Design of an Improved HTTP Server

Design of an Improved HTTP Server
A Simple Network Application in Java

Computer Science Department

bernstdh@jmu.edu

Comments on our Current Design

Handling GET Requests:
- We can do very little in response to a GET request
- Adding functionality will complicate the code
Handling Other Requests:
- Adding support for POST requests will further complicate the code

Improving the Current Design

What's Needed?
- A way to "instruct" the connection handler how to handle requests.
A Solution:
- The Strategy Pattern

The Servlet Interface

javaexamples/http/v3/HttpServlet.java

An Improved HTTP Connection Handler

javaexamples/http/v3/HttpConnectionHandler.java

An Abstract Servlet

javaexamples/http/v3/AbstractHttpServlet.java

Invoking Servlets

A General Approach:
- Map servlet to URLs
Different Kinds of Mappings
- Map one servlet to one URL
- Map one servlet to one directory
- Map one servlet to files with a given extension

A Servlet Factory

javaexamples/http/v3/HttpServletFactory.java

A Default Servlet

javaexamples/http/v3/DefaultHttpServlet.java

An Example

The Motivation:
- Many WWW sites use a single "template" for all of their pages
- The easiest way to do this is to include all of the template information (e.g., headers, menu bars, footers) in each page
- The problem with this approach is that you have the same information in multiple files which makes it difficult to change, etc...
Using a Servlet:
- Have a servlet that writes the common information into each response

An Example (cont.)

javaexamples/http/v3/TemplatedHttpServlet.java

There's Always More to Learn