Thanks to my colleague Dave Screen for highlighting a useful technote relating to sharing library modules in WebSphere ESB and Process Server. The WebSphere Integration Developer concept of a library is typically only used for development time sharing of artifacts i.e. when you deploy a module that depends on that library, a copy of the JAR file is included in the enterprise application that is deployed. The technote describes how to deploy the library as a WebSphere shared library and have multiple modules depend on the same instance at runtime. This has the potential to reduce memory usage (the library is on a shared classloader) and ease managability. It does, however, mean that you need to be more careful about versioning of the library and breaking other dependent modules. If you’re not on 6.2 then note the list of APARs at the bottom of the document.