Notes

Tomcat Architecture

Key Components

1. Connector (Coyote)
   • Accepts web requests from clients
   • Handles HTTP protocol communication
2. Web Container (Catalina)
   • Processes servlet requests
   • Manages servlet lifecycle
   • Contains servlet engine
3. JSP Container (Jasper)
   • Handles JSP processing
   • Converts JSP to servlets
4. Web Applications
   • Applications running within Tomcat

Thread Model

• Thread Pool Creation: Web container creates a collection of threads during startup (executor thread pool)
• Request Processing:
  • Each request to connector gets a thread assigned from the pool
  • Thread processes the request
  • Upon completion, thread returns back to pool
• Configuration: Maximum number of threads in pool can be configured in server.xml

Request Processing Flow

1. Bootstrap: Main method starts the server
2. URL Mapping: Maps incoming requests to appropriate servlets
3. Servlet Object: Created on first request (singleton pattern)
4. Response Generation: doXxx() methods generate response
5. HTTP Response: Sent back to client

Java Servlets

Servlet Definition

• Java class executed in web server when request is received from client