pageflow for struts

[Pa...@Dell.com]

Dear struts users,
 
I have launched a sub-project at the struts sourceforge site which provides
flow functionality for struts. Essentially it is a re-write of the struts
controller and provides a significant set of additional features. I am
currently working on finalizing the struts example and writing
documentation, but the basic framework is there. Im looking for reviewers to
help guide the direction of the framework. 
 
 
PAGEFLOW EXAMPLE
 
Heres what a page looks like...
<page name="logon">
<location value="/logon.jsp"/>
<form>
<form-property... (same as Struts 1.1)
</page>
<page name="main">
... page declaration
</page>
 
Heres what a page flow looks like...
<flow>
<page-instance ref="logon" name="logon1">
<action name="submit" defaultDestination="main">
<steps>
            <step type="LogStep">
                        <param name="message" value="Message to log"
            </step>
            <step type="CallSessionBean">
                        <param name="beanName" value="value"
                        ... additional params
            </step>
</steps>
</action>
</page-instance>
<page-instance ref="main" name="main">
<action name="submit" defaultDestination="logon1">
<steps>
            <step type="LogStep">
                        <param name="message" value="Message to log"
            </step>
            <step type="CallSessionBean">
                        <param name="beanName" value="value"
                        ... additional params
            </step>
</steps>
</action>
</page-instance>
</flow>
 
PAGEFLOW FUNCTIONALITY
 
1. Contextual Pages: Re-use of pages across PageFlows. 
 
2. Re-usable Actions: Actions can be declared at the application or pageflow
level and reused inside of the workflow. 
 
3. Variable Handling: You can do almost all of your web variable handling in
the xml file instead of in code (saves loads of time!) Additionally pageflow
provides a new web scope which is automatically cleaned up for the
developer. 
 
4. Event Handling: 
- Entering, exiting, or wrapping a pageflow.
- Entering, exiting an action.
- Entering, exiting a page instance.
- Adding, removing from a scope.
- Setting values on a form, validating a form.
- Sending HTML to the client.
- An error occurs.
 
5. Re-Usable Steps: I get really tired of writing the same code over and
over again. That is why I love workflow tools (webmethods, BEA BPM, etc.).
Workflow tools offer me a meta programming language with which I can create
re-usable steps and just 
pass in different parameters. 
 
pageflow provides exactly the same functionality (uses the commons-workflow
library). If your application uses session beans out of an EJB container,
just use the InitialContext and CallSessionBean steps. Sometimes of course
this wont work, either because of the complexity of the logic involved or
your specific project context. In that case just put your custom code into a
step and put that step into the action. 
 
6. Nested PageFlows: This is really cool! pageflow allows you to nest other
PageFlows inside of each other. You can pass variables from one to the
other. If managed and thought through properly this could be a very powerful
feature. 
 
7. Fine-Grained Filters: I honestly dont know if anyone wants this, but it's
always annoyed me that I could only use filters at the top web application
level. What if 
you want to convert your application to use a new filter incrementally? What
if your filter isnt needed everywhere? Currently you would have to code the
contextual logic 
directly in your filter.pageflow allows you to put your filter at the
application, 
pageflow, page-instance and action levels.
 
8. Fine-Grained Error Handling: Another gripe I have is trying to figure out
flexible error handling in my applications.You may use or declare error
handlers at
- application layer
- pageflow layer
- action layer
 
9. Fine-Grained Form Control: I had two big beefs with Struts 1.1 forms.
Figuring out when and where forms are initialized and mapping the data
to/from my value objects. In pageflow, each page declaration is connected
with a form. The form properties have two new elements, mapTo and mapFrom.
These elemements simply connect the form property to two variables, one to
get the value from
(session.user.name) 
and one to put the changed value into (request.changeduser.name).
 
The framework is in no way complete, but it is to the point where people can
start commenting on it. Let me know what you think.
 
Paul T Smith