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> ## Updating Web Applications

> During development, you will often need to make changes to Web applications. After you modify a servlet, you must

> 1. Recompile the servlet class.
> 2. Update the application in the server.
> 3. Reload the URL in the client.

> When you update a JSP page, you do not need to recompile or reload the application, because Tomcat does this automatically.

> To try this feature, modify the servlet version of the Hello application. For example, you could change the greeting returned by `GreetingServlet` to be:

>     <h2>Hi, my name is Duke. What's yours?</h2>

> To update the file:

> 1. Edit `GreetingServlet.java` in the source directory `<``INSTALL``>/jwstutorial12/examples/web/hello1/src`.
> 2. Run `ant build`. This task recompiles the servlet into the `build` directory.

> The procedure for updating the application in the server depends on whether you installed it using the `Ant` `install` task or deployed it using the `Ant` `deploy` task.

> ### Reloading Web Applications

> If you have installed an application using the `Ant` `install` command, you update the application in the server using the `Ant` `reload` task:

>     <reload url="url" path="mywebapp"
>       username="username" password="password" />

> The example build files contain an `Ant` `remove` target that invokes the `Ant` `remove` task. Thus to update the `Hello1` application in the server, execute `ant` `reload`. To view the updated application, reload the `Hello1` URL in the client. Note that the `reload` task only picks up changes to Java classes, not changes to the `web.xml` file. To reload `web.xml`, remove the application (see Removing Web Applications) and install it again.

> You should see the screen in Figure 4-3 in the browser:

> Figure 4-3 New Greeting

> To try this on the JSP version of the example, first build and deploy the JSP version of the Hello application:

> 1. In a terminal window, go to `<``INSTALL``>/jwstutorial12/examples/web/hello2.`
> 2. Run `ant` `build`. The `build` target will spawn any necessary compilations and copy files to the `<``INSTALL``>/jwstutorial12/examples/web/hello2/build` directory.
> 3. Run `ant` `install`. The `install` target copies the build directory to `<JWSDP_HOME>``/webapps` and notifies Tomcat that the new application is available.

> Modify one of the JSP files. Then run `ant` `build` to copy the modified file into `jwstutorial12/examples/web/hello2/build`. Remember, you don't have to reload the application in the server, because Tomcat automatically detects when a JSP page has been modified. To view the modified application, reload the `Hello2` URL in the client.

> ### Redeploying Web Applications

> If you have deployed the application using the `Ant` `deploy` task you update the application by using the `Ant` `undeploy` task (see Undeploying Web Applications) and then using the `Ant` `deploy` task.

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