No, it has nothing to do with armed conflict. Making WAR files is the Java way of packaging, distributing, and deploying web applications. While JAR stands for “Java archive”, WAR stands for “Web application archive”, or simply “Web archive”. In fact, the JAR and WAR formats are both gzipped directories that include a manifest. While a JAR file typically contains a collection of class files, a WAR file contains the entire content that goes into a Java Web application. More precisely, a WAR file contains all the static content, directories, JSPs, beans and classes, libraries, as well as the web.xml deployment descriptor. If you unpack a WAR file, you get a directory structure that mirrors the document root of a deployed application in a web container, such as Tomcat. I recently had to create a Web application in Eclipse. I realised that despite having worked with Eclipse for five years, this is something I never did before, because in the past I used Netbeans for creating web applications. But it’s just as easy in Eclipse. Here are is how:
To create a Java web project, you need to have the following software installed: a Java JDK, a recent version of Eclipse that contains the WTP Web Tools Platform module for Eclipse, and a web container or an application server, such as Tomcat, JBoss, WebSphere, etc.
1…Select File/New/Project from the menu. The following dialogue appears:
2…Select Dynamic Web Project from the list and click on the Next button.
3…Type a name for the new project and select a file system location for it. In the Target Runtime option, specify the web container or application server you using. This server is used to build and deploy your web application. If the drop-down box does not contain the desired server, click New… and select one of the predefined configurations (see Step 4). If you have already defined a Target Runtime, you can skip ahead to Step 6. The Dynamic Web Module version option specifies the architecture you are going to use in the web project. Select the latest version for a new project. Unfortunately, this cannot be changed later. By clicking the Modify… button in the Configuration section, you can select “facets” for your web application. What Eclipse calls “facets” are various building blocks and APIs, such as Java Server Faces, Java Persistence API, etc., that add functionality to your application.
4…The New… button in the Target Runtime section opens a dialogue that lets you select the server on which the application is developed and deployed, which is probably the most important aspect of your configuration. Eclipse offers a number of common configurations for popular servers. If you cannot find your server in this list, click on the Download additional server adapters link and chances are that your server is listed. Make sure that the Create a new local server option is checked, so that you can find the server in the Eclipse server view later on.
5…Once you specified the server type, you need to provide some details about it, such as the installation directory of the server, or the server root, and the JRE you want the server to run on. Click Finish when done.
6…Finally, the dynamic web project wizard prompts you for some basic configuration data. The Context Root is the name that the web container matches with the location where the application is deployed and simultaneously constitutes the root URL for the web application. The Content Directory specifies the name of the directory that contains the web application files. The Java Source Directory specifies the name of the directory that contains Java source code files. These settings are only relevant to the development machine. Make sure that the Generate deployment descriptor option is checked in order to automatically create the web.xml file. In most cases, you can probably accept the default settings and click Finish.
7…Voilá. You have created a web application, or rather the framework for its development in Eclipse. The new project should now be visible in the Navigator view. There aren’t any files yet, except the ones which were generated automatically by Eclipse. The next step would be to write your web application, and possibly incorporating the application framework of your choice. Piece of cake.
8…The Server view should display the server you have chosen for your project. If everything went OK, you can start and stop the server from this view. The server can be started in normal mode, debug mode, or profiling mode. Debug mode needs to be selected if you want to define breakpoints in your Java code. While you edit sources, such as JSP files, servlets, bean classes, static content, etc., Eclipse automatically redeploys these resources to the running server as soon as you save them. You can view your web application in a separate browser window and receive debug output in Eclipse’s Console view.
9…After you have written your formidable web application, it’s time to share it with the world, or in more technical terms, to distribute and deploy it. The process of creating a distributable WAR file is extremely simple. Select File/Export from the Eclipse menu and click on the WAR file option in the Web category.
10…After clicking the Next button, specify the web project to be packaged, the file destination, and the target server. Although the latter is not a mandatory option, it is probably an important one. The selected server is likely to be the same as the one chosen in Step 3. Click Finish and there you have your masterpiece in a handy WAR format.