OpenTrader: a transactional, web application with Google Web Toolkit, OpenJPA/Slice on Tomcat

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OpenTrader is a sample web application to demonstrate integration and interaction of Google Web Toolkit (GWT), OpenJPA and Tomcat Servlet Containerrunning in Tomcat Servlet Container. GWT takes a position that is a significantly unique among the multitude of frameworks available to build a browser based client. GWT framework is based on several key concepts:

• an asynchronous RPC protocol for communication between web client and server. Such asynchronous RPC is popularized by AJAX (Asynchronous JavaScript and XML) since last several years.
• a cross-compiler that converts Java to JavaScript. This is the most critical component in the framework as it allows the client be written completely in Java. Besides adding a comfort layer for Java developers, the cross-compiler solves one of the most complex issue of browser based clients namely cross-browser compatibility. The cross-compiler generates separate JavaScript targeted to prominent browsers and the framework knows to activate the appropriate JavaScript based on the particular browser a client is using.
• a library of interactive visual widgets such as dialog boxes, combo-boxes, tables etc. This Java based library realizes the widget as the elements of a Document Object Model (DOM) for a browser to render them in HTML. For example, an instance of com.google.gwt.user.client.ui.FlexTable urns into a <table> in the displayed HTML page by the framework.

Follow the steps to view OpenTrader source code, build the application, deploy it in your favorite application container and run it in your favorite browser.

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