Note: This document is part of the Liferay Core Development Guidelines

Introduction #

This article describes the main technologies used within Liferay as well as which of their features of them are being used. As a Liferay Core developer you should use this feature set whenever you want to extend the existing functionality of Liferay or to implement a new functionality.

Frontend #

Struts and Tiles #

Most Liferay portlets are developed using Struts through a custom bridge for portlets called StrutsPortlet.

Features Not Used:

• Struts Forms: Liferay almost never uses Struts Forms. Try to avoid them as much as possible.
• Validation: We do validation in the Service Layer

Taglibs #

Liferay uses Taglibs extensively. The standard JSTL library is used, mainly for tags such as c:if and c:when / c:otherwise

Javascript #

• Alloy UI (http://alloyui.liferay.com)
• jQuery v. 1.1.4 (http://jquery.com)
• Interface (http://interface.eyecon.ro) We are currently migrating from the Interface library to jQuery UI.
• SWFObject v. 1.5 (http://blog.deconcept.com/swfobject)

Business Layer #

Spring #

Features Not Used:

• Aspects: They will be probably introduced in the near future.

Database Access #

Hibernate #

Hibernate is used to access the database in most situations.

Features Not Used:

• Criteria API: We found some problems with some of the supported databases

JDBC #

JDBC is used directly to perform custom queries. See the Finder classes.

SQL #

It's sometimes used when using JDBC instead of Hibernate.

Use very simple SQL to guarantee that it'll work in all of Liferay's supported databases.

Development #

The following tools are used to develop Liferay's core:

• Ant
• Java 5
• Tomcat
• MySQL