A request processed by an application server follows the path described in this section, which assumes you configure your web application to use PageFilter as demonstrated in atg_bootstrap.war.

When a user performs an action that prompts a response, the application server creates an instance of the HttpServletRequest and HttpServletResponse. Based on the directories and file extension of the requestURI, the application server uses servlet and filter mappings defined in web.xml to determine the next resource to call.

By default, PageFilter is mapped to handle JSP requests. When the application server invokes PageFilter, it checks the request and response for a reference to a Dynamo request and response pair. The pair does not exist, so PageFilter starts the DAF servlet pipeline by calling DynamoHandler, the first servlet in the pipeline. The DAF servlet pipeline processes through a series of servlets that modify the request and response by extracting path information and providing session, user, and security information. The last servlet in the pipeline is TailPipelineServlet. It is responsible for calling FilterChain.doFilter(), which invokes the next filter defined in web.xml. The web application, unless it uses Oracle ATG Web Commerce Portal, does not include other servlet filters.

By default, no filters are involved in request-handling process. For more information on how to implement J2EE servlets and filters in an Oracle ATG Web Commerce web application, see the Accessing Nucleus in a Web Application chapter in this guide.