MySQL Cookbook, 2nd Edition

Servlet and JavaServer Pages Overview

Java servlet technology is a means by which to execute Java programs efficiently in a web environment. The Java Servlet Specification defines the conventions of this environment, which may be summarized briefly as follows:

• Servlets run inside a servlet container, which itself either runs inside a web server or communicates with one. Servlet containers are also known as servlet engines.

• The servlet container receives requests from the web server and executes the appropriate servlet to process the request. The container then receives the response from the servlet and gives it to the web server, which in turn returns it to the client. A servlet container thus provides the connection between servlets and the web server under which they run. The container acts as the servlet runtime environment, with responsibilities that include determining the mapping between client requests and the servlets that handle them, as well as loading, executing, and unloading servlets as necessary.

• Servlets communicate with their container according to established conventions. Each servlet is expected to implement methods with well-known names to be called in response to various kinds of requests. For example, GET and POST requests are routed to methods named doGet() and doPost().

• Servlets that can be run by a container are arranged into logical groupings called “contexts.” (Contexts might correspond, for example, to subdirectories of the document tree that is managed ...