This is the third and final article in a series aimed at demystifying the frameworks that compose the BEA WebLogic Portal.

Although this month I focus on the portal framework, you should realize that the value of WebLogic Portal is in the combination of frameworks, components, and wizards that enable the creation of Web-based applications that provide value to the end customer and the hosting business. The customer benefits by being presented with a solution that is easy to use, personalizes content and services, and provides a much better user experience. The business saves money by maintaining only one portal solution that provides a view into all of its back-end systems, requiring only one portal solution throughout its departments, having a decoupled solution that allows the changing of back-end systems without enforced change to the front-end enterprise portal, and reusing application components throughout the enterprise. The core business also improves by having a solution that intelligently adapts itself to the user's dynamic user profile, provides the ability to intelligently execute campaigns, and provides the means to dynamically modify the application logic after the business analysts have completed their analysis of their online business, thus providing a 360-degree feedback loop.

The portal framework is an adaptable presentation engine that aggregates visual presentation components, called portlets, into a single presentation unit and enables the interaction between these presentation units to create a dynamic and interactive Web front end to a business application. The main components in the portal framework are the Flow Controller, Portal Page Generator, Portlet Page Generator, Portlets, and custom JSP tags. This article will describe each component in detail and walk the reader through a framework execution scenario.

Portal Framework
The portal framework can be logically divided into two major functional areas. The first is the aggregation of visual components, and the second is the management of the dynamic interaction between the different visual components and the management of incoming requests from the user. In the interest of not turning this article into a voluminous white paper, I will focus only on the aggregation of visual portal components. Those of you who want a more detailed understanding of the interaction between the different portlets, the management of incoming requests, and the wizards that increase developer productivity, are encouraged to read the material located on BEA's online documentation Web site.

The main components of the portal engine responsible for aggregating the visual components in the portal framework are the PortalWebflowServlet, the portal.jsp page, the portlet.jsp page, and the custom JSP tags (see Figure 1). The PortalWebflowServlet uses the same architecture as the WebflowServlet architecture described in "Building Adaptive Applications with Reusable Components" (WLDJ, Vol. 1, issue 6), and is the cornerstone for handling the interportlet communication and the management of incoming requests (see Figure 2).

Flow Controller
The PortalWebflowServlet is the Java servlet responsible for handling flow control for the portal framework. This portal flow controller intercepts incoming requests from the client and determines whether the request is intended for a portal Web application. If the request is intended for a portal Web application, the servlet hands control to the portal Webflow executor, which would invoke the portal page generator (see Figures 1 and 3). The portal page generator then manages the creation of the portal page and all of its composite parts.

Portal Page Generator
The portal.jsp file is the portal page generator responsible for combining the disparate visual components that make up the portal page. The portal page generator would aggregate the header and footer content for the page, and incorporate the content returned by the portlet page generator (see Figure 3). The functionality contained in the portal.jsp page can be extended by the portal developer to include custom functionality. However, it is not recommended to hard-code custom functionality into the page, as there is no guarantee that the portal page generator will not change in future releases of the product.

Portlet Page Generator
The portlet.jsp file is the portlet page generator responsible for combining all the visual portlet components into a compound visual portlet unit. The portlet page generator would aggregate all the different portlets into an HTML table that conforms to the layout and visibility strategies determined by the portal administrator. The availability of portlets is governed by the business rules processed by the entitlements engine, which also makes use of the user's user and group profile information. Like the portal page generator, the functionality contained in the portlet.jsp page can also be extended by the portal developer to include custom functionality. Again, it is not recommended that you hard-code custom functionality into the page, as there is no guarantee that the portlet page generator will not change in future releases of the product.

Portlet Pages
Portlet pages are visual components that provide specific business functionality and content. Each of the portlet pages or components can be considered to be a single reusable visual unit that is shared amongst different portal deployments. A portlet can be constructed to provide services or data from one single back-end source or multiple back-end sources. Each portlet component can be composed of a combination of the following subcomponents: titlebar, banner, header, footer, and content section. Some of the out-of-the-box portlets that come with the product include functionality for collaboration, calendaring, Webmail, chat, whiteboard, and discussion groups.

Portal and Portlet Management JSP Tag Library
These custom management tags allow JSP developers to access the portal framework functionality of WebLogic Portal without having to write EJB client code. The portal framework management JSP tag libraries are divided into three main categories; portal, portlet and utility. The JSP: tags in the portal category are used to execute management functionality that is specific to the internal workings of the portal as a whole; the JSP tags in the portlet category are used to execute portlet specific functionality; and the JSP tags in the utility category are used to perform URL validation. (For more information on the parameters for each JSP tag and for the entire WebLogic Portal JSP tag library, visit the BEA online documentation Web site: http://edocs.bea.com.)

Portlet JSP Tags
Instead of having the portlet developer write custom code to call the PortalWebflowServlet, custom JSP tags are provided to increase productivity and to minimize the potential of malformed calls. Portlet JSP tags are provided to properly construct a Webflow URL, an HTML form, and an HTML form that takes advantage of the data validation component in the portal framework. Additionally, custom JSP tags are provided to display an Edit portlet, a minimized portlet, an unminimized portlet, a maximized portlet, an unmaximized portlet, a floating portlet, and the exceptions thrown by the Webflow processor. Each of the tags in the portlet JSP tag group is focused on managing each portlet component and is meant to be called in the portlet content page.

More information on the portlet JSP tags can be found at http://edocs.bea.com/wlp/docs70/jsp/mngprtal.htm#1002046.

Portal JSP Tags
Like the portlet JSP tags, the portal JSP tags are used mainly to aid the portal developer by providing helper tags that increase the developer's productivity. Portal JSP tags are provided to properly construct a Webflow URL, an HTML form, and an HTML form that takes advantage of the validation component in the portal framework. Additionally, a custom JSP tag is provided to notify the PortalWebflowServlet of the event that the user is changing a page. Each of the tags in the portal JSP tag group is focused on managing the portal solution as a whole and is meant to be called in the portal page generator file. More information on the portal JSP tags can be found at http://edocs.bea.com/wlp/docs70/jsp/mngprtal.htm#1003563.

Utility JSP Tags
The two utility JSP tags provided are used as sanity processing rules in the JSP tag. The first utility JSP tag will process the code contained with the brackets if the URL provided is valid. The second utility JSP tag will process the code contained within the brackets if the URL provided is invalid. Since these tags can be used in either the portal page or any of the portlet pages, they are part of the utility category.

More information on the utility JSP tags for the portal framework can be found at http://edocs.bea.com/wlp/docs70/jsp/mngprtal.htm#1004198.

Conclusion
The portal framework enables the reuse of visual components, and manages the interaction between the visual components and any incoming requests. Coupling the portal framework with the personalization, entitlements, and campaign frameworks provides the ability to create intelligent applications that can adapt themselves to each specific user.

My goal in this series of articles was to provide a clearer understanding as to the components and functionality that the portal, event, and advisor frameworks provided. The key concepts that are embodied in each of these frameworks are that they can be used in a unified manner, they are simple to use, and they can easily be extended to suit custom business needs.

Finally, I strongly suggest that each of you visit the BEA Portal Solution Center (http://portalsolutions.bea.com/index.jsp). This Web site contains white papers; development documents; sample code; and a catalog of partner portlets, integrated offerings, and total portal solutions.