Thanks for your response Ernst!
Yeah, I have looked around at pretty much every JSF AJAX framework out
there and it isn't that I'm not impressed. There are definitely some
smart people working to create generic components to be consumed by the
masses. In our current position though I don't think these frameworks
make a lot of sense for us to use. We have an extremely strong UI
developer and we just want to be able to expose his talents, and in our
current circumstance having to use pre-built AJAX components or having
to create our own would severely hamper his abilities.
So anyway I have solved my problem via the following process. It allows
us to interact with JSF, i.e. forms, via AJAX without having to write
components. It has some significant short comings if it was going to be
used for general consumption by the JSF community (i.e. lacking
configuration, you can shoot your foot off easily, etc...) but works for
us. So keeping with good list etiquette I'm posting my solution below
for those, if any, that get a hit on my initial question.
I have created a PhaseListener that runs after the RESTORE_VIEW phase
and checks for the presence of a known parameter. Every parameter on
every request is checked which I'm not a fan of but from what I have
seen most other JSF/AJAX solutions do the same and it appears to run
super fast. If a 'known' parameter exists the PhaseListener instantiates
the class associated with the parameter for processing. In my case all
of these 'processor' classes implement a simple interface with one
method, process(), that takes a CaseInsensitiveMap as an argument. This
map contains the map returned value from the getParameterMap() method on
HttpServletRequest:
HttpServletRequest req = (HttpServletRequest)
event.getFacesContext().getExternalContext().getRequest();
CaseInsensitiveMap map = new CaseInsensitiveMap();
map.putAll(req.getParameterMap());
The process() method then does what it needs to do. Typically finding
components by their ids in the restored view, that are either known by
the class or sent as parameters, and updating their values accordingly.
Then the class composes an XML document that our client side JavaScript
(taconite and/or JQuery) understands and returns this XML string. The
PhaseListener then determines if the returned string contains a
javax.faces.ViewState placeholder we came up with and substitutes the
placeholder with the new ViewState value generated below. If there is no
placeholder, i.e. not interacting with a JSF form, we can omit the
updating of the ViewState value. In that case though we typically do
straight HTTP and bypass JSF completely.
try {
UIViewRoot viewRoot = context.getViewRoot();
StateManager stateMgr =
context.getApplication().getStateManager();
ComponentSupport.removeTransient(viewRoot);
SerializedView serializedView =
stateMgr.saveSerializedView(context);
Object[] savedState = new Object[3];
Object treeStruct = serializedView.getStructure();
if (treeStruct != null) {
if (treeStruct instanceof String) {
savedState[0] = treeStruct;
}
}
savedState[2] = viewRoot.getViewId();
String viewState = StateUtils.construct(savedState,
context.getExternalContext());
return viewState;
} catch (Exception e) {
throw new RuntimeException(e);
}
The PhaseListener writes out the string to the response stream and marks
the response as complete. The client JavaScript interprets the XML and
updates the DOM. The DOM should now match the DOM stored on the server.
It works well for us and results in the creation of only one class,
after the initial PhaseListener creation, per Ajaxable event. The above
code does tinker with the internal workings of MyFaces which may/will
cause us issues on an upgrade. I haven't tested it for thread-safety yet
but everything I have seen with other frameworks leads me to believe all
is well.
Thanks,
Stan
Ernst Fastl wrote:
Hi,
I can understand you don't like to write your own component for
soving this problem (although seeing the stuff you posted I guess
you are skilled enough for that).
Anyway, have you tried the
existing solutions like PPRPanelGroup from the tomahawk sandbox
or Ajax4JSF?
regards
Ernst
