Hack 43. Integrate DWR into Your Java Web Application
The Direct Web Remoting code comes in the form of an archived or zipped Java Archive (JAR) file, dwr.jar. The download address is http://www.getahead.ltd.uk/dwr/download.html.
To get started with DWR, you must first set it up in your server-side web application. Place the dwr.jar file in the /WEB-INF/lib directory of your Java web application on the server, then restart or reload the application.
Configuring the Application
<servlet> <servlet-name>dwr-invoker</servlet-name> <servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class> <init-param> <param-name>debug</param-name> <param-value>true</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>dwr-invoker</servlet-name> <url-pattern>/dwr/*</url-pattern> </servlet-mapping>
Figure 5-1. Calling a Java method remotely
The URL that the script tag uses, such as /parkerriver/dwr/interface/JsBean.js, connects to the special DWR servlet that we enabled. The servlet in turn makes available to our code the public methods of the Java classes that we configured in XML. The next few hacks will use these classes and functions.