Re: [sca-j] ISSUE-179: Need type support for @Property when usedwith SDO

[Simon Nash <oasis@cjnash.com>]

Dave,
Responses inline below.

   Simon

David Booz wrote:
> Hi Simon,
> 
> Thanks for the research. Don't you think it would be quite odd if the 
> spec required the use of JAXB emitters (this is what I find the most 
> troubling) in order to use SDO with a specific schema type?
 >
JAXB is built built into the JDK, so I'm not sure why it is burdensone
to run the JAXB emitters.  The emitted class could be placed in a
separate Java package that clearly identifies it as an emitted
JAXB artifact and doesn't interfere with any classes in Java packages
used by the implementation.

>                                                             My argument 
> remains the same. We need a way to simplify the use of SDO as a 
> databinding technology, enabling the developers to work with the minimal 
> number of building blocks. While I agree that the @XmlJavaTypeAdapter 
> seems to "work", it doesn't meet the requirement as something that would 
> be intuitive to use because it introduces extra concepts that the 
> developer doesn't really need. The simple extension that I've proposed 
> provides an easily understandable integration point because the 
> developer only has to deal with the SDO API and XML schema.
> 
Support for @XmlJavaTypeAdapter is already mandated in SCA-J, and JAXB
is a standard part of the JDK.  It seems very strange to me to invent
a new facility that duplicates existing capabilities that are included
in SCA-J and the JDK.  IMO this is more confusing for developers than
explaining how they can use existing capabilities to do what they need.

> The @XmlAnyElement seems like a reasonable approach for the mapping of 
> SDO to <any/>, so I can probably live with it for those use cases that 
> require <any/>. Are there any other JAXB annotations that would have to 
> appear in the Java class in order to make this work?
> 
No other annotations are needed.

   Simon

> Dave Booz
> STSM, BPM and SCA Architecture
> Co-Chair OASIS SCA-Policy TC and SCA-J TC
> "Distributed objects first, then world hunger"
> Poughkeepsie, NY (845)-435-6093 or 8-295-6093
> e-mail:booz@us.ibm.com
> 
> Inactive hide details for Simon Nash ---09/05/2009 07:46:03 AM---On 
> Friday's call I took an action to see whether JAXB annotatiSimon Nash 
> ---09/05/2009 07:46:03 AM---On Friday's call I took an action to see 
> whether JAXB annotations can be used to override the defaul
> 
> 
> From:	
> Simon Nash <oasis@cjnash.com>
> 
> To:	
> sca-j@lists.oasis-open.org
> 
> Date:	
> 09/05/2009 07:46 AM
> 
> Subject:	
> Re: [sca-j] ISSUE-179: Need type support for @Property when used with SDO
> 
> ------------------------------------------------------------------------
> 
> 
> 
> On Friday's call I took an action to see whether JAXB annotations can be
> used to override the default JAXB mapping from a Java property type
> to a schema type.
> 
> The answer is that this can be done with the @XmlJavaTypeAdapter annotation.
> If there is a property whose Java type is the interface DataObject and it
> needs to be mapped to a specific schema type such as "address", the 
> following
> steps are needed:
>  1. Create an xsd file for the "address" schema type.
>  2. Generate a Java class Address from this xsd file using JAXB.
>  3. Create a JAXB adapter class to specify the property mapping, for 
> example:
>      public class AddressAdapter extends XmlAdapter<Address, DataObject> {
>        public DataObject unmarshal(Address value) {
>          // If the SCA runtime will use the JAXB unmarshaller to convert
>          // the property value to a Java object, this method needs to
>          // contain code to create an instance of DataObject from an Address
>          // object passed in by the JAXB unmarshaller. If the property
>          // conversion will be done in some other way (e.g., by SDO), this
>          // method can just return null.
>        }
>        public Address marshal(DataObject value) {
>          return null; // SCA properties are never converted from Java to XML
>        }
>      }
>  4. Annotate the property whose Java type is DataObject with the
>     annotation @XmlJavaTypeAdapter(AddressAdapter.class)
> A separate adapter class is required for every schema type that is a 
> possible
> mapping target for the property.
> 
> If the property needs to be mapped to a specific schema element instead of
> a schema type, the steps are the same except that an "address" schema 
> element
> is used in step 1, and an additional annotation @XmlElement(name="address")
> is used on the property in step 4.
> 
> If the property needs to be mapped to a schema <any> element, steps 1, 2 and
> 3 are not needed.  In step 4, the annotation @XmlAnyElement is used on the
> property instead of @XmlJavaTypeAdapter.
> 
> I have verified all of the above with some simple test code.
> 
>   Simon
> 
> David Booz wrote:
>  > http://www.osoa.org/jira/browse/JAVA-179
>  >
>  > Dave Booz
>  > STSM, BPM and SCA Architecture
>  > Co-Chair OASIS SCA-Policy TC and SCA-J TC
>  > "Distributed objects first, then world hunger"
>  > Poughkeepsie, NY (845)-435-6093 or 8-295-6093
>  > e-mail:booz@us.ibm.com
>  >
>  > Inactive hide details for David Booz---08/24/2009 04:16:58 PM---TARGET:
>  > Java CAA CD03 and Java POJO CD01 DESCRIPTION:David Booz---08/24/2009
>  > 04:16:58 PM---TARGET: Java CAA CD03 and Java POJO CD01 DESCRIPTION:
>  >
>  >
>  > From:
>  > David Booz/Poughkeepsie/IBM@IBMUS
>  >
>  > To:
>  > sca-j@lists.oasis-open.org
>  >
>  > Date:
>  > 08/24/2009 04:16 PM
>  >
>  > Subject:
>  > [sca-j] NEW ISSUE: Need type support for @Property when used with SDO
>  >
>  > ------------------------------------------------------------------------
>  >
>  >
>  >
>  > TARGET: Java CAA CD03 and Java POJO CD01
>  >
>  > DESCRIPTION:
>  > SDO DataObject can be mapped to any XML schema type, and therefore
>  > literally <any> as well. There is no way to specify the concrete XML
>  > type of a Java property who's Java type is SDO DataObject.
>  >
>  > PROPOSAL:
>  > Will be attached to JIRA once the issue is logged.
>  > Basically, the proposal will introduce two new attributes on @Property,
>  > xmlType (for specifying the XML schema type) and xmlElement (for
>  > specifying an XML global element that denotes the type). The new
>  > attributes are mutually exclusive.
>  >
>  >
>  > Dave Booz
>  > STSM, BPM and SCA Architecture
>  > Co-Chair OASIS SCA-Policy TC and SCA-J TC
>  > "Distributed objects first, then world hunger"
>  > Poughkeepsie, NY (845)-435-6093 or 8-295-6093
>  > e-mail:booz@us.ibm.com
>  >
> 
> 
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