ISSUE 13: Difficulty using source= attribute to pull values into complex types

[Scott Vorthmann <scottv@tibco.com>]

http://www.osoa.org/jira/browse/ASSEMBLY-13

On Oct 30, 2007, at 1:54 AM, Mike Edwards wrote:

>
> Folks,
>
> Matthew Peters originally raised this issue on the OSOA Assembly  
> mailing list, but I think that it is worthy of consideration
> within the OASIS Assembly TC, so I am raising it formally as an issue.
>
>
> Yours,  Mike.
>
> Strategist - Emerging Technologies, SCA & SDO.
> Co Chair OASIS SCA Assembly TC.
> IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.
> Phone & FAX: +44-1962-818014    Mobile: +44-7802-467431
> Email:  mike_edwards@uk.ibm.com
>
>
> I have a property which is a complex type, and I wanted to use  
> source= attribute to pull the values down from a global property  
> within my .composite. This turned out to be not quite as easy as I  
> thought. I have been through several options.
>
> _________________________
> My first idea, which was wrong
>
> I have a composite containing several different components. I want  
> to specify some proerties at a global level. One of the components  
> wants to use a omplex type for one of the properties. The complex  
> type is already defined elsewhere. For this example I'll simplify  
> it so it has two elements, which are long and short titles that the  
> component will use:
>
> <complexType name="titles-type">
>   <sequence>
>     <element name="long-title" type="xs:string"/>
>     <element name="short-title" type="xs:string"/>
>   </sequence>
> </complexType>
>
> I want to define some global properties in my composite, with  
> values which will be pulled down into this and other components.  
> But the structure of the globals, and the names of the elements are  
> not the same as the component's and I don't want them to be the  
> same - I don't want the structure of the global properties forced  
> on me by the structure of the property for the one component.  
> Here's the global property where just two of the elements are the  
> titles I want:
>
> <property name="global-properties" type="app-namespace:global- 
> properties-type">
>     <application-full-name>Whizzo Insurance, a subsidiary of Fizzo</ 
> application-full-name>
>     <application-short-name>Whizzo Insurance</application-short-name>
>   . <!-- and lots of other elements in here as well -->
> </property>
>
> Here's what I really wanted to write in the component before I was  
> thinking clearly. I imagined that I was going to use source= but  
> hadn't realised that I was about to put the source= on the wrong  
> elements:
>
> <component ...
>    <implementation....../>
>    <property name="app-titles" type="titles-type"
>       <app-titles xsi:type="titles-type">
>          <long-title source="global-properties/application-full- 
> name"/>
>          <short-title source="global-properties/application-short- 
> name"/>
>       </my-app-complex-element>
>    </property>
> </component>
>
> The mistake I made here of course is that source= means something  
> to sca on a property element, but where I wanted to put it was on  
> an element that is part of a complex type that is nothing to do  
> with sca. And I don't control the complex type myself so I can't  
> add to the schema to allow it to take an sca:source= attribute.
>
> ___________
> Two options
>
> ******Option 1.
> I can give up using the info-type complex type altogether and  
> flatten all the elements out into separate properties and write e.g.
> <property name="long-title" source="global-properties/application- 
> full-name"/>
> <property name="short-title" source="global-properties/application- 
> short-name"/>
> A bit of a shame, but I can do that
>
> ******Option 2.
> I can copy the complex type for app-titles-type and add a source=  
> attribute, allowing me to write more or less what I proposed the  
> first time. But this is a bit weird - I am taking the SCA idea of  
> source=<XPath expression> but at runtime someone is actually going  
> to have to make it happen and I guess it will be up to the  
> implementation to do it for me somehow. I can't expect it to just  
> happen.
>
> _______________
> What I really want is for SCA to have a more powerful mapping  
> system to allow me to do more than source= on scalar properties. Or  
> some other magic.
>
> I don't think I will be the only one to run into this. Any  
> suggestions?
> Matthew Peters
>
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