Reloading Considerations | Java Servlets tutorial pdf

Reloading Considerations

Although a Container Provider implementation of a class reloading scheme for ease of development is not required, any such implementation must ensure that all servlets, and classes that they may use, are loaded in the scope of a single class loader. This requirement is needed to guarantee that the application will behave as
expected by the Developer. As a development aid, the full semantics of notification to session binding listeners should be supported by containers for use in the monitoring of session termination upon class reloading.
Previous generations of containers created new class loaders to load a servlet, distinct from class loaders used to load other servlets or classes used in the servlet context. This could cause object references within a servlet context to point at unexpected classes or objects, and cause unexpected behavior. The requirement is needed to prevent problems caused by demand generation of new class loaders.

Temporary Working Directories

A temporary storage directory is required for each servlet context. Servlet containers must provide a private temporary directory for each servlet context, and make it available via the javax.servlet.context.tempdir  context attribute. The objects associated with the attribute must be of type java.io.File. The requirement recognizes a common convenience provided in many servlet engine implementations. The container is not  required to maintain the contents of the temporary directory when the servlet container restarts, but is  required to ensure that the contents of the temporary directory of one servlet context is not visible to the servlet contexts of other Web applications running on the servlet container.