Google Apps: An Overview

Supported Languages & Database Java Python

Bigtable(Bt) is a distributed storage system for managing structured data that is designed to scale to a very large size.

Query Language is GQL

Supported Java Enterprise Edition Technologies

Java Data Objects (JDO) Java Persistence API (JPA Java Server Faces (JSF) 1.1 - 2.0 Java Server Pages (JSP) + JSTL Java Servlet API 2.4 JavaBeans™ Activation Framework (JAF) Java Architecture for XML Binding (JAXB) JavaMail XML processing APIs including DOM, SAX,

and XSLT

Not supported

Enterprise Java Beans (EJB) JAX-RPC JAX-WS Java Database Connectivity (JDBC) Java EE™ Connector Architecture (JCA) Java Management Extensions (JMX) Java Message Service (JMS) Java Naming and Directory Interface

(JNDI) Remote Method Invocation (RMI)

An App Engine application cannot

Write to the filesystem. Open a socket or access another host directly. spawn a sub-process or thread. Applications must use the App Engine

datastore for storing persistent data. A web request to an application must be

handled in a single process within a few seconds.

Processes that take a very long time to respond are terminated to avoid overloading the web server.

FLASH/AJAX/OTHER APIS

It supports Flash Ajax APIS

Let us see an example Shujaathussain.appspot.com Guestnust.appaspot.com

APIS in Google SDK An app can use the Mail service to send

email messages on behalf of the application's administrators, or on behalf of the currently signed in user. Java apps use the JavaMail interface for sending email messages.

The App Engine Memcache provides fast, transient distributed storage for caching the results of datastore queries and calculations. The Java interface implements JCache

Continued The Images service lets applications

transform and manipulate image data in several formats, including cropping, rotating, resizing, and photo color enhancement.

Apps use the URL Fetch service to access resources over the web, and to communicate with other hosts using the HTTP and HTTPS protocols. Java apps can simply use java.net.URLConnection and related classes from the Java standard library to access this service.

Continued An application can use Google Accounts for

user authentication. Apps can use the App Engine Datastore

for reliable, scalable persistent storage of data. The datastore supports 2 standard Java interfaces: Java Data Objects (JDO) 2.3 and Java Persistence API (JPA) 1.0. These interfaces are implemented using DataNucleus Access Platform, the open source implementation of these standards.