问题
Can a Java 6 application work on Webpshere 8.5 if the nodes are built using Java 7? I have an EAR which was developed using Java6 and deployed on Websphere 8.5 using EA but the Webservice always gives 404.
Thanks.
回答1:
It appears that that no support is provided for Java SE 6 in that version of WebSphere.
From the online documentation for WebSphere 8.5.5 (not sure if this is the version you are using tho')
Notice: Java SE 6 is being removed from service. Java SE 8 is the recommended Java SDK because it provides the latest features and security updates. You can continue to use Java SE 6, but no service can be provided after the end of the support date, which might expose your environment to security risks.
In fact, it appears that not even Java SE 7 is supported in this version of WebSphere either
回答2:
There is a confusion here about the meaning of "version" and how it applies to JavaEE applications:
There is the version of the JVM which is selected to run the server.
There is the JavaEE specification level used to encode XML documents (web.xml, application.xml, ejb-jar.xml, etc) which are within an application.
There is the JavaEE specification level which is supported by the server.
There is the java compiler level which is set for classes packaged within an application.
There is, technically speaking, no specific version associated with an application. That an application is at Java 7 can mean "the classes of the application were compiled to java7", or, "the XML descriptors are set to the versions available to JavaEE7", or, "the function of the application requires a container which supports JavaEE7".
A key detail is that when running with WebSphere, its the server which decides to which JavaEE specification the application is run, not any feature of the application.
I'm guessing that in the original question, "Java 6 application" means the application was compiled to java6 and that the application features are limited to those available in java6. That should work on all of WebSphere v7.0, v8.0, v8.5, and v9.0 (at all service levels).
There are some complications to consider when using a distributed topology (having a DMGr node and more than one application server nodes). A frequent complication is that one or more of the application server nodes is at a lower version than the DMgr node. This is a supported scenario (with some limits on how big of a version difference is supported). The scenario is typical when a topology (a collection of federated nodes) is being migrated gradually from a particular WebSphere version to a higher version, and during the migration a mixture of node versions is available. When this is the case, the DMgr tracks the version of the application server nodes and constrains processing of the application to ensure the deployment is valid to all of the application server nodes to which the application is deployed.
Since the JavaEE level is set by the application server version, and since, generally, higher versions of the application server implement higher JavaEE levels, applications can function differently when migrated between application server versions. Whether this is the case for this question cannot be known without looking in more detail at the exact failure which is occurring.
来源：https://stackoverflow.com/questions/48347968/websphere-java-version