In J2EE agents, the agent filter component manages authentication. The agent filter is a servlet filter, which is supported starting with J2EE 1.3. The agent filter intercepts an inbound request to the server. It checks the request to see if it contains a session token. If one is available, the agent filter validates the token using the Access Manager Session Service. If no token is available, the browser is redirected to the Authentication Service as in a typical SSO exchange. Once the user credentials are authenticated, the request is directed back to the server where the agent filter once again intercepts it, and then validates the newly acquired token. After the user's credentials are validated, the filter enforces J2EE policies or fine-grained URL policies on the resource the user is trying to access. Through this mechanism, the agent filter ensures that only requests with a valid Access Manager token are allowed to access a protected application.