Oracle9iAS Portal Developer Kit (PDK)
An Overview of Portlets

Introduction

A portlet is a reusable component  on an Oracle9iAS Portal page containing key information.  This information can originate from any application, and the portlet can expose that information on the page.  You can think of portlets as "web components" which act as a launching pad for other applications.  For example, a News Feed portlet may supply news article headlines with a sentence describing the articles.  The news headlines are hyperlinks that take the reader to the full text of the article on an external news service.  Portlets no only display excerpts of other web sites, but also generate summaries of key information, perform searches, and access assembled collections of information.

The benefit of portlets is the ability to provide a seamlessly integrated view of data by integrating seemingly disparate systems.  Since many portlets can be placed on the same page with other portlets, a user receives a singly system experience, when in reality the content is derived from multiple systems.  An example of an Oracle9iAS Portal page is show below.

Figure A, An Oracle9iAS Portal page

Portlets are rendered by web browsers just like any other part of a web page.  Typically, portlets use standard HTML to display information to users, but their interfaces can be extended using other browser-capable technologies such as Cascading Style Sheets (CSS), eXtensible Style Language (XSL), JavaScript, and even Java applets.

Portlets communicate with Oracle9iAS Portal through an entity called a provider and one provider can manage one or many portlets. The provider is the primary communication link between the portal framework and portlets. There are two main types of provider interfaces - Database and Web. A portlet is written in any language and exposed to Oracle9iAS Portal as either a Web Provider or a Database Provider.
 

Common Applications of Portlets

Portlets can be used to access nearly any type of web-accessible information --- from files stored on the corporate intranet and reports on data managed by corporate applications to news and stock quotes from the Internet.  Because of their dynamic nature, portlets are often used to highlight important information, alert users to new developments, and summarize key data.  Here are some common applications for portlets:.  

Centralizing access to intranet sites.  In large organizations with many intranet web sites, users are often confused about where to go to find specific information they need to do their jobs.  Oracle9iAS Portal makes it easy to gather links to all these sites in one place, then organize these access points so that users have a simple way to find what they are looking for.  Sets of these links can be published as portlets so that users can readily access frequently used sites from their own personalized page.

Publishing information and documents.  Putting content on the web is simple with Oracle9iAS Portal because all editing and file uploading is done through the browser.  You can arrange your contents into folders and then place these folders as portlets onto any portal page, allowing you to mix and match the specific content you wish to see.

Integrating dynamic data services.  Portlets are useful for rendering content provided from external data sources and displaying that information on portal pages.  For example, portlets allow real-time news stories to be displayed within the portal from XML data sources.

Providing an interface to web applications.  Organizations may have many different applications that users need.  However, it is not always efficient for users to navigate through entire applications in order to find one frequently needed piece of information.  Instead, portlets can be used to automatically login to that application (or its data store) and retrieve a summary of that information.  The portlet can then display the information on a portal page.

Integrating with other corporate systems.  Organizations have many different, sometimes incompatible, systems.  Portlets allow the interfaces for these systems to be presented in a consistent manner within the Oracle9iAS Portal environment.

Areas of a Portlet

A Portlet consists of many different required and optional components.  This section will describe the many areas of a portlet.

Figure 1, A Sample Portlet

Show Modes

Out of the box, Oracle9iAS Portal portlets can render in eight show modes: shared screen, edit, edit defaults, help, about, full screen, preview, and link.

Shared Screen Mode is the only required show mode and renders the body of the portlet.  In the portlet shown above, the main area of the portlet where the information is displayed is shared screen mode.

Figure 2,  Shared Screen Mode

Edit Mode is an optional show mode and enables per user / per instance personalization.  This means that a user can personalize (customize) a portlet without affecting the same portlet for a different user or another instance of the same portlet on the same page.  When a user click on Customize, they are using Edit Mode.

Figure 3, Edit Mode

Edit Default Mode is an optional show mode and enables administrators to set the defaults of a portlet for all users.  Users that do not personalize their portlet will see the administrator's default settings.  This show mode is not seen in figure 1.  This show mode is available to administrators by clicking on Edit for a portal page.

Figure 4, Edit Defaults Mode

Preview Mode is an optional show mode and provides a preview of shared screen mode before a user add the portlet to a page.  This show mode is not seen in figure 1, it is available in the 'Add Portlets' screen.

Figure 5, Preview Mode

Full Screen Mode is an optional show mode and provides more details than can be shown when sharing a page with other portlets.

Figure 6, Full Screen Mode

 

Help Mode is an optional show mode and displays information about the functionality of the portlet and how to use it. 

Figure 7, Help Mode

About Mode is an optional show mode and displays information about the portlet's copyright, version, and author.

Figure 8, About Mode

Link Mode is an optional show mode and enables portlets to render themselves within PDA / mobile devices.

Figure 9, Link Mode

There are a few other features to a portlet that this article will discuss.

Remove Portlet

This feature allows users to remove portlets from a page based on the page privileges.  For example, in Figure 1, if a user clicks on , the portlet will be removed from the page.  The user can add the portlet back, by going into the 'Add Portlets' page.

Minimize Portlet

This feature allows users to minimize a portlet on a page based on the page privileges.  For example, in Figure 1, if a user clicks on , the portlet will minimize itself on a page.

Figure 10, Minimize Portlet