Build Your Own Portlets

This Quick Tour has already shown you how easy it is to create new content areas and applications and add them to your portal. But does Oracle Portal let you add your existing content and applications to your portal without you having to start all over again? The answer to this question is "yes!" Seamless integration of existing content and applications built with other tools is possible by utilizing Oracle Portal's extensive portal services.

In this section of the Quick Tour, you will learn more about the portal services and how you can build your own portlets.

• What Is a Portlet?
• What Is a Portlet Provider?
• What Portlets Are Available for My Portal?
• How Are Custom Portlets Implemented?
• Why Build Programmable Custom Portlets?
• Common Portal Services
• Securing Your Portlets

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What Is a Portlet?

Portlets provide a standardized, reliable, secure way to represent and package enterprise information. A portlet is made up of snippets of HTML that are added to a user-specified region on a page when the page is drawn. From a developer's perspective, portlets are PL/SQL procedures or Java servlets that execute on the server and are rendered as HTML or XML/XSL within the page. You can build portlets with a variety of tools, including Java tools such as Oracle JDeveloper.

Examples of application and content-driven portlets include a corporate data report or chart, news links from the Internet, a central directory of Intranet sites, and a folder containing items which you can easily retrieve and publish.

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What Is a Portlet Provider?

Before portlets can be added, you must create an entity that owns the portlet, named the portlet provider, and register it with Oracle Portal. A portlet provider is a Java class or PL/SQL package that exposes a data source or application to Oracle Portal through one or more portlets.

A portlet provider has the following characteristics:

• Provides a communication link between the portal services and portlets.
• Implements session startup and provider login.
• Acts as a proxy to all portlet calls.
• Manages the portlet repository list.

The best example of a portlet provider is Oracle Portal itself. All Oracle Portal product features are exposed as portlets including Oracle Portal security, administration, application building, and self-service publishing.

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What Portlets Are Available for My Portal?

The portlets that make up a page are drawn from a library of portlets, called the portlet repository, which is accessible to an authorized Oracle Portal user. This library consists of the following portlets:

• Bundled Portlets: Pre-defined and integrated portlets that are bundled with Oracle Portal. These portlets include administrative portlets such as those for creating and deleting users and groups, development portlets such as those for finding portal objects and creating a portlet from HTML, end user portlets such as those for bookmarking favorite URLs, content area searches, and saved searches, and sample Internet content portlets.
• Partner Portlets: Portlets made available by Oracle partners such as traditional independent software vendors (ISVs), system integrators (SIs), Web application vendors, and Internet-based service partners, for example, iSyndicate.
• Custom Portlets: Portlets created to access and display portal specific information. Custom portlets can be developed declaratively using Oracle Portal's publishing services or programmatically using the Oracle Portal Development Kit (PDK).

The portlet repository is refreshed periodically to update the list with newly added or deleted portlets.

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How are Custom Portlets Implemented?

You can implement portlets by using either:

• Built-in Portlets: Lets you build portlets declaratively, without any coding whatsoever! Use built-in portlets to leverage Oracle Portal content and data publishing services such as components, dynamic pages, and content areas. For example, you can capture, display, and manipulate corporate data in portlets built with the component build wizards, or you can use dynamic pages to componentize external sites and services. In addition, you can even publish content area objects to the portal such as folders, categories, navigation bars, and perspectives.

  In addition to Oracle Portal's built-in portlets, you will soon be able to use other integrated approaches to custom portlet development. Oracle development tools including Oracle Forms, Oracle Reports, Oracle Discoverer, and JDeveloper will be incorporating portlet technology that will allow you to create an application component and easily publish it as a portlet.

Programmable Portlets: Lets you build portlets programmatically using the Oracle Portal Development Kit (PDK) according to published APIs. Two forms of programmatic portlets are supported:

• Database: Portlet code is written as stored procedures in PL/SQL or Java and is executed within the database. This is particularly appropriate for portlets that require significant interaction with the database and in situations where the development team has extensive Oracle experience.
• Web: Portlet code is written in any Web development environment and called via HTTP. This is most suitable for external information sources such as Internet news or business information and in development groups possessing an extensive Web development background.

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Why Build Programmable Custom Portlets?

As you become more familiar with Oracle Portal, you'll want to build custom portlets to support your company's specific business needs. You'll also need to build your own portlets, in the following situations:

• Specific logic or rules are required to call the source application.
• The source application is secure and requires authentication.
• The source application produces dynamic results that must be further processed.
• Additional flexibility and user interface control is required.

If you are an IT staff member, an SI, or an ISV called upon to develop portlets, refer to the Oracle Portal Development Kit (PDK). This is a self-service guide detailing the Oracle Portal API set as well as numerous examples that demonstrate API implementation. You can find the PDK on the Oracle Technology Network at http://technet.oracle.com/.

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Common Portal Services

While building your own portlets, you can take advantage of the common portal services provided by the Oracle Portal framework. This rich set of services enables you to build powerful portlets without having to create your own infrastructure entirely yourself! These common portal services include:

• End-user personalization: Provides customization options to enable users to tailor portlet appearance and behavior.
• Session storage: Provides a mechanism for storing and retrieving a user's session-specific information.
• Logging: Provides a mechanism to enable developers to log activities within their portlets.
• Translation: Provides a utility to store and retrieve translation strings for multiple languages without having to hardcode them.
• Security: Adheres to the Oracle Portal Single Sign-On architecture to securely access information and applications.
• Error handling: Traps invalid entries and displays meaningful error messages.

You can refer to the examples provided with the PDK which explain in detail how to use these services to extend your own portlets.

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Securing Your Portlets

Oracle Portal leverages Oracle's Web-based Login Server architecture for user authentication. The Login Server provides a single, enterprise-wide authentication mechanism that allows users to identify themselves securely to multiple applications through a single authentication step, called Single Sign-On.

The Oracle Portal Security API package secures the portlet by verifying that the current portal user is a member of a privileged portal group. Using Oracle Portal's security package, Oracle Portal applications can verify user access privileges before routines are executed, and can redirect browsers to the Login Server when authentication is required.

Access to pages within the portal are also defined by security privileges. Users requesting a page can access public pages as well as those portlets and pages for which they have been granted access.

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