The servlet container is a compiled, executable program. The container is the intermediary between the Web server and the servlets in the container.The container loads, initializes, and executes the servlets.When a request arrives, the container maps the request to a servlet, translates the request into C++ objects, and then passes the request to the servlet. The servlet processes the request and produces a response. The container translates the response into the network format, then sends the response back to the Web server.

The container is designed to perform well while serving large numbers of requests. A container can hold any number of active servlets, filters, and listeners. Both the container and the objects in the container are multithreaded. The container creates and manages threads as necessary to handle incoming requests. The container handles multiple requests concurrently, and more than one thread may enter an object at a time. Therefore, each object within a container must be threadsafe.