Portlets in Liferay

There are 3 approaches to building portlets that can be deployed in liferay

1. JSR 168/286 Compliant Portlet - This is a standards compliant portlet and can hence be deployed not only in Liferay but in any portal server. The downside is it cannot use Liferay specific APIs.

2. Liferay plugin portlet - These portlets are liferay plugins. They may have a dependency on Liferay APIs (Portal kernel and Portal Service). Having dependencies on Liferay APIs restricts their portability to Liferay only.

3. Web application exposed as a portlet - One type of a Liferay plugin is a web applications (webs). So a simple web application can be exposed as a portlet in Liferay using the webs plugin.

Source: Liferay Portal System Development