A rather provocative subject, so let me first say that I like the flow, even if unfortunately I didn't have the occasion to use it up to know. Ovidiu did a wonderful job and Adrew is now adding features that make it more usable.
But I think we reached a point where we have to be careful at how the flow is slowly spreading inside other components and do some design before it's too late. This is mainly about the way the flow gives its output to other components : it adds two attributes to the *Environment* object, which is an object used internally by the pipeline machinery, and *should not be used* by other components (nor shoud it theroretically be accessible).
The way this Enviromnent object is fetched says it by itself :
public void setup(SourceResolver resolver, Map objectModel, String src, Parameters params) {
Object bean = ((Environment)resolver).getAttribute("bean-dict");
WebContinuation kont = (WebContinuation)((Environment)resolver).getAttribute("kont");
...
This is a hack that relies on the fact that the SourceResolver also implements Environment, which is absolutely not guaranteed by its contract ! Furthermore, this "resolver" parameter in C2.1 should be considered deprecated and is replaced by the Excalibur SourceResolver which is a regular component looked up on the ComponentManager and doesn't implement Environment !
So why don't we use the ObjectModel to pass the flow information ? It already contains the request and the response, and this seems the natural place for flow values. And more : if we consider components such as FlowVelocityGenerator, why would we want to publish only flow data and not elements of the object model ? If everything was in the object model, we could have some generic publication code that would publish all that is in the object model, regardless of what it actually is, and thus no need for a second VelocityGenerator.
Thoughts ? What's the reason for using the Environment ?
Also, I prefer longer but more explicit names than "$this" to access the flow bean : "$flowDict" is not much longer but way more explicit in the huge name base that is Cocoon. Oversimplifying names leads to too much magic that kills the understandability of the whole thing.
Sylvain
-- Sylvain Wallez Anyware Technologies http://www.apache.org/~sylvain http://www.anyware-tech.com { XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects }
