Hi,
According to the specification of the servlets :
SRV.3.7.1 Temporary Working Directories
A temporary storage directory is required for each servlet context. Servlet
containers must provide a private temporary directory per 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.
