U.S. patent application number 09/835875 was filed with the patent office on 2002-01-03 for system and method for shifting functionality between multiple web servers.
Invention is credited to Vange, Mark.
Application Number | 20020002611 09/835875 |
Document ID | / |
Family ID | 22729619 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020002611 |
Kind Code |
A1 |
Vange, Mark |
January 3, 2002 |
System and method for shifting functionality between multiple web
servers
Abstract
A system for providing network functionality from a plurality of
network-connected servers to at least one network-connected client
computer. A management component is coupled to each of the servers.
A shifting component coupled to or within the management component
operates to shift data and program components between the
networkconnected servers so as to configure a selected server to
implement a specified set of functionality. A redirection component
responsive to a client request for the specified set of
functionality redirects the requesting client to the selected
server(s).
Inventors: |
Vange, Mark; (Toronto,
CA) |
Correspondence
Address: |
Stuart T. Langley, Esq.
Hogan & Hartson, LLP
Suite 1500
1200 17th Street
Denver
CO
80202
US
|
Family ID: |
22729619 |
Appl. No.: |
09/835875 |
Filed: |
April 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60197490 |
Apr 17, 2000 |
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Current U.S.
Class: |
709/223 ;
709/203; 709/227; 709/236 |
Current CPC
Class: |
H04L 63/1408 20130101;
H04L 69/329 20130101; H04L 67/02 20130101; H04L 67/10015 20220501;
H04L 67/1021 20130101; H04L 63/0428 20130101; H04L 67/568 20220501;
H04L 63/1458 20130101; H04L 67/01 20220501; H04W 8/04 20130101;
H04L 67/5681 20220501; H04L 67/61 20220501; G06F 2209/5021
20130101; H04L 67/1001 20220501; H04L 69/16 20130101; H04L 61/4511
20220501; H04L 63/1416 20130101; H04L 67/561 20220501; Y10S
707/99944 20130101; Y10S 707/99945 20130101; G06F 9/505 20130101;
H04L 67/5682 20220501; H04L 67/1008 20130101; H04L 67/563 20220501;
H04L 67/565 20220501; H04L 63/0272 20130101; H04L 67/142 20130101;
H04L 67/564 20220501; G06F 9/5055 20130101; H04L 47/10 20130101;
H04L 47/193 20130101; H04L 67/1029 20130101; H04L 67/1031 20130101;
H04L 45/14 20130101; H04L 67/101 20130101; H04L 9/40 20220501; H04L
47/24 20130101; H04L 67/1034 20130101; G06F 9/5027 20130101; G06F
9/5088 20130101; H04L 67/303 20130101 |
Class at
Publication: |
709/223 ;
709/203; 709/227; 709/236 |
International
Class: |
G06F 015/16; G06F
015/173 |
Claims
We claim:
1. A system for providing functionality over a network comprising:
a plurality of network-connected servers, each providing access to
a set of functions implemented by program components within the
server; at least one network-connected client computer; a
management component coupled to each of the network-connected
servers; a shifting component within the management component
operable to shift data and program components between the
network-connected servers so as to configure a selected server to
implement a specified set of functions; and a redirection component
responsive to a client request for the specified set of functions
to redirect the requesting client to the selected server.
2. The system of claim 1 wherein the selected network server
further comprises: a data storage mechanism; processes responsive
to client requests to accesses data in the data storage mechanism;
and processes operable to generate a response to the client
requests using the accessed data.
3. The system of claim 2 further comprising: processes operating
independently of client requests to update data contained within
the data storage mechanism.
4. The system of claim 2 wherein the data storage mechanism
comprises a cache.
5. The system of claim 1 wherein the program components implement a
database management system interface.
6. The system of claim 1 wherein at least one of the
network-connected servers is designated as a central authority for
a particular set of functions and the program components implement
processes for communicating with the central authority.
7. A system for providing functionality over a network comprising:
a plurality of network-connected servers, each providing access to
a set of functions implemented by program components within the
server; at least one network-connected client computer; and a
redirection component responsive to a client request for selecting
a particular one of the network-connected servers that implements a
set of functions suitable for responding to the client request and
redirecting the requesting client to the selected server.
8. The system of claim 7 wherein the plurality of network-connected
servers comprise: a first network-connected server in communication
with the client; a second network-connected server in communication
with the first network-connected server, wherein the redirection
component operates within the first network-connected server to
identify and communicate with the second network-connected server
to enable the first network-connected server to respond to the
client request.
9. The system of claim 8 wherein the first and second
network-connected servers communicate with each other over an
enhanced communication channel.
10. A system for implementing a web site comprising: a first web
server configured to provide a preselected set of content and
service applications in response to client requests; a second web
server configured to provide a preselected set of content and
service applications in response to requests from the first web
server; a communication channel established between the first and
second web servers, wherein the web site is implemented by
delivering web pages from at least one of the first and second web
servers by distributed and cooperative interaction using services
and content provided by both first and second web servers.
11. The system of claim 10 wherein the web site includes
functionality that is implemented by service applications running
on both the first and second web servers.
12. The system of claim 10 wherein the web site content is provided
by the first web server and the web site functionality is provided
by service applications running on the second web server.
13. The system of claim 10 wherein the web site content is provided
by the second web server and the web site functionality is provided
by service applications running on the first web server.
14. A system for rendering graphical information in a network
environment comprising: a network; providing a first network
service for accessing raw data from a data store; providing a
second network service configured to obtain the raw data from the
first network service over the network; application software in the
second network service for rendering a graphic display of the raw
data; and a client interface in the second network service for
communicating the rendered graphic display from the second network
service to a client application.
15. A method for delivering customized content from one or more
network services to a client computer comprising the acts of:
providing a plurality of network servers each providing access to a
set of raw data; requesting the content from the network servers;
causing the network server to incorporate the raw data into a
"usuable format"; and delivering the "usuable format"from the
network server to a client computer.
16. A system for supplying rendered information in a network
environment comprising: providing a first server for accessing raw
data from a data store; providing a second server configured to
obtain the raw data from the first network resource; application
software in the second server for transforming the raw data into a
rendered format; and a client interface in the second server for
communicating the rendered format from the second server to a
client application.
17. A system for delivering functionality from a network resource
comprising: a client machine coupled to a network, the client
machine having a user interface and a preferred format for
presenting data using the user interface; a gateway machine coupled
to the network and having a client interface for receiving requests
from the client and supplying responses to the client, the gateway
machine having knowledge of the preferred format; and formatting
mechanisms within the gateway machine for receiving content in a
first format from the network resource and reformatting the
received content to a second format for communication to the client
machine.
Description
BACKGROUND OF THE INVENTION
RELATED APPLICATIONS
[0001] The present invention claims priority from U.S. Provisional
Patent Application No. 60/197,490 entitled CONDUCTOR GATEWAY filed
on Apr. 17, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates, in general, to network
information access and, more particularly, to software, systems and
methods for shifting functionality between multiple web servers in
a coordinated multi-server web site.
RELEVANT BACKGROUND
[0003] Increasingly, business data processing systems,
entertainment systems, and personal communications systems are
implemented by computers across networks that are interconnected by
internetworks (e.g., the Internet). The Internet is rapidly
emerging as the preferred system for distributing and exchanging
data. Data exchanges support applications including electronic
commerce, broadcast and multicast messaging, videoconferencing,
gaming, and the like.
[0004] The Internet is a collection of disparate computers and
networks coupled together by a web of interconnections using
standardized communications protocols. The Internet is
characterized by its vast reach as a result of its wide and
increasing availability and easy access protocols. Unfortunately,
the ubiquitous nature of the Internet results in variable bandwidth
and quality of service between points. The latency and reliability
of data transport is largely determined by the total amount of
traffic on the Internet and so varies wildly seasonally and
throughout the day. Other factors that affect quality of service
include equipment outages and line degradation that force packets
to be rerouted, damaged and/or dropped. Also, routing software and
hardware limitations within the Internet infrastructure may create
bandwidth bottlenecks even when the mechanisms are operating within
specifications.
[0005] Often, a given entity will provide multiple services using
multiple servers. For example, a typical suite of Internet services
might include a web server, a mail server, a file transfer server,
a chat server and the like. These servers may execute on a single
machine or on multiple machines. Characteristically, the services
are provided on a well-defined machine at a known network address
so that users can readily find the machine that is needed to
perform a particular function. As a result, the functionality is
bound to particular servers. More recently, efforts have been made
to replicate services on geographically or topologically
distributed servers to improve capacity and performance. However,
these solutions maintain the static binding between functionality
and particular hardware/software platforms that implement the
functionality.
[0006] Unfortunately, the ubiquitous nature of the Internet results
in variable bandwidth and quality of service between points. The
latency and reliability of data transport is largely determined by
the total amount of traffic on the Internet and so varies wildly
seasonally and throughout the day. Other factors that affect
quality of service include equipment outages and line degradation
that force packets to be rerouted, damaged and/or dropped. Also,
routing software and hardware limitations within the Internet
infrastructure may create bandwidth bottlenecks even when the
mechanisms are operating within specifications.
[0007] As a result of this static allocation of functionality, the
functionality provided by the network-connected servers behaves
unpredictably, and may give less than optimal performance. Even
where functionality is replicated across multiple servers, service
remains suboptimal. Moreover, load balancing across multiple
servers providing replicated functionality is problematic and often
leads to inefficient use of some resources while other resources
are overburdened.
[0008] A particular need exists in environments that involve
multiple users accessing a network resource such as a web server.
Web servers are typically implemented with rich functionality and
are often extensible in that the functionality provided can be
increased modularly to provide general-purpose and special-purpose
functions. Examples include information services, broadcast,
multicast and video conference services, as well as most electronic
commerce (e-commerce) applications. In these applications it is
important to that functionality provided by network-connected
resources be provided in a dependable, timely and efficient
manner.
[0009] In e-commerce applications, it is important to provide a
satisfying buyer experience that leads to a purchase transaction.
To provide this high level of service, a web site operator must
ensure that data is exchanged with the customer in the most usable
and efficient fashion. An e-commerce transaction may involve
several services including search services, file retrieval
services, shopping cart services and payment services. These varied
services are typically delivered from a single network node,
however the node may be less than optimal for a particular
customer. Even if multiple server nodes were available, current
technology does not provide a way to select a particular network
node. Moreover, there is no mechanism for selectively shifting
particular functionality among available serving nodes to improve
performance on a function-by-function basis.
[0010] Until now, however, the e-commerce site owner has had little
or no control over the transport mechanisms through the Internet
that affect the latency and quality of service. This is akin to a
retailer being forced to deal with a customer by shouting across
the street, never certain how often what was said must be repeated,
and knowing that during rush hour communication would be nearly
impossible. While efforts are continually being made to increase
the capacity and quality of service afforded by the Internet, it is
contemplated that congestion will always impact the ability to
predictably and reliably offer a specified level of service.
Moreover, the change in the demand for bandwidth increases at a
greater rate than does the change in bandwidth supply, ensuring
that congestion will continue to be an issue into the foreseeable
future. A need exists for a system to exchange data over the
Internet that provides a high quality of service even during
periods of congestion. Many electronic commerce transactions are
abandoned by the user because system performance degradations
frustrate the purchaser before the transaction is consummated.
While a transaction that is abandoned while a customer is merely
browsing through a catalog may be tolerable, abandonment when the
customer is just a few clicks away from a purchase is highly
undesirable. However, existing Internet transport mechanisms and
systems do not allow the e-commerce site owner any ability to
distinguish between the "just browsing" and the "about to buy"
customers. In fact, the vagaries of the Internet may lead to the
casual browser receiving a higher quality of service while the
about-to-buy customer becomes frustrated and abandons the
transaction.
[0011] Partial solutions have been implemented by systems that
cache Internet content at multiple distributed locations. In
theory, when content can be served from a cache location, it can be
delivered with lower latency than if it were served from a single
originating web server. However, the content must be copied from
its origin to the multiple caches resulting in a tremendous volume
of data that must be duplicated and transported. Moreover, it is
difficult to keep all of the cache copies coherent with the origin.
Furthermore, a cache handles only static content and does not
distribute functionality to locations from which it can be more
efficiently delivered. Hence, caching is only a partial solution to
the many web sites that use dynamically generated web pages.
SUMMARY OF THE INVENTION
[0012] Briefly stated, the present invention involves a system for
providing functionality and services from a plurality of
network-connected resources where the mechanisms, such as computer
code modules, implementing the functionality are dynamically
assigned to one or more of the various network connected resources.
Users are dynamically and preferably transparently directed to the
network resource in which requested functionality currently
resides.
[0013] A system for providing network resources from a plurality of
network-connected resources to at least one network-connected
client computer. A management component is coupled to each of the
resources. A shifting component within the management component
operates to shift data and program components between the
network-connected resources so as to configure a selected resource
to implement a specified set of functionality and/or provide a
specified set of resources. A redirection component responsive to a
client request for the specified set of functionality redirects the
requesting client to a server offering the specified
functionality.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 illustrates a general distributed computing
environment in which the present invention is implemented;
[0015] FIG. 2a-FIG. 2d show in block-diagram form entity
relationships in a system in accordance with the present
invention;
[0016] FIG. 3 illustrates in block-diagram form significant
components of a particular implementation of a system in accordance
with the present invention;
[0017] FIG. 4 shows a domain name system used in an implementation
of the present invention; FIG. 5 shows front-end components of FIG.
2 in greater detail;
[0018] FIG. 6 shows back-end components of FIG. 2 in greater
detail; and
[0019] FIG. 7 shows a conceptual block diagram of the system of
FIG. 2 in an alternative context.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] In establishing a network architecture for providing
services, there is a continuous compromise made in selecting where,
topologically, to locate the hardware and software that provides
the services. In almost all networks, quality of service amongst
the nodes using the services will differ. This compromise is more
apparent in Internet-based systems because the differential between
users is greater, is unpredictable, and varies significantly over
time. Often, the architect has incomplete knowledge of where the
nodes that will access the services exist. The present invention
addresses this compromise by providing a generic software/hardware
infrastructure in which the functionality is provided by any or all
of a large number of nodes. Functionality is dynamically shifted
amongst the available nodes to provide improved service to all
participants.
[0021] The present invention generally involves systems, methods
and software for delivering functionality from network-connected
resources (e.g., servers) to networkconnected appliances (e.g.,
clients). It is recognized that the roles of client and server are
flexibly defined in an operating network as some entities play both
roles at any given time and may in fact play both roles at the same
time. These terms are used for convenience herein for ease of
explanation, however, unless expressly indicated otherwise the
terminology is not to be considered a limitation on the broader
teachings of the present invention as set forth in the claims.
Further, the examples are directed at web-based systems using the
Internet, however, more generally, the present invention relates to
any type of functionality or resources provided over a network and
need not be implemented as a web-based system. Hence, unless
specified otherwise, a "web server" is synonymous with a "server"
or other entity that delivers functionality in response to
requests. Likewise, a "browser" is synonymous with a client or
other entity that requests and uses a particular set of
functionality.
[0022] The particular examples herein often refer to a system in
which a particular set of functionality is embodied in a specific
web site controlled by an entity such as a business or service
provider. This model fits conventional Internet services deployment
in which functionality is statically bound to one or more specific
network nodes. In one respect, the present invention can be viewed
as an augmentation of this conventional model that enables
functionality to be distributed from its statically assigned
location to a variety of dynamically assigned nodes that implement
the web site's functionality. In a second aspect, the present
invention contemplates that the entity-controlled web site may
exist only virtually (e.g., none of the web site functionality is
statically bound to a particular node) and that all of the site
functionality is embodied in the nodes to which the functionality
is distributed.
[0023] The present invention is illustrated and described in terms
of a distributed computing environment such as an enterprise
computing system using public communication channels such as the
Internet. However, an important feature of the present invention is
that it is readily scaled upwardly and downwardly to meet the needs
of a particular application. Accordingly, unless specified to the
contrary, the present invention is applicable to significantly
larger, more complex network environments, including wireless
network environments, as well as small network environments such as
conventional LAN systems.
[0024] The present invention is particularly useful in applications
where there is an large amount of data communicated between web
servers and web clients (i.e., browser software) or where
timeliness (e.g., low latency transport) is important. For example,
real-time stock quotes, multi-player games, multi-tiered service to
ASP (application service provider) software distribution models
benefit from the improvements provided by the present invention.
Although the present invention will be described in terms of
particular applications, these examples are provided to enhance
understanding and are not a limitation of the essential teachings
of the present invention.
[0025] The current experience of using an overloaded, topologically
distant or unavailable web site that is one of frustration and
constant and unexplained errors. In terms of conventional
phone-order shopping, this is akin to a customer phoning a favorite
mail order company only to receive a constant busy signal or
non-stop ringing or to be connected to an operator only to be
disconnected prior to the completion of the order placement. Under
the present invention, web site operators have a mechanism to
communicate with their customers even if they cannot handle their
web query immediately. One aspect of the present invention is an
ability to serve alternative content and/or functionality in
response to a request for particular content and/or functionality.
For example, the invention contemplates a system that presents the
user with a pre-defined set of web pages which can apologize for
delays, instruct the user on what to do in case of an emergency,
advertise additional options or new product offerings, and/or
provide other functionality such as call-center type features
including queue management.
[0026] The present invention uses a web site delivery system in
which a plurality of front-end web servers and back-end web servers
cooperate to deliver content and services of the web site. A
front-end web server is an application program that is enabled to
generate web pages (e.g., HTML pages) in response to HTTP requests
received from a client software application such as a web browser.
A back-end or "originating" web server is a software application
that receives requests from the front-end web server and is
logically close to one or more network resources (e.g., data
storage, database servers, and the like). The term "logically
close" as used herein refers to quality of service between two
points and may reflect physical proximity, topological proximity or
other factors that affect quality of service and speed of service
between two points.
[0027] A web site is conventionally implemented by including all
the functionality implemented by the web site in a web server or
web servers that are logically close to the network resources to be
served by that web site. In contrast, the present invention
implements web site functionality and behavior within one or more
front-end web server(s) that communicate over the public network or
WAN to obtain the network resources or possess the network
resources locally. Preferably, the front-end web server includes an
enhanced communication channel for communicating with the back-end
web server. This shift in functionality from the back-end to the
front-end provides improved performance in many applications. CPU
intensive processing can be performed by the front-end server
thereby relieving the back-end web server to handle requests. Also,
because multiple front-ends may access the same back-end servers,
the CPU intensive functionality is distributed over a larger number
of machines as needed to provide improved performance and access to
a larger number of clients.
[0028] For purposes of this document, a web server is a computer
running server software coupled to the World Wide Web (i.e., "the
web") that delivers or serves web pages. The web server has a
unique IP address and accepts connections in order to service
requests by sending back responses. A web server differs from a
proxy server or a gateway server in that a web server has resident
a set of resources (i.e., software programs, data storage capacity,
and/or hardware) that enable it to execute programs to provide an
extensible range of functionality such as generating web pages,
accessing remote network resources, analyzing contents of packets,
reformatting request/response traffic and the like using the
resident resources. In contrast, a proxy simply forwards
request/response traffic on behalf of a client to resources that
reside elsewhere, or obtains resources from a local cache if
implemented. A web server in accordance with the present invention
may reference external resources of the same or different type as
the services requested by a user, and reformat and augment what is
provided by the external resources in its response to the user.
Commercially available web server software includes Microsoft
Internet Information Server (IIS), Netscape Netsite, Apache, among
others. Alternatively, a web site may be implemented with custom or
semi-custom software that supports HTTP traffic.
[0029] FIG. 1 shows an exemplary computing environment 100 in which
the present invention may be implemented. Environment 100 includes
a plurality of local networks such as Ethernet network 102, FDDI
network 103 and Token ring network 104. Essentially, a number of
computing devices and groups of devices are interconnected through
a network 101. For example, local networks 102, 103 and 104 are
each coupled to network 101 through routers 109. LANs 102, 103 and
104 may be implemented using any available topology and may
implement one or more server technologies including, for example
UNIX, Novell, or Windows NT networks, or peer-to-peer type network.
Each network will include distributed storage implemented in each
device and typically includes some mass storage device coupled to
or managed by a server computer. Network 101 comprises, for
example, a public network such as the Internet or another network
mechanism such as a fibre channel fabric or conventional WAN
technologies.
[0030] Local networks 102, 103 and 104 include one or more network
appliances 107. One or more network appliances 107 may be
configured as an application and/or file server. Each local network
102, 103 and 104 may include a number of shared devices (not shown)
such as printers, file servers, mass storage and the like.
Similarly, devices 111 may be shared through network 101 to provide
application and file services, directory services, printing,
storage, and the like. Routers 109 provide a physical connection
between the various devices through network 101. Routers 109 may
implement desired access and security protocols to manage access
through network 101. Network appliances 107 may also couple to
network 101 through public switched telephone network 108 using
copper or wireless connection technology. In a typical environment,
an Internet service provider 106 supports a connection to network
101 as well as PSTN 108 connections to network appliances 107.
[0031] Network appliances 107 may be implemented as any kind of
network appliance having sufficient computational function to
execute software needed to establish and use a connection to
network 101. Network appliances 107 may comprise workstation and
personal computer hardware executing commercial operating systems
such as Unix variants, Micrsosoft Windows, Macintosh OS, and the
like. At the same time, some appliances 107 comprise portable or
handheld devices using wireless connections through a wireless
access provider such as personal digital assistants and cell phones
executing operating system software such as PalmOS, WindowsCE, and
the like. Moreover, the present invention is readily extended to
network devices such as office equipment, vehicles, and personal
communicators that make occasional connection through network
101.
[0032] Each of the devices shown in FIG. 1 may include memory, mass
storage, and a degree of data processing capability sufficient to
manage their connection to network 101. The computer program
devices in accordance with the present invention are implemented in
the memory of the various devices shown in FIG. 1 and enabled by
the data processing capability of the devices shown in FIG. 1. In
addition to local memory and storage associated with each device,
it is often desirable to provide one or more locations of shared
storage such as disk farm (not shown) that provides mass storage
capacity beyond what an individual device can efficiently use and
manage. Selected components of the present invention may be stored
in or implemented in shared mass storage.
[0033] FIG. 2a-FIG. 2d illustrate entity relationships involved in
an interaction in which functionality provided by an originating
web site 210 is provided from a variety of sources including
front-ends 201. A single client 205 is shown in FIG. 2a-FIG. 2d,
however, a number of clients will be enabled to use the system
simultaneously. Each client 205 has a network connection that
supports a communication channel to one or more originating servers
210 in which a particular web site is implemented.
[0034] In a typical client-server transaction shown in FIG. 2a, a
client makes a request for resources and/or functionality
implemented on originating server 210. In a web-based
implementation, this request takes the form of an HTTP request
datagram specifying a uniform resource locator (URL) that
identifies originating server 210. As in conventional networks,
various routing actions are taken within network 101 (described
below) to direct the request datagram to its intended destination.
In a conventional environment, client 205 waits for a response to
the request datagram.
[0035] Management component 207 shown in FIG. 2c, in practice,
embodies a number of routing and control functions that may be
implemented in a number of servers as opposed to the single entity
shown in FIG. 2b-FIG. 2c.Mechanisms shown in FIG. 4 are used to
redirect client 205 to one of a plurality of front-end servers 201
shown in FIG. 2c. Another function of management component 207 is
to dynamically maintain and shift content and functionality between
originating server 210 and the various available front-end machines
201. In a particular implementation, management component 207
maintains an outof-band or in-band connection 202 with each
front-end server 201 and each originating server 210. Connection
202 enables the dynamic shifting of functionality as needed to meet
the needs of a particular application.
[0036] Unlike conventional networks, the present invention operates
as shown in FIG. 2b to route the request from client 205 to a
particular front-end 201 that is able to respond to the request
from client 205 as shown in FIG. 2d. Non-selected front-ends 201,
shown in phantom in FIG. 2d, are not involved in responding to the
request. Preferably, client 205 is unaware that content and/or
functionality is being provided by an entity other than originating
server 210. In fact, it is contemplated that originating server 210
may not exist in a physical sense at all. So long as the desired
functionality is provided by the available front-ends 201,
originating server 210 may become unnecessary as a physical
entity.
[0037] Management component 207 may shift functionality after the
request is received, or proactively before the request is received
based on predictive logic. Front-end servers may cache or locally
store content and program code that are frequently used to control
delays in porting functionality between nodes. It is contemplated
that management component may select originating server 210 itself
in some circumstances to provide content and functionality that is
most efficiently deployed at a particular time or in particular
circumstances by server 210. In this manner, functionality,
content, and behavior is dynamically shifted amongst available
resources.
[0038] In a particular example, management component 207 measures
and maintains metrics associated with each front-end server 201
over channel 202. These metrics include, for example, processor
load, quality of service between various points, memory resource
load, and other measurements that impact the ability of a front-end
server to efficiently respond to requests. Management component 207
uses these metrics in the selection of a particular front-end 201
to respond to a particular request. Preferably, management
component 207 also maintains an inventory of the content and
functionality available at each front-end server 201 so that
requests can be directed to a front-end that is already configured
to provide the desired functionality.
[0039] In the preferred web-based implementation, front-end servers
201 are implemented by web server software that supports dynamic
expansion of functionality. Several commercial off-the-shelf web
server packages offer such extensible functionality through the use
of plug-ins, servelets, agents and other modular program
components. In some cases, it is contemplated that special purpose
web server software will be used in front-ends 201 that implement
more streamlined and compact software than is possible with
off-the-shelf general purpose products. It is contemplated that any
computer upon which front-end 201 executes will support multiple
instances of front-end 201. In other words, a network node upon
which a front-end 201 resides may actually have multiple front-ends
201 in existence at any given time. In this specific example,
client 205 comprises a network-enabled graphical user interface
such as a World Wide Web (web) browser. However, the present
invention is readily extended to client software other than
conventional web browser software. Any client application that can
access a standard or proprietary user level protocol or language
for network access is a suitable equivalent. For convenience, the
term "web site" is used interchangeably with "web server" in the
description herein although it should be understood that a web site
comprises a collection of content, programs and processes
implemented on one or more web servers. A web site is owned by the
content provider such as an e-commerce vendor whereas a web server
refers to set of programs running on one or more machines coupled
to an Internet, intranet, or other network node. The web site 210
may be hosted on the site owner's own web server, or hosted on a
web server owned by a third party. A web hosting center is an
entity that implements one or more web sites on one or more web
servers using shared hardware and software resources across the
multiple web sites. In a typical web infrastructure, there are many
web browsers, each of which has a TCP connection to the web server
in which a particular web site is implemented. The present
invention adds two components to the infrastructure: a front-end
201 and back-end 203. Front-end 201 and back-end 203 are coupled by
a managed data communication link 202 that forms, in essence, a
private network.
[0040] FIG. 3 shows a particular implementation of the
functionality shifting system of FIG. 2a-FIG. 2d. that uses not
only front-end servers 201, but also one or more back-end servers
203 to further improve functionality shifting performance. In the
particular implementation shown in FIG. 3, functionality can be
served from originating server 210, back-end server 203 and/or
front-end servers 201 as needed to meet the needs of a particular
application.
[0041] In FIG. 3, a private network 200 implemented within the
Internet infrastructure. Private network 200 expedites and
prioritizes communications between a client 205 and a web site 210.
In the specific examples herein client 205 comprises a
network-enabled graphical user interface such as a web browser.
However, the present invention is readily extended to client
software other than conventional web browser software. Any client
application that can access a standard or proprietary user level
protocol for network access is a suitable equivalent. Examples
include client applications for file transfer protocol (FTP)
services, voice over Internet protocol (VOIP) services, network
news protocol (NNTP) services, multi-purpose Internet mail
extensions (MIME) services, post office protocol (POP) services,
simple mail transfer protocol (SMTP) services, as well as Telnet
services. In addition to network protocols, the client application
may access a network application such as a database management
system (DBMS) in which case the client application generates query
language (e.g., structured query language or "SQL") messages. In
wireless appliances, a client application may communicate via a
wireless application protocol (WAP) or the like.
[0042] Front-end mechanism 201 serves as an access point for
client-side communications. Front-end 201 implements a gateway
that, from the perspective of client 205, appears to be the web
site 210. Front-end 201 comprises, for example, a computer that
sits "close" to clients 205. By "close", it is meant that the
average latency associated with a connection between a client 205
and a front-end 201 is less than the average latency associated
with a connection between a client 205 and a web site 210.
Desirably, the connection between front-end computers and clients
205 have low latency and high bandwidth. For example, the fastest
available connection may be implemented in point of presence (POP)
of an Internet service provider (ISP) 106 used by a particular
client 205. However, the placement of the front-ends 201 can limit
the number of browsers that can use them. Because of this, in some
applications, it may be more practical to place one front-end
computer in such a way that several POPs can connect to it. Greater
distance between frontend 201 and clients 205 may be desirable in
some applications as this distance will allow for selection amongst
a greater number front-ends 201 and thereby provide significantly
different routes to a particular back-end 203. This may offer
benefits when particular routes and/or front-ends become congested
or otherwise unavailable.
[0043] Enhanced communication channel 212 is implemented by
cooperative actions of the front-end 201 and back-end 203. Back-end
203 processes and directs data communication to and from
originating server 210. In a particular example, transport
mechanism 212 communicates data packets using a proprietary
protocol over the Internet. Hence, the present invention does not
require heavy infrastructure investments and automatically benefits
from improvements implemented in the general-purpose network 101.
Unlike the general purpose Internet, front-end 201 and back-end 203
may be assigned to serve accesses to one or more particular
originating servers 210 at any given time.
[0044] It is contemplated that any number of front-end and back-end
mechanisms may be implemented cooperatively to support the desired
level of service required by the web site owner. The present
invention implements a many-to many mapping of front-ends to
back-ends. Because the front-end to back-end mappings can by
dynamically changed, a fixed hardware infrastructure can be
logically reconfigured to map more or fewer front-ends to more or
fewer back-ends and web sites or servers as needed.
[0045] Front-end 201 together with back-end 203 function to reduce
traffic across the transport morphing protocol TMPTM link 212 and
to improve response time for selected browsers. Traffic across the
TMP link 212 is reduced by compressing data and serving browser
requests from cache for fast retrieval. Also, the blending of
request datagrams results in significantly fewer
request:acknowledge pairs across the TMP link 212 as compared to
the number required to reliably send the packets individually
between front-end 201 and back-end 203. This action reduces the
overhead associated with transporting a given amount of data,
although conventional request:acknowledge traffic is still
performed on the links coupling the front-end 201 to client 205 and
back is end 203 to a web server. Moreover, resend traffic is
significantly reduced further reducing the traffic. Response time
is further improved for select privileged users and for specially
marked resources by determining the priority for each HTTP
transmission.
[0046] In one embodiment, front-end 201 and back-end 203 are
closely coupled to the Internet backbone. This means they have high
bandwidth connections, can expect fewer hops, and have more
predictable packet transit time than could be expected from a
general-purpose connection. Although it is preferable to have low
latency connections between front-ends 201 and back-ends 203, a
particular strength of the present invention is its ability to deal
with latency by enabling efficient transport and traffic
prioritization. Hence, in other embodiments front-end 201 and/or
back-end 203 may be located farther from the Internet backbone and
closer to clients 205 and/or web servers 210. Such an
implementation reduces the number of hops required to reach a
front-end 201 while increasing the number of hops within the TMP
link 212 thereby yielding control over more of the transport path
to the management mechanisms of the present invention.
[0047] Clients 205 no longer conduct all data transactions directly
with the web server 210. Instead, clients 205 conduct some and
preferably a majority of transactions with front-ends 201, which
simulate the functions of web server 210. Client data is then sent,
using TMP link 212, to the back-end 203 and then to the web server
210. Running multiple clients 205 over one large connection
provides several advantages:
[0048] Since all client data is mixed, each client can be assigned
a priority. Higher priority clients, or clients requesting higher
priority data, can be given preferential access to network
resources so they receive access to the channel sooner while
ensuring low-priority clients receive sufficient service to meet
their needs.
[0049] The large connection between a front-end 201 and back-end
203 can be permanently maintained, shortening the many TCP/IP
connection sequences normally required for many clients connecting
and disconnecting.
[0050] Using a proprietary protocol allows the use of more
effective techniques to improve data throughput and permits better
use of existing bandwidth during periods when the network is
congested.
[0051] A particular advantage of the architectures shown in FIG.
2a-FIG. 2d and FIG. 3 is that it is readily scaled. Any number of
client machines 205 may be supported. In a similar manner, a web
site owner may choose to implement a site using multiple web
servers 210 that are co-located or distributed throughout network
101. To avoid congestion, additional front-ends 201 may be
implemented or assigned to particular web sites. Each front-end 201
is dynamically re-configurable by updating address parameters to
serve particular web sites. Client traffic is dynamically directed
to available front-ends 201 to provide load balancing. Hence, when
quality of service drops because of a large number of client
accesses, an additional front-end 201 can be assigned to the web
site and subsequent client requests directed to the newly assigned
front-end 201 to distribute traffic across a broader base.
[0052] In the particular examples, this is implemented by a
front-end manager component 217 that communicates with multiple
front-ends 201 to provide administrative and configuration
information to front-ends 201. Each frontend 201 includes data
structures for storing the configuration information, including
information identifying the back-ends 203 of web servers 210 to
which they are currently assigned. Other administrative and
configuration information stored in front-end 201 may include
information for prioritizing specific data from and to particular
clients, quality of service information, and the like.
[0053] Similarly, additional back-ends 203 can be assigned to a web
site to handle increased traffic. Back-end manager component 219
couples to one or more back-ends 203 to provide centralized
administration and configuration service. Back-ends 203 include
data structures to hold current configuration state, quality of
service information and the like. In the particular examples,
front-end manager 217 and back-end manager 219 serve multiple web
sites 210 and so are able to manipulate the number of front-ends
and back-ends assigned to each web site 210 by updating this
configuration information. When the congestion for the site
subsides, the front-ends 201 and back-ends 203 can be reassigned to
other, busier web sites. These and similar modifications are
equivalent to the specific examples illustrated herein.
[0054] In the case of web-based environments, front-end 201 is
implemented using custom or off-the-shelf web server software.
Front-end 201 is readily extended to support other, non-web-based
protocols, however, and may support multiple protocols for
varieties of client traffic. Front-end 201 processes the data
traffic it receives, regardless of the protocol of that traffic, to
a form suitable for transport by TMP 212 to a back-end 203. Hence,
most of the functionality implemented by front-end 201 is
independent of the protocol or format of the data received from a
client 205. Hence, although the discussion of the exemplary
embodiments herein relates primarily to front-end 201 implemented
as a web server, it should be noted that, unless specified to the
contrary, web-based traffic management and protocols are merely
examples and not a limitation of the present invention.
[0055] As shown in FIG. 2, in accordance with the present invention
a web site is implemented using an originating web server 210
operating cooperatively with the web server of front-end 201. More
generally, any network service (e.g., FTP, VoIP, NNTP, MIME, SMTP,
Telnet, DBMS) can be implemented using a combination of an
originating server working cooperatively with a front-end 201
configured to provide a suitable interface (e.g., FTP , VOIP, NNTP,
MIME, SMTP, Telnet, DBMS, WAP) for the desired service. In contrast
to a simple front-end cache or proxy software, implementing a
server in front-end 201 enables portions of the web site (or other
network service) to actually be implemented in and served from both
locations. The actual web pages or service being delivered
comprises a composite of the portions generated at each server.
Significantly, however, the web server in front-end 201 is close to
the browser in a client 205 whereas the originating web server is
close to all resources available at the web hosting center at which
web site 210 is implemented. In essence the web site 210 is
implemented by a tiered set of web servers comprising a front-end
server 201 standing in front of an originating web server.
[0056] This difference enables the web site functionality to be
implemented and distributed so as to take advantage of the unique
position each web server has with respect to the client 205. By way
of a particular example, assume an environment in which the
front-end web server 201 is located in the ISP's location for a
particular set of clients 205. In such an environment, clients 205
can access the front-end web server 205 without actually traversing
the network 101. Hence, network delays and variability are
substantially eliminated.
[0057] In order for a client 205 to obtain service from a front-end
201, it must first be directed to a front-end 201 that can provide
the desired service. FIG. 4 illustrates a domain name server (DNS)
redirection mechanism that illustrates an example of how a client
205 is connected to a particular front-end 201. Preferably, client
205 does not need to be aware of the location of front-end 201, and
initiates all transactions as if it were contacting the originating
server 210. The public DNS system is defined in a variety of
Internet Engineering Task Force (IETF) documents such as RFC0883,
RFC 1034 and RFC 1035 which are incorporated by reference herein.
In a typical environment, a client 205 executes a browser 301,
TCP/IP stack 303, and a resolver 305. For reasons of performance
and packaging, browser 301, TCP/IP stack 303 and resolver 305 are
often grouped together as routines within a single software
product.
[0058] Browser 301 functions as a graphical user interface to
implement user input/output (I/O) through monitor 311 and
associated keyboard, mouse, or other user input device (not shown).
Browser 301 is usually used as an interface for web-based
applications, but may also be used as an interface for other
applications such as email and network news, as well as
special-purpose applications such as database access, telephony,
and the like. Alternatively, a special-purpose user interface may
be substituted for the more general-purpose browser 301 to handle a
particular application.
[0059] TCP/IP stack 303 communicates with browser 301 to convert
data between formats suitable for browser 301 and IP format
suitable for Internet traffic. TCP/IP stack also implements a TCP
protocol that manages transmission of packets between client 205
and an Internet service provider (ISP) or equivalent access point.
IP protocol requires that each data packet include, among other
things, an IP address identifying a destination node. In current
implementations the IP address comprises a 32-bit value that
identifies a particular Internet node. Non-IP networks have similar
node addressing mechanisms. To provide a more user-friendly
addressing system, the Internet implements a system of domain name
servers that map alpha-numeric domain names to specific IP
addresses. This system enables a name space that is more consistent
reference between nodes on the Internet and avoids the need for
users to know network identifiers, addresses, routes and similar
information in order to make a connection.
[0060] The domain name service is implemented as a distributed
database managed by domain name servers (DNSs) 307 such as DNS_A,
DNS_B and DNS_C shown in FIG. 3. Each DNS relies on <domain
name:IP> address mapping data stored in master files scattered
through the hosts that use the domain system. These master files
are updated by local system administrators. Master files typically
comprise text files that are read by a local name server, and hence
become available through the name servers 307 to users of the
domain system.
[0061] The user programs (e.g., clients 205) access name servers
through standard programs such as resolver 305. Resolver 305
includes an address of a DNS 307 that serves as a primary name
server. When presented with a reference to a domain name (e.g.,
http://www.circadence.com), resolver 305 sends a request to the
primary DNS (e.g., DNS_A in FIG. 3). The primary DNS 307 returns
either the IP address mapped to that domain name, a reference to
another DNS 307 which has the mapping information (e.g., DNS_B in
FIG. 3), or a partial IP address together with a reference to
another DNS that has more IP address information. Any number of
DNS-to-DNS references may be required to completely determine the
IP address mapping.
[0062] In this manner, the resolver 305 becomes aware of the IP
address mapping which is supplied to TCP/IP component 303. Client
205 may cache the IP address mapping for future use. TCP/IP
component 303 uses the mapping to supply the correct IP address in
packets directed to a particular domain name so that reference to
the DNS system need only occur once.
[0063] In accordance with the present invention, at least one DNS
server 307 is owned and controlled by system components of the
present invention. When a user accesses a network resource (e.g., a
web site), browser 301 contacts the public DNS system to resolve
the requested domain name into its related IP address in a
conventional manner. In a first embodiment, the public DNS performs
a conventional DNS resolution directing the browser to an
originating server 210 and server 210 performs a redirection of the
browser to the system owned DNS server (i.e., DNC_C in FIG. 3). In
a second embodiment, domain:address mappings within the DNS system
are modified such that resolution of the of the originating
server's domain automatically return the address of the systemowned
DNS server (DNS_C). Once a browser is redirected to the
system-owned DNS server, it begins a process of further redirecting
the browser 301 to the best available front-end 201.
[0064] Unlike a conventional DNS server, however, the system-owned
DNS_C in FIG. 3 receives domain:address mapping information from a
redirector component 309. Redirector 309 is in communication with
front-end manager 217 and back-end manager 219 to obtain
information on current front-end and back-end assignments to a
particular server 210. A conventional DNS is intended to be updated
infrequently by reference to its associated master file. In
contrast, the master file associated with DNS.sub.C is dynamically
updated by redirector 309 to reflect current assignment of
front-end 201 and back-end 203. In operation, a reference to web
server 210 (e.g., http://www.circadence.com) may result in an IP
address returned from DNS_C that points to any selected front-end
201 that is currently assigned to web site 210. Likewise, web site
210 may identify a currently assigned back-end 203 by direct or
indirect reference to DNS_C.
[0065] Front-end 201 typically receives information directly from
front-end manager 217 about the address of currently assigned
back-ends 203. Similarly, back-end 203 is aware of the address of a
front-end 201 associated with each data packet. Hence, reference to
the domain system is not required to map a front-end 201 to its
appropriate backend 203.
[0066] FIG. 5 illustrates principle functional components of an
exemplary front-end 201 in greater detail. Primary functions of the
front-end 201 include translating transport control protocol (TCP)
packets from client 205 into TMP packets used in the system in
accordance with the present invention. Transport morphing
protocol.TM. and TMP.TM.are trademarks or registered trademarks of
Circadence Corporation in the United States and other countries. It
is contemplated that the various functions described in reference
to the specific examples may be implemented using a variety of data
structures and programs operating at any location in a distributed
network. For example, a front-end 201 may be operated on a network
appliance 107 or server within a particular network 102, 103, or
104 shown in FIG. 1. The present invention is readily adapted to
any application where multiple clients are coupling to a
centralized resource. Moreover, other transport protocols may be
used, including public and proprietary transport protocols.
[0067] TCP component 401 includes devices for implementing physical
connection layer and Internet protocol (IP) layer functionality.
Current IP standards are described in IETF documents RFC0791,
RFC0950, RFC0919, RFC0922, RFC792, RFC1112 that are incorporated by
reference herein. For ease of description and understanding, these
mechanisms are not described in great detail herein. Where
protocols other than TCP/IP are used to couple to a client 205, TCP
component 401 is replaced or augmented with an appropriate network
protocol process.
[0068] TCP component 401 communicates TCP packets with one or more
clients 205. Received packets are coupled to parser 402 where the
Internet protocol (or equivalent) information is extracted. TCP is
described in IETF RFC0793 which is incorporated herein by
reference. Each TCP packet includes header information that
indicates addressing and control variables, and a payload portion
that holds the user-level data being transported by the TCP packet.
The user-level data in the payload portion typically comprises a
user-level network protocol datagram.
[0069] Parser 402 analyzes the payload portion of the TCP packet.
In the examples herein, HTTP is employed as the user-level protocol
because of its widespread use and the advantage that currently
available browser software is able to readily use the HTTP
protocol. In this case, parser 402 comprises an HTTP parser. More
generally, parser 402 can be implemented as any parser-type logic
implemented in hardware or software for interpreting the contents
of the payload portion. Parser 402 may implement file transfer
protocol (FTP), mail protocols such as simple mail transport
protocol (SMTP), structured query language (SQL) and the like. Any
user-level protocol, including proprietary protocols, may be
implemented within the present invention using appropriate
modification of parser 402.
[0070] To improve performance, front-end 201 optionally includes a
caching mechanism 403. Cache 403 may be implemented as a passive
cache that stores frequently and/or recently accessed web pages or
as an active cache that stores network resources that are
anticipated to be accessed. In non-web applications, cache 403 may
be used to store any form of data representing database contents,
files, program code, and other information. Upon receipt of a TCP
packet, HTTP parser 402 determines if the packet is making a
request for data within cache 403. If the request can be satisfied
from cache 403, the data is supplied directly without reference to
web server 210 (i.e., a cache hit). Cache 403 implements any of a
range of management functions for maintaining fresh content. For
example, cache 403 may invalidate portions of the cached content
after an expiration period specified with the cached data or by web
sever 210. Also, cache 403 may proactively update the cache
contents even before a request is received for particularly
important or frequently used data from web server 210. Cache 403
evicts information using any desired algorithm such as least
recently used, least frequently used, first in/first out, or random
eviction. When the requested data is not within cache 403, a
request is processed to web server 210, and the returned data may
be stored in cache 403.
[0071] Several types of packets will cause parser 402 to forward a
request towards web server 210. For example, a request for data
that is not within cache 403 (or if optional cache 403 is not
implemented) may require a reference to web server 210. Some
packets will comprise data that need be supplied to web server 210
(e.g., customer credit information, form data and the like) . In
these instances, HTTP parser 402 couples to data blender 404.
[0072] Optionally, front-end 201 implements security processes,
compression processes, encryption processes and the like to
condition the received data for improved transport performance
and/or provide additional functionality. These processes may be
implemented within any of the functional components (e.g., data
blender 404) or implemented as separate functional components
within front-end 201. Also, parser 402 may implement a
prioritization program to identify packets that should be given
higher priority service. A prioritization program requires only
that parser 402 include a data structure associating particular
clients 205 or particular TCP packet types or contents with a
prioritization value. Based on the prioritization value, parser 402
may selectively implement such features as caching, encryption,
security, compression and the like to improve performance and/or
additional functionality. The prioritization value is provided by
the owners of web site 210, for example, and may be dynamically
altered, statically set, or updated from time to time to meet the
needs of a particular application.
[0073] Blender 404 slices and/or coalesces the data portions of the
received packets into a more desirable "TMP units" that are sized
for transport through the TMP mechanism 212. The data portion of
TCP packets may range in size depending on client 205 and any
intervening links coupling client 205 to TCP component 401.
Moreover, where compression is applied, the compressed data will
vary in size depending on the compressibility of the data. Data
blender 404 receives information from front-end manager 217 that
enables selection of a preferable TMP packet size. Alternatively, a
fixed TMP packet size can be set that yields desirable performance
across TMP mechanism 212. Data blender 404 also marks the TMP units
so that they can be re-assembled at the receiving end.
[0074] Data blender 404 may also serve as a buffer for storing
packets from all appliances 177 that are associated with front-end
201. In accordance with the present invention, data blender 404 may
associate a prioritization value with each packet.
[0075] In an exemplary implementation, a "TMP connection" comprises
a plurality of "TCP connection buffers", logically arranged in
multiple "rings". Each TCP socket maintained between the front-end
201 and a client 205 corresponds to a TCP connection buffer. When a
TCP connection buffer is created, it is assigned a priority. For
purposes of the present invention, any algorithm or criteria may be
used to assign a priority. Each priority ring is associated with a
number of TCP connection buffers sockets having similar priority.
In a specific example, five priority levels are defined
corresponding to five priority rings. Each priority ring is
characterized by the number of connection buffers it holds
(nsockets), the number of connection buffers it holds that have
data waiting to be sent (nReady) and the total number of bytes of
data in all the connection buffers that it holds (nBytes).
[0076] When composing TMP data packets, the blender goes into a
loop comprising the steps:
[0077] 1) Determine the number of bytes available to be sent from
each ring (nBytes), and the number of TCP connections that are
ready to send (nready)
[0078] 2) Determine how many bytes should be sent from each ring
(nSend). This is based on a weight parameter for each priority. The
weight can be thought of as the number of bytes that should be sent
at each priority this time through the loop.
[0079] 3) The nSend value computed in the previous step reflects
the weighted proportion that each ring will have in a blended TMP
packet, but the values of nSend do not reflect how many bytes need
to be selected to actually empty most or all of the data waiting to
be sent a single round. To do this, the nSend value is normalized
to the ring having the most connections waiting. This involves a
calculation of a factor: S=nBytes/(Weight*nReady) for the ring with
the greatest nReady. Then, for each ring, calculate nSend.times.S
to get the normalized value (nSendNorm) for each priority ring.
[0080] 4) Send sub-packets from the different rings. This is done
by taking a sub-packet from the highest priority ring and adding it
to a TMP packet, then adding a sub-packet from each of the top two
queues, then the top three, and so on.
[0081] 5) Within each ring, sub-packets are selected round robin.
When a sub-packet is selected from a TCP connection buffer the ring
is rotated so the next subpacket the ring adds will come from a
different TCP connection buffer. Each sub-packet can be up to 512
bytes in a particular example. If the connection buffer has less
than 512 bytes waiting, the data available is added to the TMP
packet.
[0082] 6) When a full TMP packet (roughly 1.5 kB in a particular
example)is built, it is sent. This will usually have three or more
sub-packets, depending on their size. The TMP packet will also be
sent when there is no more data ready.
[0083] TMP mechanism 405 implements the TMP protocol in accordance
with the present invention. TMP is a TCP-like protocol adapted to
improve performance for multiple channels operating over a single
connection. Front-end TMP mechanism 405 and a corresponding
back-end TMP mechanism 505 shown in FIG. 6 are computer processes
that implement the end points of TMP link 212. The TMP mechanism in
accordance with the present invention creates and maintains a
stable connection between two processes for high-speed, reliable,
adaptable communication.
[0084] TMP is not merely a substitute for the standard TCP
environment. TMP is designed to perform particularly well in
heterogeneous network environments such as the Internet. TMP
connections are made less often than TCP connections. Once a TMP
connection is made, it remains up unless there is some kind of
direct intervention by an administrator or there is some form of
connection breaking network error. This reduces overhead associated
with setting up, maintaining and tearing down connections normally
associated with TCP.
[0085] Another feature of TMP is its ability to channel numerous
TCP connections through a single TMP pipe 212. The environment in
which TMP resides allows multiple TCP connections to occur at one
end of the system. These TCP connections are then mapped into a
single TMP connection. The TMP connection is then broken down at
the other end of the TMP pipe 212 in order to traffic the TCP
connections to their appropriate destinations. TMP includes
mechanisms to ensure that each TMP connection gets enough of the
available bandwidth to accommodate the multiple TCP connections
that it is carrying.
[0086] Another advantage of TMP as compared to traditional
protocols is the amount of information about the quality of the
connection that a TMP connection conveys from one end to the other
of a TMP pipe 212. As often happens in a network environment, each
end has a great deal of information about the characteristics of
the connection in one direction, but not the other. By knowing
about the connection as a whole, TMP can better take advantage of
the available bandwidth.
[0087] In contrast with conventional TCP mechanisms, the behavior
implemented by TMP mechanism 405 is constantly changing. Because
TMP obtains bandwidth to host a variable number of TCP connections
and because TMP is responsive information about the variable status
of the network, the behavior of TMP is preferably continuously
variable. One of the primary functions of TMP is being able to act
as a conduit for multiple TCP connections. As such, a single TMP
connection cannot behave in the same manner as a single TCP
connection. For example, imagine that a TMP connection is carrying
100 TCP connections. At this time, it loses one packet (from any
one of the TCP connections) and quickly cuts its window size in
half (as specified for TCP) . This is a performance reduction on
100 connections instead of just on the one that lost the
packet.
[0088] Each TCP connection that is passed through the TMP
connection must get a fair share of the bandwidth, and should not
be easily squeezed out. To allow this to happen, every TMP becomes
more aggressive in claiming bandwidth as it accelerates. Like TCP,
the bandwidth available to a particular TMP connection is measured
by its window size (i.e., the number of outstanding TCP packets
that have not yet been acknowledged). Bandwidth is increased by
increasing the window size, and relinquished by reducing the window
size. Up to protocol specified limits, each time a packet is
successfully delivered and acknowledged, the window size is
increased until the window size reaches a protocol specified
maximum. When a packet is dropped (e.g., no acknowledge received or
a resend packet response is received), the bandwidth is decreased
by backing off the window size. TMP also ensures that it becomes
more and more resistant to backing off (as compared to TCP) with
each new TCP connection that it hosts. A TMP should not go down to
a window size of less than the number of TCP connections that it is
hosting.
[0089] In a particular implementation, every time a TCP connection
is added to (or removed from) what is being passed through the TMP
connection, the TMP connection behavior is altered. It is this
adaptation that ensures successful connections using TMP. Through
the use of the adaptive algorithms discussed above, TMP is able to
adapt the amount of bandwidth that it uses. When a new TCP
connection is added to the TMP connection, the TMP connection
becomes more aggressive. When a TCP connection is removed from the
TMP connection, the TMP connection becomes less aggressive.
[0090] TMP pipe 212 provides improved performance in its
environment as compared to conventional TCP channels, but it is
recognized that TMP pipe 212 resides on the open, shared Internet
in the preferred implementations. Hence, TMP must live together
with many protocols and share the pipe efficiently in order to
allow the other transport mechanisms fair access to the shared
communication bandwidth. Since TMP takes only the amount of
bandwidth that is appropriate for the number of TCP connections
that it is hosting (and since it monitors the connection and
controls the number of packets that it puts on the line), TMP will
exist cooperatively with TCP traffic. Furthermore, since TMP does a
better job at connection monitoring than TCP and TMP is better
suited to throughput and bandwidth management than TCP.
[0091] Also shown in FIG. 5 are data filter component 406 and HTTP
reassemble component 407 that process incoming (with respect to
client 205) data. TMP mechanism 405 receives TMP packets from TMP
pipe 212 and extracts the TMP data units. Using the appended
sequencing information, the extracted data units are reassembled
into HTTP data packet information by HTTP reassembler 407. Data
filter component 406 may also implement data decompression where
appropriate, decryption, and handle caching when the returning data
is of a cacheable type.
[0092] FIG. 6 illustrates principle functional components of an
exemplary back-end 203 in greater detail. Primary functions of the
back-end 203 include translating transmission control protocol
(TCP) packets from web server 210 into TMP packets as well as
translating TMP packets received from a front-end 201 into the one
or more corresponding TCP packets to be send to server 210.
Further, back-end 203 is able to implement similar or complementary
functionality to that of front-end 203. In this manner, back-end
203 can operate as a web server to retrieve content and generate
web pages, analyze and reformat web pages and components within web
pages, and similar server functionality that would conventionally
be implemented in a server 210. In general, any functionality and
behavior described herein that can be implemented on server 210
and/or front-end server 201 can also be implemented on back-end
server 203.
[0093] TMP unit 505 receives TMP packets from TMP pipe 212 and
passes them to HTTP reassemble unit 507 where they are reassembled
into the corresponding TCP packets. Data filter 506 may implement
other functionality such as decompression, decryption, and the like
to meet the needs of a particular application. The reassembled data
is forwarded to TCP component 501 for communication with web server
210.
[0094] TCP data generated by the web server process are transmitted
to TCP component 501 and forwarded to HTTP parse mechanism 502.
Parser 502 operates in a manner analogous to parser 402 shown in
FIG. 5 to extract the data portion from the received TCP packets,
perform optional compression, encryption and the like, and forward
those packets to data blender 504. Data blender 504 operates in a
manner akin to data blender 404 shown in FIG. 5 to buffer and
prioritize packets in a manner that is efficient for TMP transfer.
Priority information is received by, for example, back-end manager
219 based upon criteria established by the web site owner. TMP data
is streamed into TMP unit 505 for communication on TMP pipe
212.
[0095] FIG. 7 illustrates a conceptual block diagram of an
exemplary implementation of the system shown in FIG. 2 in an
alternative context. In the example of FIG. 6, frontend 201 is
implemented as a front-end web server 601 operating at an ISP 602.
ISP 602 supports modem, digital subscriber line (DSL), ISDN, leased
line, or other communication ports for communicating with one or
more clients 605. ISP 602 serves as a bridge to couple client
connections to IP connections with network 101. ISP 602 may be
considered to be outside of network 101 in that quality of service
between client 605 and ISP 602 is not dependent on congestion or
equipment failure or other factors affecting quality of service
within network 101.
[0096] In operation, client 605 generates an HTTP request
specifying web site 610 in the URL. In the manner described
hereinbefore, the client request is redirected to front-end 601.
Once the redirection is completed, front-end 601 serves web pages
embedded in HTTP response packets using both content and
functionality obtained from web site 610 as well as content and
functionality present on front-end 601 or obtained from database
603. In this manner, front-end web server 601 can dynamically
controls the source of the delivered content. The web page(s)
served to client 605 comprise a composite of multiple sources from
multiple independent web servers.
[0097] Significantly, the content served from content database 603
may differ from the content and functionality that would have
otherwise been served by web site 610. For example, if web site 610
returns an HTTP 404 "page not found" error page, front-end web site
601 may supply a more informative or instructive web page derived
from content database 603. Alternatively, front-end web site 601
may detect periods of low quality of service or slow response and
provide substitute content from content database 603 or elsewhere.
In a particular example, web site 610 publishes a load index that
can be read by frontend 601 and used to generate a wait page
intended to occupy a user of client 605 until content can be
obtained directly from web site 610.
[0098] In another embodiment, the desired format of content is
specified by client 605, information maintained about the desired
or required format for client 605 by the system and/or the system
can determine the required format for client 605 and its connection
to front-end 601 indirectly. In response, front-end web server 601
formats and converts content and data to be provided to client 605
based on custom requests forwarded to web server 610 and/or on a
common data set provided by website 610 for purposes of responding
to one or more clients 605.
[0099] In a particular example, the owner of web site 610
establishes rules for how front-end web server 601 handles various
conditions. These rules are stored in front-end web server 601.
Hence, the owner of web site 610 is not losing control over how web
site 610 is presented, but instead is gaining control over how
presentation occurs during periods where network 101 is unavailable
or provides unacceptable quality of service. By placing a web
server in front of the origin web server 610, overall user
experience as well as efficacy of the web site 610 for the site
owner are improved.
[0100] It should be understood that the essence of systems in
accordance with the present invention, i.e., dynamically shifting
functionality amongst a network of servers can be expressed in a
variety of implementations. For example, a network-connected server
may obtain program code, data, and other resources to provide a
desired set of functionality either in response to a client
request, or independently of the client request in a manner that
proactively or anticipatorily. Proactive operation allows a
network-connected server to maintain a set of functionality such
that services can be provided without reference to a central
authority when a client request is actually received. In such
cases, processes within the front-end 201, for example, will make
requests to another network-connected server (e.g., another
front-end 201) or to an originating server 210 to obtain the
program code, data, and resources, and then independently respond
to client requests using the obtained program code, data and
resources. The connections between front-ends 201 and origin
servers 210 can benefit from features of the enhanced channel
202.
[0101] Any number of front-ends 201 may be involved in providing a
particular service or set of functionality. It is contemplated that
a client 205 may connect to a particular front-end 201 and that
particular front-end 201 may establish connections with one or more
other front ends 201 to access functionality, data and resources
available in those other front-ends.
[0102] Although the invention has been described and illustrated
with a certain degree of particularity, it is understood that the
present disclosure has been made only by way of example, and that
numerous changes in the combination and arrangement of parts can be
resorted to by those skilled in the art without departing from the
spirit and scope of the invention, as hereinafter claimed. For
example, while devices supporting HTTP data traffic are used in the
examples, the HTTP devices may be replaced or augmented to support
other public and proprietary protocols and languages including FTP,
NNTP, SMTP, SQL and the like. In such implementations the front-end
201 and/or back end 203 are modified to implement the desired
protocol. Moreover, front-end 201 and back-end 203 may support
different protocols and languages such that the front-end 201
supports, for example, HTTP traffic with a client and the back-end
supports a DBMS protocol such as SQL. Such implementations not only
provide the advantages of the present invention, but also enable a
client to access a rich set of network resources with minimal
client software.
* * * * *
References