Use Eclipse to create mashups on Google App engine, part 1th

Tapping into social software is a great way to add value to your application. Using social networks makes it easier to get and aggregate data to create innovative new WEB applications. However, you still have to deal with all the common problems of creating a scalable Web application. Now, using the Google App Engine (GAE) can also simplify work. With GAE, you do not have to consider all the transactions that govern the application server pool. You don't have to worry about storing large amounts of static content and dynamic Data. Instead, you can focus on creating a good mashup. This article is part of a three-part series, "Creating Mashups on Google App Engine using Eclipse", to learn how to start a Gae application and how to use Eclipse to simplify gae development.

About this series

In this series, you will learn how to get started with the Google App Engine (GAE). In part 1th, you will learn how to set up your development environment so that you can start creating applications running on GAE. Learn how to use Eclipse to simplify development and debugging of your application. In part 2nd, you will use Eclipse to build an Ajax mashup and deploy it to GAE. Finally, in part 3rd, you return to the ecosystem by creating the RESTful Web service for your application so that others can use it to create their own mashups.

GAE is the platform for creating WEB applications. The most important prerequisite for using it is Python knowledge, because Python is used as the programming language (currently Python V2.5.2) in GAE. For this series, it will be helpful to have some typical Web development skills (e.g. HTML, JavaScript, and CSS knowledge). To develop for GAE, you need to download three packages.

Eclipse Classic I am using the Eclipse Classic V3.3.2. Newer versions can also be used. Google App Engine SDK reads the official documentation from the GAE site and finds links to download the SDK. PyDev uses the update site http://pydev.sourceforge.net/updates/to download PyDev from within Eclipse, which translates eclipse into a Python IDE.

The installation of the latter two packages is discussed in detail below.

Set up GAE

If you've spent a lot of time developing a WEB application, you're likely to get used to downloading libraries, Web servers, and databases when you want to start using the new application stack. Sometimes, you can bind all of these packages to a good setup program, making it easier to use all the active parts. When you are ready, you usually need to make more settings to normally use your favorite development environment. Fortunately, this is not the case when using GAE. Let's see how to set it up and how to combine it with Eclipse.

The first thing you need to do to set up GAE is to download the SDK for microsoft®windows®, Mac OS X, and linux®. Windows and Mac OS x,sdk are installed with the installer, not only to install the SDK on the system, but to place several key executable scripts in the path to use. Figure 1 shows the directory structure diagram for the SDK.

Figure 1. GAE SDK directory structure

In the root directory, you should see two Python scripts: appcfg.py and dev_appserver.py. The dev_appserver.py script is used to start the development application server. There is no stand-alone installation or deployment for development and test applications. When you are ready to deploy your application to GAE, you will use the appcfg.py script.

You can find all the APIs that form the basis of the GAE platform in the Google directory. You will inevitably use and extend the classes in that directory. Therefore, if you need to run the GAE application code, you need to know the directory because you need to know the APIs that your application code uses. As an example, let's take a look at how to set up Eclipse for developing GAE code.