Introduction

Applications can be developed in Python and Java.

Java Development

You develop and upload Java applications for Google App Engine using the App Engine Java software development kit (SDK). The SDK includes software for a web server that you can run on your own computer to test your Java applications (see #Development_Environment).

App Engine Java applications use the Java Servlet standard for interacting with the web server environment. An application's files, including compiled classes, JARs, static files and configuration files, are arranged in a directory structure using the WAR standard layout for Java web applications.

GAE uses Java 6.

Development Environment

Installation

PlugIn
Path extended to %JAVA_HOME%, to enable call to javac.exe
port change from 8080 to 8090 in C:\Uwes\eclipse\v351\eclipse\plugins\com.google.appengine.eclipse.sdkbundle.1.3.0_1.3.0.v200912141120\appengine-java-sdk-1.3.0\config\user\ant-macros.xml
in eclipse Run -> Run Configuration -> Web Application -> <Project> -> Port from 8888 to 8090

Eclipse Plugin

see plugins/com.google.appengine.eclipse.sdkbundle_VERSION/

Java Development Server

The App Engine Java SDK includes a development web server for testing your application on your computer. The server simulates all of the App Engine services, including a local version of the datastore, Google Accounts, and the ability to fetch URLs and send email from your computer using the App Engine APIs. The Google Plugin for Eclipse can run the server in the Eclipse debugger or you can run it from the command line.

Test

Demos

C:\Uwes\eclipse\v351\eclipse\plugins\com.google.appengine.eclipse.sdkbundle.1.3.0_1.3.0.v200912141120>appengine-java-sdk-1.3.0\bin\dev_appserver.cmd --port=8090 appengine-java-sdk-1.3.0\demos\guestbook\war

Development Process

New Project

The wizard creates a directory structure for the project, including a src/ directory for Java source files, and a war/ directory for compiled classes and other files for the application, libraries, configuration files, static files such as images and CSS, and other data files. The wizard also creates a servlet source file and two configuration files. The complete directory structure looks like this:

Guestbook/
  src/
    guestbook/
      server/
        GuestbookServlet.java
    META-INF/
      jdoconfig.xml
    log4j.properties
    logging.properties
  war/
    WEB-INF/
      lib/
        ...App Engine JARs...
      appengine-web.xml
      web.xml
    index.html

Spefici Configuration Files

appengine-web.xml

appengine-web.xml is specific to App Engine, and is not part of the servlet standard.

<?xml version="1.0" encoding="utf-8"?>
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
   <application></application>
   <version>1</version>
</appengine-web-app>