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From "Rahul Akolkar" <rahul.akol...@gmail.com>
Subject Re: [SCXML] Help with Data()
Date Thu, 11 Dec 2008 16:33:31 GMT
On Thu, Dec 11, 2008 at 5:40 AM, Jaroslav Pullmann
<jaroslav.pullmann@fit.fraunhofer.de> wrote:
>
>  Dear Rahul,
>
>  your quick response and dedication to the project are very appreciated!
>
>  Suprisingly the last WD does not contain the assign/@src anymore.
>  I hope this decision will be revised to preserve a standard means
>  to access remote data and assign it to the (static) data model.
>
>  Your proposal to interpret assign/@src as an expression follows
>  the way how e.g. send/@target is treated. This shortcut syntax
>  (ommiting @srcexpr) would be fine, when consistent and intuitive
>  throughout the spec. Such, exceptions like invoke/@srcexpr should
>  be removed. Could you please address this question within the
>  working group ?
>
<snip/>

I noticed the absence of assign/@src right after I sent out the email below :-)

I agree with you on both the points above (reintroduction of "src" for
<assign> and removing "srcexpr" for <invoke>). I will indeed bring
this up to the WG's attention (may take a bit of time since we are
largely on year-end break). I've opened SCXML-102 to facilitate
tracking this:

  http://issues.apache.org/jira/browse/SCXML-102

-Rahul



>  Best regards
>    Jaroslav
>
>
> Rahul Akolkar wrote:
>>
>> On Wed, Dec 10, 2008 at 10:38 AM, Jaroslav Pullmann
>> <jaroslav.pullmann@fit.fraunhofer.de> wrote:
>>>
>>>  Dear all,
>>>
>>>  could you please give me a short hint on these questions ?
>>>
>>>  1) where to find documentation and source code for the "Data"-function
>>> for
>>> JEXL evaluator ?
>>>    I need to clarify which subset of XPath is supported.
>>>
>> <snip/>
>>
>> There is some documentation of this page (towards the bottom):
>>
>>  http://commons.apache.org/scxml/guide/datamodel.html
>>
>> Source is here, for example (trunk version):
>>
>>
>>  http://commons.apache.org/scxml/xref/org/apache/commons/scxml/Builtin.html
>>
>>
>>>  2) there is no "name" attribute on <data> in current working draft, but
>>> Data() depends on it:
>>>
>>>
>>>     a) <data ID="foo"><foo>bar</foo></data>
>>>     b) <data name="foo"><foo>bar</foo></data>
>>>
>>>   the action <log expr="Data(foo,'node()')"/>
>>>
>>>   - throws an error for a: Data(): Cannot evaluate an XPath expression in
>>> the absence of a context Node
>>>   - returns "bar" for b)
>>>
>>>  Will the Data() implementation be adapted to the spec ?
>>>
>> <snap/>
>>
>> In this case, it happens to be the other way around :-)
>>
>> The casing of the ID attribute (all uppercase) in the draft was
>> unfortunate, and this has been discussed (and in all likelihood will
>> change to lowercase in the next draft). So, please use lowercase i.e.
>>
>>  <data id="foo"><foo>bar</foo></data>
>>
>>
>>>  3) How to address nodes in a specific namespace via Data() ?
>>>
>>>     <data name="foo"><f:foo xmlns:f="fooNS"><baz>bar</baz></f:foo></data>
>>>     <!-- how to address f:foo ? -->
>>>     <log expr="Data(foo,'foo')"/>
>>>
>> <snip/>
>>
>> I'm running out of time for email, so let me point to a fairly
>> comprehensive test case SCXML document that demonstrates use of
>> namespace prefixes in XPath expressions (the bottom line is prefixes
>> in an expression are resolved based on the enclosing namespace
>> declarations at the location where the expression occurs in the
>> document -- and so these prefixes may be different from the prefixes
>> specified in the <data>). Here is the test document (long URL, may get
>> fragmented):
>>
>>
>>  http://svn.apache.org/repos/asf/commons/proper/scxml/trunk/src/test/java/org/apache/commons/scxml/env/jexl/datamodel-03.xml
>>
>> Please feel free to bring up anything that isn't clear after going
>> through that test document.
>>
>>
>>>  4) assign supports static source-URLs via @src. Is there a way to supply
>>> an
>>> srcexpr,
>>>  or what would be the recommended way to perform and store XML data from
>>> parametrized GET-requests ?
>>>
>>>  broken example:
>>>
>>>   <data ID="MyId">3q495</data>
>>>   <assign location="Data(test,'response')" expr="
>>> 'http://localhost:8080/exist/ess/queries/getData.xqy?id=' + MyId "/>
>>>
>> <snap/>
>>
>> I think the src attribute value should be evaluated as an expression
>> (that way, there isn't any need for another srcexpr attribute and
>> static URLs / string attribute values can be surrounded by single
>> quotes if needed). This will cover usecases as illustrated by your
>> example above.
>>
>> Please open an enhancement request in JIRA [1] so we remember this,
>> thanks.
>>
>> -Rahul
>>
>> [1] http://commons.apache.org/scxml/issue-tracking.html
>>
>>
>>>  Many thanks !
>>>  Jaro
>>>
>>>
>>
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>
>
> --
> Jaroslav Pullmann
> Web Compliance Center - Fraunhofer FIT
> Schloss Birlinghoven, D-53757 Sankt Augustin, Germany
> Phone: +49-2241-142623    Fax: +49-2241-142065
>

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