Thought about it a little bit, and in some offline discussion a while ago
Jeremy was also interested in that. I think there does need to be a balance
so as to not lose the simplicity of the client environment and to utilize
its dynamic nature. I'm definately interested in any feedback or
suggestions. The SCA PHP guys have had similar issues so it would be useful
to talk to them or align this with what they do rather than what Java SCA
does.
I'm really interested in looking at utilizing Flash.
One technique is to have in the HTML page a hidden Flash movie with no
visual content and expose its XMLSocket to the JavaScript environment. This
would work really well when Tuscany has the HTTP system service that Jeremy
has mentioned for the XMLSocket to talk to.
Not all browsers will have the Flash plugin so you still need to support the
other ways like HTML streaming, and older browsers don't support streaming
so sometimes you'd fall back to using periodic refresh. But all thats hidden
from the client as the Tuscany server and client code can interrogate the
environment and use what is most appropriate for the environment and the
parameters on the SCA binding. The client HTML and scripts remain really
simple and it runs on any browser.
There are other projects working on these types of things but this seems to
have a some benefits over them. One of the problems with other web remoting
technologies is they use custom protocols which are often platform specific,
but this using JSON makes it platform independent. That and using the SCA
config model means these SCA AJAX clients could theoretically be hosted on
any SCA platform, and when using the Tuscany HTTP service the performance
would be very competitive.
...ant
On 3/22/06, Jim Marino <[EMAIL PROTECTED]> wrote:
>
> This seems interesting but I have a few questions, which are not
> really important but arise from curiosity:
>
> I'm curious if you thought about making this look more like SCA
> Client & Implementation specs? For example, it may be convenient to
> have the APIs look more like the Java C&I spec such as instead of
> SCA.xxx doing:
>
> ModuleContext moduleContext =
> CurrentModuleContext.getContext();
> HelloWorldService helloworldService = HelloWorldService
> (moduleContext.locateService("HelloWorldServiceComponent"));
>
> I also think dependency injection, metadata, and dynamic generation
> of proxies for external services could be supported (with invocation
> handlers for policies). I've seen people attach "markers" to the
> function object's prototype and/or prototype of a class in
> JavaScript. It would also be nice to be able to support the
> asynchronous C&I spec model more closely, e.g. callbacks and ending
> sessions by calling a business method. What would be really cool IMO
> is an SDO implementation in JavaScript. These things would provide an
> interesting client-side model, which could actually be done as a
> Javascript-based implementation of an SCA container.
>
> As a side note, I've found Actionscript and Flash have a lot of
> capabilities for doing these types of things - e.g. the ability to do
> "real" client side async with sockets, including binary sockets in
> Flash Player 8.5. It may even be worth looking at using a
> lightweight flash client that just keeps a socket open to the server
> and communicates with Javascript to provide real async and local
> persistent storage.
>
> Unfortunately, I'm drowning in a bunch of other work right now so I
> can't really volunteer for any of this.
>
> Jim
>
> On Mar 22, 2006, at 2:29 AM, ant elder wrote:
>
> > Below is the note I posted a few weeks ago about what the JSON-RPC
> > binding
> > does, which is to support entryPoints which enabled web pages in a
> > browser
> > to make RPC style calls into SCA components on the server. (The
> > code has
> > moved from the sandbox now so those links below are wrong)
> >
> > I'd like to also add support for externalServices which would
> > enable the
> > server to push events asynchronously out to the browser client. It
> > would
> > work something like the following:
> >
> > As before the HTML page includes the SCA system script "scripts/
> > sca.js"
> > which gets initialised when the page is loaded. That makes the SCA.
> > object
> > available in the script environment which is used to make RPC calls
> > to the
> > SCA entryPoints as before, but now it also supports registering
> > handlers for
> > the methods on any SCA externalServices. For example:
> >
> > SCA.myExternalService.foo(fooHandler);
> >
> > The fooHandler here is a JavaScipt function, such as:
> >
> > function fooHandler(s) {
> > alert(s);
> > }
> >
> > So that would pop up an alert box on the browser every time the
> > server side
> > externalService received a foo message.
> >
> > The act of registering the handler establishes the channel back to the
> > server. It could be closed by the client making the call with null
> > to remove
> > the handler:
> >
> > SCA.myExternalService.foo(null);
> >
> > There are various techniques for doing these asynchronous
> > communications,
> > HTTP streaming, periodic refresh, etc, there's a lot of info about the
> > techniques at: http://ajaxpatterns.org/HTTP_Streaming.
> >
> > Exactly how its done is completely transparent to the web client.
> > There
> > would be configuration parameters on the SCA binding to configure
> > which ever
> > technique is most appropriate for that application and the options
> > that may
> > require such as timeout or heartbeat intervals.
> >
> > This seems way cool to me, but there wasn't any comments on the
> > original
> > post so maybe I'm missing something, what do others think about this?
> >
> > ...ant
> >
> >
> > ---------- Forwarded message ----------
> > From: ant elder <[EMAIL PROTECTED]>
> > Date: Mar 8, 2006 8:59 PM
> > Subject: Re: How do you register SCDL for a new binding?
> > To: [email protected]
> >
> > Thanks to Jeremy and Sebastien for helping with this, I have it
> > going now
> > and I've updated the sandbox with code that works:
> > http://svn.apache.org/repos/asf/incubator/tuscany/sandbox/ant/jsonrpc/
> >
> > It enables JavaScript running in a browser to access SCA components
> > defined
> > in the web app with an entryPoint using the new binding. All you
> > have to do
> > is add one extra script definition line to the HTML:
> >
> > <script type="text/javascript" src="scripts/sca.js"></script>
> >
> > and then user scripts can access all the entryPoints from an SCA
> > variable
> > that gets automatically defined:
> >
> > var result = SCA.HelloWorldService.getGreetings(name);
> >
> > There's a sample helloworld app that demonstrates it:
> > http://svn.apache.org/repos/asf/incubator/tuscany/sandbox/ant/
> > jsonrpc/helloworldajax/
> >
> >
> > ...ant
> >
> > On 3/6/06, ant elder <[EMAIL PROTECTED]> wrote:
> >
> >
> >> You're a star, thanks!
> >>
> >>
> >> On 3/6/06, Jean-Sebastien Delfino <[EMAIL PROTECTED]> wrote:
> >>
> >>>
> >>> ant elder wrote:
> >>>
> >>>> I'm messing about trying to add a new binding to Tuscany but
> >>>> can't get
> >>>>
> >>> it to
> >>>
> >>>> work. There must be something I'm missing to register the new
> >>>> binding
> >>>>
> >>> SCDL
> >>>
> >>>> as all I get is the exception below saying "Feature ' binding.ajax'
> >>>>
> >>> not
> >>>
> >>>> found". Could someone have a quick look if its something
> >>>> obvious? The
> >>>> code's up at http://svn.apache.org/repos/asf/incubator/tuscany/
> >>>> sandbox/ant/
> >>>>
> >>> ,
> >>>
> >>>> the AJAXAssemblyLoaderTestCase shows the problem.
> >>>>
> >>>> Thanks,
> >>>>
> >>>> ...ant
> >>>>
> >>>> java.lang.RuntimeException:
> >>>>
> >>>>
> >>> file:/C:/SCA/SVN/WORK/sca/binding.ajax/bin/org/apache/tuscany/
> >>> binding/ajax/assembly/tests/sca.module
> >>>
> >>>
> >>>> at
> >>>>
> >>> org.apache.tuscany.model.scdl.loader.impl.SCDLXMLReader.getRootObjec
> >>> t
> >>>
> >>>> (SCDLXMLReader.java:103)
> >>>> at
> >>>>
> >>> org.apache.tuscany.model.scdl.loader.impl.SCDLXMLReader.getModule(
> >>>
> >>>> SCDLXMLReader.java :61)
> >>>> at
> >>>>
> >>>>
> >>> org.apache.tuscany.model.scdl.loader.impl.SCDLAssemblyModelLoaderImp
> >>> l.loadModule
> >>>
> >>>> (SCDLAssemblyModelLoaderImpl.java:101)
> >>>> at
> >>>>
> >>>>
> >>> org.apache.tuscany.binding.ajax.assembly.tests.AJAXAssemblyLoaderTes
> >>> tCase.testLoader
> >>>
> >>>> (AJAXAssemblyLoaderTestCase.java:63)
> >>>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> >>>> at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
> >>>> at sun.reflect.DelegatingMethodAccessorImpl.invoke (Unknown
> >>>>
> >>> Source)
> >>>
> >>>> at java.lang.reflect.Method.invoke(Unknown Source)
> >>>> at junit.framework.TestCase.runTest(TestCase.java:154)
> >>>> at junit.framework.TestCase.runBare(TestCase.java:127)
> >>>> at junit.framework.TestResult$1.protect(TestResult.java:106)
> >>>> at junit.framework.TestResult.runProtected(TestResult.java:124)
> >>>> at junit.framework.TestResult.run(TestResult.java:109)
> >>>> at junit.framework.TestCase.run (TestCase.java:118)
> >>>> at junit.framework.TestSuite.runTest(TestSuite.java:208)
> >>>> at junit.framework.TestSuite.run(TestSuite.java:203)
> >>>> at
> >>>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(
> >>>> RemoteTestRunner.java:478)
> >>>> at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(
> >>>> RemoteTestRunner.java:344)
> >>>> at
> >>>> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main (
> >>>> RemoteTestRunner.java:196)
> >>>> Caused by:
> >>>>
> >>> org.eclipse.emf.ecore.resource.Resource$IOWrappedException:Feature '
> >>>
> >>>> binding.ajax' not found. ( http:///temp.xml, 23, 24)
> >>>> at org.eclipse.emf.ecore.xmi.impl.XMLLoadImpl.load(
> >>>>
> >>> XMLLoadImpl.java:283)
> >>>
> >>>> at org.eclipse.emf.ecore.xmi.impl.XMLResourceImpl.doLoad(
> >>>> XMLResourceImpl.java:646)
> >>>> at org.eclipse.emf.ecore.xmi.impl.XMLResourceImpl.load (
> >>>> XMLResourceImpl.java:614)
> >>>> at org.apache.tuscany.sdo.helper.XMLDocumentImpl.load(
> >>>> XMLDocumentImpl.java:246)
> >>>> at org.apache.tuscany.sdo.helper.XMLDocumentImpl.load(
> >>>> XMLDocumentImpl.java :225)
> >>>> at org.apache.tuscany.sdo.helper.XMLHelperImpl.load(
> >>>>
> >>> XMLHelperImpl.java
> >>>
> >>>> :72)
> >>>> at org.apache.tuscany.sdo.helper.XMLHelperImpl.load(
> >>>>
> >>> XMLHelperImpl.java
> >>>
> >>>> :66)
> >>>> at
> >>>>
> >>> org.apache.tuscany.model.scdl.loader.impl.SCDLXMLReader.getRootObjec
> >>> t
> >>>
> >>>> (SCDLXMLReader.java:100)
> >>>> ... 18 more
> >>>>
> >>>>
> >>>>
> >>> Ant,
> >>>
> >>> Good news, I took a look at your AJAX binding in your sandbox and
> >>> was
> >>> able to get your test case working... You just had a few minor
> >>> problems
> >>> in your XSD, missing a namespace prefix declaration, and some
> >>> left-over
> >>> references to axis2.
> >>>
> >>> I am committing the fixes for you. Here are the details:
> >>> - In sca-binding-ajax.xsd, removed the <include
> >>> location="sca-core.xsd"/> which actually included a copy of the
> >>> whole
> >>> SCDL schema in your Ajax binding namespace. This is not necessary,
> >>> instead the base SCDL XSD needs to be correctly imported so that
> >>> your
> >>> AJAXBinding can extend the correct base SCDL Binding type.
> >>> - Fixed the location attribute in the <import location="....
> >>> sca-core.xsd"> to a correct relative location pointing to sca-
> >>> core.xsd
> >>> in the java/sca/model project from your sandbox/ant/binding.ajax.
> >>> - In sca.module, added an ajax namespace prefix declaration for your
> >>> Ajax binding namespace and changed <binding.ajax/> to
> >>> <ajax:binding.ajax
> >>> />.
> >>> - Changed the left over references to axis2 to ajax in sca.module
> >>> and
> >>> the test case itself.
> >>>
> >>> Hope this helps...
> >>>
> >>> --
> >>> Jean-Sebastien
> >>>
> >>>
> >>>
> >>
> >
>
>
