Understanding Web Application Structure
A web application is a collection of web resources, such as JSP pages, HTML pages, servlets,
and configuration files, organized into a hierarchy as specified in the Servlet specification. You
have two ways in which to organize a web application: packed and unpacked. The packed form
is called a web archive (WAR) file, and the unpacked form is a collection of directories stored
on the file system.
The unpackaged format is convenient for web application developers, as it allows them to
replace individual files while the application is being developed and debugged.
However, in a deployment environment, it’s often more convenient to provide a single file
that can be automatically deployed. This reduces the deployment process to placing the file and
setting up system resources. Tomcat can also automatically expand a web application once
the server has booted. The automatic expansion of WAR files is configured in the server.xml
file as part of the element that configures hosts.
Web Application Context
Each web application corresponds to a context component, as discussed in Chapter 1, and
you assign a context path to each. The default context is called ROOT and corresponds to the
name of the server with no other context information. For example, the ROOT web application
on your local machine will correspond to http://localhost:8080.
If you’ve configured Domain
Name System (DNS) settings for your server, it may also be accessible from a location such as
Users access other web applications by requesting a context relative to the server. For
example, users can access Tomcat’s manager web application with the following URL:
http://
localhost:8080/manager.
Applications that you place in the webapps folder are named after the directory they’re in.
So, you can access the web application in the tomcat-docs directory with the following:
http://localhost:8080/tomcat-docs.
Each application on the server is known by its name,
and users can access resources according to the remainder of the uniform resource locator
(URL) after the web application’s name.