Electrical computers and digital processing systems: multicomput – Computer-to-computer session/connection establishing – Network resources access controlling
Reexamination Certificate
1996-09-09
2001-05-29
Donaghue, Larry D. (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer-to-computer session/connection establishing
Network resources access controlling
C709S241000, C709S239000
Reexamination Certificate
active
06240454
ABSTRACT:
TECHNICAL FIELD
This invention relates to information network architecture, such as the Internet or an intranet architecture.
BACKGROUND OF THE INVENTION
In an information network, such as the Internet, user's computers, referred to as clients, request information from information-providers' computers, referred to as servers, and the servers supply the requested information to the clients. In the World Wide Web (WWW), which is a de-facto standard for storing, finding, and transferring information on the Internet, the information is supplied in the form of pages. A page is a display screen-full of information expressed in textual, graphical, scriptural, and/or other form. A page comprises one or more information objects. An object is an information element that has its own network address—preferably a unique single address—called a URL (Uniform Resource Locator). For example, a page may comprise one or more text objects, one or more picture objects, and one or more script objects that are presented on the display screen in a layout defined by a frame object.
Typically, a server has a main page that serves as the entry point to the information and services that the server provides. This page typically points to other pages and to objects (e.g., graphic images, video/audio/text files, etc.), which are typically served by the same server.
Generally, when a client accesses the server, the server provides the main page to the client and then interacts with the client to provide the client with desired additional information and/or services. As increasing numbers of clients access the server, the server's processing load increases and its performance eventually degrades, so that users experience increasing delays between the time at which they place a request to the server and the time at which their request is satisfied by the server.
To avoid overloading of a server, typically an administrator must manually reconfigure the server and redirect some of the requests to other servers in order to lessen the load on the subject server. Some service providers store replicas of the served information in a plurality of servers and have different ones of the servers serve different requests, e.g., on a round-robin basis, thereby spreading the load of requests over multiple servers. This has several disadvantages. Firstly, an administrator's manual intervention is slow, inefficient, prone to error, and often not prompt. Secondly, using a plurality of servers to serve requests on a round-robin basis results in underutilization of the servers during periods when relatively few requests are being made, and hence it is inefficient. Furthermore, it requires all server information to be replicated on each server; the servers cannot take advantage of a common cache for common data.
SUMMARY OF THE INVENTION
This invention is directed to solving these and other problems and disadvantages of the prior art. Generally according to the invention, a portion of the information which a primary server uses to process client requests is replicated on one or more supplemental, stand-by, servers, and as the clients' demand for service increases and the processing load on the primary server becomes excessive, the primary server automatically off-loads the processing of those portions of the client requests that require the replicated portion of the information onto the supplemental servers. As demand for service decreases and the primary server becomes underloaded, preferably the primary server automatically resumes serving the entire client requests.
The advantages of the invention include the following: the load-shedding and load-sharing happen automatically, without human intervention, based on the present processing load. Only one server, or one group of servers, out of the entire server set serves an individual portion of the information (e.g., a page, or an object, or a group of pages or objects) at any one time, which allows for efficient caching of the information. And more uniform response times are provided to clients even as client demand for services varies greatly. Moreover, while a standby server is not serving the primary server's clients, its processing power may be used for other processing activities, such as serving other clients whose demand for service peaks at a time different from the primary server's clients, thereby resulting in efficient server utilization.
According to a first aspect of the invention, a client-server system comprises a plurality of servers for processing client requests, wherein at least one first server of the plurality of servers has first information and second information related to the first information, for processing portions of the client requests that require the first information and portions of the client requests that require the second information. The at least one first server processes both portions of the client requests while the processing load on the at least one server is not excessive, e.g., does not exceed a predetermined first limit. In response to the processing load on the at least one first server becoming excessive, the at least one first server processes the portions of the client requests which require the first information without also processing the portions of the client requests which require the second information, and automatically redirects the portions of the client requests which require the second information to at least one second server for processing. The at least one server of the plurality of servers has the second information and processes the redirected portions of the client requests which require the second information, automatically in response to the redirection. Preferably, the at least one first server automatically ceases redirecting the portions of the client requests that require the second information and resumes processing of both portions of the client requests in response to the processing load on the at least one first server ceasing to be excessive, e.g., falling below a predetermined second limit.
According to a second aspect of the invention, a method of operating a client-server system that includes a plurality of servers for processing client requests comprises the following steps. While a processing load on at least one first server of the plurality of servers is not excessive, the at least one first server processes both portions of client requests that require first information and portions of the client requests that require second information related to the first information; the at least one first server has both the first information and the second information. In response to the processing load on the at least one first server becoming excessive, the at least one server processes the portions of the client requests that require the first information without also processing the portions of the client requests that require the second information, and automatically redirects the portions of the client requests that require the second information to at least one second server of the plurality of servers. In response to the redirection, the at least one second server automatically processes the redirected portions of the client requests that require the second information; the at least one second server has the second information. Preferably, when the processing load on the at least one server falls below a predetermined limit, the at least one server automatically ceases to redirect the portions of the client requests that require the second information and resumes processing both portions of the client requests.
These and other advantages and features of the invention will become more apparent from the following description of an illustrative embodiment of the invention taken together with the drawing.
REFERENCES:
patent: 5548724 (1996-08-01), Akizawa et al.
patent: 5633999 (1997-05-01), Clowes et al.
patent: 5818448 (1998-10-01), Katiyar
patent: 5828847 (1998-10-01), Gehr et al.
patent: 5835718 (1998-11-01), Blewett
patent: 5862348 (1999-01-01), Pedersen
patent:
Avaya Technology Corp.
Donaghue Larry D.
Volejnicek David
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