Public access to the Google search engine through custom applications is possible through the Google API's. These are a set of public web development services accessible by anyone who can code and can provide an email address to retrieve an access key. The Google API stands for ‘Application Programmable Interface’. As it’s name implies, it is an interface that queries the Google database to help programmers in the development of their applications. By definition, Google API’s consist basically of specialized web services and programs and specialized scripts that enable Internet application developers to better find and process information on the Web. In essence, Google APIs can be used as an added resource in their applications.

 

Application programmers, web developers and integrators write software programs that can connect remotely to the Google API's. All data communications are executed via the "Simple Object Access Protocol" (SOAP), which is a Web services standard as defined by the industry. The SOAP protocol is an XML-based technology meant to easily exchange information entered into a Web application.

Google's API can better assist developers in easily accessing Google's web search database, empowering them in developing software that can query billions of Web documents, constantly refreshed by Google's automated crawlers. Programmers can initiate search queries to Google's vast index of more than three billion pages and have results delivered to them as structured data that is simple to analyse and work with.
Google are frequently introducing new API’s and updates for the old ones. Some examples of the recent releases are the Google Health Data API, Google Visualization API update, Google Contacts API update and many others.

 

Google's API is an experimental program that is provided free to anybody that agrees to it's terms. As of now, the available resources to fully implement and support the program are rather limited, which explains why there is a 1,000 queries a day limit on all accounts.Another great achievement in web development technologies is Google Web Toolkit. GWT is a major step forward in the development of dynamic JavaScript applications that run in users' web browsers. Using GWT, developers can design the user interface (UI) and event model using familiar Java techniques while GWT does the hard work of making the code friendly for all the major browsers.

With GWT, every programmer can develop Ajax applications in the Java programming language. The hallmark of an Ajax application is a rich, interactive environment more often associated with traditional UI applications.

GWT's most unique feature is that you can create your Ajax application and still write your code in the Java language. You can use your favorite Java integrated development environment (IDE) and you can also debug your client in that Java IDE. You can communicate between the client and server using Java objects, and it's all much more lightweight in the client than a Java applet would be.

At base, GWT is a compiler. It converts the Java code you write into JavaScript code that is then inserted into the HTML page and used to run the client side of your application. This functionality frees you from the details of supporting JavaScript code on multiple browsers, allowing you to focus on the interface and interaction of your program.

Using Google Web Toolkit, developers can rapidly develop and debug AJAX applications in the Java language using the Java development tools of their choice.