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Subject: Re: [sca-assembly] [ASSEMBLY-195] import and export of the same namespacefor some testcases - PROPOSAL
Jim, Why do you assume that: 1. References to X from artifacts in B will resolve to the version of X contained in C 2. References to X from artifacts in A will resolve to the version of X contained in B is a problem or is somehow an invalid or incorrect behavior for XML artifacts? Are you asking for additional functionality that would enable the OSGI uses behavior when desired or necessary (similar to what we have in the SCA-J specs)? 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 |------------> | From: | |------------> >--------------------------------------------------------------------------------------------------------------------------------------------------| |Jim Marino <jim.marino@gmail.com> | >--------------------------------------------------------------------------------------------------------------------------------------------------| |------------> | To: | |------------> >--------------------------------------------------------------------------------------------------------------------------------------------------| |OASIS Assembly <sca-assembly@lists.oasis-open.org> | >--------------------------------------------------------------------------------------------------------------------------------------------------| |------------> | Date: | |------------> >--------------------------------------------------------------------------------------------------------------------------------------------------| |03/18/2010 12:38 PM | >--------------------------------------------------------------------------------------------------------------------------------------------------| |------------> | Subject: | |------------> >--------------------------------------------------------------------------------------------------------------------------------------------------| |Re: [sca-assembly] [ASSEMBLY-195] import and export of the same namespace for some testcases - PROPOSAL | >--------------------------------------------------------------------------------------------------------------------------------------------------| Comments inline. On Mar 11, 2010, at 4:36 PM, Mike Edwards wrote: Folks, I propose that ASSEMBLY-195 is Closed with No Action ASSEMBLY 195 is concerned about testcase contributions which both import and export the same namespace. The claim is made that this behaviour is not explicitly defined in the Assembly specification and that it could lead to cyclic dependencies that would cause an error. However, I think that the Assembly specification is very clear about the meaning of import and export statements in Section 10.2.1 and there is a specific normative statement - ASM12023 - that indicates that any resolution of an artifact through an import statement must only be a one-deep search and that searches do not recurse through multiple levels of Contributions. As a result, cyclic dependencies of the kind mentioned in this issue are not possible. The claim that there needs to be a definition of an import/export pair in the Assembly spec is also unnecessary, since its meaning is well defined by ASM12023, with no ambiguity. To be precise, the claim is that the Assembly spec is unclear about what the runtime should do in this situation, not that it will lead to cyclic dependencies. After rereading the paragraph cited, I still do not think ASM12023 is clear on the appropriate behavior. As I mentioned in a previous post, consider the following: Contribution A ---(resolve {urn:foo}bar) ---> Contribution B ---(resolve {urn:foo}bar) ---> Contribution C ---(resolve {urn:foo}bar) ---> Contribution C Assuming contributions B and C both contain an artifact X in {urn:foo:bar} and Contribution B imports and exports (resolve {urn:foo}bar), the following may result: 1. References to X from artifacts in B will resolve to the version of X contained in C 2. References to X from artifacts in A will resolve to the version of X contained in B Note that this behavior is different than OSGi and there are directives in the former that can be used to avoid this from happening. At a minimum, I think this needs to be clarified in the assembly spec as users will invariably encounter this. Import/export of the same namespace is valuable in some situations but it needs specification. Another way to look at this is: what normative statement is import/export of the same namespace testing? Jim 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 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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