Typically, you use Oracle HTTP Server to front end a cluster of WebLogic servers. Oracle HTTP Server acts as a front end for the cluster of WebLogic servers. When a request is made to a managed server, the mod_wl_ohs directive specifies a comma-separated list of cluster members to balance the server load. The process works as follows:
- When mod_wl_ohs receives a request that requires a managed server, it sends that request to one of the WebLogic cluster members that is listed in the directive. At least one server must be available to service the request.
- The Managed server processes the request and sends a complete list of cluster members back to mod_wl_ohs.
- When mod_wl_ohs receives the updated list, it dynamically adds any previously unknown servers, that may have been down during the initial request, to the list of known servers, which enables all future requests to be load balanced across the full cluster member list defined in the mod_wl_ohs configuration.
This process also enables new managed servers to be added to the cluster without having to manually update mod_wl_ohs as long as the new managed server host and port is determined ahead of time.
In an example scenario, assume that the WebLogic Cluster consists of WLS1, WLS2, and WLS3. Also assume that all three managed servers have been added to the mod_wl_ohs clustering directive, but only WLS1 and WLS2 are known to mod_wl_ohs during an initial request because WLS3 is offline.
When mod_wl_ohs first receives a request, it attempts to send that request to either WLS1 or WLS2. If during the request WLS3 becomes active, the list of available servers is updated to include WLS3 for future requests. If, however, WLS1 and WLS2 are unavailable, but WLS3 becomes available during the request, the request is rejected because mod_wl_ohs has no way of knowing WLS3 exists.
To configure mod_wl_ohs:
- Go to <OHS_Middleware_Home>/user_projects/domains/<Primavera_Domain>/config/fmwconfig/components/OHS/instances/<instance_name>.
- Edit mod_wl_ohs.conf.
- Add the following information to mod_wl_ohs:
<Location /p6>
WLSRequest On
WebLogicCluster <WebLogic_server1>:<port1>, <WebLogic_server2>:<port2>, <WebLogic_server3>:<port3>
</Location>
<Location /p6tmweb>
WLSRequest On
WebLogicCluster <WebLogic_server1>:<port1>, <WebLogic_server2>:<port2>, <WebLogic_server3>:<port3>
</Location>
<Location /p6ws>
WLSRequest On
WebLogicCluster <WebLogic_server1>:<port1>, <WebLogic_server2>:<port2>, <WebLogic_server3>:<port3>
</Location>
- Restart Oracle HTTP Server.
- Go to <OHS_Middleware_Home>/user_projects/domains/base_domains/bin.
- Depending on your operating system, complete the following:
- For Unix, run the following in a terminal:
./stopComponent.sh <component_name>
./startComponent.sh <component_name>
- For Windows, run the following in a command prompt:
stopComponent.bat <component_name>
startComponent.bat <component_name>