NonStop Servlets for JavaServer Pages (5.0) System Administrator's Guide

Configuring NSJSP

NonStop Servlets for JavaServer Pages (NSJSP) System Administrator’s Guide—525644-002

3-20

Map Requests to Applications and Servlets

Mapping requests to servlets is closely linked to the concept of a context path.

The application name and the context path lead to the application subdirectory. The

<servlet-mapping> and <servlet> tags are needed to find a servlet or JSP within

that application.

The location of the application directory (and, therefore, the servlet or JSP) is

determined in the docBase attribute of a Context if an absolute path is specified or

then as a relative path to the value of the appBase attribute of the Host this Context

belongs to.

The servlet or JSP could be any name (given the <servlet-name> and <servlet-

class> XML elements of the web.xml file) not just the class name. Using these

elements allows separation between the web pages (using a servlet name) and the

underlying Java code (using the class name), and makes maintenance easier.

URL Mapping to the Application

In a NSJSP container, each application is associated with a context, and all resources

exist relative to that context. The context path starts at the root level of the application

directory. In Configuring Web Applications on page 3-14, the context is /myapp1, the

name of the application.

Consider the URL that locates that context:

http://www.hostname.com/myapp1

The http://www.hostname.com is a URL for the HTTP scheme located at

www.hostname.com. The URI path is /myapp1. Together they form the URL.

As well as the www.hostname.com notation shown above, URLs can take the form

http://hostname:portnumber/myapp1

Each web application must be mapped to a unique URL path prefix, for instance,

/myapp1. The NSJSP container uses this prefix to map requests to resources within

the web application. The path name serves as the document root for serving resources

within the application.

URL Mapping to the Servlet

The mapping process has two parts. The first part is to provide servlet name and,

optionally, an alias for the full servlet class name. Therefore you could have a servlet

name such as start that refers to the servlet class startCartRequest.

The second part is to use the <servlet-mapping> elements of the deployment

descriptor to provide a more complex mapping than the usual inclusion of servlet name

(or class name) in the URL.

Example 3-13 is a sample fragment of a web.xml file that maps any URL containing

the application name to a specific servlet.