Torsten Curdt wrote:
var bookmark = cocoon.createWebContinuation(ttl);
+ + // Attach the form to the continuation so that we can
access by just knowing the continuation id
+ bookmark.setAttribute("form", this.form);
<snip/>
+ + Form form = (Form)wk.getAttribute("form");
+ if (form == null) {
+ throw new ProcessingException("No form is attached to
the continuation");
+ }
Ah ...I missed that
The selection list generator, which is called through an Ajax
request, needs to access data in the form that is currently
displayed. And this form is held by the continuation.
Since we don't want to _call_ the continuation but just access some
attached data, the quick'n dirty solution was to use the knowledge
that WebContinuation.getUserObject() returns a FOM_WebContinuation
and from there use Rhino methods to access the "form" property.
That seemed bad to me, strongly coupling the SelectionListGenerator
to the flow implementation. I guess Mr JavaFlow will agree on this ;-)
I cannot hide the reason why I've asked ;-)
Then I considered that a continuation is actually an application
scope, just as Context, Session and Request are. The lifetime and
visibility of a continuation is in-between Request and Session. And
other scopes do have attributes that we use to pass data around,
whereas a continuation did not. That's why I added attributes to
Continuation.
We can then attach some data to a continuation without being tied to
the actual flow implementation.
Hm... I see your point and it does make kinda sense. But still it
feels a bit ugly.
I need to think about that.
And at the moment is also not yet flow implementation agnostic because
javaflow does not provide access to the WebContinuation object but
only the underlying java continuation. The only connection to the
cocoon machinery is through the continuation execution context.
I see.
Actually I would like to change this flow machinery a bit anyway. Eg.
it would be nice if WebContinuation would be an interface an the flow
implementation a WebContinuation factory.
+1. This may allow to avoid this wrapping that happens under the hood
with this userObject property.
For full flow serialization support it needs some work anyway.
Yup.
Sylvain
--
Sylvain Wallez Anyware Technologies
http://people.apache.org/~sylvain http://www.anyware-tech.com
Apache Software Foundation Member Research & Technology Director
