Introduction To Struts 2 Framework

Servlet expert Craig R. McClanahan's donated his brainchild to the Apache Software Foundation in May 2000 and Struts 1.0 was released in June 2001. It soon became, and still is, the most popular framework for developing Java web applications. Its web site is http://struts.apache.org/.

In the meantime, on the same planet, some people had been working on another Java open source framework called WebWork. Similar to Struts 1, WebWork never neared the popularity of its competitor but was architecturally superior to Struts 1. For example, in Struts 1 translating request parameters to a Java object requires an "intermediary" object called the form bean, whereas in WebWork no intermediary object is necessary. The implication is clear, a developer is more productive when using WebWork because fewer classes are needed. As another example, an object called interceptor can be plugged in easily in WebWork to add more processing to the framework, something that is not that easy to achieve in Struts 1.

Another important feature that WebWork has but Struts 1 lacks is testability. This has a huge impact on productivity. Testing business logic is much easier in WebWork than in Struts 1. This is so because with Struts 1 you generally need a web browser to test the business logic to retrieve inputs from HTTP request parameters. WebWork does not have this problem because business classes can be tested without a browser.

A superior product (WebWork) and a pop-star status (Struts 1) naturally pressured both camps to merge. According to Don Brown in his blog (www.oreillynet.com/onjava/blog/2006/10/my_history_of_struts_2.html), it all started at JavaOne 2005 when some Struts developers and users discussed the future of Struts and came up with a proposal for Struts Ti (for Titanium), a code name for Struts 2. Had the Struts team proceeded with the original proposal, Struts 2 would have included coveted features missing in version 1, including extensibility and AJAX. On WebWork developer Jason Carreira's suggestion, however, the proposal was amended to include a merger with WebWork. This made sense since WebWork had most of the features of the proposed Struts Ti. Rather than reinventing the wheel, 'acquisition' of WebWork could save a lot of time.

As a result, internally Struts 2 is not an extension of Struts 1. Rather, it is a re-branding of WebWork version 2.2. WebWork itself is based on XWork, an open source command-pattern framework from Open Symphony (http://www.opensymphony.com/xwork). Therefore, don't be alarmed if you encounter Java types that belong to package com.opensymphony.xwork2 throughout the struts2 programs.

Struts is a framework for developing Model 2 applications. It makes development more rapid because it solves many common problems in web application development by providing these features:

• page navigation management

• user input validation

• consistent layout

• extensibility

• internationalization and localization

• support for AJAX

Because Struts is a Model 2 framework, when using Struts you should stick to the following unwritten rules:

• No Java code in JSPs, all business logic should reside in Java classes called action classes.

• Use the Expression Language (OGNL) to access model objects from JSPs.

• Little or no writing of custom tags (because they are relatively hard to code).

Posted in: Struts 2