Introduction to Tomcat

Tomcat source code

Reading the Tomcat source code Tomcat architecture

What This Covers

1. Tomcat structure diagram
2. Tomcat startup process
3. Tomcat request handling process

1. Tomcat structure

• Service
  • Connector
    • Container
      • Engine
        • Host
          • Context
            • Wrapper: corresponds to one Servlet class

2. Tomcat startup process

3. Tomcat request handling process

• Data arrives on a local port and is picked up by the Connector
  • Connector: listens for TCP connection requests on the port
    • Creates the Request and Response
    • Spawns a thread to pass the request to Container.Engine
      • The Container’s Engine receives the request and hands it to the Host
        • The Host receives the request and hands it to the Context
          • The Context receives the request, matches the Servlet, and hands it over
            • Constructs the HttpServletRequest and HttpServletResponse
          • Context returns the HttpServletResponse to the Host
        • Host returns the HttpServletResponse to the Engine
      • Engine returns the HttpServletResponse to the Connector
  • Connector returns the HttpServletResponse to the Browser