BEA attempts to support binary and source-level compatibility between the current version of WebLogic Server and all versions as far back as 7.0 in the areas of persistent data, generated classes, and API compatibility. In some cases, it is impossible to avoid incompatibilities. Where incompatibilities arise, they are fully documented in the Upgrading WebLogic Application Environments guide.

J2EE 1.4 Compatibility

BEA WebLogic Server is one hundred percent J2EE 1.4 compatible across all operating system platforms for WebLogic Server 9.1. This compatibility allows a J2EE 1.4 compliant application to be developed on one operating system platform (such as a Windows platform) and deployed for production on another (such as UNIX, Linux, Tru64, OpenVMS, or HP NonStop), without requiring J2EE application code changes. BEA ensures this compatibility of J2EE application portability within a WebLogic Server release level.

Persistent Data Compatibility

Upgrading to WebLogic Server 9.1 does not require you to make any changes to WebLogic Server 7.0, 8.1, or 9.0 persistent data storage, including configuration files, deployment descriptors, transaction logs, and JMS messages.

Generated Classes Compatibility

With one exception, upgrading to WebLogic Server 9.1 does not require you to recompile applications in order to create new generated classes.

The 9.1 version of the EJBGen utility recognizes only JDK 5.0 metadata annotation-style EJBGen tags and not the old Javadoc-style tags. This means that source files that use the Javadoc-style tags must be upgraded to use the equivalent annotation, and then recompiled using the 9.1 version of EJBGen.

API Compatibility

WebLogic Server 7.0, 8.1, and 9.0 applications deployed on WebLogic Server 9.1 will function without modification. Exceptions to this rule include cases where API behavior was changed in order to conform to a specification or to fix incorrect behavior. In certain circumstances, a correction may cause your application to behave differently.

Protocol Compatibility

Interoperability between WebLogic Server 9.1 and WebLogic Server 7.0, 8.1, and 9.0 is supported in the following scenarios:

• A WebLogic Server 7.0, 8.1, or 9.0 client can invoke RMI-based applications hosted on a WebLogic Server 9.1 server using IIOP, T3, T3S, HTTP, and HTTPS. JMS applications can be invoked using T3, T3S, HTTP, and HTTPS.
• A WebLogic Server 9.1 client can invoke RMI-based applications hosted on a WebLogic Server 7.0, 8.1, or 9.0 server using IIOP, T3, T3S, HTTP, and HTTPS. JMS applications can be invoked using T3, T3S, HTTP, and HTTPS.
• A WebLogic Server 9.1 Web server plug-in can proxy to the latest service pack release of a 7.0, 8.1, or 9.0 server

JMX Compatibility

See JMX 1.2 Implementation in Upgrading WebLogic Application Environments.

Compatibility Within a Domain

• All WebLogic Server instances within the same Administrative domain must be at the same major and minor version. You cannot mix server versions within a domain.
• Servers within an Administrative domain can be at different Service Pack levels as long as the Administration Server is at the same Service Pack Level or higher than its Managed Servers.
• All servers within a cluster must be at the same Service Pack level.