Chapter 3. Connector

As mentioned in Introduction, there are two main modules in Catalina: the connector and the container. In this chapter you will enhance the applications in Chapter 2 by writing a connector that creates better request and response objects. A connector compliant with Servlet 2.3 and 2.4 specifications must create instances of javax.servlet.http.HttpServletRequest and javax.servlet.http.HttpServletResponse to be passed to the invoked servlet’s service method. In Chapter 2 the servlet containers could only run servlets that implement javax.servlet.Servlet and passed instances of javax.servlet.ServletRequest and javax.servlet.ServletResponse to the service method. Because the connector does not know the type of the servlet (i.e. whether it implements javax.servlet.Servlet, extends javax.servlet.GenericServlet, or extends javax.servlet.http.HttpServlet), the connector must always provide instances of HttpServletRequest and HttpServletResponse.

In this chapter’s application, the connector parses HTTP request headers and enables a servlet to obtain headers, cookies, parameter names/values, etc. You will also perfect the getWriter method in the Response class in Chapter 2 so that it will behave correctly. Thanks to these enhancements, you will get a complete response from PrimitiveServlet and be able to run the more complex ModernServlet.