Oracle Web Cache Administration and Deployment Guide Release 1.0.2 Part Number A86722-01 |
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# 7
Configuration Considerations for Web Sites with Multiple Application Web Servers

This chapter describes additional configuration options available for deployments with two or more application Web servers. This chapter contains these topics:

- Configuring Load Balancing

- Binding a Session to an Application Web Server

## Configuring Load Balancing

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.

See Also: "Load Balancing of Application Web Servers" for an overview of load balancing

1. Start Oracle Web Cache Manager.

   See Also: "Starting Oracle Web Cache Manager"

2. Configure application Web server settings in the Edit/Create Application Web Server dialog box, following the steps in "Task 4: Specify Web Site Settings". In Step 2 of the procedure, enter the number of concurrent connections that the application Web server can sustain in the Capacity field. The weighted load percentage of each application Web server is derived from the entered capacity.

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.

## Binding a Session to an Application Web Server

You can configure Oracle Web Cache to support application Web server binding, whereby a user session is bound to an application Web server in order to maintain state for a period of time.

See Also: "Application Web Server Binding" for an overview of application Web server binding

As long as the session information is contained within a 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 application Web server session binding:

1. Start Oracle Web Cache Manager.

   See Also: "Starting Oracle Web Cache Manager"

2. In the navigator pane, select Administering Web Sites > Session Management > Session Binding.

   The Application Web Server Session Binding page appears in the right pane.

3. In the Application Web Server Session Binding page, choose Edit.

   The Change Application Web Server Session Binding dialog box appears.

4. From the Please select a session list, select a session and skip to Step 7.

   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.

5. Create a session definition in the Edit/Create Session Definitions dialog box:

   1. In the Session Name field, enter an easy-to-remember unique name for the attribute.

   1. Enter the cookie name in the Cookie Name field and/or the embedded URL parameter in the URL Parameter field.

   2. Choose Submit.

6. In the Change Application Web Server Session Binding dialog box, select the session definition from the Please select a session list.

7. In the Inactivity Timeout field, enter the number of minutes you want Oracle Web Cache to wait before timing out an inactive session to the application Web server. Oracle Corporation recommends setting the value to a higher value than the inactivity timeout set for the Web site.

8. Choose Submit.

9. Apply changes and restart Oracle Web Cache:

   1. In the Oracle Web Cache main window, choose Apply Changes.

   1. In the navigator pane, select Administering Oracle Web Cache > Web Cache Operations.

      The Oracle Web Cache Operations page appears in the right pane.

   2. In the Oracle Web Cache Operations page, choose Stop and then Start to restart Oracle Web Cache.

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