Electrical computers and digital processing systems: multicomput – Computer-to-computer session/connection establishing
Reexamination Certificate
1999-07-02
2003-09-02
Dinh, Dung C. (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer-to-computer session/connection establishing
C709S226000
Reexamination Certificate
active
06615265
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of availability management of an application executed by a computer system. More particularly, the invention relates to a method of discontinuing availability of an application-server connected to at least one application-client by taking the application-server out of service in a polite manner.
BACKGROUND OF THE INVENTION
Enterprises depend on the availability of the systems that support their day to day operation. A system is called available if it is up and running and is producing correct results. The availability of a system is the fraction of time it is available. With the advent of distributed systems, techniques have been invented which use two or more address spaces on different machines running the same software to improve availability (often called active replication). Further details on these aspects may be found in S. Mullender, “Distributed Systems”, ACM Press, 1993. In using two or more address spaces on the same machine running the same software which gets its request from a shared input queue, the technique of warm backups is generalized by the hot pool technique; refer for instance to F. Leymann and D. Roller, “Building a robust workflow management system with persistent queues and stored procedures”, in: Proc. Intl. Conf. on Data Engineering ICDE 98 (Orlando, Fla., Feb. 25-28, 1998).
Despite progress, further improvements are urgently required to support enterprises by increasing the availability of their applications and allowing for electronic business on a 7 (days)*24 (hour) basis; due to the ubiquity of world-wide computer networks, at any point in time, somebody might have interest in accessing a certain application server.
SUMMARY OF THE INVENTION
The invention is based on the objective of increasing the availability of an application executed by a computer system due to a dedicated method of discontinuing availability of an application server.
This objective is solved by claim 1. The method of discontinuing availability of an application-server (
110
) connected to at least one application-client (
101
) is executed by an computer system. Said connected-application-server offers execution of application-service-requests to said connected-application-client. Said method comprises a connected-application-client-determination-step (
206
) executed by said connected-application-server which determines said connected-application-client having an open connection (
102
) to said connected-application-server. Said method comprises a switch-demand-step (
208
) executed by said application-server sending said connected-application-client a demand to switch to a substitute-application-server. Said method further comprises a connect-to-substitute-application-server-step (
209
) executed by said connected-application-client opening a substitute-connection to a substitute-application-server. Moreover said method comprises a close-connection-step (
210
) executed by said connected-application-client closing said connection to said connected-application-server. Finally said method comprises a termination-step (
212
-
218
) executed by said connected-application-server discontinuing availability of said connected-application-server by terminating said connected-application-server.
The current invention is of advantage in the area of systems management, especially in the area of availability management. The invention allows to take application servers out of service in a polite manner. Application clients depending on the availability of application services provided by the application server will be informed that the application server is going to discontinue its application services so that the application clients can switch over to another application server as subsitute application server. As a result, users will not realize any downtime of the overall application services because the whole processing is completely transparent to the user. Therefore these users no longer realize a reduced availability of the requested service, i.e. they do not realize the outage. Affected users no longer have to determine substitute application servers themselves for instance by queries against a directory, or calling a help desk or other administrative personnel. Also affected users do not have to open a communication connection to the substitute application servers themselves.
Additional advantages are accomplished by preceding said method by a refuse-new-connection-step (
205
) executed by said connected-application-server. Said step prevents another application-client to open a new connection to said connected-application-server.
Based on this feature the current teaching allows that new application clients, in the search of a connection to an application server, will not be able to establish such a connection, which soon afterwards would have to be closed again.
Additional advantages are accomplished by preceding said method by an optional substitute-application-server-determination-step (
203
) executed by said connected-application-server, which uses a specified-substitute-application-server (
203
) (specified on invocation of said method of discontinuing) as substitute-application-server (
120
). Moreover in said switch-demand-step an identification (
104
) of said specified-substitute-application-server is sent to said connected-application-client. Furthermore in said connect-to-substitute-application-server-step said connected-application-client opens a substitute-connection (
103
) to said specified-substitute-application-server.
Based on this feature the current teaching allows the specification of which application server is to be used as a substitute application server. Therefore, the application server, as well as the connected application clients, are relieved from the need to determine any substitute application server. This results in performance gains. Moreover, this gives the administrator or the program dedicated control on defining the specific substitute application server to be used.
Additional advantages are accomplished if said method is preceded by an optional substitute-application-server-determination-step (
203
) executed by said connected-application-server, which determines a collection of substitute-application-servers comprising one or more substitute-application-servers. Moreover according the current teaching in said switch-demand-step identifications (
104
) of said collection of substitute-application-servers are sent to said connected-application-client. Finally in response to said demand in said connect-to-substitute-application-server-step said connected-application-client selects a substitute-application-server (
120
) from said collection of substitute-application-servers and opens a substitute-connection (
104
) to said selected substitute-application-server.
Based on this feature of the current teaching the application clients are relieved from determining the substitute application servers themselves. The application server which is going to discontinue its application services is doing that once for all affected application clients increasing overall efficiency.
Additional advantages are accomplished if said substitute-application-server-determination-step determines said collection of substitute-application-servers by retrieving (
204
) from a first database (
202
,
130
) a collection of currently active application-servers (
110
,
120
,
140
). In addition the application server is optionally negotiating with said currently active application-servers whether it may discontinue its availability. Finally, if discontinuing availability is confirmed, the application server selects one or more of said currently active application-servers as said collection of substitute-application-servers.
By maintaining the list of active application servers in database it becomes very performance-effective to determine these active application servers: it is reduced to a database access. From this list a further subset can be determined according any criteria; for instance proximity be
Leymann Frank
Roller Dieter
Carstens Yee & Cahoon LLP
Clay A. Bruce
Dinh Dung C.
Flynn Kimberly
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