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From Ate Douma <...@douma.nu>
Subject Re: [scxml] passing datamodel elements into method call
Date Mon, 27 Oct 2014 00:53:46 GMT
Hi Rinke,

I've been diving into the datamodel handling, the Data() function and supporting 
Builtin Java class the last several days.

I've now come to the conclusion that what you are asking for *should* be 
supported by Commons SCXML, and actually *is* supported through the SCXML 
specification.

The current implementation of this functionality in Commons SCXML however is 
very problematic, not just for your use-case but overall, and I've created issue 
SCXML-213 to address this.

I'm working on the SCXML 2.0 Milestone 2 goal and trying to execute (and pass) 
the SCXML IPR tests, which is pretty much blocked because of this issue.

Anyway, once I've solved this, I expect your requirement will be covered 
automatically as well!

Note though that the scope of SCXML-213 is pretty extensive and will take large 
scale (breaking) changes, for which I also just send out a separate heads-up to 
the list...

This will take a while to complete, so intermediately implementing a custom 
action to cover your requirements probably is still worthwhile.

Kind regards,

Ate


On 08-10-14 20:54, Ate Douma wrote:
> On 08-10-14 11:31, R.C. Hoekstra wrote:
>>> Hi Rinke, I think you would get a node if you used DataNode function
>>> instead: <cs:var name="treatment1Name"
>>> expr="DataNode(treatmentData,'treatments/treatment[1]/name')" /> Could you
>>> try that?
>>>
>>> Regards, Woonsan
>>>
>>
>> Hi Woonsan,
>>
>> thanks for your answer. But are you sure about that? If I use it like that, I
>> get an "unknown, ambiguous or inaccessible method dataNode" error.
>
> Correct, DataNode() is not a function available (registered) within the context
> of the expression evaluator.
>
>>
>> I found the dataNode method in Builtin.java. Its javadoc says:
>>
>> "Manifests within location attribute of <assign> element, for Commons JEXL
>> and Commons EL based documents."
>>
>> So what I get from it, is that dataNode can only be used to assign something
>> to a dataNode via <assign>.
>>
>> That is not what I want. I want to pass a dataNode including subElements to
>> some java object via the cond attribute, so I can write a java method which
>> is able to check conditions with use of the passed dataNode.
>>
>>
>> So: is there a way in which I can pass a dataNode to a java object in the
>> context which is used in a cond attribute? Data obviously doesn't work, as I
>> can see in the Builtin code that it always is parsed to Double or String.
>
> Not by the SCXML spec, and neither (directly) through Commons SCXML extensions.
>
> However, it should be trivial to add such functionality yourself through a
> custom Action. Then you can access and use the Builtin#dataNode method and do
> whatever you like with a data node element.
>
> For a quick intro in writing a custom Action (for Commons SCXML 2.0), see for
> example slides 12,13 of my presentation at the ApacheCon earlier this year:
>
>
> http://events.linuxfoundation.org/sites/events/files/slides/ApacheConUS2014%20-%20Apache%20Commons%20SCXML%202.0.pdf
>
>
> and I suggest looking at the Commons SCXML Var action as simply example.
>
> HTH, Ate
>
>
>>
>> best regards, Rinke
>>
>>
>>
>>
>>
>>> On Thursday, October 2, 2014 3:53 AM, R.C. Hoekstra
>>> <r.c.hoekstra@erasmusmc.nl> wrote:
>>
>>>> Hi list, Hi people @ scxml commons,
>>>>
>>>> Can I pass datamodel nodes to a rootContext var, in order to process it
>>>> in java?
>>>>
>>>> like this: <target event="bla" cond="agent.check(datamodelNodeRef)"
>>>> .../>, where: * agent is an object of a java class made available to the
>>>> RootContext, having a check method returning Boolean. I want this check
>>>> method to evaluate the datamodelNode, in order to return true or false
>>>> depending on elements. * datamodelNodeRef is a reference to some node in
>>>> the datamodel.
>>>>
>>>> I managed to pass final nodes as string here, like this:
>>>>
>>>> <cs:var name="treatment1Name"
>>>> expr="Data(treatmentData,'treatments/treatment[1]/name')" />, <transition
>>>> ... cond="agent.check(treament1Name)"...
>>>>
>>>> where the treatments/treatment[1]/name is a final node.
>>>>
>>>>
>>>> However, I would like to pass non final nodes of the datamodel, but
>>>> everything seems to be evaluated as strings first, before it is passed
>>>> into the method of the context var.
>>>>
>>>> Hope you can give me a clue.
>>>>
>>>> And, if these kind of constructions are possible, how would they do in
>>>> terms of performance?
>>>>
>>>> thanks, Rinke
>>
>>
>


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