U.S. patent application number 10/335609 was filed with the patent office on 2003-05-15 for virtual connection of a remote unit to a server.
Invention is credited to Anastasi, Mark Nicholas, Dowling, Eric Morgan.
Application Number | 20030093459 10/335609 |
Document ID | / |
Family ID | 22608443 |
Filed Date | 2003-05-15 |
United States Patent
Application |
20030093459 |
Kind Code |
A1 |
Dowling, Eric Morgan ; et
al. |
May 15, 2003 |
Virtual connection of a remote unit to a server
Abstract
A computer system, a communication module and a method are
provided to allow a fast reconnection of a first computer to a
second computer. The invention includes a telephone modem for
coupling to a telephone line. Modem protocol control software
adapts the telephone modem save channel parameters and to thereby
renegotiate a connection speed over a telephone line in less time
than required to perform an initial line rate negotiation.
Inventors: |
Dowling, Eric Morgan; (San
Jose, CA) ; Anastasi, Mark Nicholas; (Bartonville,
TX) |
Correspondence
Address: |
Eric M. Dowling
Interlink 731
PO Box 025635
Miami
FL
33102-5635
US
|
Family ID: |
22608443 |
Appl. No.: |
10/335609 |
Filed: |
January 2, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10335609 |
Jan 2, 2003 |
|
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09167698 |
Oct 7, 1998 |
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Current U.S.
Class: |
709/201 |
Current CPC
Class: |
H04L 69/24 20130101;
H04L 9/40 20220501 |
Class at
Publication: |
709/201 |
International
Class: |
G06F 015/16 |
Claims
What is claimed is:
1. A computerized system comprising: a central processing unit; a
memory; a display monitor; a communication module; wherein the
communication module comprises a telephone modem and a software
module controllably coupled to the telephone modem, wherein the
software module implements at least a communication protocol which
adapts the telephone modem to perform an initial line rate
negotiation and a subsequent line rate renegotiation in a manner
that allows the subsequent line rate renegotiation to complete in
less time than is required for the initial line rate negotiation to
complete, and wherein the software module further comprises: a
first program code that causes a first communication connection
over a wireline telephone communication channel to be initialized
using said telephone modem, said initializing being performed at
least partially by performing the initial line rate negotiation
sequence with a far end modem to determine a set of parameters to
be used to support communications over said wireline telephone
communication channel; a second program code that causes the set of
parameters to be stored in a memory structure; a third program code
that causes communication to proceed at a negotiated data rate via
said first communication connection with said remote entity using
said parameters; a fourth program code that causes the first
communication connection to be terminated; a fifth program code
that causes said parameters to be accessed from said memory
structure and used by said telephone modem in the subsequent line
rate renegotiation to renegotiate a second communication connection
over the wireline telephone communication channel so that data
communication can be resumed on the second communication connection
at a renegotiated data rate.
2. The computerized system of claim 1, wherein the telephone modem
supports aspects of the V.34 modem standard, and the initial line
rate negotiation is performed at least partially in accordance with
the V.34 modem standard.
3. The computerized system of claim 1, wherein the telephone modem
supports aspects of the V.90 modem standard, and the initial line
rate negotiation is performed at least partially in accordance with
the V.90 modem standard.
4. The computerized system of claim 1, wherein the memory structure
is a table structure.
5 The computerized system of claim 1, wherein said parameters
comprise adjustable echo cancellation coefficients that are
adjusted in response to a training signal sent through said
wireline telephone communication channel.
6. The computerized system of claim 1, wherein said parameters
comprise adjustable equalizer coefficients that are adjusted in
response to a training signal sent through said wireline telephone
communication channel.
7. The computerized system of claim 1, wherein said parameters
comprise adjustable signal constellation configuration
parameters.
8. The computerized system of claim 1, wherein a session is
established in conjunction with said first communication
connection, the session is placed in an inactive state
substantially when the first communication connection is
terminated, and said session is placed back into an active state
substantially in conjunction with the initialization of the second
communication connection.
9. The computerized system of claim 1, wherein the second
connection is directed to said far end modem.
10. The computerized system of claim 1, wherein the computerized
system is a server system that further implements a server-side
application layer protocol.
11. The computerized system of claim 1, wherein the computerized
system is a client-side computerized device that further implements
a client-side application layer protocol.
12. The computerized system of claim 1, wherein the software module
further comprises a physical layer software code adapted to
generate a physical layer modem communication signal for
transmission to the far end modem.
13. The computerized system of claim 1, wherein the software module
further comprises a physical layer software code adapted to extract
information from a physical layer modem communication signal
received from the far end modem.
14. The computerized system of claim 1, further comprising: an
interconnection network comprising at least one bus; wherein said
central processing unit, said memory, said display monitor and said
communications module are all coupled to said interconnection
network.
15. The computerized system of claim 1, wherein the software module
further comprises a software code adapted to transfer an
authorization code associated with a session placed into a
suspended state.
16. The computerized system of claim 1, wherein the software module
further comprises a software code adapted to transfer application
data in the first communication connection using a lower speed
modem set-up protocol before the modem line rate has been
negotiated.
17. The computerized system of claim 1, wherein the software module
further comprises a software code adapted to transfer application
data in the second communication connection using a lower speed
modem set-up protocol before the modem line rate has been
renegotiated.
18. The computerized system of claim 1, wherein the software module
further comprises a software code adapted to perform line rate
negotiation in the background in order to allow application data to
be passed by a lower speed modem set-up protocol while the line
rate is being negotiated.
19. The computerized system of claim 1, wherein the software module
further comprises a software code adapted to perform line rate
renegotiation in the background in order to allow application data
to be passed by a lower speed modem set-up protocol while the line
rate is being renegotiated.
20. The computerized system of claim 1, wherein the software module
operates under the control of a protocol stack, and the protocol
stack includes at an upper layer a virtual session software layer,
and the parameters are accessed from the memory structure as a
portion of the reactivation of the virtual session.
21. The computerized system of claim 1, wherein the software module
operates under the control of a protocol stack, and the protocol
stack includes at an upper layer a virtual session software layer,
and the parameters are accessed from a table associated with the
virtual session software layer.
22. A communication module, comprising: a telephone modem including
a connector for coupling to a telephone line; a software module
controllably coupled to said telephone modem; wherein the software
module implements a communications protocol which adapts the
telephone modem to perform an initial line rate negotiation and a
subsequent line rate renegotiation in a manner that allows the
subsequent line rate renegotiation to complete in less time than is
required for the initial line rate negotiation to complete, and
wherein the software module further comprises: a first program code
that causes a first communication connection over a wireline
telephone communication channel to be initialized using said
telephone modem, said initializing being performed at least
partially by performing the line rate negotiation sequence with a
far end modem to determine a set of parameters to be used to
support communications over said wireline telephone communication
channel; a second program code that causes the set of parameters to
be stored in a memory structure; a third program code that causes
communication to proceed at a negotiated data rate via said first
communication connection with said remote entity using said
parameters; a fourth program code that causes the first
communication connection to be terminated; a fifth program code
that causes said parameters to be accessed from said memory
structure and used by said telephone modem in the subsequent line
rate renegotiation to renegotiate a second communication connection
over the wireline telephone communication channel so that data
communication can be resumed on the second communication connection
at a renegotiated data rate.
23. The communication module of claim 22, wherein the telephone
modem supports aspects of the V.34 modem standard, and the initial
line rate negotiation is performed at least partially in accordance
with the V.34 modem standard.
24. The communication module of claim 22, wherein the telephone
modem supports aspects of the V.90 modem standard, and the initial
line rate negotiation is performed at least partially in accordance
with the V.90 modem standard.
25. The communication module of claim 22, wherein the memory
structure is a table structure.
26. The communication module of claim 22, wherein said parameters
comprise adjustable echo cancellation coefficients that are
adjusted in response to a training signal sent through said
wireline telephone communication channel.
27. The communication module of claim 22, wherein said parameters
comprise adjustable equalizer coefficients that are adjusted in
response to a training signal sent through said wireline telephone
communication channel.
28. The communication module of claim 22, wherein said parameters
comprise adjustable signal constellation configuration
parameters.
29. The communication module of claim 22, wherein a session is
established in conjunction with said first communication
connection, the session is placed in an inactive state
substantially when the first communication connection is
terminated, and said session is placed back into an active state
substantially in conjunction with the initialization of the second
communication connection.
30. The communication module of claim 22, wherein the second
connection is directed to said far end modem.
31. The communication module of claim 22, wherein the communication
module is implemented as a portion of a server system that further
implements a server-side application layer protocol.
32. The communication module of claim 22, wherein the communication
module is implemented as a portion of a client-side computerized
device that further implements a client-side application layer
protocol.
33. The communication module of claim 22, wherein the software
module further comprises a software code adapted to generate a
physical layer modem communication signal for transmission to the
far end modem.
34. The communication module of claim 22, wherein the software
module further comprises a software code adapted to extract
information from a physical layer modem communication signal
received from the far end modem.
35. The communication module of claim 22, wherein the software
module further comprises a link layer software code adapted to
transfer an authorization code associated with a session placed
into a suspended state.
36. The communication module of claim 22, wherein the software
module further comprises a link layer software code adapted to
transfer application data in the first communication connection
using a lower speed modem set-up protocol before the modem line
rate has been negotiated.
37. The communication module of claim 22, wherein the software
module further comprises a link layer software code adapted to
transfer application data in the second communication connection
using a lower speed modem set-up protocol before the modem line
rate has been renegotiated.
38. The communication module of claim 22, wherein the software
module further comprises a link layer software code adapted to
perform line rate negotiation in the background in order to allow
application data to be passed by a lower speed modem set-up
protocol while the line rate is being negotiated.
39. The communication module of claim 22, wherein the software
module further comprises a link layer software code adapted to
perform line rate renegotiation in the background in order to allow
application data to be passed by a lower speed modem set-up
protocol while the line rate is being renegotiated.
40. The communication module of claim 22, wherein the software
module operates under the control of a protocol stack, and the
protocol stack includes at an upper layer a virtual session
software layer, and the parameters are accessed from the memory
structure as a portion of the reactivation of the virtual
session.
41. The communication module of claim 22, wherein the software
module operates under the control of a protocol stack, and the
protocol stack includes at an upper layer a virtual session
software layer, and the parameters are accessed from a table
associated with the virtual session software layer.
42. A method of reconnecting a telephone modem with a reduced delay
by reducing a time associated with line rate renegotiation, the
method comprising: initializing a first communication connection
over a wireline telephone communication channel using said
telephone modem, said initializing comprising a line rate
negotiation sequence with a far end modem to derive a set of echo
canceller coefficients, equalizer coefficients, and signal
constellation parameters to be used to configure communications
processing to operate at a negotiated line rate over said wireline
telephone communication channel; storing said echo canceller
coefficients, equalizer coefficients, and signal constellation
parameters in a memory structure; communicating at said negotiated
data rate via said first communication connection with said far end
modem using said echo canceller coefficients, equalizer
coefficients, and signal constellation parameters; terminating the
first communication connection; accessing from said memory
structure said echo canceller coefficients, equalizer coefficients,
and signal constellation parameters and using said echo canceller
coefficients, equalizer coefficients, and signal constellation
parameters to accelerate the renegotiation of a second
communication connection having a renegotiated data rate for use
over the wireline telephone communication channel using said
telephone modem; and communicating at a re-negotiated data rate via
said second communication connection by reusing said echo canceller
coefficients, equalizer coefficients, and signal constellation
parameters; whereby a setup delay time associated with the line
rate negotiation of said first communication connection is longer
than a setup delay time associated with the line rate renegotiation
of said second communication connection.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to client-server computing
architectures and communication techniques. More particularly, the
invention relates to a system whereby a mobile worker and a central
server may maintain a virtually continuous connection without the
need to maintain a physical connection continuously.
[0003] 2. Description of the Related Art
[0004] The concept of a virtual connection has arisen in connection
with telecommuting and related applications. Such a system is
described in U.S. Pat. No. 5,764,639. A telecommuter dials into a
server using a standard telephone line. The telecommuter's modem
and a modem controlled by the central server establish a connection
therebetween. Once a connection is established, the telecommuter
may access a computer connected to the server, read emails and
receive phone calls and faxes. For example, if a customer attempts
to call the telecommuter at work by dialing into a private branch
exchange (PBX), the server will convert the incoming call to a
packetized form, such as H.323, and redirect the call via the
existing connection between the telecommuter and the server. Using
this system, the telecommuter may access a computer at work, answer
phone calls and answer emails. The telecommuter thus appears to be
present in his or her office and thus has a virtual presence there.
Note for this system to properly function, the telecommuter must
stay connected to the server at all times. While this does not
present a significant problem for local telecommuting, this
solution is quite costly for long distance telecommuting. Likewise,
this solution is very costly if the telecommuter is mobile and must
maintain a virtual presence with the server using a cellular
wireless connection. Furthermore, in some areas it may be difficult
to maintain a wireless connection continuously. A lost connection
may also prevent one from regaining access to the system until some
period of time has passed. Some mobile workers require only
intermittent access to the server, but find it too inconvenient to
place a dial-in call and to log onto the system every time access
is needed.
[0005] There is a need to provide mobile workers with various forms
of virtual connectivity. Mobile workers differ from telecommuters
in that while a telecommuter typically works from a single home
location or remote office, a mobile worker moves from location to
location during the course of a normal working day. An example of a
mobile worker is a home-care professional. A home-care professional
is a medical worker who periodically travels to visit with
different sets of homebound patients according to their individual
needs. The individual patients each have a set of medical records
indicative of their medical histories. A patient's medical record
is preferably maintained as an interactive electronic document
containing multiple parts. For example, the medical record
indicates to the home-care professional precisely what procedures
are to be performed and what medications are to be administered or
otherwise given to the patient. Once the services are performed,
the home-care professional must annotate the medical record
accordingly. The medical record is updated to reflect the patient's
vital signs and other information related to patient progress.
Also, a billing system takes note to track expendables and services
rendered. For example, the patient may be billed per visit and each
visit may involve the expenditure of billable resources such as
medicines.
[0006] In the above scenario, a mobile worker must interact with a
central server during the course of a day. The worker may wish to
access the central server while visiting a patient. The worker may
also wish to access the server from a location where only a
wireless connection can be established. From a performance
perspective, an ideal solution is to provide the mobile worker with
a wireless connection from a remote unit to a central server. Such
a wireless connection could be established via a high-powered radio
connection with a broad area of coverage or via an existing
cellular or personal communication system (PCS) network. Solutions
using high-powered radio links have the disadvantage that costly
spectrum may be required. Maintaining a link on a cellular or PCS
system is expensive in that a continuous connection consumes
billable airtime which is also very costly. From an airtime-cost
perspective, an ideal solution would be to force the worker to
create a connection, download or up load information, and work
locally with data on the remote unit as often as possible. This
solution is tedious, and while saving airtime costs, may actually
represent the more costly solution when professional service costs
are factored in. This method has the added disadvantage that when
files are uploaded or downloaded the data must be synchronized in
case another user has changed the data in parallel with the mobile
worker. Alternatively, other users must be "locked out" of the file
from the time the mobile user downloads it until it is finally
uploaded with any changes made. This is the problem solved using
semaphores in shared memory systems. In the context of the present
invention, a "file semaphore" is a semaphore used to lock a second
user out of a file while a first user is using it. Due to the
aforementioned reasons, in many applications forcing the worker to
repeatedly connect, disconnect, upload and download information is
unacceptable.
[0007] Some mobile networks have been constructed using what is
known as cellular digital packet data (CDPD). In a CDPD network, a
remote unit transmits a data packet on an unused analog channel. In
this sense the mobile unit remains virtually connected to a CDPD
communication server. Wireless airtime is only consumed when data
is actually sent. A disadvantage to this approach is CDPD networks
are not universally available. Cellular coverage is much more
ubiquitous than CDPD coverage. Also, CDPD network subscribers must
often pay high fees and hence CDPD may not represent the most
economical solution.
[0008] In some systems such as packet switched network routers,
offices make use of dial-out links. Dial-out links are useful when
remote offices are separated by long distances. In such systems,
when a packet must be routed from a first office to a second
office, a call is placed to route the packet. The dial-out
connection remains connected until a no-traffic condition is
detected, indicating the line is no longer active. When the
no-traffic condition is detected the connection is dropped until it
is again needed. Dial-out links are thus used to reduce long
distance fees associated with maintaining a constant connection,
and represents a useful starting point for solving the foregoing
problems relating to the establishment of a virtual presence of a
mobile worker. Client-server protocols and fast automated
connection strategies employing dial-out links are needed to
provide new ways for a mobile worker to maintain a virtual
presence. Also, new methods are needed to enable dial-out links to
be set up with low delays to make them more useful for novel
systems.
[0009] It would be desirable to provide a system whereby a remote
worker could maintain a seamless connection with a central server
without the need to maintain a dedicated channel. It would be
desirable if the remote worker could communicate with the central
server without the need to spend time to enter a password,
reconnect, and wait for a line negotiation sequence to proceed
before being able to use the connection. It would be desirable for
a protocol stack to activate a virtual session based on a
prediction derived from a workflow. It would be desirable to use
this prediction to set up a connection in the background without
disturbing the mobile worker while the mobile worker performed
tasks in a workflow. It would also be desirable to have a remote
unit which contains most of the screen-related information needed
to provide the appearance of an established connection before the
connection has been fully established. It would be desirable for
the remote unit to download information before it is needed and
upload information after it is gathered without the user even being
aware these actions are being performed. It would further be
desirable to establish a virtual session using a first
communication medium such as a landline and to later communicate
using the same virtual session using a second communication medium
such as a wireless link. This would allow a mobile worker to select
the most economical or convenient means of communications at a
given time. In embodiments involving modem-based connections, it
would be desirable to transmit data immediately using instantly
available but lower line speeds. It would be desirable to then
negotiate a higher line speed in the background while the remote
worker and/or the server perform other tasks. Moreover, it would be
desirable to establish a session between a remote unit and a server
so that various forms of communications may proceed while providing
the user with the appearance the user is continuously connected to
the server and has a virtual presence with the server.
SUMMARY OF THE INVENTION
[0010] The present invention solves these and other problems by
providing systems and methods to enable a remote worker to stay
virtually connected to a central server without the need to
continuously remain connected via a physical channel. The present
invention is useful when costs are associated with maintaining a
connection, for example when the connection has associated with it
long distance, wireless, or other usage-related toll charges.
[0011] A first aspect of the present invention involves a
communication protocol making use of a virtual session layer. The
virtual session layer allows a communication session and an
application session to be maintained in a deactivated state when no
physical connection exists. When a remote unit later reconnects
with a server, the virtual session is placed into an active state
and session communications resumes as though uninterrupted. A
remote unit, a virtual session server, and a communication system
including the remote unit and the virtual session server are
presented to support virtual sessions communications. In one
embodiment, the virtual session server manages a logon session
between the remote unit and a server-side application program. The
virtual session server emulates the presence of the remote unit to
the server-side application program and thereby maintains the
logon. In related embodiments, the server-side application program
involves a communication server capable of relaying messages and
establishing communication channels with the remote unit using the
virtual session layer.
[0012] A second aspect of the present invention involves a method
of accessing a central server from a remote unit. A first step
involves presenting a workflow to a user via a user interface. A
second step involves predicting, based upon the workflow, when the
user will require connectivity to the central server. Based upon
the prediction and in the background, a third step involves
initiating the establishment of a physical layer communication
connection to the central server.
[0013] A third aspect of the present invention involves a method of
establishing a connection with a low connection set-up time. In a
first step, the method initiates the establishment of a
communication connection to be used to communicate with a remote
entity. Next the method communicates application layer data via the
communication connection prior to the completion of a line-rate
negotiation process. Next the method negotiates a line speed in the
background.
[0014] A fourth aspect of the present invention involves a method
of setting up and operating a virtual session. This method can be
practiced by a client-side remote unit or a server-side virtual
session server. A first connection is established to a remote
entity. This first connection is then used to establish a set of
parameters needed to define a communication session with the remote
entity. Next the first connection disconnected and a set of
communication session parameters are maintained. Next a second
connection to the remote entity is established and an authorization
sequence is communicated. The communication session is next
reactivated using the communication session using the second
connection. A related method is used to allow a remote unit to
maintain a virtual communications presence with a remote
communication server coupled to a virtual session server.
BRIEF DESCRIPTION OF THE FIGURES
[0015] The various novel features of the present invention are
illustrated in the figures listed below and described in the
detailed description which follows.
[0016] FIG. 1 is a block diagram representing an embodiment of a
remote unit designed in accordance with the present invention.
[0017] FIG. 1A is a block diagram illustrating a layered software
architecture representative of the communication protocols of the
present invention.
[0018] FIG. 2 is a block diagram illustrating a system comprising a
remote unit operably coupled to a server via a communication
medium.
[0019] FIG. 3 is a flow chart illustrating a method of processing
whereby an application program implementing a workflow provides a
prediction of when the user will need a connection and establishes
a connection in the background just before it is needed.
[0020] FIG. 4 is a flow chart illustrating a method of establishing
communication with a remote entity with a near-immediate set up
time.
[0021] FIG. 5 is a flow chart illustrating a method of
communicating by maintaining a virtual presence without the need to
continuously maintain a physical connection.
[0022] FIG. 6 is a flow chart illustrating a method of processing
performed on a server acting as a front-end to an application
program to maintain sessions for remote users who are not
continuously physically connected to the application program.
[0023] FIG. 7 is a flow chart illustrating a method of processing
performed on a server managing virtual connections for users who
are not continuously physically connected to the server.
[0024] FIG. 8 is a flow chart illustrating a method of processing
performed by a remote unit to accept different types of incoming
calls.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] FIG. 1 is a block diagram representing an embodiment of a
remote unit 100 designed in accordance with the present invention.
The remote unit 100 may be implemented as a laptop computer, a
personal digital assistant, a desktop computer or workstation, or
as a dedicated unit customized for a particular application. The
remote unit 100 includes a central processing unit (CPU) 105
connected to a central bus 110. The central processing unit may be
implemented using an available microprocessor, microcontroller, or
customized logic. For example, a Pentium.TM. processor from Intel
Corp. may be used to implement the CPU 105. The central bus is
preferably constructed as a set of unbroken wires used to carry
signals between a set of component subsystems within the remote
unit 100. It should be noted, in some embodiments of the present
invention, the bus 110 may be implemented equivalently using a set
of direct parallel and/or serial connections between individual
modules. The bus 110 as illustrated in FIG. 1 shows a low cost and
a preferred means to connect the illustrated subsystems. Any
combination of bus connections and direct serial or parallel links
may be used to implement the connection structure provided by the
bus 110. Different implementations represent different
price-to-performance ratios and will be dictated by the needs of an
individual embodiment. The bus 110 also comprehends multi-layered
bus structures. For example, some embodiments make use of a local
processor bus connected to the CPU 105, and a peripheral
interconnect bus for other subsystems. In multi-layered bus based
designs, the different layers are preferably connected by bus
bridges. All of these and other equivalent embodiments of the bus
110 are known to the skilled artisan. From here forward, the
discussion will center on the illustrated embodiment of the remote
unit 100 whereby all subsystems are directly connected via the bus
110. Embodiments where the bus 110 represents a different physical
interconnection topology are implicitly included in the discussion
below.
[0026] A memory 115 is also coupled to the bus 110. The memory 115
may be implemented using static random access memory (SRAM) or
dynamic random access memory (DRAM). One type of SRAM is read-only
memory (ROM). Preferably the memory 115 includes a ROM for use at
boot-up, and a DRAM to hold a significant amount of data storage
for use while executing programs. The remote unit 100 also includes
a control program module 120. The control program module 120 is
controllably coupled to the CPU 105 and is also coupled to the bus
110. The central program module 120 typically exists as a software
module executed from the memory 115 by the CPU 105. The control
program module 120 effectively configures the remote unit 100 to
operate in accordance with aspects of the present invention as
discussed herein below.
[0027] A communications module 125 is also coupled to the bus 110.
The communications module includes at least one communication
interface to allow the remote unit to communicate with a remote
entity such as a virtual session server as will be discussed in
detail hereinafter. In a preferred embodiment, the communications
module 125 includes a plurality of communication interfaces. For
example, a first interface 126 provides a wireless link, and a
second communication interface 127 provides one or more wireline
links. Also, the wireline communication interface 127 may include a
standard telephone modem interface and a packet style interface
designed to plug directly into an Ethernet connection to be coupled
to a local area network (LAN), a wide area network (WAN) or the
Internet. The Internet is the well-known and ubiquitous World Wide
Web. In some embodiments, the communications module 125 includes a
caller-identification packet processor. A caller-identification
packet processor receives a caller-identification packet, extracts
information therefrom, and passes the information to the CPU 105.
Caller-identification packets may be advantageously used to
identify incoming calls with a virtual session as discussed in
connection with FIGS. 7-8. The communications module 125 may
optionally include a voice interface to allow a user to engage in
telephone conversations using the remote unit 100. In this case a
separate handset or a built-in handset may be used. Alternatively a
speakerphone may be built into the remote unit using a microphone,
a speaker, and an echo canceller.
[0028] The remote unit 100 also includes a display monitor 130. The
display monitor 130 is also coupled to the bus 110. The display
monitor 130 is preferably implemented using a liquid crystal
display (LCD), although other display technologies may equivalently
be used. Also connected to the bus 110 is an optional universal
input-output (I/O) module 135. The universal I/O module includes a
coupling to a set of external devices 138. The external devices are
preferably data collection units as described below. The universal
I/O module preferably provides a standard link layer interface to
the software module 120 executing on the CPU 105. The remote unit
100 also preferably includes a mass storage device 140. The mass
storage device 140 is also connected to the bus 110. The mass
storage device is preferably implemented using magnetic disk or
optical disk technology, but any mass storage device, to include a
non-volatile memory, may be used.
[0029] The remote unit 100 also includes a power module 145. The
power module is preferably and optionally coupled to the bus 110 to
receive power management control information. The power module
preferably includes a battery, an alternating current (AC)
connector, a direct current (DC) connector, and a power management
control interface. The AC connector allows the remote unit 100 to
be powered from a standard 110 V wall outlet. The DC connector
allows the remote unit 100 to be powered from a vehicle, for
example by plugging the unit into a cigarette lighter outlet.
Either of these connectors may be preferably used to also charge
the battery in the remote unit. The power module 145 is coupled to
supply power to a power bus which is connected to all subsystems.
Depending on the power management configuration of an individual
system, different subsystems may accept power from separate
connections to allow portions of the remote unit to be selectively
turned off while they are not being used.
[0030] The remote unit 100 is operative to execute an application
program. The application program is operative to supply a sequence
of interactive screens or a menu based interface to the user. The
sequence of interactive screens or a particular usage of a menu
based system implements a workflow. In an example embodiment, the
remote unit 100 is carried by a home-care professional. The home
care professional has a sequence of procedures which need to be
implemented in the course of working with a patient. This sequence
of procedures gives rise to the workflow implemented in the control
program 120 which executes on the remote unit 100. In the example
embodiment involving a home-care professional, the universal I/O
module is connected to a set of peripheral units to collect vital
information such as blood pressure, temperature, insulin level and
the like. Other information such as the patient's weight may be
entered manually by the home-care professional as a part of the
workflow. At certain times in the workflow, an external
communication connection will be needed because data may need to be
uploaded or downloaded to/from a central server. In accordance with
the present invention, the remote unit 100 is operative to provide
a seamless and transparent virtual presence with the central
server. In general, the central server may itself be segmented into
two or more individual central servers. The discussion herein
focuses on an embodiment whereby a virtual presence is maintained
with a single central server having multiple server components. The
present invention may be equivalently practiced by embodiments
involving a virtual presence with more than one central server.
Thus, one remote unit could maintain multiple virtual connections
to totally separate server systems. In such a configuration the
application workflow would dictate to which server system the
remote unit would physically connect while other servers remain
virtually connected.
[0031] A key aspect of the operation of the remote unit 100 is its
ability to maintain a virtual presence with the central server
without continuously maintaining a physical connection. The remote
unit 100 is operative to provide communications when it is needed
without the user needing to go through a set of normally associated
connection sequences. For example, in accordance with one aspect of
the invention, the user need only interact with the screens
provided to implement the workflow while the remote unit 100
automatically sets up a connection in the background to be
available when it is needed. In embodiments where file
synchronization is not an issue or is handled using file
semaphores, the software implementing the workflow automatically
downloads information before it is needed and later automatically
uploads new information after it has been gathered. This way, users
need not even be aware they are not connected at all times. The
user is not burdened with the need to connect and reconnect, and
need not be burdened with downloading and uploading data. The user
experiences the full benefit of being continuously connected to the
central server without the associated cost of remaining
continuously connected via a physical connection. In systems where
file semaphores are not employed, the physical connection is
established just before the workflow indicates it will be needed
and is dropped when the workflow indicates it will not be needed
for some time. Further details of the operation of the remote unit
100 are given in the discussions provided in connection with FIGS.
2-8.
[0032] A central aspect of the present invention involves the
concept of a "virtual session." A session as defined herein is
similar to the definition provided in the open systems interconnect
(OSI) reference model from the International Standards Organization
(ISO). The OSI model is a model of a layered software structure
used in computer communications. A software system which implements
a layered model of communication is known as a "protocol stack."
The OSI model is well known and divides a computer communications
process into seven layers. At each layer is a software module which
communicates with a peer software module at the same layer. Within
a protocol stack, each layer communicates with the layer above
and/or below. Actual communication systems often deviate from the
seven layer OSI model. A protocol stack using basic concepts
similar to the seven layer OSI model is next discussed which
represents an aspect of the present invention.
[0033] FIG. 1A illustrates a representative protocol 150 used to
support the present invention. At the top layer is an application
session layer. A first protocol stack with an application session
layer software module 151 communicates with a second protocol stack
with an applications session layer software module 152. The
application session layer software module 151 is typically
implemented as a client-side software module which presents a user
interface to a user. The application session layer software module
152 is typically implemented by a server-side software module
operative to provide communication and/or computer related services
to the client-side software module. For example the application
sessions layer software module 152 may involve a logon session with
a database program, or may represent a unified messaging server
supplying voice mail, email and fax mail. Similarly, the
application session layer software module 152 may involve a
telephony application operative to provide a packet switched or a
circuit switched telephone connection to the client-side
application session layer software module 151. One layer down in
the protocol stack is a virtual session layer. In the example
embodiment, the first protocol stack implements a virtual session
layer software module 154 in the remote unit 100. The virtual
session layer software module 154 communicates with a peer virtual
session software module 156 via the peer-to-peer communication path
182. In the exemplary embodiment, the virtual session layer
software module 156 is implemented within a virtual session server
as discussed in connection with FIG. 2. The virtual session server
typically maintains a table linking one or more application
sessions to a virtual session. For example, this linking of
application sessions into the table structure may be accomplished
by including a pointer to a data structure containing application
session control data, or by placing the data structure holding the
application session control data directly in the table structure.
Additionally, the table structure allows the virtual session server
to maintain a plurality of virtual sessions with a plurality of
client remote units. In the OSI model, the OSI-session layer
provides a set of rules used to establish and terminate data
streams between nodes in a network. A set of OSI-session layer
services include establishing and terminating node connections,
message flow control, dialog control, and end-to-end data control.
The session layer controls dialogs, which involve conversational
protocols as used in mainframe computer terminal communications.
The virtual session layer 154, 152 of the protocol 150 may perform
any of these functions in addition to maintaining the table linking
to the application sessions.
[0034] The next software modules in the first protocol stack are
the transport layer 158, the network layer 164, the link layer 170
and the physical layer 176. These software modules respectively
perform peer communications with the server-side protocol stack's
software modules 160, 166, 172, and 178. The physical layer defines
the low-level mechanical and electrical channel protocols and the
physical connection itself. These four lower layers are well known
in the art of data communications and can be implemented in various
well-known ways. Likewise, alternative and equivalent protocol
stacks may be constructed, for example, with the transport layer
removed, various layers merged into one, or new layers added.
[0035] An important aspect of a virtual session oriented
communication protocol such as the protocol 150 is the ability to
maintain a peer-to-peer virtual session communication path 182
without the presence of a physical layer communication path 180.
The physical layer communication path 180 represents a physical
layer communication connection, for example, a wireline connection,
a cellular wireless connection, or a network connection to the
Internet. When the physical layer communication path 180 is
disconnected, no physical channel exists between the client-side
software and the server-side software, and the physical layer
communication path 180 is said to be in a "disconnected state."
However, data structures maintained at the virtual session layer
allow one or more peer-to-peer application session communication
paths 184 to remain in a deactivated but existent state, even when
the physical layer communication path is in the disconnected state.
Likewise, the virtual session communication path 182 established
between the remote unit and the virtual session server also remains
in a deactivated but existent state. This is made possible through
the use of the table structure maintained in memory which retains
its information after the physical layer communication path 180 has
been disconnected. When the physical layer communication path 180
has been reconnected, the physical layer communication path is said
to be placed into a "connected state." At such time, the virtual
session layer software modules 154 and 156 are operative to
reactivate the virtual session layer communication path 182 and the
application sessions layer communication path 184. When these paths
are reactivated, peer-to-peer communication may once again proceed
over the application session layer communication path 184 and the
virtual session layer communication path 182.
[0036] As defined herein, a distinction is made between a
communication session and an application session. A communication
session is defined as a session between nodes or communication
endpoints, and an application session is defined as a session
between applications. For example, a remote unit may establish a
communication session with a central server. In this case a
communication session is established between the communication
endpoints, i.e., the remote unit and the central server. Also, an
application program running on the remote unit may need to
establish an application session with an application program
running on the central server. In such case an application session
is created using a connection stream provided and governed by the
communication session. A table structure is used to maintain both
the communication session parameters and the application session
parameters. For example, a first user authentication parameter may
be used to establish a communication session with the server. A
second user authentication parameter may be used to establish an
application session with the application program. This second user
authentication parameter may include a user identification
parameter and a password, for example.
[0037] In light of the aforesaid concepts, a "virtual session" is
next defined. A virtual session is preferably implemented as a
communication session as defined above. A virtual session, like an
OSI session, provides a set of rules for establishing data streams
between nodes or endpoints. The virtual session also may provide
other session features such as dialog control, message flow
control, and end-to-end data control. A virtual session is
controlled using a data structure which provides a way to associate
the virtual session with the lower layers of a protocol stack,
leading down to a physical layer. As mentioned above, in most
embodiments, a virtual session is implemented as a communication
session. Application sessions are then added onto the virtual
session as connection streams within the communication session.
[0038] In a virtual session, a communication session may be
suspended with some or all of the lower layers of the protocol
stack missing. In particular, a virtual session may be maintained
while a physical layer connection has been removed. The virtual
session can then be reassociated with a physical layer connection
at a later time. The virtual session thus also preferably provides
connect and reconnect rules used to establish a virtual session and
then to reassociate the virtual session to a new physical
connection to set up a new data stream in support of a dialog at a
later time. Related activities such as the initiation of dial-out
links to reestablish a physical layer communication path is also
preferably handled by the virtual session in response to a signal
from an application layer program.
[0039] An aspect of a virtual session is the maintenance of an
application between an application program and a virtual session
server as will be described below. A virtual session server acts as
a proxy agent for a remote unit. When the remote unit is not
connected via a physical layer communication path, the virtual
session server maintains a proxy-presence with the application
program on behalf of the disconnected remote unit. At a later time,
when the remote unit reconnects into the virtual session by passing
a set of communication session authentication parameters, the
remote unit is thereby granted access to one or more application
sessions which have been maintained in proxy by the virtual session
server.
[0040] In a preferred embodiment, the virtual session uses a set of
authentication parameters and a set of encryption keys to maintain
a secure connection. A separate set of authentication parameters is
used by an application running on the remote unit to gain access to
an individual application session. Once the application session has
been established over a virtual session, a table is used to
maintain a set of parameters needed to maintain the application
session, even though no physical layer connection exists between
the endpoints of the virtual session. When a virtual session data
structure is set up and no physical layer connection exists to
support communication over the virtual session, the virtual session
is said to be "inactive." When a virtual session data structure is
set up and a physical layer connection does exist to support
communication over the virtual session, the virtual session is said
to be "active." A transition from an active state to an inactive
state is called "deactivating a virtual session," and a transition
from an inactive state to an active state is called "activating a
virtual session." The process of transitioning from an active state
to an inactive state is also known as "disconnecting from a
physical connection." When this occurs, the physical layer
connection is no longer available to support communication over the
virtual session. In a preferred embodiment, a table structure is
used to maintain the virtual session parameters as well as a set of
parameters for each application session established over the
virtual session. When a virtual session is activated, there is no
need to reauthenticate the individual application sessions. This is
because the table typically includes a user identification
parameter, a user password, a set of application session
parameters, a communication session identification parameter, and
an encryption key for the communication session. Additional data
such as modem initiation parameters may be added to the table as
required by the system configuration and usage.
[0041] Referring now to FIG. 2, a block diagram illustrating a
system configuration 200 is shown. The system configuration 200
includes the remote unit 100 operatively coupled to a communication
interface 210. A direct wireless link 207 optionally couples the
remote unit 100 to the communication interface 210. A direct
wireless link is used in embodiments where the remote unit 100
maintains a direct wireless link with the communication interface
210. The communication interface thus provides an air interface for
the direct wireless link. Alternatively or in addition to the
direct wireless link 207, a wireline link 208 couples the remote
unit 100 to the communication interface 210. The communication
interface 210 maintains the connection 208 via a network interface
coupled to a public switched telephone network (PSTN) or a network
such as the Internet. This connection 208 may itself involve a
microwave link, a wireless link through a public switched cellular
network or a wireless link in a PCS network.
[0042] The communication interface 210 is preferably coupled to a
communication server 212. The communication server 212 may be
thought of as generalization of a private branch exchange (PBX).
The communication server 212 accepts tele-traffic from any variety
of sources and provides switchable connections to couple different
sources together. For example, the communication server 212 may be
implemented as a PBX which receives a set of direct inward dial
lines from a central office operated by the public telephone
network. The PBX then provides local users with extensions and
allows local users to call each other by dialing the last four
digits of their telephone numbers. The PBX typically provides an
outside line to a user once the user has dialed a nine.
[0043] The communication server 212 may also be configured to
provide additional types of connections, such as packet based voice
and video connections according to the H.323 international
standard. In such an embodiment, the communication server 212
provides a gateway function passing calls between the public
switched telephone network and a network such as the Internet. The
communication server 212 may also provide other communications
services such as voice mail, email, fax-mail, call distribution and
the like. In systems involving Internet telephony, the
communication server may operate only using packet protocols and
not include an interface for circuit switched connections.
[0044] The communication interface 210 is also coupled to a virtual
session server 215. The virtual session server 215 is coupled to a
table structure 225 and an application program 220. The table
structure 225 is preferably implemented as a software entity and
may be located in a memory module within the server 215. The
virtual session server 215 may be implemented as a software entity
which executes on a hardware platform. The hardware platform of the
virtual session server 215 may be designed with an internal
architecture similar to the remote unit 100 but is designed to
provide a higher computation capacity and to handle multiple users.
When supporting a virtual session server, the display monitor 130
is optional as users may control the virtual session server 215
remotely. The control program module 120, when implemented in the
virtual session server 215 provides the server side of the
communication protocols discussed in connection with FIGS. 3-8.
Hence the remote unit 100 and the virtual session server 215
involve similar architectures and respectively implement the client
and server sides of a set of virtual-session-related communication
protocols of the present invention.
[0045] The application program 220 may execute on the same hardware
platform as the virtual session server 215. In general, both the
virtual session server 215 and the application program 220 may be
implemented as software modules running on personal computers,
workstations, dedicated custom hardware, mainframe, or file
servers. For example, the virtual session server 215 may be
implemented as a software module running on an UltaSparc.TM.
workstation or file server from Sun Microsystems Inc. The software
may be written to execute over a multitasking operating system such
as Solaris.TM. from Sun Microsystems Inc. or WindowsNT.TM. from
Micrsoft Inc. In a first preferred embodiment, the application
program 220 includes a distributed database program running on a
collection of networked servers such as Sun UltraSparc.TM. servers.
In a second preferred embodiment, the application program may
itself be a communication server as provided by an Internet service
provider (ISP).
[0046] The system 200 is operative to implement a set of virtual
session communication protocols according to the present invention.
The remote unit 100 establishes a session via the virtual session
server 215 to set up a virtual presence with the application
program 220. Preferably, the virtual session server 215 also
provides a link to the communication server 212 to provide it
access to the virtual session. When the remote unit 100 disconnects
from a physical connection 207 or 208, the virtual session is
maintained within the table structure 225. When the remote unit 100
later wishes to reestablish communication with the application
program 220, the virtual connection server 215 is operative to keep
the virtual session active and to allow the user rapid and nearly
transparent access to the application program 220. Similarly, the
virtual session also preferably is used to provide a virtual
communication link between the communication sever 212 and the
remote unit 100. In some systems, a first virtual session is
established between the remote unit 100 and the application program
220, and a second virtual session is established between the remote
unit 100 and the communication server 212. The details of the
operation of the virtual session server 215 and the virtual session
protocols are discussed below in connection FIGS. 3-8. Before
proceeding to these portions of the detailed description, two
embodiments of the system 200 are described.
[0047] In a first exemplary embodiment of the system 200, a mobile
worker such as a home-care professional operates the remote unit
100 to establish and maintain a virtual session with the
application program 220. In one embodiment, the application program
220 controls access to a database including complete medical and
billing records for individual patients. Depending on working
conditions, the home-care professional may require access from a
wireless connection such as a cellular connection, or else may be
able to communicate via a wireline connection provided within a
patient's home. As the home care professional proceeds through a
given workflow, the professional will eventually need to
communicate with the application program 220. When this time
arrives, the present invention is operative to establish a physical
connection between the home-care professional and the application
program 220. The professional need not be aware the physical
connection has not been available since the time the virtual
session was first established. The virtual session is maintained by
the virtual session server 215 and the protocols of the present
invention are employed to ensure such a virtual connectivity is
provided without the need for the remote unit 100 to be
continuously connected to the application program 220.
[0048] In a second exemplary embodiment, the application program
220 is a communication server operated by an ISP. In this example,
the remote unit 100 is operated by an Internet user. After the
Internet user has remained inactive for a period of time, the
connection 208 is terminated. At a later time, when the Internet
user clicks on a hyperlink, thus demanding service, a short delay
is incurred while the connection is reestablished. The remote unit
is provided access without the user needing to reestablish a
connection. When the user clicks on a hyperlink, the telephone is
rapidly dialed without presenting dialing tones to the user. An
authentication packet and a request packet are sent using a low
data rate protocol such as one used for line-rate negotiation in
modems. The user is authenticated by the server and the request
packet is forwarded through the Internet to the Internet site
referenced by the hyperlink. While the remote Internet server takes
time to respond to the request, a higher line speed is negotiated
in the background without burdening the user. Because a home
Internet user uses the same analog connection between the user's
premises and a network interface, the modem parameters may be
preferably saved by the server in the table 225 to accelerate
renegotiation. The user is provided access almost immediately, and
the connection is reestablished transparently. Note while this
example focuses on an Internet application, the techniques apply to
any application whereby a network site is accessed by activating a
hyperlink.
[0049] As will be discussed below, the virtual session between the
remote unit 100 and the virtual session server 215 provides a means
to initiate transfers in both an uplink and a downlink direction.
The uplink direction is from the remote unit 100 to the virtual
session server 215, and the downlink direction is from the virtual
session server 215 to the remote unit 100. A virtual session is
said to exist between the remote unit and the virtual session
server 215. This virtual session may be used to create individual
virtual sessions between the remote unit 100 and the application
program 220, and between the remote unit 100 and the communication
server 212. For example, an uplink connection is established, and
when a home Internet user has been inactive for a period, the
connection is dropped. As discussed above, the connection is
reactivated transparently when the user once again activates an
Internet link, as in an Internet browser. In the same example, a
user may have an email reader program connected through a virtual
session. If an email comes in for the user and the virtual session
is in place, the email should be rapidly forwarded to the user. To
do this, the user's phone is dialed in a downlink direction
dial-out link by the virtual session server 215 via the
communication interface 210. The remote unit preferably suppresses
the first ring and examines caller identification data. When the
caller identification data indicates the calling party is the
virtual session server 215, the remote unit 100 automatically picks
up the call and in this example, accepts the email. If caller
identification is not used, a substitute protocol should be
employed to assure that connection has been made to the proper
application session defined within the virtual session. The
substitute protocol preferably involves sending a packet header at
the beginning of a call whereby the packet header contains one or
more fields which identify associated the application session.
Again, the user need not even realize a connection has been
reestablished. Instead, the user receives the email message as
though the connection had remained continuously active.
[0050] Another type of operation may occur when the user of the
remote unit 100 is actively connected to the virtual session server
215 and a call comes in directed to the remote user's extension. At
this point the call is preferably converted into packets and is
sent to the user over the existing connection. In an alternative
embodiment, the physical connection is automatically and
temporarily dropped and the call is forwarded to the remote user.
The virtual connection to the application is maintained through the
virtual server. The communications module 125 preferably analyzes
caller-identification data to determine the incoming call is a
voice call to cause the optional telephone aspect of the remote
unit 100 to ring. More details related to the foregoing system
operation are discussed in connection with FIGS. 3-8 below.
[0051] The virtual session server 215 is able to maintain an open
logon to the application program 220. In one embodiment, the
virtual session server 215 executes a client-side software which
interfaces with the application program 220. That is, if the
application program 220 employs a client-server architecture, the
application program 220 will implement a server-side software
module which interacts with the client-side software. The
server-side program performs database or other server oriented
functions, while the client-side software provides a user interface
to the user. The remote unit 100 can then control the operations of
the virtual session server 215 using standard remote session
software. An example of commercially available remote session
software is PCAnywhere.TM. from Semantec Corporation. In another
embodiment, the virtual session server executes the client-side
software in parallel with the remote unit. In still another
embodiment, the remote unit executes the client-side software, and
the virtual session server merely provides a connection stream to
pass data from the application program 220 to the remote unit 100.
When the virtual session is in a deactivated state, the virtual
session server emulates the client-side software as needed to
maintain an active session with the application program 220 in the
absence of the remote unit 100. A wide variety of equivalent
techniques may be used to allow the virtual session server 215 to
maintain a pointer or re-entry point into the application 220 while
acting as a proxy agent to maintain the logon for the remote unit
100. A table structure is preferably used to allow the virtual
session server to simultaneously maintain a plurality of logons for
a plurality of different remote units.
[0052] In some embodiments, the remote unit 100 may need to
maintain a plurality of virtual sessions with a plurality of
different virtual session servers. For example, an independent
contractor may provide home-care services for two distinct health
regions. Each health region may use a separate database. The remote
unit 100 may then access these separate databases using a first and
a second client-side application software module. During the course
of a day, the remote unit may need to activate the first or the
second client-side application software modules. In such case the
remote unit 100 is operative to maintain a table structure similar
to the table structure 225. The table structure maintained by the
remote unit links an application software module through an
application session to a virtual session. When the first
client-side application program demands access to a first database,
the virtual session layer software 154 in the remote unit causes a
physical connection to be established to support virtual session
communications 182 with the first database application program.
Likewise, if the second client-side application software module
desires to access a second database, the virtual session layer
software module 154 activates a physical layer connection back to
the second database server. In other applications a single
application program may be used which accesses information on more
than one virtual session server. In such case a single application
program can select the virtual session to activate based on the
communications request generated from within the application
program. In still other embodiments, a single physical connection
208 or 207 may be used to communicate with the communication
interface 210. The communication server 212 then forwards packets
to a first local virtual session server such as the virtual session
server 215. If the received communication packets are destined for
a second virtual session server, then the communication server 212
preferably forwards the packets to a remote virtual session server
using a network connection such as an Internet connection.
[0053] Referring now to FIG. 3, a method 300 is illustrated to show
how the remote unit 100 preferably operates to activate a
connection. The method 300 is preferably practiced by the remote
unit 100 in support of a virtual session with the virtual session
server 215. A first step 305 of the method 300 involves actions
within a workflow process 305. The workflow process 305 includes
the step 305 of the method 300 and also performs other activities
to interact with a user's workflow requirements. Control loops from
the first step 305 back to the first step 305 via a control path
310. The workflow, as discussed above, is preferably made up of a
menu system and/or a set of interactive screens traversed by a
worker in performing a set of tasks. For example, a home-care
professional's workflow involves accessing and displaying a
patient's medical record, entering a set of data into the medical
record, and performing tasks indicated by the doctor's directions
as annotated in the medical record. In this example, as the
home-care professional moves from one screen to the next, control
loops via the control path 310. The workflow process 305 is an
application program which executes on the CPU 105. The workflow
process 305 is preferably implemented as a process running on the
CPU 105 in a multitasking operating environment. A multitasking
operating environment is one in which multiple programs or
processes may execute in parallel by sharing time slots within the
CPU 105. Multitasking operating system software is well known and
is readily available. In a multitasking-programming environment a
first process may execute in a normal fashion and provide an
interface to a user. At the same time a second process may be
executed by sharing CPU cycles without the user's intervention or
knowledge. In such a case the second process is said to be a
background process or is said to perform background processing. At
some point in the course of the workflow, a physical layer
communication connection will be needed to communicate information
between the remote 100 and the application program 220.
[0054] When a step in the workflow process 305 is performed leading
up to the need for a physical layer communication connection,
control next passes from the first step 305 to a second step 320
via the control path 315. The control path 315 is activated when
the workflow process 305 provides a prediction indicating a
physical layer communication connection will subsequently be
needed. In some cases the prediction may be provided right when the
physical layer communication connection is needed. In other cases,
the prediction 315 may be used to initiate background processing to
download data which will not be needed until a later time. In menu
based systems, the prediction 315 may be learned by observing the
workflow habits of a user. The prediction 315 is a function of the
application program or workflow 305 and is optional. In the second
step 320, a connection is established in the background. Background
processing enables the user to continue interacting with the
workflow process 305 while a physical layer communication
connection is simultaneously and transparently established. That
is, the physical layer communication path is reestablished without
inhibiting the user from interacting with the workflow 305. Hence
when control passes via the control path 315 to the step 320,
control preferably simultaneously passes via the control path 317
back into the workflow. The background process is preferably forked
as a separate task and two execution flows proceed in parallel by
time sharing the CPU 105. Multitasking is well known in the art and
is implemented using interrupt based processing. In alternative
embodiments the control path 317 may be deleted and a single
control flow may be implemented using the control path 315.
However, this embodiment may require the user to wait for the
connection to be established and is hence not deemed to be the
preferred embodiment of the method. Other equivalent embodiments
set up the communication path transparently by multiplexing the CPU
105's computation cycles from within the workflow process or some
other process.
[0055] Once control has been forked via the control path 315 to the
second step 320, a dialer within the communications module 125
preferably dials to establish a physical layer communication
connection with the communication interface 210. In embodiments
using dedicated radio links, the connection may be established over
the wireless link 207. One preferred embodiment of a remote unit
100 incorporates a cellular radio. In this case the dialer dials a
telephone number and a connection is established using a public
switched cellular telephone network so that the connection is set
up on the link 208. Stationary Internet based embodiments perform
the second step 320 by dialing a telephone number using an
automatic dialer which dials a land line connection for a modem. In
all cases, it is preferred to suppress the dialing tones and
line-rate negotiation signals so the connection may be established
transparently to the user.
[0056] Control next passes from the second step 320 to a third step
325. In the step 325, an authentication code is transmitted from
the remote unit 100 to the communication interface 210. This
authentication code is then passed to the virtual session server
215. The virtual session server evaluates the authentication code
to determine if access is to be permitted. In a preferred
embodiment, the authentication code involves a digital signature as
is known in the field of public key cryptography. In a preferred
embodiment, all transmissions are encrypted using public key
cryptography. Some systems may be implemented using various
encryption standards such as secure sockets layer based encryption.
The amount of authentication and encryption used in any given
embodiment is left to the system designer, but preferably all
transactions are encrypted as described above.
[0057] Control next passes from the third step 325 to a fourth step
330. In the fourth step 330, a session is established/reactivated
with the virtual session server 215. The session is established the
first time the method 300 passes control to the step 330.
Subsequently the step 330 is operative to reactivate the session
with the virtual session server. When the session between the
remote unit 100 and the virtual session server 220 is reactivated,
virtual session communications resume. At this point, the virtual
session server 215 correlates information stored in the table
structure 225 with the connection and provides the remote unit 100
access to the application program 220. If no data is stored in
table structure 225, access is provided to a default logon screen
allowing remote unit 100 to establish a new application session.
The virtual session server 215 then populates the table structure
225 to establish a virtual session. The step 330 involves setting
up a stream connection between the workflow process 305 and a
protocol stack. The protocol stack is operative to read information
bits from the stream connection and communicate the bits across an
external communication link. Bits received over the external
communication link are converted by the protocol stack into
information bits to be sent back to the workflow process 305 across
the connection stream. Once the appropriate communication processes
are configured, control next passes back to the workflow process
305. Due to the aforementioned forking operation, the passing of
control back to the workflow process 305 may have already occurred
via the control path 317. In this case the passing of control from
the step 330 to the workflow process is not explicitly
performed.
[0058] When control loops back from the fourth step 330 to the
workflow process 305, a physical layer communication connection is
activated for current or subsequent communication. When the user
gets to a point in the workflow where communication with the
application program 220 is needed, the connection has already been
transparently set up in the background. Hence the user gets the
feel of being connected to the application program 220 all the
time, where in fact the remote 100 is connected via a physical
channel to the application program 220 only a fraction of the time.
This virtual connection saves communication resources and money
when a toll is charged based on the amount of usage on the link 207
or the link 208. In some embodiments, the fourth step 330, or an
execution thread within the workflow 305 is operative to upload or
download information in the background. This way the user has ready
access to data contained in the application program 220, but in
general a shorter connect time is required. While with prior art
systems it is burdensome for a user to connect to a central server
and download and upload information, with the virtual session of
the present invention the user need not even be aware this process
is occurring. Rather the user feels as though he or she is
continuously connected with a fast connection because the data
needed at a given point in the workflow is already available
locally or has been uploaded in the background transparently
without user intervention. In systems where server synchronization
is an issue, file semaphores and/or direct active sessions not
employing uploading and/or downloading of records may be used.
[0059] Based on another point in the workflow, another prediction
is made to predict when the communication channel will not be
needed for some time. For example, it may be known, based on the
workflow, the home-care professional will next perform a sequence
of tests and enter data into a screen displayed on the remote unit.
Only at a later time will the workflow come to a point where this
information is to be uploaded to the application program 220. When
such a prediction is made, control passes from the first step 305
via the control path 318 to a fifth step 335. The fifth step 335 is
operative to deactivate the connection established over the link
207 or the link 208. The step 335 may optionally involve forking a
separate execution thread or otherwise accessing a separate process
in a multitasking environment. Alternatively, the fifth step 335
may be performed by executing a set of instructions in the workflow
process 305. At a later time, a prediction may be made indicating
the link 207 or 208 needs to once again be activated, whereby
control again passes over to the second step 320 via the control
path 315. It should be noted different systems will typically set
their prediction times according to the economic conditions
involved. For example, in some systems the first minute of
connection time may cost five times as much as all subsequent
minutes. In this case predictions would be preferably set according
to a criterion to minimize cost by not establishing and terminating
connections more often than necessary. If a flat rate were charged
per minute connections would be set-up and terminated more often.
If automatic uploading and downloading is performed in the
background, a very efficient use of air-time can often be achieved
while presenting the user with the appearance of being continuously
connected to the application program 220.
[0060] Referring now to FIG. 4, a method 400 of establishing a
communication link with low delay is illustrated. The method 400
may be practiced by both the remote unit 100 and the communication
interface 210. This method is most applicable to systems involving
modems whereby digital data is transferred over an analog channel
requiring receiver training. Receiver training involves
transmitting data sequences through a channel and allowing a
receiver to adjust its receiver parameters. Receiver parameters
include echo canceller and equalizer filter coefficients. Most
systems also adjust their data rates and signal constellations
based on observed conditions. In modems, this entire process is
known as line-rate negotiation. Prior art systems involving
receiver training are tedious to use because they force the user to
wait while the receiver is trained. Most systems play the training
signals though a speaker to allow the user to hear the training
process. This lets the user know what the computer is doing for the
duration of the delay. The method 400 improves upon this prior art
solution by allowing the user to gain almost immediate access
without a significant delay.
[0061] In a first step 405, a protocol stack or other process
practicing the method 400 receives a communications request from a
user program. For example, this occurs when a user clicks on an
icon to initiate the establishment of an Internet connection.
Control next passes to a step 410 where the connection is
initiated. This step typically involves an automatic dialer dialing
the number of an Internet service provider (ISP). The ISP software
may be implemented as a communication server application
corresponding to the application program 220. In this case access
to the application program is governed by the virtual session
server 215.
[0062] Control next passes from the second step 410 to a third step
415. In the third step 415 an authorization sequence is exchanged.
In a preferred embodiment public key cryptography involving digital
signatures and keys is used. Embodiments involving a virtual
session server 215 either set up a session or activate an existing
session during the third step 415. Control next passes from the
third step 415 to a fourth step 420. In the fourth step 420, one or
more initial application layer data packets are transmitted across
the connection using a low speed protocol. A low speed protocol is
used by the transmitter and receiver when performing line-rate
negotiations. For more details of line-rate negotiation protocols,
see, for example, the V.34 and V.90 standards from the
International Telecommunications Union. In the present invention,
the low speed protocol is used to transmit application layer data
before the line-rate negotiation procedures have completed. This
avoids the need for the user to wait for line-rate negotiation to
complete before being able to access a communication path.
[0063] Control next passes from the fourth step 420 to a fifth step
425. In the fifth step 425, initial data is displayed. Software
located locally in the remote unit 100 preferably contains
high-volume graphics related data so that the initial data exchange
of the step 420 only requires a small amount of data to be
transferred. For example, the user logs onto the Internet and
almost immediately sees a screen of information indicating the user
is connected and the system is ready to accept inputs. This is made
possible by displaying locally held screens of graphical data and
allowing a small amount of specific information such as time, date,
and headlines to be received and displayed. If the user then
immediately clicks on a link, an application layer request packet
is sent using the line-rate negotiation protocol's data format.
This allows the user to immediately begin making requests before
the line-rate negotiations have completed. In many cases the user
will pause and read the headline information, giving the system
even more time to perform line-rate negotiation in the
background.
[0064] Control next passes from the fifth step 425 to a sixth step
430. In the sixth step 430, a background process is forked to
perform line-rate negotiation. Line-rate negotiation is allowed to
proceed in the background while the user is reading the information
provided on the initial display of the step 425. Likewise, if the
user had rapidly clicked on a link, a request packet is sent out
and while the server is responding to the request, the background
line-rate negotiation may proceed. The step 430 is operative to
perform line-rate negotiation so as to set up a high-speed
connection for subsequent higher volume data transfers. In
embodiments involving a virtual session server 215, the user's line
speed parameters may be stored in the table structure 225. For
example, if the user is an Internet user and the application
program 220 is an ISP, the user will often dial in from the same
location. Thus parameters derived in a previous activation of a
communication channel will be either identical or similar to those
used in a current activation. Hence the sixth step 430 optionally
involves accessing from the table 225 a set of starting parameters
derived from the activation of the communication channel. If
communication is needed before the line-rate negotiation has
completed, communication preferably proceeds at the highest rate
negotiated up to that point.
[0065] Once the line-rate negotiation process of the step 430 has
completed, control passes to a seventh step 435. In the step 435,
communication is able to proceed at full speed. In most cases where
this method is implemented, the user will get the full benefit of
being connected almost immediately without the normal delay
associated with prior art systems. This is so because initial
low-volume data is allowed to pass through the channel before the
line-rate negotiation has completed. Line rate negotiation then
proceeds in the background in parallel with other activities such
as the user reading headline information or a distant server
accessing data and responding to the initial data request packet
sent across the Internet. This technique is useful when a user is
maintaining a virtual session with a remote server because it is
imperative to allow the user to appear to be connected without
having to experience delays when accessing data. The method 300 and
the method 400 may be performed together in a complementary fashion
to make the virtual session appear to be constantly available.
[0066] The method 400 may be practiced by the remote unit 100 and
the virtual session server 215. When the remote unit 100 initiates
the method, the virtual session server 215 executes steps 410, 415,
420, 430 and 435. When the virtual session server 215, the
application program 220, or the communication server 212 initiates
the method, one or a combination of these servers practice the
steps 405, 410, 415, 420, 430, and 435. The first step 405
involves, for example, receiving a communication request such as a
telephony call or an email for the remote unit 100. In some
systems, the first step 405 may involve a request generated from
within the application program 220.
[0067] Referring now to FIG. 5, a method 500 of establishing and
operating a virtual session is illustrated. For example, the method
500 establishes a virtual session between the remote unit 100 and
the virtual session server 215. The method 500 is practiced by both
the remote unit 100 and the virtual session server 215. In a first
step 505 a first physical layer communication connection is
established with a remote entity. If the method is practiced by the
remote unit 100, then the remote entity typically corresponds to
the virtual session server 215. The virtual session may be used to
support virtual sub-sessions between the remote unit 100 and the
application program 220. Also, a virtual sub-session may be
established between the remote unit 100 and the communication
server 212. For the purposes of discussion herein, all of these
virtual sessions will be referred to simply as virtual sessions. If
the method 500 is practiced by the virtual session server 215, then
the remote entity typically corresponds to the remote unit. The
step 505 may be activated according to the prediction 315, and the
step 505 may use the method 400 to allow the connection to be set
up with very low delay.
[0068] Control next passes from the first step 505 to a second step
510. In the second step 510 a session is established with the
remote entity. In a preferred embodiment, this involves exchanging
password information and agreeing upon a set of keys to encrypt
data transacted in the session. Also, the virtual session server
215 preferably sets up a table entry in the table structure 225.
The table entry indicates the presence of a virtual session. The
table entry may include modem parameters as discussed in connection
with FIG. 4. Also, the virtual session as set up in the table entry
links the remote unit to a user identification and a password as
presented to the application program 220. For example, a user name
and a password may be used as user authentication parameters.
Preferably public key encryption is used to encrypt all information
so the password sent from the remote unit 100 to the application
program 220 cannot be effectively intercepted. The remote unit 100
also preferably sets up a virtual session data structure to hold
similar information related to the virtual session. Once the
virtual session has been set up, the remote unit 100 may access the
application program 220. Also, the remote unit 100 may optionally
access the communication server 212 for communication services.
[0069] Control next passes from the second step 510 to a third step
515. In the third step 515, the physical connection established in
the first step 505 is dropped. Meanwhile the virtual session data
structures and table entries established in the second step 510 are
retained. The session is allowed to proceed while no physical layer
connection exists. That is, the step 510 is operative to set up a
table structure including one or more data structures which allows
a virtual session to be maintained in memory while other activities
occur. Hence a passive background thread of execution passes from
the step 510 to a passive step 540 whereby the virtual session is
maintained. This allows the remote unit 100 to stand by or be used
for steps of the workflow process 305 not requiring communication
with the application program 220. Once the user needs to
communicate with the application program 220, or when a prediction
315 is made, control next passes from the third step 515 to a
fourth step 520. The step 520 is operative to reestablish a second
physical layer communication connection to allow communication to
proceed once again using the session established in the second step
510. This connection reestablishment may be performed in response
to the prediction 315 and may use the low-delay connection
establishment technique of the method 400.
[0070] In some embodiments, the present invention involves using
distinct and separate communications media to perform the step 505
and the step 520. For example, a mobile worker may call in from
home to set up the virtual session in the step 510 using the first
physical layer communication connection established in the step
505. Later in the day, the worker may call in from a restaurant
while catching up on some records keeping. This second use of the
virtual session involves use of the second physical layer
communication connection which in this example is a wireless
connection different from the landline connection used to initiate
the session from home earlier in the day. At a still later time,
the worker may call in from a patient's home via a third physical
layer communication connection while performing home-care services.
If modem starting parameters have been stored in table 225, they
are preferably updated whenever the communication connection is
changed. Hence the virtual session of the present invention enables
a mobile worker to continue communications via the most expedient
and/or economical means without causing the user to have to
reestablish a communication connection. Preferably, when the remote
unit 100 is connected to a communications source via the connector
127, the remote unit 100 automatically detects this connectivity
and makes use of it for subsequent virtual-session communications.
That is, the present invention contemplates the availability of
various forms of "pigtail" connectors being available so the remote
unit 100 can operate in a "plug-and-play" fashion. Pigtails may be
supplied to allow the remote unit to connect to the PSTN, the
Internet, or to another computer via a universal serial bus, for
example.
[0071] Control next passes from the fourth step 520 to a fifth step
525. In the fifth step 525 an authorization sequence is exchanged.
This is preferably implemented using public key encryption and
digital signatures. Some embodiments may be developed which do not
implement the fifth step 525, but preferred embodiments do make use
of user authentication. After the fifth step 525 has completed, the
session is resumed in a sixth step 530. Over the course of the
virtual session, control may loop back to the third step 515 as
many times as the virtual session is activated with a new physical
connection. When the sixth step 530 is entered, the virtual session
is once again activated so that the passive step 540 also passes
control to the sixth step 530. In a minimal implementation of the
method, no looping occurs and the method terminates after the first
pass through the sixth step 530.
[0072] Referring now to FIG. 6, a method 600 practiced by the
virtual session server 210 is illustrated. In a first step 605, a
first physical layer communication connection is established for
communicating with the remote unit 100. Control next passes to a
second step 610 whereby a set of authorization parameters are
accepted and authenticated. As discussed in connection with FIG. 5,
the authentication parameters preferably include the exchange of
public keys which include a digital signature in accordance with
public key cryptography. Control next passes to a third step 615
where a user identification and a password are passed by the
virtual session server 215 to the application program 220 on behalf
of the remote unit 100. As discussed in connection with FIG. 5, the
user identification and the password to be presented to the
application program 220 are preferably transmitted in encrypted
form. Once the application program 220 authenticates the user
identification and password needed to gain access, the virtual
session server 215 enters an entry into the table structure 225 to
hold a set of session parameters. The session parameters include
the user identification, a session identifier, encryption data and
possibly other data such as modem starting parameters. Once the
session has been logged into the table, the user may use it to
communicate with the application program 220.
[0073] Control next passes from the fourth step 620 to a fifth step
625. In the fifth step 625 the physical layer connection is
dropped. This step is performed when the remote unit does not
currently require communications with the application program 220.
In step 650 the virtual server maintains the application session
while the physical connection is disconnected. At a later time,
when the user needs access to the application program or when the
prediction 315 is made, control next passes to a sixth step 630. In
the sixth step 630 a second physical layer connection is
established to allow communication between the remote unit 100 and
the application 220 to resume. As discussed in connection with FIG.
5, the second physical layer connection may involve a different
communication path and/or medium as was used for the first physical
layer connection. That is, a plurality of communications media are
preferably supported to allow the user to call in via different
means, for example via a wireless or a wireline connection. The
step 630 may be initiated due to actions at the remote unit 100 or
in response to events occurring in the server. For example, the
communication server 212 may receive a call for the remote unit.
Alternatively an email may be received which needs to be forwarded
to the remote unit. In such a case, the sixth step 630 optionally
involves sending a caller identification packet to let the remote
unit know what type of communication, such as a voice telephony
call, an email, or a fax, is inbound. A caller identification
packet is a sequence of information bits sent across a
communication connection identifying the calling party of the
connection. In standard telephone systems, the caller
identification packet is transmitted between the first and second
rings when the telephone call is being set-up. More details
relating to communications initiated by the virtual session server
215 back to the remote unit 100 are discussed in connection with
FIG. 7.
[0074] Once the second physical layer communication connection is
established in the sixth step 630, possibly according to the method
400, control next passes to a seventh step 635. In the seventh step
635, authorization codes are verified similarly to the second step
610. Once the user codes have been verified to be correct, control
next passes to an eighth step 640 whereby communication once again
resumes using the previously established virtual session.
[0075] Referring now to FIG. 7, a method 700 of processing
communication requests in a virtual session is illustrated. This
method is preferably practiced by the virtual session server 215
simultaneously with the method 600. In a first step 705 a virtual
session is established between the virtual session server 215 and
the remote unit 100 as discussed in connection with FIGS. 5 and 6.
At some later time, while the virtual session is active, the
communication server 212 receives an incoming communication request
for the remote unit 100. Because the virtual session server 215
practices the method 500 and/or the method 600, depending on the
time of arrival of the communication, the remote unit 100 may or
may not be physically connected to the virtual session server 215
by a physical communication link. Hence when the communication is
received, control passes from the step 705 based on a decision 710
which determines whether a physical connection currently exists to
the remote unit 100.
[0076] If the virtual session is presently in a state whereby the
physical connection has been disconnected, control passes from the
first step 705 to a second step 715. In the second step 715 the
communication request is accepted by the communication server 212
through a direct connection or via the communication interface 210.
Control next passes to a third and optional step 720 whereby a
specific caller identification packet is associated with the
communication type. For example, if the communication involves a
telephone call a fist caller identification packet is sent
identifying an extension used for telephone calls. If the
communication involves an email, a second caller identification
packet is sent identifying an extension used for email. On the
other hand, if the communication comes from the application program
220, still another caller identification packet is sent. When this
optional use of a caller identification packet is employed, the
remote unit 100 has the information needed to properly and
immediately respond to an incoming call as discussed in connection
with FIG. 8. If a call is received by the remote unit from a source
other than the virtual connection server 215, the caller
identification information will identify the call as not being
associated with the virtual session. Control next passes to a
fourth step 725 whereby an automatic dialer responds to
communication requests and the communication is forwarded to the
remote unit 100.
[0077] Another situation arises when the communication request
arrives while the remote unit 100 and the virtual session server
215 are currently connected by an existing physical channel.
According to one mode of processing, control stays in the first
step 705 while communication proceeds in an active phase of a
virtual session. When the communication request arrives, the
communication server 212 signals to the virtual session server that
a new call has arrived for the remote unit 100. The virtual session
server then causes the existing physical layer communication
connection to be dropped and thus control passes from the first
step 705 to the second step 715 as in the foregoing discussion. In
another mode of processing, the existing physical layer
communication connection is left in tact and control passes from
the first step 705 to a fifth step 745. In the fifth step 745, the
communication is packetized, and in a sixth step 750 the
communication packets are passed along the existing physical layer
communication connection. Control continues to loop back from the
sixth step 750 to the fifth step 745 during the course of the
communication. In this mode of operation the existing physical
layer communication connection is shared to provide the remote user
with a means to stay connected to the application program 220 and
communicate at the same time. In this case the physical layer is
time shared by the virtual session to allow multiple modes of
communications to proceed in parallel.
[0078] Note the method 700 provides the user of the remote unit 100
with a virtual presence in the work place while actually being
remote. Independent of whether the remote unit is presently
actively connected to the virtual session server, the communication
request may be forwarded to the remote unit 100 making the remote
user appear to be present in the office at all times. The only time
the remote unit 100 would not be reachable is when it is engaged in
a communication with an entity other than the virtual connection
server. This problem may be mitigated by allowing the remote unit
to only be reachable through the access number provided by the
communication server 212. If a call is placed from the remote unit
to another point, this call too may be routed through the
communication server 212. Systems which do allow the remote unit to
make calls outside the virtual session may preferably employ voice
mail at the communication server 212. When the remote unit again
becomes available, the virtual session server 215 may forward the
communication to the remote unit according to the method 700.
Remote units may also be designed using call-waiting concepts
whereby the virtual session may be re-activated by interrupting
another call.
[0079] Referring now to FIG. 8, an optional method 800 practiced by
the remote unit 100 is illustrated. This method is practiced when a
virtual session exists, the remote unit and the virtual session
server are presently not connected via a physical channel, and a
communication request is to be forwarded to the remote unit 100. In
a first step a first ring signal is detected. Optionally, the first
ring signal is suppressed so the user will not hear it. In some
systems a vibrational first ring signal may be allowed to pass
through to notify the user of an incoming communication. In still
other embodiments, the remote unit may be programmed to sound a
normal ring on the first ring signal. In some embodiments the ring
signal will not be a traditional telephone ring signal but will in
general be any signal indicative of an incoming communication
request.
[0080] In current systems, a caller identification packet is
presented to the called party after the first ring signal. Hence
identification of the calling party becomes available at this time.
After the first ring signal, control passes from the first step 805
to a second step 810. In the second step 810, the caller
identification information is evaluated. Note it would be
preferable to accept the caller identification data before the
first ring, and the present invention contemplates systems whereby
the virtual session server 215 signals to the PSTN to provide a
caller identification packet before the first ring. This service
does not appear to be available from telephone service providers at
this time. Embodiments also comprehended by the present invention
include systems whereby the remote unit 100 immediately picks up an
incoming call and caller identification information is sent by the
virtual connection server 215 over the connection identifying the
call-type. During the second step 810, the caller identification
packet is evaluated. As discussed in connection with the third step
720 of the method 700, the virtual session server 215 sends out a
caller identification packet to identify the type of incoming call.
For example, different caller identification packets indicate
whether the incoming call is an email, a voice telephone call, or a
communication from the application program 220.
[0081] Control next passes from the second step 810 to a third step
815. In the third step 815, an application layer program is
selected to process the incoming call. In the foregoing examples,
an application may be launched to accept an email message, a voice
telephone call, or to accept a communication from the application
program 220. If the communication is an email, it may be desirable
to pop a mailbox icon on the screen or to produce a speech signal
stating "you've got mail." If the incoming call is a voice call, it
may be desirable to allow the telephone to ring like a normal
telephone. If the communication is from the application program
220, it may be desirable to update data located in the screens of
the workflow or otherwise signal the presence of new data. Once the
appropriate application has been launched to handle the incoming
communication, control next passes to a fourth step 820 whereby
communication session is reactivated and the communication is
processed. For example, one or more packets of information may be
received and related information such as an email message may be
displayed. Also, a telephone call may be allowed to proceed or a
set of information may be downloaded from the application program
220.
[0082] Although the present invention has been described with
reference to specific embodiments, other embodiments may occur to
those skilled in the art without deviating from the intended scope.
For example, other forms of communications such as fax messages may
be accepted and displayed by the remote unit 100. Also, the present
invention may be used for applications other than mobile workers
and Internet users. Virtual sessions according to the present
invention are applicable to any situation where a continual
connectivity is required but the cost to remain continuously
connected is high. Vehicle computers with cellular radio based
Internet connections are an example. In such systems, the remote
unit 100 may be a vehicle-mounted computer or may include a
connection to a vehicle-mounted computer. Also, virtual sessions
according to the present invention are applicable to any situation
where the user should not be burdened with the need to upload
and/or download data and go through connection and disconnection
procedures. Therefore, it is to be understood that the invention
herein encompasses all such embodiments which do not depart from
the spirit and scope of the invention as defined in the appended
claims.
* * * * *