If you open the GAEJ___ChapterThree.html file from the web application archive (war
directory) you can see the following HTML elements.
GWT, using the add() method of the RootPanel class, knows to insert the GWT
components in that section of the application's HTML. You can see how quickly and
easily you can leverage the power of Google Web Toolkit to build a pretty impressive
Local Development Server
The App Engine SDK comes with a local development server for App Engine testing
and debugging. This is required because the Java Runtime on App Engine is slightly
different from the standard distribution. For example, you can't open ports or sockets
in App Engine. To make a remote HTTP request you need to implement App Engine's
URL Fetch service (covered in Chapter 8). The development server is part of the SDK.
You can't use your own development server for App Engine debugging and testing. The
App Engine JRE differs from other implementations. Let's take a deeper look at some of
the features of the local development server and some miscellaneous tools to
accelerate application development on App Engine.
Ready to Launch
Soon after the birth of App Engine, a few Google employees used their “20 percent time”
(one day a week to work on projects that may not be part of their official jobs) to create
an App Engine launcher for Mac. With the release of the App Engine 1.2.5 SDK there was
a second group of 20-percenters that released a Windows/Linux version of the launcher.
The source code for all these distributions is available at code.google.com.
Figure 3-8 shows the App Engine Launcher for Mac. The launcher helps you
edit the configuration files for both Python and Java App Engine projects, browse
your applications locally, and even deploy your applications to the production
environment. If you're interested, the source code for the Mac launcher is located
here on Google Code : http://code.google.com/p/google-appengine-mac-launcher .