Struts 2.0

Apache Struts had become the de facto standard for web development for several years. Struts2 is the next generation of Apache Struts, developed by Patrick Lightbody. It is a mixture of Struts and WebWork.

When we speak about WebWork we are really referencing two projects – XWork and WebWork. XWork is a generic command framework. It provides many of the core features such as actions, validation and interceptors, and is completely execution context independent. XWork also provides an internal dependency inject mechanism that is used for configuration and factory implementation management.
WebWork, on the other hand, is a completely context dependent. It provides a wrapper around XWork with the context that is needed when working on web applications, along with specific implementations that make web developer easier.

The goal of Struts2 is simple – to make web development easier for the developer. To achieve this goal Struts2 provides features to reduce XML configuration via intelligent defaults, utilizes annotations and provides conventions over configuration.
Actions are now POJOs which increases testability and reduces coupling in the framework, and HTML form field data is converted to proper types for the action to use. Still further decreasing coupling is request processing has been made more modular by allowing a series of interceptors (custom or Struts2 provided) to provide pre-processing and post-processing functionality.

There are a lot of features in Struts 2 which are of interest. I’ll discuss a few here.

Action classes

An Struts 2 Action may implement an Action interface, along with other interfaces to enable optional and custom services. Struts 2 provides a base ActionSupport class to implement commonly used interfaces. Albeit, the Action interface is not required. Any POJO object with a execute signature can be used as an Struts 2 Action object.

Threading Model

Struts 2 Action objects are instantiated for each request, so there are no thread-safety issues. (In practice, servlet containers generate many throw-away objects per request, and one more object does not impose a performance penalty or impact garbage collection.)

Testability

Struts 2 Actions can be tested by instantiating the Action, setting properties, and invoking methods. Dependency Injection support also makes testing simpler.

Servlet Dependency

Struts 2 Actions are not coupled to a container. Most often the servlet contexts are represented as simple Maps, allowing Actions to be tested in isolation. Struts 2 Actions can still access the original request and response, if required. However, other architectural elements reduce or eliminate the need to access the HttpServetRequest or HttpServletResponse directly.

Harvesting Input

Struts 2 uses Action properties as input properties, eliminating the need for a second input object. Input properties may be rich object types which may have their own properties. The Action properties can can be accessed from the web page via the taglibs. Struts 2 also supports the ActionForm pattern, as well as POJO form objects and POJO Actions. Rich object types, including business or domain objects, can be used as input/output objects. The ModelDriven feature simplifies taglb references to POJO input objects.

Expression Language

Struts 2 can use JSTL, but the framework also supports a more powerful and flexible expression language called “Object Graph Notation Language” (OGNL).
The complete language guide can be found here.

Binding values into views

Struts 2 uses a “ValueStack” technology so that the taglibs can access values without coupling your view to the object type it is rendering. The ValueStack strategy allows reuse of views across a range of types which may have the same property name but different property types.

Type Conversion

Struts 2 uses OGNL for type conversion. The framework includes converters for basic and common object types and primitives.

Validation

Struts 2 supports manual validation via the validate method and the XWork Validation framework. The Xwork Validation Framework supports chaining validation into sub-properties using the validations defined for the properties class type and the validation context.

Control Of Action Execution

Struts 2 supports creating different lifecycles on a per Action basis via Interceptor Stacks. Custom stacks can be created and used with different Actions, as needed.

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One thought on “Struts 2.0

  1. Yes, Deadly combination!! It doesn’t means that there would some super stars of the film who would go the devil place and finish him. No No !!

    I am talking about the deadly combination used in the development of the web sites. I am talking about the tools used for the Java development. Any guesses so far….

    Yes, they are Struts2, Spring, and Hibernate

    I am currently working all these tools. I am amazed to see the power of all the three technologies and how they makes the life of a developer like me, so easy.
    All of three would make your project a huge success.

    Now talking about Struts2… It is great framework with the inbuilt Ajax tags that would help many developers. Many new features of the struts2 are marvelous.

    Hibernate… I already told in my last post about this. Hibernate would provide you a greater facility for your data persistence. its in built architecture that is fully object oriented which makes it a powerful tool. And yes, not to forget about the HQL (Hibernate Query Language).

    Spring… Again a master piece framework which lets you to do handle hibernate and specially the IOC (Inversion of Control) that lets programmers to walk to the higher level. Spring have many in built functionalities that help in various ways. One of them is scheduling of tasks. Before this you have to do manually write lots of code but now with a fewer code you can achieve greater flexibility.

    So enjoy working with the deadly combination

    Cheers,
    Vinod

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