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.
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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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