Wiley Professional Portal Development with Open Source Tools 978-0-471-46951-3 Benutzerhandbuch

The Java Por tlet API 

(JSR 168)

This chapter discusses the centerpiece of portal development, the Java Portlet API, Java Specification
Request 168 (JSR 168). The chapter explains the concepts in the specification, explaining how they fit
into portal architectures to enable the developer to be an effective portal developer.

Por tlet Fundamentals

A portal server handles client requests. Much like a Web application server has a Web container
to manage running Web components (servlets, JSPs, filters, and so on), a portal has a portlet con-
tainer

to manage running portlets. Note that most Web application servers, such as Tomcat, have

additional features beyond the Web container (management console, user databases, and so on),
including some specialized Web applications (an administration Web application, for example).
Portals are expected to follow a similar pattern, providing higher level functionality wrapped
around the portlet container that adheres to the specification, enabling portlet applications to be
portable, just as Web applications are.

The Portlet API is an extension to the servlet specification, which means that a portlet container is
also, by definition, a Web container. Figure 1.1 demonstrates the Portal stack, which indicates how
the various parts build upon each other to provide a portal server.

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