Portlet

Servlet과 같은 형태의 웹 컴포넌트이지만, 포탈 웹페이지에 삽입되어 실행될 수 있는 속성을 가지고 있다. 서로 다른 사용자 및 인스턴스 포탈 데이터 별 파라미터에 따라, 동일한 포틀릿에 대한 다수의 인스턴스들은 동일한 포탈 페이지에 같이 놓일 수 있다.

When you access a web site, you interact with an application. That application may be simple: it may only show you information, such as an article. The application may be complex: you may be doing your taxes online, inputting lots of data into an application that calculates whether you owe or are due a refund. These applications run on a platform that provides application developers the building blocks they need to make applications.

Figure 4: Many Liferay applications can run at the same time on the same page.

Liferay Portal is a platform, and its applications are called portlets. One difference between a Liferay application and an application built on another platform is that Liferay Portal can serve many applications at the same time on the same page. Usually, a web application takes up the entire page, and if you want, you can do this with Liferay as well. But Liferay has the added benefit of being able to run many applications on the same page. For this reason, you’ll find that the framework takes this into account at every step. We’re saying this up front, because you’ll be experiencing this soon, and we want you to know why certain things, like platform-generated URLs, are necessary.

With all of that said, the next thing to do is to jump in and create your Guestbook portlet.