Would it be possible for one GWT app to be included every time (with v2.0
the initial download can be quite small as it allows you to lazy-load code
chinks as needed with code-splitting). This one app then checks for certain
IDs added by the portlets. If they exist, it does its stuff.
RootPanel p;
p = RootPanel.get("instance1");
if(p != null) ...
p = RootPanel.get("instance2");
if(p != null) ...
(or a for-next - there are any number of possibilities)
Ian
http://examples.roughian.com
2009/10/30 Raziel <[email protected]>
>
> It's a forms framework where different elements in a complex page (you
> can call them portlets, or just randomly arranged elements) include
> forms they wish to render. Given that not all my app is GWT, I cannot
> nicely control the integration with the forms rendering framework
> which I'm going to develop in GWT.
>
> I guess an option is just loading the GWT application once, have it
> available always so when forms need to render the GWT application can
> just be "called" with the form data and proper information to
> namespace the rendering; internally the application would handle
> creating a new separate instance per call to render a form.
>
> However I was hoping for a more hmmm traditional approach where the
> GWT application is loaded as usual: including the nocache.js, and then
> the application instance is in charge of rendering just one form (as
> opposed of possibly handling the rendering of many, as with the
> previous option). But as I said in my last post that doesn't quite
> work out of the box given that GWT is not quite designed (at least the
> default selection script) to have many instances in the same page.
>
> I understand this is not an ideal GWT app. scenario, but I'm just
> pondering my options to come up with the best approach.
>
> Thanks
>
> On Oct 30, 11:37 am, Ian Bambury <[email protected]> wrote:
> > Hi Raziel,
> >
> > It might help if you explained what the problem is that you are trying to
> > solve.
> >
> > I can't think of any situation where an html page needs more than one GWT
> > app in it.
> >
> > Ian
> >
> > http://examples.roughian.com
> >
> > 2009/10/30 Raziel <[email protected]>
> >
> >
> >
> >
> >
> > > Hi Thomas, thanks for the links, although like the ticket says they're
> > > not very conclusive, and not quite what I'm looking for.
> >
> > > In general I'm thinking through all the considerations I have to keep
> > > in mind to build this application which can be injected into the same
> > > page, by different and unrelated sections of code.
> >
> > > The obvious scenarios, like creating or looking for elements by
> > > specific IDs, I'm aware of. When I said "generate IDs for a widget
> > > these must be namespaced according to the application's instance that
> > > created it" I meant exactly what you said: the application instance
> > > has to know, somehow (probably passed from the snipped of code that
> > > included it), something that "identifies" it and thus can serve to
> > > name-space it and be able to truly generate different IDs to the other
> > > instances.
> >
> > > My concern is with those things that are not obvious, at least to me.
> > > For example: if you end up with code like the one below, generated
> > > from unrelated pieces of code, the three nocache scripts will create
> > > the exact same selection script named after the module, with the exact
> > > same implementation. Thus, by default there will be 3 iframe generated
> > > containing the injected JS of the application. That's bad HTML since
> > > the iframe tags have an assigned ID equal to the module name, and thus
> > > the document will end up with 3 elements with the same ID. But not
> > > only that: the selection bootstrap script uses the ID to grab the
> > > iframe and call the gwtOnLoad function of the application instance
> > > living within. You can see how this would be error prone since there's
> > > no guarantee that the right iframe will be obtained.
> >
> > > <div id="instance1">
> > > <script src="/blah/blah/myapp.nocache.js">
> > > </div>
> > > <div id="instance2">
> > > <script src="/blah/blah/myapp.nocache.js">
> > > </div>
> > > <div id="instance3">
> > > <script src="/blah/blah/myapp.nocache.js">
> > > </div>
> >
> > > There's not much (if anything) I can do during compile time since the
> > > parameters to identify the applications are available only at runtime.
> > > Even worst in my case, as I said, the instances (injection snippets)
> > > can be done by different unrelated sections of the page. So I have to
> > > figure out how to parameterize the selection script with the runtime
> > > values it needs to 1) uniquely identify the script to avoid calling
> > > one of the exposed function on the wrong script 2) put different IDs
> > > to the iframes 3) obtain the right iframe using the right ID. So this
> > > calls for a new primary linker to change the bootstrap logic. The main
> > > issue being how the script should retrieve the runtime values (since
> > > there's no central place that can provide them).
> >
> > > Anyway, that's my specific problem, but I'm wondering if there are
> > > other considerations I should be aware of.
> >
> > > Thanks
> >
> > > On Oct 29, 9:20 pm, Thomas Broyer <[email protected]> wrote:
> > > > On 30 oct, 01:15, Raziel <[email protected]> wrote:
> >
> > > > > Hi, I have a legacy application and thus I'm migrating to GWT by
> > > > > reimplementing parts of it at a time. However, one of this "parts"
> may
> > > > > appear in a document more than once, displaying different
> information.
> >
> > > > > Aside from ensuring that if I generate IDs for a widget these must
> be
> > > > > namespaced according to the application's instance that created it
> (in
> > > > > case I retrieve them by ID somewhere), are there any other
> precautions
> > > > > that I should take to avoid collisions between application
> instances?
> > > > > For example, since the GWT application is put inside an iframe
> whose
> > > > > id is the name of the application's module, shouldn't it be
> necessary
> > > > > to generate the iframes with different ids? Otherwise we'll end up
> > > > > with elements (the iframes) with the same ID.
> >
> > > > If you included the very same JS script, why would it run differently
> > > > than the previous one? I mean, you use RootPanel.get(XXX) or
> > > > Document.get().getElementById(XXX) somewhere in your app; and XXX
> > > > cannot be different for 2 "instances" of the same app in the page
> > > > (it's either hard-coded or taken from the same Dictionnary –whose
> name
> > > > is hard-coded– or the URL), right?
> >
> > > > If you want your app to appear more than once, in different
> > > > "containers" of the same page, you'd have to use a Dictionnary or
> > > > similar to pass the containers' IDs to the app, and the app loops
> > > > through the list to instantiate as many "root components" as
> > > > necessary.
> > > > Seehttp://
> > > groups.google.com/group/Google-Web-Toolkit-Contributors/browse...
> > > > andhttp://code.google.com/p/google-web-toolkit/issues/detail?id=2592
> >
> > > > Or am I misunderstanding you?
> >
>
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