5.6.2 Switching the Web application by partially locking the service
With service lock of the Web application, you can also lock the services partially. You can lock the Web application service partially to switch the J2EE application and perform system maintenance without stopping the service.
- Organization of this subsection
(1) System configuration wherein partially locking the service is possible
The system configurations where partially locking the service is possible are as follows:
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Configuration in which the load balancer is used to distribute requests to multiple Web servers
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Configuration in which the Web server and J2EE server are in a 1:1 or 1:n configuration
Note that in the case of an application that uses a session, it is necessary to process requests of the same session in the same J2EE server. However, if you perform partial lock of the Web application service, the request is processed in another J2EE server that is different from the J2EE server that has the locked Web application. In order to inherit the session information, use the session failover functionality. For the session failover functionality, see 5. Inheriting Session Information Between J2EE Servers in the uCosminexus Application Server Expansion Guide.
(2) Method of partially locking the service
To partially lock a Web application service, change the request distribution destination of the load balancer and ensure that the request is not forwarded to the Web application that you want to lock.
At this time, in order to ensure that an error is not returned for the request, confirm that there is no request executed in the J2EE server. Implement the following depending upon the Web server used:
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When using Cosminexus HTTP Server as the Web server
Terminate Cosminexus HTTP Server. No request will be forwarded to the J2EE server if Cosminexus HTTP Server is terminated.
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When using Microsoft IIS as the Web server
Confirm that there is no request being executed in the corresponding J2EE server. To check the number of requests being executed in a J2EE server, obtain the information by using the mngsvrutil command of the Management Server. For details, see mngsvrutil (Management Server management command) in the uCosminexus Application Server Command Reference Guide.
Note that when changing the request distribution destination, the load balancer requires a function to maintain the connection between the load balancer and the Web server prior to change until the request processing is completed. If a load balancer without this function is used, an error is returned in the request being executed.