Solr with IBM WebSphere
Solr doesn't run out of the box on IBM WebSphere Application Server. The minimum version for Running Solar is WAS 6.1.x, cause WAS 6.0 doesn't support Java 5. This page is just about WebSphere specific instructions, see the instructions in the generic Solr installation page for general info before consulting this page.
Required Modifications for WAS 6.1
The following instructions are the required modifications for the apache-solr-1.3.0.war on WebSphere 6.1. This modifications should work with all versions of the the WAS 6.1 series.
Enabling Java 5 for JSP pages
Cause WebSphere 6.x is a J2EE 1.4 container, it doesn't support Java 5 out of the box. You have to explicit enable Java 5 for the JSP compiler. To do this, you've got to create (or modify) 2 files:
Adding index.jsp to Welcome File List
In the apache-solr-1.3.0.war there is now welcome file section. WebSphere doesn't handle index.jsp as auto welcome file, so you've got to modify the web.xml to get a page displayed. Add the 'welcome-file' section add the bottom of the web.xml file.
Working with the Admin Console and Multicore
If you're having trouble using the various pages on the admin console when specifying the core name in your URL path you may see errors around WebSphere not finding the JSPs. This could be related to a known issue with Websphere not running filters when a static file is not found on the expected path.
The SolrDispatchFilter removes the core name from the path when forwarding to the correct JSPs. To force Websphere to run the filter before returning a 404 add the custom property from the linked issue above to the app server running your Solr instance.
Enable remote JMX monitoring on WebSphere and register Solr MBeans
When you try to access Solr on WebSphere (with <jmx/> config enabled in solrconfig.xml) it fails to register beans (query, facet, etc) and throws "javax.management.InstanceAlreadyExistsException". To resolve this you need to add following System property to your server (Application servers > server > Process definition > Java Virtual Machine > Custom properties)
Restart the server and now WebSphere should not throw exception. To confirm that beans have been registered successfully make sure that you have following line in your logs
Once you have the beans registered you can connect and access Solr configurations and statistics via JMX remotely by adding following System properties to server.
Restart the server and now you can use tool like JConsole to connect and access Solr configurations and statistics remotely via JMX by specifying the hostname and port.