Application Recommendations for All Migrations

This section brings to light some of the many situations in which you'll want to alter your existing applications to take advantage of the many new features of WebLogic Server version 8.1.

Servlet Recommendations

Version 8.1 is compliant with the Servlet 2.3 specification of the J2EE 1.3 specification. If your Web application is using an older specification, you might want to take advantage of some of the features in the newer specification.

Version 6.1 used the Servlet 2.2 specification, and your servlets should work exactly the same in version 7. However, if you're using WebLogic Server as a proxy to another server or cluster, you might want to use the two new proxy servlets in version 8.1. To do so, make the following changes in your web.xml deployment descriptor:

Change

weblogic.servlet.internal.Http.ClusterServlet

to

weblogic.servlet.proxy.Http.ClusterServlet

Also change

weblogic.t3.srvr.HttpProxyServlet

to

weblogic.servlet.proxy.HttpProxyServlet

EJB Recommendations

Version 8.1 is compliant with the EJB 2.0 specifications of the J2EE 1.3 specification. If you're migrating a 1.0 EJB application, you'll need to recompile it to one of the newer specifications. Also consider recompiling your EJBs to the EJB 2.0 specification and taking advantage of the new local home and local interfaces not found in previous versions. The local interfaces give local clients (on the same VM) quicker access to EJB objects.

If your EJBs still use the WebLogic Query Language (WL QL), consider converting to the new EJB Query Language (EJB-QL), which is compliant with the EJB 2.0 specification. EJB-QL is portable and includes features not found in WL QL. If you used EJB-QL in version 6.1, remember that in version 8.1 queries require a SELECT clause. Also new to version 8.1 is the support for dynamic EJB-QL queries. Queries were previously hard-coded into the ejb-jar.xml deployment descriptor. With dynamic queries, you can construct your queries programmatically and implement new queries dynamically without having to redeploy the EJB. You'll also need to upgrade the deployment descriptors. You can read about how to upgrade deployment descriptors at http://edocs.bea.com/wls/docs81/upgrade/upgrade70to81.html#1075478.

JMS Recommendations

Version 8.1 is compliant with JMS version 1.0.2b of the J2EE 1.3 specification, and includes many new and improved features not found in previous versions. If you're migrating any JMS applications, you might want to take advantage of some of these improvements.

The first is the use of version 8.1's distributed JMS destinations. In a clustered environment, you were previously able to define only one physical JMS destination. By being able to define multiple destinations, you can add failover capability to JMS.

JMS also includes new flow control and message pooling features that can be used to prevent missing messages when the number of messages exceeds JMS server or destination thresholds.