Oracle Web Cache Administration and Deployment Guide Release 1.0.2.3 Part Number A86722-03 |
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This chapter describes additional configuration options available for deployments with two or more application Web servers. This chapter contains these topics:
For those requests that Oracle Web Cache cannot serve, you can distribute the requests over a set of application Web servers with Oracle Web Cache's load balancing feature. To configure load balancing, you prescribe the relative load of each application Web server.
When load balancing is configured and an application Web server is no longer available, Oracle Web Cache automatically performs backend failover of the application Web servers. Oracle Web Cache knows if an application Web server is down when there are five continuous request failures to the server. An application Web server can become unavailable if it is taken down for reconfiguration or there is a network or hardware failure. In these scenarios, Oracle Web Cache automatically distributes the load over the remaining application Web servers and polls the failed application Web server for its current up/down status every 60 seconds until it is back online. Existing requests to the failed application Web server result in errors. However, new requests are directed to the other application Web servers. When the failed server returns to operation, Oracle Web Cache includes it in the load distribution.
You can configure Oracle Web Cache to support application Web server session binding, whereby a user session is bound to an application Web server in order to maintain state for a period of time. To utilize this feature, the application Web server itself must maintain state, that is, it must be stateful.
As long as the session information is contained within a session cookie or an embedded URL parameter, Oracle Web Cache can keep track of sessions between Web browsers and application Web servers. This enables Oracle Web Cache to bind a particular user session to a specific application Web server.
To configure Oracle Web Cache to support binding a user session to application Web servers that are stateful:
The Application Web Server Session Binding page appears in the right pane.
The Change Application Web Server Session Binding dialog box appears.
If the sessions listed do not contain the definition you require, choose Create A New Session Definition to create a new session definition. The Edit/Create Session Definitions dialog box appears. Continue to Step 5.
If you enter both a cookie name and an embedded URL parameter, keep in mind that both must be used to support the same session. If they support different sessions, create separate session definitions. You can specify up to 20 session definitions for each page.
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