video areas can be designed to vary
over time, using two or more different colors for each pixel.
[0156] Detection code can be extended to derive information about
semi-transparent overlay from captured screen pixels. To do this,
detection code would compare expected pixel colors with actual
captured pixels. For the simplest implementation with two
alternating colors, and assuming a linear blending model at two
instances in time:
(pixel color at time 1)=(1-alpha)*(underlay color at time
1)alpha*(overlay color) 1)
(pixel color at time 2)=(1-alpha)*(underlay color at time
2)+alpha*(overlay color) 2) [0157] Both alpha and overlay color can
be recovered with acceptable loss of precision:
[0157] alpha=1-(pixel color at time 2-pixel color at time
1)/(underlay color at time 2-underlay color at time 1)
overlay color=(pixel color-(1-alpha)*underlay color)/alpha
[0158] FIG. 13 is an illustrative table diagram 500 for the method
of detecting semi-transparent overlays described above. The input
column 510 specifies different combinations of overlay colors
described in terms of red (R), green (G) and blue (B) pixel color
values and opacity, or alpha value. The blended column 520
specifies two different colors, a black blend 522 and a white blend
524 in this example, that can be used by the injected code at two
different times, e.g., time 1 and time 2, as discussed above.
[0159] The captured/recovered column 530 specifies the respective
computed, values for the alpha and pixel colors, which are
recovered by the graphics capture and remoting code. For example,
when alpha value is zero (0), the overlay is completely invisible.
In this particular case the overlay colors cannot be detected due
to divide-by-zero error, as illustrated by zeroes in the detected
color pixels. However, this is not even necessary because with
opacity of zero (0), the overlay is not visible anyway. In another
example, and at the other extreme case of alpha value of one (1),
the overlay completely obscures the blending colors.
[0160] FIG. 14 is a sample color bars image 540 used in a test run
of the method of detecting semi-transparent overlays described
above.
[0161] FIG. 15 is an illustrative image comparison diagram for a
test run of the method of detecting semi-transparent overlays
described above. In particular, FIG. 15 provides a visual
illustration of a test run of the method described above on the
sample image of FIG. 14 containing color bars with different colors
and opacities.
[0162] The image on the top left 550 is the original (before)
image, while the image on the top right 552 is the computed or
detected (after) image. There is no perceptible difference between
the two images. However, at extreme values of opacity, for example,
when the alpha value is close to zero (0) or close to one (1), due
to pixel color value rounding inaccuracies, the before and after
images may start to differ slightly. This is illustrated in the
bottom image 554, which renders a grayscale version of the detected
color bar image. For strictly illustrative purposes the following
is provided.
[0163] Pixels that have the same color values in both of the
original (before) image and the detected (after) image are rendered
in a grayscale representation of that shared color value.
[0164] Pixels that have differing color values in the original
(before) image and the detected (after) image, where the difference
is below a preset threshold, are rendered in a blue-scale
representation of the detected color value.
[0165] Pixels that have differing color values in the original
(before) image and the detected (after) image, where the difference
is above a preset threshold, are rendered in a red-scale
representation of the detected color value.
[0166] In this example, the threshold has been defined as 5 unit's
difference out of 255 unit's total, or approximately 2 percent
difference.
[0167] FIG. 16 is an illustrative image 560 of a step in the method
of detecting semi-transparent overlays described above. In
particular, FIG. 16 illustrates the image 560 observed by the
detection code at time one (1) after applying a black blend in
combination with the color bars image of FIG. 14.
[0168] FIG. 17 is another illustrative image 570 of another step in
the method of detecting semi-transparent overlays described above.
In particular, FIG. 17 illustrates the image 570 observed by the
detection code at time two (2) after applying a white blend in
combination with the color bars image of FIG. 14. More alternating
colors may be used to improve accuracy and address corner
cases.
[0169] As will be discussed in further detail below in reference to
FIG. 18, accuracy of this process can be improved by providing a
feedback channel from the detection code to the injected code.
Using this feedback channel, detection code would be able to
request video area painting using specific, or adaptive, colors or
patterns, to improve robustness and accuracy of detection
process.
[0170] Spatial filtering techniques can be used to improve this
process as well. For example, it is likely that the same alpha
value will be used for large adjacent areas of semi-transparent
overlays. Taking this into account, a filter can be used to average
recovered per-pixel alpha values and accept the more accurate
filtered value for further calculations.
[0171] Information about semi-transparent overlays, including alpha
and pixel color values, can be transmitted from the server 302' to
the client 304' and rendered on top of client-local video,
resulting in an accurate reproduction of application UI.
[0172] In the instrumentation of the server-side HTML rendering
engine, the two techniques above make it possible to detect video
area geometry without instrumenting the HTML rendering engine.
Direct instrumentation of the rendering engine provides another way
of achieving the same purpose. For this technique, the HTML
rendering engine in the browser or application framework 312' can
be hooked or partially replaced so that information about video
element positioning and overlays can be retrieved directly.
[0173] As yet another approach, a customized Chromium-based browser
engine can be used to instrument the HTML rendering. For example,
as part of the Citrix Secure Browser Cloud Service.
[0174] As discussed above, the architecture 300 illustrated in FIG.
3 supports detection and repainting of semi-transparent overlays
406 as directed to webRTC API redirection. In other embodiments,
the architecture 300 may be modified to support any accelerated
graphics media that includes a semi-transparent overlay 406. Such
an architecture 300' is provided in FIG. 18.
[0175] In the illustrated architecture 300', the application
framework 312' now includes a media application 311' instead of the
real-time media application 310, an accelerated content redirection
module 315' instead of the injected redirection code module 314 and
the native RTC engine 316, and a host-side virtual channel
redirection module 307' instead of the RTC API code redirection
module 306. On the client computing device 304' the RTC API engine
308 is replaced with a client-side virtual channel redirection
module 309' that communicates with the host-side virtual channel
redirection module 307'.
[0176] The accelerated content redirection module 315' redirects
the portion of the media streaming based on at least one of the
following: DirectShow filter, DirectX Media Object (DMO) filter,
Media Foundation filter, HTML5 video redirection module, Flash
video redirection module, Browser Helper Object (BHO), and browser
extension. DirectShow filter, DirectX Media Object (DMO) filter,
and Media Foundation filter are used by Citrix RAVE (Remoting Audio
and Video Extensions) technology. HTML5 video redirection module is
used by Citrix HTML5 video redirection technology. Flash video
redirection module is used by Citrix Flash video redirection
technology.
[0177] For the media application 311' to play a file, various
factors are taken into account, such as source of the file, file
format, and media format inside the file. Based on these factors,
one or more filters may be registered. The filters include source
filters, transform filters, and rendering filters that allow the
decompression and rendering of the file to be redirected to the
client computing device 304'.
[0178] The host-side filters proxy the still compressed video and
audio data from the virtual desktop server 302' to the client
computing device 304'. At the client computing device 304', one or
more client-side native filters are loaded to decompress the video
and audio data, render the video and play the audio. Control
information which includes window positioning information and
additional stream control information is also provided by the one
or more host-side filters.
[0179] Still referring to FIG. 18 and architecture 300', the
accelerated content redirection module 315' generates the
non-accelerated graphics but does not generate the accelerated
graphics. This means that the geometry tracking module 332'
analyzes the non-accelerated graphics for the at least one
placeholder. The virtual desktop server 302' also includes a
non-accelerated graphics producer 340' that provides
non-accelerated graphics over the virtual channel 319' to a
non-accelerated graphics module 342' in the client computing device
304'.
[0180] The architecture 300' includes at least one video source
305' to provide at least one video stream 313'. The video source
305' may be referred to as an accelerated content media source. The
virtual desktop server 302' includes the application framework 312'
that includes the media application 311 to provide media streaming.
The media stream includes the at least one video stream 313' with
at least one overlay 406 to be positioned on the at least one video
stream 313'. The accelerated content redirection module 315' is to
redirect a portion of the media streaming by providing a
placeholder 402 to indicate positioning geometry of the at least
one video stream 313' within a media window 334'. The placeholder
402 is to include the overlay 406.
[0181] Providing the placeholder 402 includes providing a first
color 522 for an underlay of the placeholder 402 at a first time,
and providing a second color 524 for the underlay of the
placeholder 402 at a second time.
[0182] The geometry tracking module 332' is to detect the
placeholder 402 and determine positioning geometry associated
therewith, and determine a color and an alpha blending factor of
the overlay 406 based on calculations involving the first color 522
for the underlay of the placeholder 402 at the first time, and the
second color 524 for the underlay of the placeholder 402 at the
second time. The calculations are as described above using
equations one (1) and two (2).
[0183] The determined color and the alpha blending factor of the
overlay 406 are illustratively provided in the captured/recovered
column 530 in FIG. 13. Comp. A is the alpha blending factor. Each
of the red (R), green (G) and blue (B) pixel color values are
represented by Comp. R, Comp. G, and Comp. B.
[0184] The client computing device 304' includes a display to
display the media window 334'. The virtual channel redirection
module 309' on the client side communicates with the accelerated
content redirection module 315' through a virtual channel 318' to
execute the redirected portion of the media application.
[0185] The display composition module 336' is to receive the video
stream 313', the positioning geometry of the placeholder 402, and
the color and the alpha blending factor for each pixel of the
overlay 406 so as to overlay the video stream 313' over the
placeholder 402 within the displayed window 334' based on the
positioning geometry, and to overlay the overlay 406 in the color
and alpha blending factor associated therewith.
[0186] As discussed above in one example, the API code redirection
module 306 in the virtual desktop server 302 rendered a green
rectangle 402 (as a placeholder) on where the peer video from the
second client computing device 305 is to be placed. Similarly, in
the context of the architecture 300' illustrated in FIG. 18, the
host-side redirection module 307' in the virtual desktop server
302' may render a green rectangle 402 (as a placeholder) on where
the peer video from the second client computing device 305' is to
be placed. Since the overlay 406 positioned over the green
rectangle 402 had an opacity of zero (0), there was no need to
determine an alpha blending factor and a color of the overlay.
[0187] For a semi-transparent overlay 406 two (2) or more blended
colors will be generated instead of a single color. Each pixel
color value in the placeholder 402 (which includes the overlay
color) is determined by the geometry tracking module 332'.
[0188] For the architecture 300' illustrated in FIG. 18, the
accelerated content redirection module 315' generates the
placeholder 402 with an underlay color 522 at time one (1), and
then generates the placeholder 402 with an underlay color 524 at
time two (2). The accelerated content redirection module 315' tells
the geometry tracking module 332' the underlay colors used at time
one (1) and two (2). The geometry tracking module 332' uses
Equations (1) and (2) as discussed above to calculate the alpha
blending factor and the color for each pixel of the overlay 406.
Since there are two equations and two unknowns, the two unknowns
(i.e., alpha blending factor and overlay color) may be
determined.
[0189] In some cases, the black and white underlay colors may be
too close to the colors of the overlay 406. To improve color
contrast between the underlay colors and the overlay color, the
geometry tracking module 332' provides feedback to the accelerated
content redirection module 315' to vary the first and second
underlay colors. For example, yellow and green may be used to
provide a better color contrast instead of black and white.
[0190] The displayed media window 334' includes a composited
display of non-accelerated graphics and accelerated graphics, with
the accelerated graphics defined by the video stream 313'. The
redirected portion of the media streaming only generates the
non-accelerated graphics, and the geometry tracking module 332'
analyzes the non-accelerated graphics for the placeholder 402 and
the overlay 406.
[0191] The video source may be a camera 330 coupled to the client
computing device 304 as illustrated in FIG. 3. Alternatively or in
addition to, the video source may be a camera coupled to a
different client computing device 305' in peer-to-peer
communications with the client computing device 304'.
[0192] The video source is an accelerated content media source. The
accelerated content media source is at least one of the following:
video streaming website, video Content Delivery Network (CDN),
video file share, DVD.
[0193] The video source may include a shared display surface
coupled to a different client computing device 305' in peer-to-peer
communications with the client computing device 304'. This covers
screen sharing where a shared display surface may be overlaid with
a semi-transparent overlay 406.
[0194] Another aspect of detection and repainting of
semi-transparent overlays 406 is directed to a method for operating
a computing system 300 comprising at least one video source 305',
and a virtual desktop server 302', with the virtual desktop server
302' comprising a geometry tracking module 332', an application
framework 312' and an accelerated content redirection module 315'.
The application framework 312' includes a media application 311'.
The method includes providing at least one video stream 313' from
the at least one video source 305', and providing media streaming
based on operation of the media application, with the media
streaming including the at least one video stream 313' and at least
one overlay 406 on the at least one video stream 313'.
[0195] A portion of the media streaming is redirected by providing
a placeholder 402 to indicate positioning geometry of the at least
one video stream 313' within a media window 334', with the
placeholder 402 to include the at least one overlay 406.
[0196] Providing the placeholder 402 includes providing a first
color 522 for an underlay of the placeholder 402 at a first time,
and providing a second color 524 for the underlay of the
placeholder 402 at a second time.
[0197] The method further includes operating the geometry tracking
module 332' to detect the placeholder 402 and determine positioning
geometry associated therewith, and determine a color and an alpha
blending factor of the at least one overlay 406 based on
calculations involving the first color 522 for the underlay of the
placeholder 402 at the first time, and the second color 524 for the
underlay of the placeholder 402 at the second time.
[0198] Yet another aspect is directed to a non-transitory computer
readable medium for operating a virtual desktop server 302' within
a computing system 300' comprising at least one video source 305',
with the virtual desktop server 302' comprising a geometry tracking
module 332', an application framework 312' and an accelerated
content redirection module 315'. The application framework 312'
includes a media application 311'.
[0199] The non-transitory computer readable medium has a plurality
of computer executable instructions for causing the virtual desktop
server 302' to provide media streaming based on operation of the
media application 311', with the media streaming including the at
least one video stream 313' and at least one overlay 406 on the at
least one video stream 313'.
[0200] A portion of the media streaming is redirected by providing
a placeholder 402 to indicate positioning geometry of the at least
one video stream 313' within a media window 334', with the
placeholder 402 to include the at least one overlay 406.
[0201] Providing the placeholder 402 includes providing a first
color 522 for an underlay of the placeholder 402 at a first time,
and providing a second color 524 for the underlay of the
placeholder 402 at a second time.
[0202] The geometry tracking module 332' is operated to detect the
placeholder 402 and determine positioning geometry associated
therewith, and determine a color and an alpha blending factor of
the at least one overlay 406 based on calculations involving the
first color 522 for the underlay of the placeholder 402 at the
first time, and the second color 524 for the underlay of the
placeholder 402 at the second time.
[0203] Referring now to FIGS. 3 and 12, the illustrated computing
system 300 will be discussed in terms screen sharing functionality
to achieve seamless redirection of WebRTC functionality. WebRTC
includes APIs (getDisplayMedia) and other related API elements,
defined in [screen-capture], that allow applications to share the
visual contents of the local browser window, a single window of a
different application, all windows of a specific application, a
single monitor, or a collection of monitors including the whole
desktop.
[0204] Screen sharing under desktop virtualization presents a
particular challenge due to a complexity of how the complete
user-visible desktop is composed from parts running on one or more
virtual desktop servers as well as on the local desktop.
Application or framework code running on any particular physical or
virtual computer may be able to enumerate all sources of shareable
screen content that the user may be interested in, or may not have
access to pixels of a particular window or monitor. WebRTC
redirection framework can be designed to deal with this complexity
while providing optimized user experience for screen sharing.
[0205] Citrix patent application ID1167US, filed on Jan. 26, 2018
as U.S. patent application Ser. No. 15/880,938, "Virtual Computing
System Providing Local Screen Sharing from Hosted Collaboration
Applications and Related Methods" is incorporated by reference
herein in its entirety. The methods discussed in ID1167US fully
apply to WebRTC redirection. The present disclosure offers
additional incremental enhancements discussed below: 1) distributed
enumeration of sharable content sources, and 2) optimizations of
content sharing media and network pipeline.
[0206] In the distributed enumeration of shareable content sources,
elements of WebRTC redirection framework (connector, engine, and
possibly virtual desktop server and client code) can be designed to
enumerate possible sources of content sharing (applications and
their windows, monitors and desktops) in parallel on virtual
desktop servers 302 and client computing devices 304, 305.
Information internal to the desktop virtualization system may be
used to create correct descriptions of these sources (e.g.,
correctly associate windows with corresponding applications).
Inter-component protocols may be used to consolidate this
information into a single list, and present the resulting list to
the user when the application calls getDisplayMedia( ).
[0207] In the optimizations of content sharing media and network
pipelines, when a particular screen sharing source is selected by
the user, WebRTC redirection code can select the optimal location
for capturing the content of that source. For example, if the user
chooses a virtual application window, contents of that window
should be captured on the virtual desktop server 302 because the
window may be obscured on the client computing device 304.
Alternatively, if the whole client desktop is selected for sharing,
pixels of the desktop should be captured on the client computing
device 304, since the graphics have already been delivered to the
client computing device anyway and to avoid additional load on the
virtual desktop server 302.
[0208] A further optimization may combine the screen rendering
pipeline in the virtual desktop client application with the WebRTC
redirection capture pipeline for screen content sharing.
[0209] In addition to choosing the optimal location for capturing
shareable screen content, WebRTC redirection code can select the
optimal location and method for compressing this content using a
suitable video codec, and a network endpoint for transmitting this
content to a remote destination. For example, screen content
captured on the virtual desktop server 302 may be suitably
compressed on the virtual desktop server 302, streamed from there
to the client computing device 304, and transmitted to the network
from the client computing device 304.
[0210] Alternatively, the same screen content may be only mildly
compressed on the virtual desktop server 302, and achieve final
compression on the client computing device 304. Alternatively, the
same screen content may be compressed and transmitted from the
virtual desktop server 302, not involving the client computing
device 304 at all. These choices present different server and
network scalability and network connectivity tradeoffs, and may be
chosen based on policies or other criteria.
[0211] As illustrated in FIG. 12, the computing system 300
advantageously provides for sharing of both local and virtual
client surfaces 331, 335 on the first client computing device 304
with the second client computing device 305. The injected
redirection code 314 is used to enumerate shared surfaces from the
client computing device 304 (local client surface 331) and from the
virtual desktop server 302 (virtual desktop session 355) and
combine them together into a single list. The virtual desktop
server 302 includes a monitor 353 to generate the virtual desktop
session 355.
[0212] One or more elements of the virtual desktop session 355 are
rendered at the first client computing device 304 as a virtual
client surface 335 on a first monitor 333 illustratively including
a virtual session user interface (UI) 337. However, the first
client computing device 304 also generates its own local client
graphics surface 331, here on a second monitor 329. The local
graphics surface 331 may include applications (web browser,
document processing applications, etc.) installed locally at the
client computing device 304.
[0213] It should be noted that both the local and virtual client
surfaces 331, 335 may be displayed on a same monitor in different
embodiments, i.e., they need not be on multiple monitors in all
embodiments. As noted above, with the real-time media application
310 there is currently no way for the user of the first client
computing device 304 to share the local graphics surface 331.
[0214] Yet, once the real-time media application 310 is launched,
the virtual desktop server 302 uses the injected redirection code
314 to enumerate shared surfaces from the client computing device
304 (local client surface 331) and from the virtual desktop server
302 (virtual client surface 335) and combine them together into a
single list that is presented to the user of the first client
computing device 304.
[0215] This is accomplished without the need for virtual web cams
and virtual plug-and-play (PnP) monitors at the virtual desktop
server 302 as is needed in the above referenced Citrix patent
application IDll67US. In the Citrix patent application IDll67US,
the client surfaces are being enumerated in the virtual desktop
server environment. Here, the illustrated computing system 300 is
doing the reverse. The computing system 300 enumerates the client
surfaces (local and/or virtual) and projects them to the first
client computing device 304 so they can be more efficiently sent
peer-to-peer to the second client computing device 305.
[0216] The second client computing device 305 generates a virtual
client shared surface 365 on a first monitor 363. The second client
computing device 305 also generates its own local client graphics
shared surface 361, here on a second monitor 359.
[0217] A single list of enumerated surfaces is provided by the
real-time media application 310. The user of the first client
computing device 304 may click on a button or prompt to share
surfaces (e.g., windows, monitors or desktops) and this triggers
enumeration of those surfaces. Since the getDisplayMedia API
element is intercepted, the enumerated local and virtual client
surfaces 331, 335 can be combined.
[0218] More particularly, the illustrated computing system 300
includes the first client computing device 304 to display a local
client surface 331 and a virtual client surface 335, with the local
client surface 331 and the virtual client surface 335 to be shared
with a second client computing device 305 having peer-to-peer
communications with the first client computing device 304.
[0219] The virtual desktop server 302 communicates with the first
client computing device 304 through a virtual channel 318 to
provide the virtual client surface 335, and includes an application
framework 312 that includes a real-time media application 310 to
provide real-time communications (RTC), and a native RTC engine 316
to execute a portion of the real-time media application 310 when
received by the native RTC engine 316.
[0220] An API code redirection module 306 within the virtual
desktop server 302 redirects intercepted APIs of the real-time
media application 310 intended for the native RTC engine 316 based
on redirection code 314 injected into the real-time media
application 310 so that the portion of the real-time media
application 310 is redirected, with the injected redirection code
314 enumerating the local and virtual client surfaces 331, 335.
[0221] The first client computing device 304 includes a client RTC
API engine 308 communicating with the API code redirection module
306 through the virtual channel 318 to execute the redirected
portion of the real-time media application 310, and to share the
local and virtual client surfaces 331, 335 with the second client
computing device 305 based on the intercepted APIs enumerating the
local and virtual client surfaces 331, 335.
[0222] As noted above, there may be an optimal location for
capturing source content. For example, the virtual client surface
335 may include overlapping windows. If one of the overlapping
windows is selected to be shared with the second client computing
device 305, then pixels of the selected window are obtained from
the virtual desktop server 302. As another example, a whole virtual
desktop session 355 of the virtual desktop server 302 is to be
shared. In this case pixels of the virtual desktop session 355 are
captured on the first client computing device 304 to be delivered
to the second client computing device 305.
[0223] As also noted above, a screen rendering pipeline and an RTC
redirection capture pipeline may be combined. For example, the
virtual desktop session 355 may include at least one window that is
to be shared with the second client computing device 305. Then
pixels of the shared window are to be provided by the virtual
desktop server 302 to the second client computing device 305.
[0224] In terms of compression, the optimal location for
compressing shareable screen content can be selected. For example,
the virtual desktop server 302 may compress the pixels of the at
least one window. If the window is to be shared with the second
client computing device 305, then the compressed pixels of the
shared window are sent to the first client computing device 304 for
sharing with the second client computing device 305.
[0225] Another aspect of WebRTC redirection with screen sharing is
directed to a method for operating a computing system 300
comprising a virtual desktop server 302 and a first client
computing device 304 comprising a client RTC API engine 308, as
discussed above. The method includes operating the first client
computing device 304 to display a local client surface 331 and a
virtual client surface 335, with the local client surface 331 and
the virtual client surface 335 to be shared with a second client
computing device 305 having peer-to-peer communications with the
first client computing device 304.
[0226] The virtual desktop server 302 is operated to communicate
with the first client computing device 304 through a virtual
channel 318 to provide the virtual client surface 335. Real-time
communications (RTC) is provided based on operation of the
real-time media application 310, with a portion of the real-time
media application 310 to be executed by the native RTC engine 316
when received by the native RTC engine 316.
[0227] The API code redirection module 306 redirects intercepted
APIs of the real-time media application 310 intended for the native
RTC engine 316 based on redirection code 314 injected into the
real-time media application 310 so that the portion of the
real-time media application 310 is redirected, with the injected
redirection code 314 enumerating the local and virtual client
surfaces 331, 335.
[0228] The client RTC API engine 308 is operated to communicate
with the API code redirection module 306 through the virtual
channel 318 to execute the redirected portion of the real-time
media application 310. The client RTC API engine 308 is further
operated to share the local and virtual client surfaces 331, 335
with the second client computing device 305 based on the
intercepted APIs enumerating the local and virtual client surfaces
331, 335.
[0229] Yet another aspect is directed to a non-transitory computer
readable medium for operating a virtual desktop server 302 within a
computing system 300 as described above. The non-transitory
computer readable medium has a plurality of computer executable
instructions for causing the virtual desktop server 302 to
communicate with the first client computing device 304 through a
virtual channel 318 to provide the virtual client surface 335, and
provide real-time communications (RTC) based on operation of the
real-time media application 310. A portion of the real-time media
application 310 is to be executed by the native RTC engine 316 when
received by the native RTC engine 316.
[0230] The API code redirection module 306 intercepts APIs of the
real-time media application 310 intended for the native RTC engine
316 based on redirection code 314 injected into the real-time media
application 310 so that the client RTC API engine 308 communicates
with the API code redirection module 306 through a virtual channel
318 to execute t
[0231] The redirected portion of the real-time media application
310. The injected redirection code 314 enumerates the local and
virtual client surfaces 331, 335 so that the first client computing
device 304 shares the local and virtual client surfaces 331, 335
with the second client computing device 305 based on the
intercepted APIs enumerating the local and virtual client surfaces
331, 335.
[0232] In thin client resource management, WebRTC may be active in
more than one browser tab, such as for video rendering, for
example. A browser may decide to suspend video playback in an
inactive tab. Presumably, this will be reflected onto the
MediaStream object connected to the HTML5 video element in the
inactive tab of the hosted app. The real-time media application 310
may be active in a plurality of browser tabs, and the client
computing device 304 suspends video playback in an inactive browser
tab and/or stops rendering in a non-visible area.
[0233] In addition, independent of the actions of the inactive
browser tab of the hosted app, a receiver may decide to
automatically stop the WebRTC rendering in a non-visible area. This
may be done conditionally, e.g., on a thin client device, which may
be resource challenged, or in conditions of limited bandwidth,
which may improve UX in other active tabs and WebRTC channels.
[0234] Security policies will now be discussed. Real time media
support in browser applications involves a very large number of
security and privacy considerations. An incomplete list of examples
of such considerations includes the possibility of breaching users'
privacy by gaining unauthorized access to microphones and video
cameras in users' workspaces or homes; security leaks due to
unauthorized content sharing; and the possibility of undesired
fingerprinting of users or their endpoints through enumeration of
connected devices. For example, the virtual desktop server 302
includes at least one security policy, and execution by the client
RTC API engine 308 of at least part of the redirected portion of
the real-time media application is based on the at least one
security policy. WebRTC redirection needs to address these
concerns, and may also implement a number of additional policy and
monitoring features in the area of security and privacy, including
the following.
[0235] Enabling administrators to define "automatic allow",
"automatic deny", or "ask user" policies for WebRTC redirection in
general and for specific subsets of WebRTC functionality (e.g.,
access to microphones, cameras, speakers, or screen content, as
well as all the same features in the fallback scenario.).
[0236] Allowing user identity, membership in a security group, or
other user attributes, to be used as input to a Web-RTC related
policy.
[0237] Allowing application identity to be used as input to a
WebRTC related policy. For example, the application virtualization
framework may automatically detect a particular SaaS application,
and apply policies specific to that application.
[0238] Allowing endpoint location (physical or network) to be used
as input to a WebRTC related policy. For example, for endpoints in
a secure location the framework may automatically disallow video
and content sharing, allowing only audio sessions.
[0239] Network connectivity steering, ICE extensions and SDP
rewriting will now be discussed. A large portion of WebRTC
functionality lies in enabling peer to peer network connectivity
for real-time media. The following briefly identifies the
technologies used for this:
[0240] WebRTC implements the ICE (Interactive Connectivity
Establishment) procedure to identify all possible connectivity
options between two real time media endpoints.
[0241] As part of ICE procedure, WebRTC collects all connectivity
candidates-local network endpoints (transport/IP address/port
tuples) available for communications.
[0242] WebRTC can work with one or more connectivity servers
(alternatively known as media relay servers, STUN servers, TURN
servers, or ICE servers)-network servers that facilitate
connectivity by allowing endpoints to probe the network for
existence of NAT (using the STUN protocol), and to create media
relay points on the servers and use these ports as alternative
connectivity candidates (using the TURN protocol).
[0243] WebRTC uses the SDP protocol (Session Description Protocol)
to encode and exchange network connectivity details. SDP messages
(session description) contain full descriptions of media sessions,
including information about connectivity candidates.
[0244] Lack of network connectivity or impaired network
connectivity are very typical concerns for desktop virtualization
deployments. To address these, the WebRTC redirection framework can
use the following novel techniques: 1) tunneled server-side
transport fallback, and 2) changing the set of ICE servers.
[0245] In the tunneled server-side transport fallback, ideally,
endpoints should be able to exchange media streams directly over
UDP, and if that is not possible, use TURN servers to relay the
media packets. If neither of these options is available, real-time
connectivity would not be possible.
[0246] WebRTC redirection has components running on the virtual
desktop server and on the client, providing an additional
connectivity option. Namely, it is possible to tunnel the stream of
media packets between the client and the server through a dedicated
or shared virtual channel, and use a port or a set of ports on the
server as the network endpoint. This transport option can be very
useful in many scenarios, for example when neither direct
connectivity nor relay servers are available.
[0247] To implement this option, the WebRTC redirection framework
must a) implement the functionality to open a server-side UDP port
from the connector on demand, and relay media packets between it
and the client-side engine through a virtual channel, b) use the
server-side IP address and port as an additional candidate for the
ICE process. ICE requires this to be repeated for all media streams
where additional connectivity is necessary.
[0248] In changing the set of ICE servers, a WebRTC application
typically receives the set of ICE servers from an application
specific source--e.g., the server-side portion of the application.
The WebRTC redirection framework can extend, change, or replace the
application-defined set of ICE servers with a framework specific
set of one or more servers, to implement various types of traffic
steering functionality.
[0249] For example, a multipurpose gateway or branch appliance
integrated with the desktop virtualization framework may serve as
an additional ICE (media relay) server. The WebRTC redirection
framework may make this server automatically available for media
traffic managed by virtualized WebRTC application. Alternatively,
the WebRTC framework may replace the set of ICE servers that the
application intends to use with a different set. This may be
determined using network connectivity probing, dynamic DNS, or
other similar techniques, to improve media quality by optimal media
stream routing.
[0250] In WebRTC activity and quality monitoring, WebRTC
redirection framework has complete visibility into real-time media
activity and can implement various types of activity and quality
monitoring. For example, real-time media monitoring statistics can
be combined with other resource usage and quality metrics produced
by the desktop virtualization framework, and used to present a more
comprehensive view to systems and applications administrators and
other decision makers.
[0251] In a virtual app/desktop session collaboration, a shared HDX
session use case will be discussed. During HDX virtual session
sharing or collaboration there will be an initiator and any number
of collaborators. The HDX session will always be owned by the
initiator. The initiator invites the collaborators to join or share
the session. All collaborators will have separate protocol stacks
at Receiver.
[0252] At the Virtual Desktop server all collaborators could share
the protocol stack. The management of the collaboration session,
including policies, invitation, authentication, security, input
arbitration, and other core mechanisms related to the shared HDX
session lifetime are outside the scope of this disclosure.
[0253] The server connector code could aggregate devices from all
endpoints. For example, Webcams can be enumerated from the
initiator and all collaborators and presented to the get user media
WebRTC API (NavigatorUserMedia, getUserMedia( )) in the context of
the app. Thereafter, all the info (Webcam names) will be sent to
the initiator and the collaborators so Receivers can implement
accelerated Peer-to-Peer (P2P) overlays. Each client endpoint
should filter out their own Webcam.
[0254] In case any one of the initiator or the collaborators does
not support the accelerated WebRTC functionality, the virtual
desktop server connector code could operate in "dual" mode, i.e.,
remote WebRTC where possible, and fallback to host-side rendering
for purposes of remoting to WebRTC-redirection incapable client
endpoints.
[0255] Upon fallback, injected code will defer to the built-in
WebRTC engine to enumerate local devices, which may in turn invoke
other virtual channel functionality to enumerate client devices and
perform non-optimized redirection, for example via generic Audio
redirection or graphics remoting virtual channels. The support of
non-optimized redirection in shared sessions is VC specific and
outside the scope of this disclosure. An alternative approach would
be to disable WebRTC remoting for all collaborators, but this is
more limiting.
[0256] In the event the initiator or a collaborator disconnects
from the shared session, either on purpose or accidentally, e.g.,
as a result of network disruption, disconnect events will be raised
to the server connector code. This in turn will notify the hosted
app via the WebRTC API that media devices from the disconnected
endpoint are no longer available. Thereafter, the event will be
sent to the other client endpoints (remaining initiator or
collaborators) so receivers can update the list of accelerated
Peer-to-Peer (P2P) overlays.
[0257] Functional background may be provided in the following
references, all of which are assigned to the current assignee of
the present application and which are all incorporated by reference
in their entirety: [0258] Remoting Audio and Video Extensions
(RAVE); Methods and Apparatus for Generating Graphical and Media
Displays at a Client: U.S. Pat. Nos. 8,131,816; 8,671,213; and
9,325,759. [0259] Reverse RAVE (Webcam Redirection); Systems and
Methods for Remotely Presenting a Multimedia Stream: U.S. Pat. Nos.
9,191,425; and 9,203,883. [0260] Flash Redirection; Systems and
methods for remoting multimedia plugin calls: U.S. Pat. No.
8,296,357. [0261] HTML5 Video Redirection; Multimedia redirection
in a virtualized environment using a proxy server: U.S. Pat. Nos.
9,124,668; and 9,571,599. [0262] Browser Content Redirection;
Redirection of Web Content: Provisional-ID1340 (B&W ref
007737.00826); Managing [0263] Browser Session Navigation Between
One or More Browsers: Provisional-ID1368US (B&W ref
007737.00827). [0264] Several patents that cover Citrix HDX
Real-time Optimization Pack component architecture include: U.S.
Pat. Nos. 8,949,316; 8,869,141; 8,799,362; and 8,601,056, sharing
the title "Scalable high-performance interactive real-time media
architectures for virtual desktop environments".
[0265] However, as explained in detail above, the novelty of this
disclosure lies in specific functions and interactions of the
injected code, connector, and engine modules that are designed to
optimize real time media APIs and WebRTC in particular.
[0266] Many modifications and other embodiments will come to the
mind of one skilled in the art having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is understood that the disclosure is not to
be limited to the specific embodiments disclosed, and that
modifications and embodiments are intended to be included within
the scope of this disclosure.
* * * * *