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Subject: Re: [sca-assembly] NEW ISSUE (v1.2): Remotable interface compatibilityshould not be restricted to a WSDL 1.1 mapping


FWIW, The Assembly spec could be enhanced considerably WRT parameter type
compatibility even when XML Schema is used in both interface definitions.
I'd suggest we focus on type compatibility use cases.

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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  |Eric Johnson <eric@tibco.com>                                                                                                                     |
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  |Bryan Aupperle/Raleigh/IBM@IBMUS                                                                                                                  |
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  |OASIS SCA Assembly <sca-assembly@lists.oasis-open.org>                                                                                            |
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  |07/16/2010 05:58 PM                                                                                                                               |
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  |Re: [sca-assembly] NEW ISSUE (v1.2): Remotable interface compatibility should not be restricted to a WSDL 1.1 mapping                             |
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Hi Bryan,

Yes, thanks for throwing that information into the mix.

I note, from the current CD05 rev1 draft, lines 2787, 2788:
"An interface is defined in terms of a WSDL 1.1 portType with the arguments
and return of the service operations described using XML schema."  (Hmmm,
that "s" in "schema" should be capitalized - editorial nit.)

While this statement does not appear to influence any normative
constraints, it certainly aligns with the expectations that everyone brings
to bear on WSDL 1.1.

If you allow for the notion that WSDL 1.1 with alternate type systems
aligns with SCA Assembly's remotable concept, then we *definitely* need
more text around how type systems should be determined to be compatible.
In a sense, you're just "squeezing the balloon", in that the problem pops
up in a different place, but has exactly the same implications.

Should we change the issue in question to be:
"Remotable interface compatibility should not be restricted to a WSDL 1.1
mapping, nor should it be restricted to WSDL 1.1 using XML Schema."

... or maybe that's two issues?

-Eric.

P.S. http://www.w3.org/TR/wsdl20-altschemalangs/

On 07/16/2010 10:57 AM, Bryan Aupperle wrote:
      I realize that we have not opened this issue yet. but I recognize the
      validity of allowing transport representations other than XML
      documents.

      Having said that, there seems to be an assumption here that WSDL 1.1
      requires a XML 1.0 data format and the use of the XSD type system.
      This is not correct.  WSDL 1.1 explicitly allows for other type
      systems and also notes that the XSD type system can be used even if
      the data format is not XML 1.0.  I am not sure if the WS-I Basic
      profiles require either the use of the XSD type system or an XML 1.0
      data format, but I do not believe that the Assembly spec currently
      says anything about WSI-Basic Profile compliance.

      An excellent view of how a view of the XSD type system can be used
      with other data formats is defined in the Data Format Description
      Language (DFDL) specification (being defined by an Open Grid Forum WG
      - http://forge.gridforum.org/projects/dfdl-wg/)   The public review
      draft is here:
      http://www.ogf.org/Public_Comment_Docs/Documents/2010-03/draft-gwdrp-dfdl-core-v1.0.pdf
        DFDL allows data to be mapped between native formats (binary,
      textual) and information sets – and thus XML.  The information set is
      described using XSDL types and annotated constructs. The data can
      contain any character in ISO 10646, including those not legal in XML
      documents. In addition to facet validation, assertions can be added
      to test data during parsing. Allows data from native representation
      to be excluded from the information set, information set values to be
      calculated on parse and native representation data to be calculated
      on generation.

      I am not positive that DFDL will cover all of the use cases Eric
      notes, but it would appear that:
      1) A number of the are currently possible
      2) The assembly spec could be clearer and more robust in the
      treatment of this topic.

      Bryan Aupperle, Ph.D.
      STSM, WebSphere Enterprise Platform Software Solution Architect
      WW Center of Excellence for Enterprise Systems & Banking Center of
      Excellence Application Integration Architect

      Research Triangle Park,  NC
      +1 919-254-7508 (T/L 444-7508)
      Internet Address: aupperle@us.ibm.com

                                                                           
 From: Mike Edwards <mike_edwards@uk.ibm.com>                              
                                                                           
                                                                           
 To:   OASIS SCA Assembly <sca-assembly@lists.oasis-open.org>              
                                                                           
 Date: 06/29/2010 05:14 AM                                                 
                                                                           
                                                                           
 Subje Re: [sca-assembly] NEW ISSUE (v1.2): Remotable interface            
 ct:   compatibility should not be restricted to a WSDL 1.1 mapping        
                                                                           







      Logged as: http://www.osoa.org/jira/browse/ASSEMBLY-235

      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
                                                                           
 From: Eric Johnson <eric@tibco.com>                                       
                                                                           
                                                                           
 To:   OASIS SCA Assembly <sca-assembly@lists.oasis-open.org>              
                                                                           
 Date: 28/06/2010 18:56                                                    
                                                                           
                                                                           
 Subje [sca-assembly] NEW ISSUE (v1.2): Remotable interface compatibility  
 ct:   should not be restricted to a WSDL 1.1 mapping                      
                                                                           







      Target: sca-assembly-1.2-spec-wd01.doc

      Title: Remotable interface compatibility should not be restricted to
      a WSDL 1.1 mapping

      Description:

      The latest version of the Assembly specification
      (sca-assembly-1.1-spec-cd05), in section 6.2, defines interface
      compatibility in section 6.2.1, item #6 "for checking the
      compatibility of 2 remotable interfaces which are in different
      interface languages, both are mapped to WSDL 1.1 (if not already WSDL
      1.1) and compatibility checking is done between the WSDL 1.1 mapped
      interfaces."

      There are various reasons why this will fall over and not behave as
      expected.

      False positives:
            Some other interface kind may impose data type semantic
            restrictions which are not apparent in a WSDL 1.1
            representation.  WSDL 1.1 uses XML Schema 1.0 types for its
            representation of data.  Unfortunately, there are limitations
            here, where XML Schema largely focuses on the syntactic
            representation, and not as much on the semantic values.  Some
            random examples:
                  all odd numbers/all even numbers
                  string validation via regular expressions, where some
                  semantic is required on a portion of the string.  Example
                  - credit card numbers
                  string contents - XML Schema "string" type allows for a
                  subset of all possible characters.  This means that
                  certain characters cannot be represented in XML Schema
                  representations, and must be somehow mapped.
            Object networks - representing a network of objects serialized
            to XML, certain objects should be serialized at most once, and
            then referenced.  Creating and enforcing the linking of
            representations is at best an imperfect alignment, as there are
            numerous ways that this can be accomplished, depending on the
            type of the object network.  Unfortunately, something
            conforming to the XML Schema requirements could easily not
            align on the semantic requirements, either in generating a
            request, or receiving a response.
      False negatives:
            Intrinsic to mapping to WSDL are choices about how that mapping
            might be done.  For example, implementations might map JMX to
            WSDL in myriad ways.  Forcing the consumer and provider to do
            so in a way that offers up a WSDL 1.1 mapping as part of the
            component type could lead to a declaration of "incompatible"
            even where the JMX interfaces are, in fact compatible (albeit,
            at runtime, the implementation of the JMX conduit must be
            shared)
            Bad compromises - certain existing bindings (binding.jms) allow
            for possibility of sending Java Objects via JMS.  To not be
            able to call these bindings remotable is a mockery of the
            notion of "remote", however, forcing a mapping of a generic
            Java Object to some XML representation will have "binding"
            trade-offs.  Implementers will then have to invest time to
            "maximize compatibility", whereas if they simply used existing
            interfaces compatiblity would simply be there.
      (Partial) Proposal:

      Remoting compatibility should not be restricted to WSDL 1.1 mappings.
      Interface type definitions ought to be allowed to at least define a
      compatible relationship with themselves.

      -Eric.







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