> -----Original Message----- > From: Patrick Lightbody [mailto:[EMAIL PROTECTED] > > Basically, Joe Walnes got me hooked on the idea and it's now > part of XWork in the form of the ComponentManager stuff. > > Basically, the idea is that an external service should manage > resources and components. It's called Inversion of Control, > and what the end result is that instead of your action code > actively going out and getting a resource or component, the > container (XWork) passively pushes the resource (via setXxx > methods) to the action or any other object. > > Example: Imagine your action code needed a Connection object. > Typically your code would use JNDI to look up a DataSource, > get a Connection, use the connection, then close the > Connection. Of those four steps, only one of them is unique > to that action and is part of the requirements for why you > coded the thing in the first place ("use the connection"). > The rest is accessory stuff to enable the "use the > connection" part. Using XWork's simple IoC framework (Avalon > and JBoss4 will both probably take this much further), your > action could be as simple as: > > public MyAction implements Action, ConnectionAware { > Connection conn; > > public void setConnection(Connection conn) { > this.conn = conn; > } > > public String execute() throws Exception { > // do stuff with the connection, no need to close it > return SUCCESS; > } > } > > Then the ConnectionService would have an init() and destroy() > method called by the contianer where it could handle cleanup > (such as closing the connection). > > In XWork, resources/services/components can have scope. This > is implemented in WebWork2 where there are listeners for > request, session, and application scope. Imagine how easy a > ShoppingCart would be (tag it as session scope and implement > ShoppingCartAware)! > > Even more, services can depend on other services, so you can > create very large resource dependencies such that each > resource is small by itself, but can be used to form large > building blocks. XWork examines the dependency graph and > correclty loads resources in the correct order using a simple > depth-first search on the graph. Even more, the container can > be used outside of XWork and applied in other situations, > such as OSWorkflow. In my application at Cisco, I've got > FunctionProviders (an OSWF thing) that implement the same > Aware interfaces that my Actions do, and both get access to > the same resource. > > OK, did that sell anyone? The end result is SUPER simplified > code that is much better suited for unit testing (think: > action.setConnection(mockConnection)) and only focuses on > requirements and doesn't worry about any "glue", since the > container handles all that. > > -Pat > >
I'm sold :-) Now if only the Component stuff were unit tested. ------------------------------------------------------- This SF.net email is sponsored by: Etnus, makers of TotalView, The debugger for complex code. Debugging C/C++ programs can leave you feeling lost and disoriented. TotalView can help you find your way. Available on major UNIX and Linux platforms. Try it free. www.etnus.com _______________________________________________ Opensymphony-webwork mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/opensymphony-webwork
