This figure shows how a Web client can establish its identity by passing the user name and password to a servlet within a J2EE Container. The servlet then uses that identity to communicate with other EJBs and servlets within the same J2EE Container and within other J2EE Containers. When communicating with EJBs and servlets within other containers, Common Secure Interoperability Version 2 protocol (CSIv2) is used. Thus authenticated, the EJBs and servlets communicate with the components of the Enterprise Information System tier, such as the Messaging System, the Database, and the ERP and SAP Applications.