Difference between revisions of "GCube Portal Engine"

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== Introduction ==
 
== Introduction ==
 
To provide the end user with the full functionality of the gCube system, a presentation application, based on the ASL and not on the lower level gCube services directly, has been implemented.
 
To provide the end user with the full functionality of the gCube system, a presentation application, based on the ASL and not on the lower level gCube services directly, has been implemented.

Revision as of 15:03, 11 March 2011

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Introduction

To provide the end user with the full functionality of the gCube system, a presentation application, based on the ASL and not on the lower level gCube services directly, has been implemented.

For this application the portal/portlet paradigm has been adopted. A portal is a Web-based desktop that is customizable both in the look and feel and in the content and applications which it contains. A portal, furthermore, is an aggregator of content and applications or a single point of entry to a user's set of tools and applications. The portlets are the visual components that participate into providing the user-conceived functionality of the portal. Behind the portal there is always an engine (and a framework) that powers the system.

In gCube the GridSphere1 portal framework is employed as the portlet-hosting platform. GridSphere is an open-source framework which enables developers to develop and package third-party portlet web applications that can be run and administered within the GridSphere portlet container. For its purposes, it uses the JSR 168 Portlet API, to provide reusable web applications.

For the development of portlets several technologies are involved: the JSR 168 portlet API, Java Server Pages for dynamically generation of HTML/XML documents in response to a client’s request and GWT (Google Web Toolkit) for writing high performance AJAX applications. All these technologies are hosted under the Gridsphere Portal engine.

Technologies

JSR 168

JSR (Java Specification Request) 168 establishes a standard API for creating portlets. It constitutes the integration component between applications and portals, and it enables delivery of an application through a portal. Without this standard, each version of an application needed its own portlet API, and each of the various portals required that these portlets should be specifically tailor-made for that portal.

GWT

Google Web Toolkit (GWT) is an open source Java software development framework that allows web developers to create Ajax applications in Java. It is licensed under the Apache License version 2.0. GWT emphasizes reusable, efficient solutions to recurring Ajax challenges, namely asynchronous remote procedure calls, history management, bookmarking, and cross-browser portability. For all these reasons most portlets use the GWT for a better and more efficient Ajax implementation.

JSP

Java Server Pages (JSP) is a Java technology that allows developers to dynamically generate HTML, XML or other types of documents in response to a Web client request. The technology allows Java code and certain pre-defined actions to be embedded into static content. The JSP syntax adds additional XML-like tags, called JSP actions, to be used to invoke built-in functionality. Additionally, the technology allows for the creation of JSP tag libraries that act as extensions to the standard HTML or XML tags. Tag libraries provide a platform independent way of extending the capabilities of a Web server. JSPs are compiled into Java Servlets by a JSP compiler. A JSP compiler may generate a servlet in Java code that is then compiled by the Java compiler, or it may generate byte code for the servlet directly. JSPs can also be interpreted on-the-fly reducing the time taken to reload changes.