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Minutes for OGF DFDL Working Group Call, August 25-2010
by Alan Powell 26 Aug '10

26 Aug '10

Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, August 25-2010 Attendees Alan Powell (IBM) Suman Kalia (IBM) Tim Kimber(IBM) Bob McGrath (National Center for Supercomputing Applications) Alejandro Rodriguez (National Center for Supercomputing Applications) Apologies Mike Beckerle (Oco) Stephanie Fetzer (IBM) Steve Hanson (IBM) 1. Current Actions Updated Below 2. Regular Expressions. The DFDL regular expressions should provide lookahead and backreferences. Is the current regular expression language sufficient? Discussed two aspects: a. Is the XML regular expression language the correct one to use. Tim asked if DFDL needs to specify an language at all and should leave it to implementers to pick one. That would inhibit portability of schema. b. A regular expression property on an assert/discriminator as an alternative to the test expression. Either a DFDL expression or a regular expression could be specified but not both. 3. OGF 30 OGF30 takes place on October 25-29 in Brussels Should we have a WG session? Meeting closed, 16:30 Next call Wednesday 1 September 2010 15:00 UK (10:00 ET) Next action: 115 Actions raised at this meeting No Action 112 DFDL certification process 113 2. Regular Expressions. The DFDL regular expressions should provide lookahead and backreferences. Is the current regular expression language sufficient? Discussed two aspects: a. Is the XML regular expression language the correct one to use. Tim asked if DFDL needs to specify an language at all and should leave it to implementers to pick one. That would inhibit portability of schema. b. A regular expression property on an assert/discriminator as an alternative to the test expression. Either a DFDL expression or a regular expression could be specified but not both. 114 3. OGF 30 OGF30 takes place on October 25-29 in Brussels Should we have a WG session? Current Actions: No Action 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. 21/04. Schema for TDML defined. Need to define how this and the test cases will be made public 05/05: Work still progressing 12/05: Work still progressing 02/06: Work still progressing on technical and legal considerations ... 25/08: Will chase to allow Daffodil access to test cases. The WG should define how implementation confirm that they 'conform to DFDL v1' 085 ALL: publicise Public comments phase to ensure a good review.. 14/04: see minutes 21/04: Press release, OMG and other standards bodies. 05/05: Alan and Steve H have contacted other standards bodies. Will ask them to add comments on spec 15/05: still no public comments 02/06: No public comments 16/06: Public comments period has ended with no external comments. Alan had posted changes made in draft 041. Steve suggested send a note to the WG highlighting these changes. Steve also suggested requesting an extension as other IBM groups may review. We discussed whether this was necessary as changes will need to be made during the implementation phase anyway. Alan to ask OGF what the process is for changes post public comment. 23/06: Still no comments. Alan will contact OGF to understand the rest of the process. 30/06: Alan has emailed Joel asking what the process is now public comment period is over and can we update the published version with WG updates. No response yet. 07/07: No response. Alan will chase up 14/07: No response from Joel. Sent email to Greg Newby by no response. 21/07: Still no response. 04/08: Joel has responded that it is up to the WG to decide if the changes are significant enough to need additional review. Alan to contact David Martin and Erwin Laure for guidance if we split the specification. 11/08: Received a response from Joel that the WG can decide if a re- public review is necessary before becoming a 'proposed recommendation'. Alan responded that the WG agreed that a re-review was not necessary. The next stage is for OGF review committee to approve publication. 11/08: Specification is now 'awaiting author changes' before being submitted to the OGF technical committee for approval as a 'proposed specification'. Alan would like to have the updated specification complete by Sept 10th. The WG needs to complete all actions by then or decide that they do not need to be included in this phase of the process. 099 Splitting the specification in simpler sections. 07/07: Steve sent a proposal but not discussed. Alan will arrange a separate call. 14/07:Discussed Steve's proposal and Suman's and Alan's comments. Need to add choice, validation, facets. Also how does an implementation declare which subsets it supports. Suggested levels and/or profiles. Steve highlighted a problem when a DFDL schema from an implementation of just the core functions was moved to a full DFDL implementation what should happen about the missing properties. Does the full implementation need to be aware of subsets of functions? Should it raise a schema definition error for use of a function not in the subset. 21/07: no progress 04/08: Steve had updated proposed groups of function. (Subset_proposal_v2.ppt). We discussed whether its is better to have discrete sets of functions or expanding levels of function. Purpose of subsetting is: 1. Allow simpler implementations. (main purpose) 2. Simplify tooling 3. Simplify specification. Steve to contact previous members of WG to check if we have the correct subsets 11/08: Steve sent an email to previous members of the WG asking for opinions on splitting the specification. Bob McGrath from National Center For Supercomputing responded that they had implemented about 80% of the function. Alejandro will send a description of the function they have implemented. Action will be raised to track the Daffodil implementation 11/08: not discussed 101 Semantics of 'fixed' 21/07: Discussed whether not matching the 'fixed' value should be a validation error or processing error. Decided that for consistency it should be a validation error. It would be useful however to avoid having to duplication of facet information in an assert which could become unwieldy for, say, a large enumeration. Suggestions - a parser option that 'converted all validation errors to processing errors' - a dfdl expression function that 'applied all facets' or 'applied specific facet' to a particular element. Stephanie will produce some examples of how this could be used.. 04/08: Stephanie had produced examples but they were not discussed due to lack of time 11/08: We started to discuss Stephanie's HIPPA example but ran out of time. 25/08: Not discussed 107 teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. 04/08: Not discussed 11/08: Not discussed 25/08: Not discussed 108 dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. 04/08: A lively discussion. The specification is works as currently defined so whether changes need to be made to make tooling easier. There shouldn't be 'conventions' in particular tooling as they must be able to properly deal with schema from other tools that would not obey those conventions. Steve stated that it is often dangerous to hide too much from users when they can see they underlying schema. To be continued. 25/08: there has been some offline discussions about simplifying how hidden elements are implemented. The proposal is dfdl:hidden property on xs:element only xs:minOccurs and xs:maxOccurs MUST be 0 when hidden dfdl:minOccurs and dfdl:maxOccurs for hidden elements only. An element is 'required' when dfdl:minOccurs >0 and normal default processing occurs. The schema, without dfdl annotations, must match the infoset so assumption is that non-DFDL tools, such as mappers, will ignore/not show elements with xs:minOccurs and xs:maxOccurs = '0' 109 dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. 04/08: not discussed. 11/08: Not discussed 25/08: Not discussed 110 Semantics of newVariableInstance and setVariable what should a DFDL processor ( parser or serializer ) do when it cannot evaluate the expression in a newVariableInstance or setVariable annotation? Moving the setting of variable values after the element has been parsed just creates other problems A new instance must be available to other expressions on the same component, and to the children of a group/element. So it cannot be left until the end of the element. On the other hand, there are clearly some types of setVariable / newVariableInstance annotations which *cannot* be evaluated until the element has been parsed. For the parser, it might be OK to - evaluate the expression when the component ( element or group ) is started - if it cannot be evaluated, add it to a list of annotations that must be processed at the end of the component - if in the mean time any other expressions attempt to access the variable that was being set/created then throw a processing error ( because the result will be undefined ). This will probably require the variable/instance to be placed into a 'not available' state until its expression is resolvable 25/08: There was a brief discussion as IBM needs a resolution soon. Is it possible to restrict newVariableInstance to backward references only so remove the problem? setVariable must obviously be able to access the current value. 111 Daffodil DFDL parser Bob and Alejandro described the new implementation that they have developed. It is a new code base and is not based on the Deffudle prototype. It is written in scala and implements approximately 80% of the features in the public comments draft of DFDL V1. Alejandro will send a list of the features not implemented. We discussed the scenarios that motivated the development which was to extract data from various sources and transform into canonical formats. Bob offered to make Daffodil available for the WG to assess the functionality. IBM WG members will get approval the company to allow them to receive Daffodil. Bob raised the question that if Daffodil becomes the public implementation of DFDL then we will need to work out how that would be funded and managed. It would be helpful if IBM test cases were available to Daffodil. IBM will investigate 25/08: Alejandro had sent a list of the functions that he has implemented and Steve ahd responding indicating the extra functions he thought were essential. Since then Alejandro has implemented some of the missing functions, such as escape schemes, pre-defined variables, binary decimal numbers, etc, and will update his list. Bob is planning to make the parser available on the internet to allow testing. His organisation is being reorganised and he doesn't know what the priority of Daffodill will be so it is essential that we move quickly. It would help if IBM could indicate its support for Daffodil in some semi-formal way. Discussed how to certify DFDL implementations. Alan to investigate if OGF have a defined process. 112 DFDL certification process 113 2. Regular Expressions. The DFDL regular expressions should provide lookahead and backreferences. Is the current regular expression language sufficient? Discussed two aspects: a. Is the XML regular expression language the correct one to use. Tim asked if DFDL needs to specify an language at all and should leave it to implementers to pick one. That would inhibit portability of schema. b. A regular expression property on an assert/discriminator as an alternative to the test expression. Either a DFDL expression or a regular expression could be specified but not both. 114 3. OGF 30 OGF30 takes place on October 25-29 in Brussels Should we have a WG session? Closed actions No Action 104 Expressions Discuss error behaviour when evaluating an expression in various contexts - All properties: wrong type returned : schema definition error exception when evaluating expression : schema definition error referenced variables/paths not available : schema definition error - Properties which allow a forward reference referenced variables/paths not available : no error. DFDL processor continues processing until the expression result is available, then acts on the result. 21/07: Steve stated the current definition that returning the incorrect type was a schema definition error and everything else was a processing error. 04/08: Not discussed 25/08: Closed Work items: No Item target version status 005 Improvements on property descriptions not started 012 Reordering the properties discussion: move representation earlier, improve flow of topics not started 036 Update dfdl schema with change properties ongoing 042 Mapping of the DFDL infoset to XDM none not required for V1 specification 070 Write DFDL primer 071 Write test cases. 083 Implement RFC2116 Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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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Agenda for OGF DFDL WG call 25 August 2010 15:00UK (10:00 ET)
by Alan Powell 24 Aug '10

24 Aug '10

1. Current Actions 2. Regular Expressions. The DFDL regular expressions should provide lookahead and backreferences. Is the current regular expression language sufficient? 3. OGF 30 OGF30 takes place on October 25-29 in Brussels Current Actions: No Action 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. 21/04. Schema for TDML defined. Need to define how this and the test cases will be made public 05/05: Work still progressing 12/05: Work still progressing 02/06: Work still progressing on technical and legal considerations ... 11/08: work continues 085 ALL: publicise Public comments phase to ensure a good review.. 14/04: see minutes 21/04: Press release, OMG and other standards bodies. 05/05: Alan and Steve H have contacted other standards bodies. Will ask them to add comments on spec 15/05: still no public comments 02/06: No public comments 16/06: Public comments period has ended with no external comments. Alan had posted changes made in draft 041. Steve suggested send a note to the WG highlighting these changes. Steve also suggested requesting an extension as other IBM groups may review. We discussed whether this was necessary as changes will need to be made during the implementation phase anyway. Alan to ask OGF what the process is for changes post public comment. 23/06: Still no comments. Alan will contact OGF to understand the rest of the process. 30/06: Alan has emailed Joel asking what the process is now public comment period is over and can we update the published version with WG updates. No response yet. 07/07: No response. Alan will chase up 14/07: No response from Joel. Sent email to Greg Newby by no response. 21/07: Still no response. 04/08: Joel has responded that it is up to the WG to decide if the changes are significant enough to need additional review. Alan to contact David Martin and Erwin Laure for guidance if we split the specification. 11/08: Received a response from Joel that the WG can decide if a re- public review is necessary before becoming a 'proposed recommendation'. Alan responded that the WG agreed that a re-review was not necessary. The next stage is for OGF review committee to approve publication. 099 Splitting the specification in simpler sections. 07/07: Steve sent a proposal but not discussed. Alan will arrange a separate call. 14/07:Discussed Steve's proposal and Suman's and Alan's comments. Need to add choice, validation, facets. Also how does an implementation declare which subsets it supports. Suggested levels and/or profiles. Steve highlighted a problem when a DFDL schema from an implementation of just the core functions was moved to a full DFDL implementation what should happen about the missing properties. Does the full implementation need to be aware of subsets of functions? Should it raise a schema definition error for use of a function not in the subset. 21/07: no progress 04/08: Steve had updated proposed groups of function. (Subset_proposal_v2.ppt). We discussed whether its is better to have discrete sets of functions or expanding levels of function. Purpose of subsetting is: 1. Allow simpler implementations. (main purpose) 2. Simplify tooling 3. Simplify specification. Steve to contact previous members of WG to check if we have the correct subsets 11/08: Steve sent an email to previous members of the WG asking for opinions on splitting the specification. Bob McGrath from National Center For Supercomputing responded that they had implemented about 80% of the function. Alejandro will send a description of the function they have implemented. Action will be raised to track the Daffodil implementation 101 Semantics of 'fixed' 21/07: Discussed whether not matching the 'fixed' value should be a validation error or processing error. Decided that for consistency it should be a validation error. It would be useful however to avoid having to duplication of facet information in an assert which could become unwieldy for, say, a large enumeration. Suggestions - a parser option that 'converted all validation errors to processing errors' - a dfdl expression function that 'applied all facets' or 'applied specific facet' to a particular element. Stephanie will produce some examples of how this could be used.. 04/08: Stephanie had produced examples but they were not discussed due to lack of time 11/08: We started to discuss Stephanie's HIPPA example but ran out of time. 104 Expressions Discuss error behaviour when evaluating an expression in various contexts - All properties: wrong type returned : schema definition error exception when evaluating expression : schema definition error referenced variables/paths not available : schema definition error - Properties which allow a forward reference referenced variables/paths not available : no error. DFDL processor continues processing until the expression result is available, then acts on the result. 21/07: Steve stated the current definition that returning the incorrect type was a schema definition error and everything else was a processing error. 04/08: Not discussed 11/08: Not discussed 107 teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. 04/08: Not discussed 11/08: Not discussed 108 dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. 04/08: A lively discussion. The specification is works as currently defined so whether changes need to be made to make tooling easier. There shouldn't be 'conventions' in particular tooling as they must be able to properly deal with schema from other tools that would not obey those conventions. Steve stated that it is often dangerous to hide too much from users when they can see they underlying schema. To be continued. 109 dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. 04/08: not discussed. 11/08: Not discussed 110 Semantics of newVariableInstance and setVariable what should a DFDL processor ( parser or serializer ) do when it cannot evaluate the expression in a newVariableInstance or setVariable annotation? Moving the setting of variable values after the element has been parsed just creates other problems A new instance must be available to other expressions on the same component, and to the children of a group/element. So it cannot be left until the end of the element. On the other hand, there are clearly some types of setVariable / newVariableInstance annotations which *cannot* be evaluated until the element has been parsed. For the parser, it might be OK to - evaluate the expression when the component ( element or group ) is started - if it cannot be evaluated, add it to a list of annotations that must be processed at the end of the component - if in the mean time any other expressions attempt to access the variable that was being set/created then throw a processing error ( because the result will be undefined ). This will probably require the variable/instance to be placed into a 'not available' state until its expression is resolvable 111 Daffodil DFDL parser Bob and Alejandro described the new implementation that they have developed. It is a new code base and is not based on the Deffudle prototype. It is written in scala and implements aproximately 80% of the features in the public comments draft of DFDL V1. Alejandro will send a list of the features not implemented. We discussed the scenarios that motivated the development which was to extract data from various soucres and transform into canonical formats. Bob offered to make Daffodil available for the WG to assess the functionality. IBM WG members will get approval the company to allow them to receive Daffodil. Bob raised the question that if Daffodil becomes the public implementation of DFDL then we will need to work out how that would be funded and managed. It would be helpful if IBM test cases were available to Daffodil. IBM will investigate Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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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Minute for OGF DFDL Working Group Call, August 11-2010
by Alan Powell 12 Aug '10

12 Aug '10

Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, August 11-2010 Attendees Steve Hanson (IBM) Alan Powell (IBM) Stephanie Fetzer (IBM) Tim Kimber(IBM) Bob McGrath (National Center for Supercomputing Applications) Alejandro Rodriguez (National Center for Supercomputing Applications) Apologies Mike Beckerle (Oco) Suman Kalia (IBM) 1. Current Actions Updated Below 2 Semantics of newVariableInstance and setVariable what should a DFDL processor ( parser or serializer ) do when it cannot evaluate the expression in a newVariableInstance or setVariable annotation? Moving the setting of variable values after the element has been parsed just creates other problems A new instance must be available to other expressions on the same component, and to the children of a group/element. So it cannot be left until the end of the element. On the other hand, there are clearly some types of setVariable / newVariableInstance annotations which *cannot* be evaluated until the element has been parsed. For the parser, it might be OK to - evaluate the expression when the component ( element or group ) is started - if it cannot be evaluated, add it to a list of annotations that must be processed at the end of the component - if in the mean time any other expressions attempt to access the variable that was being set/created then throw a processing error ( because the result will be undefined ). This will probably require the variable/instance to be placed into a 'not available' state until its expression is resolvable 11/08: Not discussed. Action raised 3 Daffodil DFDL parser implementation at National Center for Supercomputing Applications Bob and Alejandro described the new implementation that they have developed. It is a new code base and is not based on the Deffudle prototype. It is written in scala and implements aproximately 80% of the features in the public comments draft of DFDL V1. Alejandro will send a list of the features not implemented. We discussed the scenarios that motivated the development which was to extract data from various soucres and transform into canonical formats. Bob offered to make Daffodil available for the WG to assess the functionality. IBM WG members will get approval the company to allow them to receive Daffodil. Bob raised the question that if Daffodil becomes the public implementation of DFDL then we will need to work out how that would be funded and managed. It would be helpful if IBM test cases were available to Daffodil. IBM will investigate Meeting closed, 16:30 Next call Wednesday 25 August 2010 15:00 UK (10:00 ET) Next action: 112 Actions raised at this meeting No Action 110 Semantics of newVariableInstance and setVariable what should a DFDL processor ( parser or serializer ) do when it cannot evaluate the expression in a newVariableInstance or setVariable annotation? Moving the setting of variable values after the element has been parsed just creates other problems A new instance must be available to other expressions on the same component, and to the children of a group/element. So it cannot be left until the end of the element. On the other hand, there are clearly some types of setVariable / newVariableInstance annotations which *cannot* be evaluated until the element has been parsed. For the parser, it might be OK to - evaluate the expression when the component ( element or group ) is started - if it cannot be evaluated, add it to a list of annotations that must be processed at the end of the component - if in the mean time any other expressions attempt to access the variable that was being set/created then throw a processing error ( because the result will be undefined ). This will probably require the variable/instance to be placed into a 'not available' state until its expression is resolvable 111 Daffodil DFDL parser Bob and Alejandro described the new implementation that they have developed. It is a new code base and is not based on the Deffudle prototype. It is written in scala and implements aproximately 80% of the features in the public comments draft of DFDL V1. Alejandro will send a list of the features not implemented. We discussed the scenarios that motivated the development which was to extract data from various soucres and transform into canonical formats. Bob offered to make Daffodil available for the WG to assess the functionality. IBM WG members will get approval the company to allow them to receive Daffodil. Bob raised the question that if Daffodil becomes the public implementation of DFDL then we will need to work out how that would be funded and managed. It would be helpful if IBM test cases were available to Daffodil. IBM will investigate Current Actions: No Action 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. 21/04. Schema for TDML defined. Need to define how this and the test cases will be made public 05/05: Work still progressing 12/05: Work still progressing 02/06: Work still progressing on technical and legal considerations ... 11/08: work continues 085 ALL: publicise Public comments phase to ensure a good review.. 14/04: see minutes 21/04: Press release, OMG and other standards bodies. 05/05: Alan and Steve H have contacted other standards bodies. Will ask them to add comments on spec 15/05: still no public comments 02/06: No public comments 16/06: Public comments period has ended with no external comments. Alan had posted changes made in draft 041. Steve suggested send a note to the WG highlighting these changes. Steve also suggested requesting an extension as other IBM groups may review. We discussed whether this was necessary as changes will need to be made during the implementation phase anyway. Alan to ask OGF what the process is for changes post public comment. 23/06: Still no comments. Alan will contact OGF to understand the rest of the process. 30/06: Alan has emailed Joel asking what the process is now public comment period is over and can we update the published version with WG updates. No response yet. 07/07: No response. Alan will chase up 14/07: No response from Joel. Sent email to Greg Newby by no response. 21/07: Still no response. 04/08: Joel has responded that it is up to the WG to decide if the changes are significant enough to need additional review. Alan to contact David Martin and Erwin Laure for guidance if we split the specification. 11/08: Received a response from Joel that the WG can decide if a re- public review is necessary before becoming a 'proposed recommendation'. Alan responded that the WG agreed that a re-review was not necessary. The next stage is for OGF review committee to approve publication. 099 Splitting the specification in simpler sections. 07/07: Steve sent a proposal but not discussed. Alan will arrange a separate call. 14/07:Discussed Steve's proposal and Suman's and Alan's comments. Need to add choice, validation, facets. Also how does an implementation declare which subsets it supports. Suggested levels and/or profiles. Steve highlighted a problem when a DFDL schema from an implementation of just the core functions was moved to a full DFDL implementation what should happen about the missing properties. Does the full implementation need to be aware of subsets of functions? Should it raise a schema definition error for use of a function not in the subset. 21/07: no progress 04/08: Steve had updated proposed groups of function. (Subset_proposal_v2.ppt). We discussed whether its is better to have discrete sets of functions or expanding levels of function. Purpose of subsetting is: 1. Allow simpler implementations. (main purpose) 2. Simplify tooling 3. Simplify specification. Steve to contact previous members of WG to check if we have the correct subsets 11/08: Steve sent an email to previous members of the WG asking for opinions on splitting the specification. Bob McGrath from National Center For Supercomputing responded that they had implemented about 80% of the function. Alejandro will send a description of the function they have implemented. Action will be raised to track the Daffodil implementation 101 Semantics of 'fixed' 21/07: Discussed whether not matching the 'fixed' value should be a validation error or processing error. Decided that for consistency it should be a validation error. It would be useful however to avoid having to duplication of facet information in an assert which could become unwieldy for, say, a large enumeration. Suggestions - a parser option that 'converted all validation errors to processing errors' - a dfdl expression function that 'applied all facets' or 'applied specific facet' to a particular element. Stephanie will produce some examples of how this could be used.. 04/08: Stephanie had produced examples but they were not discussed due to lack of time 11/08: We started to discuss Stephanie's HIPPA example but ran out of time. 104 Expressions Discuss error behaviour when evaluating an expression in various contexts - All properties: wrong type returned : schema definition error exception when evaluating expression : schema definition error referenced variables/paths not available : schema definition error - Properties which allow a forward reference referenced variables/paths not available : no error. DFDL processor continues processing until the expression result is available, then acts on the result. 21/07: Steve stated the current definition that returning the incorrect type was a schema definition error and everything else was a processing error. 04/08: Not discussed 11/08: Not discussed 107 teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. 04/08: Not discussed 11/08: Not discussed 108 dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. 04/08: A lively discussion. The specification is works as currently defined so whether changes need to be made to make tooling easier. There shouldn't be 'conventions' in particular tooling as they must be able to properly deal with schema from other tools that would not obey those conventions. Steve stated that it is often dangerous to hide too much from users when they can see they underlying schema. To be continued. 109 dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. 04/08: not discussed. 11/08: Not discussed 110 Semantics of newVariableInstance and setVariable what should a DFDL processor ( parser or serializer ) do when it cannot evaluate the expression in a newVariableInstance or setVariable annotation? Moving the setting of variable values after the element has been parsed just creates other problems A new instance must be available to other expressions on the same component, and to the children of a group/element. So it cannot be left until the end of the element. On the other hand, there are clearly some types of setVariable / newVariableInstance annotations which *cannot* be evaluated until the element has been parsed. For the parser, it might be OK to - evaluate the expression when the component ( element or group ) is started - if it cannot be evaluated, add it to a list of annotations that must be processed at the end of the component - if in the mean time any other expressions attempt to access the variable that was being set/created then throw a processing error ( because the result will be undefined ). This will probably require the variable/instance to be placed into a 'not available' state until its expression is resolvable 111 Daffodil DFDL parser Bob and Alejandro described the new implementation that they have developed. It is a new code base and is not based on the Deffudle prototype. It is written in scala and implements aproximately 80% of the features in the public comments draft of DFDL V1. Alejandro will send a list of the features not implemented. We discussed the scenarios that motivated the development which was to extract data from various soucres and transform into canonical formats. Bob offered to make Daffodil available for the WG to assess the functionality. IBM WG members will get approval the company to allow them to receive Daffodil. Bob raised the question that if Daffodil becomes the public implementation of DFDL then we will need to work out how that would be funded and managed. It would be helpful if IBM test cases were available to Daffodil. IBM will investigate Closed actions No Action Work items: No Item target version status 005 Improvements on property descriptions not started 012 Reordering the properties discussion: move representation earlier, improve flow of topics not started 036 Update dfdl schema with change properties ongoing 042 Mapping of the DFDL infoset to XDM none not required for V1 specification 070 Write DFDL primer 071 Write test cases. 083 Implement RFC2116 Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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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Cancelled: OGF DFDL Working Group weekly call
by Steve Hanson 12 Aug '10

12 Aug '10

Alan and Steve both away

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Agenda for OGF DFDL WG call 11 August 2010 15:00UK (10:00 ET)
by Alan Powell 10 Aug '10

10 Aug '10

1. Current Actions 2 Semantics of newVariableInstance and setVariable what should a DFDL processor ( parser or serializer ) do when it cannot evaluate the expression in a newVariableInstance or setVariable annotation? Moving the setting of variable values into the END_ELEMENT state just creates other problems A new instance must be available to other expressions on the same component, and to the children of a group/element. So it cannot be left until the end of the element. On the other hand, there are clearly some types of setVariable / newVariableInstance annotations which *cannot* be evaluated until the END_ELEMENT state. For the parser, it might be OK to - evaluate the expression when the component ( element or group ) is started - if it cannot be evaluated, add it to a list of annotations that must be processed at the end of the component - if in the mean time any other expressions attempt to access the variable that was being set/created then throw a processing error ( because the result will be undefined ). This will probably require the variable/instance to be placed into a 'not available' state until its expression is resolvable Current Actions: No Action 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. 21/04. Schema for TDML defined. Need to define how this and the test cases will be made public 05/05: Work still progressing 12/05: Work still progressing 02/06: Work still progressing on technical and legal considerations ... 21/07: work continues 04/08: work continues 085 ALL: publicize Public comments phase to ensure a good review.. 14/04: see minutes 21/04: Press release, OMG and other standards bodies. 05/05: Alan and Steve H have contacted other standards bodies. Will ask them to add comments on spec 15/05: still no public comments 02/06: No public comments 16/06: Public comments period has ended with no external comments. Alan had posted changes made in draft 041. Steve suggested send a note to the WG highlighting these changes. Steve also suggested requesting an extension as other IBM groups may review. We discussed whether this was necessary as changes will need to be made during the implementation phase anyway. Alan to ask OGF what the process is for changes post public comment. 23/06: Still no comments. Alan will contact OGF to understand the rest of the process. 30/06: Alan has emailed Joel asking what the process is now public comment period is over andcan we update the published version with WG updates. No response yet. 07/07: No response. Alan will chase up 14/07: No response from Joel. Sent email to Greg Newby by no response. 21/07: Still no response. 04/08: Joel has responded that it is up to the WG to decide if the changes are significant enough to need additional review. Alan to contact David Martin and Erwin Laure for guidance if we split the specification. 099 Splitting the specification in simpler sections. 07/07: Steve sent a proposal but not discussed. Alan will arrange a separate call. 14/07:Discussed Steve's proposal and Suman's and Alan's comments. Need to add choice, validation, facets. Also how does an implementation declare which subsets it supports. Suggested levels and/or profiles. Steve highlighted a problem when a DFDL schema from an implementation of just the core functions was moved to a full DFDL implementation what should happen about the missing properties. Does the full implementation need to be aware of subsets of functions? Should it raise a schema definition error for use of a function not in the subset. 21/07: no progress 04/08: Steve had updated proposed groups of function. (Subset_proposal_v2.ppt). We discussed whether its is better to have discrete sets of functions or expanding levels of function. Purpose of subsetting is: 1. Allow simpler implementations. (main purpose) 2. Simplify tooling 3. Simplify specification. Steve to contact previous members of WG to check if we have the correct subsets. 101 Semantics of 'fixed' 21/07: Discussed whether not matching the 'fixed' value should be a validation error or processing error. Decided that for consistency it should be a validation error. It would be useful however to avoid having to duplication of facet information in an assert which could become unwieldy for, say, a large enumeration. Suggestions - a parser option that 'converted all validation errors to porcessing errors' - a dfdl expression function that 'applied all facets' or 'applied specific facet' to a particular element. Stephanie will produce some examples of how this could be used.. 04/08: Stephanie had produced examples but they were not discussed due to lack of time 104 Expressions Discuss error behaviour when evaluating an expression in various contexts - All properties: wrong type returned : schema definition error exception when evaluating expression : schema definition error referenced variables/paths not available : schema definition error - Properties which allow a forward reference referenced variables/paths not available : no error. DFDL processor continues processing until the expression result is available, then acts on the result. 21/07: Steve stated the current definition that returning the incorrect type was a schema definition error and everything else was a processing error. 04/08: Not discussed 107 teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. 04/08: Not discussed 108 dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. 04/08: A lively discussion. The specification is works as currently defined so whether changes need to be made to make tooling easier. There shouldn't be 'conventions' in particular tooling as they must be able to properly deal with schema from other tools that would not obey those conventions. Steve stated that it is often dangerous to hide too much from users when they can see they underlying schema. To be continued. 109 dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. 04/08: not discussed. Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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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Minutes for OGF DFDL Working Group Call, August 04-2010
by Alan Powell 05 Aug '10

05 Aug '10

Open Grid Forum: Data Format Description Language Working Group OGF DFDL Working Group Call, August 04-2010 Attendees Steve Hanson (IBM) Alan Powell (IBM) Stephanie Fetzer (IBM) Ella Belisario (IBM) Apologies Mike Beckerle (Oco) Suman Kalia (IBM) Tim Kimber(IBM) 1. Current Actions Updated Below 2. dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. Option A: Leave the DFDL specification unchanged, in which case we must expose the internal DFDL constructs to the user of the DFDL editor. That means the following: - to make a group member hidden, a local group and a global group must be created to represent the hidden item. This is a refactoring operation. - to make the UI consistent, the global group needs to be exposed as a first-class modelling construct. That means that it appears along with local element/element ref/local group/group ref in any context where the user is dealing with group members. There are more details of what the editor needs to do in Steve's comments on the first note in this chain. Option B: Make one change to the DFDL specification, to make it possible for a DFDL editor to present dfdl:hidden as a simple flag on any group member The change is to put a DFDL annotation on the global sequence group that contains the hidden items. This would allow the DFDL editor to distinguish these global groups from the real ones that belong to the user's schema. This allows a hidden item to be represented by a pair of *internal* groups, both of which have a dfdl:annotation. One is local, and appears where the hidden item used to appear, The other is global and is referenced by the local one. They are created and deleted as pairs whenever an item is hidden or un-hidden. A lively discussion. The specification works as currently defined so discussed whether changes need to be made to make tooling easier. There shouldn't be 'conventions' in particular tooling as they must be able to properly deal with schema from other tools that would not obey those conventions. Steve stated that it is often dangerous to hide too much from users when they can see they underlying schema. To be continued. 3. dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. 04/08: not discussed. Meeting closed, 16:00 Next call Wednesday 11 August 2010 15:00 UK (10:00 ET) Next action: 110 Actions raised at this meeting No Action 108 dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. 04/08: A lively discussion. The specification is works as currently defined so whether changes need to be made to make tooling easier. There shouldn't be 'conventions' in particular tooling as they must be able to properly deal with schema from other tools that would not obey those conventions. Steve stated that it is often dangerous to hide too much from users when they can see they underlying schema. To be continued. 109 dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. 04/08: not discussed. Current Actions: No Action 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. 21/04. Schema for TDML defined. Need to define how this and the test cases will be made public 05/05: Work still progressing 12/05: Work still progressing 02/06: Work still progressing on technical and legal considerations ... 21/07: work continues 04/08: work continues 085 ALL: publicize Public comments phase to ensure a good review.. 14/04: see minutes 21/04: Press release, OMG and other standards bodies. 05/05: Alan and Steve H have contacted other standards bodies. Will ask them to add comments on spec 15/05: still no public comments 02/06: No public comments 16/06: Public comments period has ended with no external comments. Alan had posted changes made in draft 041. Steve suggested send a note to the WG highlighting these changes. Steve also suggested requesting an extension as other IBM groups may review. We discussed whether this was necessary as changes will need to be made during the implementation phase anyway. Alan to ask OGF what the process is for changes post public comment. 23/06: Still no comments. Alan will contact OGF to understand the rest of the process. 30/06: Alan has emailed Joel asking what the process is now public comment period is over andcan we update the published version with WG updates. No response yet. 07/07: No response. Alan will chase up 14/07: No response from Joel. Sent email to Greg Newby by no response. 21/07: Still no response. 04/08: Joel has responded that it is up to the WG to decide if the changes are significant enough to need additional review. Alan to contact David Martin and Erwin Laure for guidance if we split the specification. 099 Splitting the specification in simpler sections. 07/07: Steve sent a proposal but not discussed. Alan will arrange a separate call. 14/07:Discussed Steve's proposal and Suman's and Alan's comments. Need to add choice, validation, facets. Also how does an implementation declare which subsets it supports. Suggested levels and/or profiles. Steve highlighted a problem when a DFDL schema from an implementation of just the core functions was moved to a full DFDL implementation what should happen about the missing properties. Does the full implementation need to be aware of subsets of functions? Should it raise a schema definition error for use of a function not in the subset. 21/07: no progress 04/08: Steve had updated proposed groups of function. (Subset_proposal_v2.ppt). We discussed whether its is better to have discrete sets of functions or expanding levels of function. Purpose of subsetting is: 1. Allow simpler implementations. (main purpose) 2. Simplify tooling 3. Simplify specification. Steve to contact previous members of WG to check if we have the correct subsets. 101 Semantics of 'fixed' 21/07: Discussed whether not matching the 'fixed' value should be a validation error or processing error. Decided that for consistency it should be a validation error. It would be useful however to avoid having to duplication of facet information in an assert which could become unwieldy for, say, a large enumeration. Suggestions - a parser option that 'converted all validation errors to porcessing errors' - a dfdl expression function that 'applied all facets' or 'applied specific facet' to a particular element. Stephanie will produce some examples of how this could be used.. 04/08: Stephanie had produced examples but they were not discussed due to lack of time 104 Expressions Discuss error behaviour when evaluating an expression in various contexts - All properties: wrong type returned : schema definition error exception when evaluating expression : schema definition error referenced variables/paths not available : schema definition error - Properties which allow a forward reference referenced variables/paths not available : no error. DFDL processor continues processing until the expression result is available, then acts on the result. 21/07: Steve stated the current definition that returning the incorrect type was a schema definition error and everything else was a processing error. 04/08: Not discussed 107 teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. 04/08: Not discussed 108 dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. 04/08: A lively discussion. The specification is works as currently defined so whether changes need to be made to make tooling easier. There shouldn't be 'conventions' in particular tooling as they must be able to properly deal with schema from other tools that would not obey those conventions. Steve stated that it is often dangerous to hide too much from users when they can see they underlying schema. To be continued. 109 dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. 04/08: not discussed. Closed actions No Action 086 AP: Nils and Defaults during unparsing - update table 31/03: TK to documetn use cases for parsing 14/04: Investigate new property to control empty string behaviour. 21/04: After investigation a new property is not required. New rules developed and tables updated. Need examples of complexTypes to confirm tables apply. Review Nils, defaulting spec section. 05/05: Discussed defaulting complex elements. Tables updated but need to add terminator. SH; to confirm WMD behaviour when infoset item has no value on unparsing Need to describe defaulting choices. 15/05: More discussion. Alan updating sections 26/05: Discussed draft updates. Stephanie to confirm asserts do not make an element required. Alan will update draft.. All: review rest of draft. 02/06: Alan updated description. Please review. Discussed Stephanie's example using discriminators. Decided no changes needed. 16/05: went through Steves comments. Steve to update draft. 23/06: Steve's updates to the rules discussed. See minutes. Rest of document needs updating. 30/06: Discussed Alans updates. Some corrections. Alan will send out updated copy for review before next call. 07/07: Discussed Alan updates and Tim and Steve's comments. Still some corrections and updates. 14/07: Discussed Alan updates (v9) Still some corrections and updates. 21/07: Discussed Draft 10. Shouldn't mention input/outputValueCalc in this section. Mention defaulting in calculated values section. Move details of nilValue from nilKind property. 04/08: Draft v11.1 was included in Spec Draft v42. Minor corrections. Closed. 102 Clarify the specification of error reporting from a DFDL processor - section 2.3 needs to be updated 21/07: Section is not clear. Alan will update. 04/08: Sections updated in draft 42. Closed 103 Asserts and discriminators - specify the scope of forward references. Must be downward-only. The expression must be resolvable by the time the component on which it is positioned goes out of scope - otherwise it is a processing error. 21/07: Agreed 04/08: Updated in draft 42. Closed Work items: No Item target version status 005 Improvements on property descriptions not started 012 Reordering the properties discussion: move representation earlier, improve flow of topics not started 036 Update dfdl schema with change properties ongoing 042 Mapping of the DFDL infoset to XDM none not required for V1 specification 070 Write DFDL primer 071 Write test cases. 083 Implement RFC2116 Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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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Fw: DFDL V1 draft 42 is available - corrected (1)
by Alan Powell 05 Aug '10

05 Aug '10

I have corrected a misspelled property name (dfdl:missingValueDelimiterPolicy should be dfdl:emptyValueDelimiterPolicy) in Draft 42 and uploaded a corrected version http://forge.gridforum.org/sf/docman/do/downloadDocument/projects.dfdl-wg/d… Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)uk.ibm.com ----- Forwarded by Alan Powell/UK/IBM on 05/08/2010 14:09 ----- From: Alan Powell/UK/IBM@IBMGB To: dfdl-wg(a)ogf.org Date: 30/07/2010 15:55 Subject: [DFDL-WG] DFDL V1 draft 42 is available DFDL V1 draft 42 is available from gridforge. http://forge.gridforum.org/sf/docman/do/downloadDocument/projects.dfdl-wg/d… Revision History Latest entry at the top please Version Author/ Contributor History Date(yyyy-mm-dd) 042 Alan Powell Rename leadingSkipBytes and trailingSkipBytes to leadingSkip and TrailingSkip to allow either to be bytes or bits. Removed restrictons on alignmentUnits Clarified trailingSkip when dfdl:lengthKind is delimited or endOfParent Removed timing from dfdl:assert. Expression for dfdl:assert and dfdl:discriminator may only refer to previous or child elements. Clarified when expression must be evaluated. Clarified defaulting arrays and separatorPolicy 'required' Improved description of xxpadCharacter Changed choicekind enumerations. Added choiceLengthKind Corrected syntax of expression predicates Allow packed or bcd calendars to be delimited Clarified that outputValueCalc ignores infoset. Other minor changes. Property expressions must not contain forward references. Improved descriptions of property types and corrected some properties. Significant update to Nils and defaults sections. Dropped dfdl:nilIndicatorPath and dfdl:nilIndicatorIndex dfdl:missingValueInitiatorPolicy applies to dfdl:element, dfdl:simpleType, dfdl:sequence, dfdl:choice, dfdl:group 2010-07-28 Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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 -- dfdl-wg mailing list dfdl-wg(a)ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg 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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Fw: Subsetting the DFDL spec
by Steve Hanson 04 Aug '10

04 Aug '10

I've thought further on this. I think any subsets need to be fairly wide ranging and independent, in order for implementations (runtime and tooling) to be able to sensibly offer support. If it becomes too fragmented then users will find it difficult to know what construct may be used when. I realise that this means it takes more effort to implement a subset in terms of content, but I think it will be easier to understand how to do it. Accordingly I've revised the strawman. Note that I have introduced choices and unordered sequences at the same point as initiators, as that provides a way of resolving uncertainty without speculation, which is introduced under an advanced expression subset. Regards Steve Hanson Strategy, Common Transformation & DFDL Co-Chair, OGF DFDL WG IBM SWG, Hursley, UK, smh(a)uk.ibm.com, tel +44-(0)1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 04/08/2010 13:50 ----- From: Steve Hanson/UK/IBM To: Suman Kalia <kalia(a)ca.ibm.com> Cc: dfdl-wg(a)ogf.org, dfdl-wg-bounces(a)ogf.org Date: 07/07/2010 18:34 Subject: Re: [DFDL-WG] Subsetting the DFDL spec Hi Suman I added hidden elements as it allows things to be omitted from the infoset, which is a very useful technique. I removed it from the expression subset because you only need hidden + expressions when for example using a hidden complex element to return a synthesised simple value. Hidden on its own just to skip things is useful, easy to implement, and does no harm in core. Defaults are a core capability. Otherwise you can't create a sparse infoset on output. If we can separate out nils then perhaps nils could be in a separate subset. I started off that way then changed my mind but we can revisit. I originally had choices in core but I removed it because without initiators or expressions how can you resolve a choice? You can't. Choices are not as common as you might think in the non-XML world, for precisely this reason. However, as I write I've realised that I've not allocated uncertainty (ie, choice or 'optionality') to any of the subsets, a major omission on my part. I was intending core to be fixed occurrences thereby avoiding the need to implement backtracking, a significant item in any implementation. I'll think more on this. My rationale for omitting delimiters from core was to keep core for fixed length data. Many scientific users will never need delimiter support - and they are the folk most likely from OGF to write an implementation. Once you add in separators you pull in a huge amount of implementation - all the scanning, escaping, etc. However, the uncertainty issue could well force us to split initiators from the other delimiters because of their role in uncertainty resolution. Thanks for your input though, I'll have a think and send out an update before next call. Regards Steve Hanson Strategy, Common Transformation & DFDL Co-Chair, OGF DFDL WG IBM SWG, Hursley, UK, smh(a)uk.ibm.com, tel +44-(0)1962-815848 From: Suman Kalia <kalia(a)ca.ibm.com> To: Steve Hanson/UK/IBM@IBMGB Cc: dfdl-wg(a)ogf.org, dfdl-wg-bounces(a)ogf.org Date: 07/07/2010 17:50 Subject: Re: [DFDL-WG] Subsetting the DFDL spec Steve - some comments I suggest we create a category DFDL Advanced features and put support for hidden elements under this as not many users would need it or implement it. One can also make the case for putting "Nils and defaults" under the DFDL advanced features as this is one of the complex part of the specification. Core - should have support for choice construct as this is the most common building block. I would like to see support for delimited data; the basic and most widely used form is comma separated records which would require lenghtKind=delimited and separators to be moved to core specification.. Suman Kalia IBM Toronto Lab WebSphere Message Broker Toolkit Architect and Development Lead WebSphere Business Integration Application Connectivity Tools http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.h… Tel : 905-413-3923 T/L 969-3923 Fax : 905-413-4850 T/L 969-4850 Internet ID : kalia(a)ca.ibm.com From: Steve Hanson <smh(a)uk.ibm.com> To: dfdl-wg(a)ogf.org Date: 07/07/2010 09:47 AM Subject: [DFDL-WG] Subsetting the DFDL spec Sent by: dfdl-wg-bounces(a)ogf.org Some thoughts about subsetting the DFDL spec to make it more consumable for readers and implementors. We need to decide how the use of a subset is indicated in a DFDL xsd. It can be implicit by the properties referenced, or explicit up front. The difference is best illustrated by an example. Let's say Bidi support is a subset and I don't want to use Bidi. If using the implicit method, then I still need the dfdl:textBidi property to be set to 'no' even when in subset mode because the same xsd could be used by a full DFDL processor and it will expect a value. If using explicit, then I don't need to set the dfdl:textBidi property at all, because the DFDL processor will never look for it unless the xsd is switched to include that subset. Here's a straw man for some subsets. Regards Steve Hanson Strategy, Common Transformation & DFDL Co-Chair, OGF DFDL WG IBM SWG, Hursley, UK, smh(a)uk.ibm.com, tel +44-(0)1962-815848 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 -- dfdl-wg mailing list dfdl-wg(a)ogf.org http://www.ogf.org/mailman/listinfo/dfdl-wg 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 #### Subset_proposal_v1.ppt moved to MyAttachments Repository V3.8 () on 13 July 2010 by Steve Hanson. 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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Agenda for OGF DFDL WG call 04 August 2010 15:00UK (10:00 ET)
by Alan Powell 03 Aug '10

03 Aug '10

1. Current Actions 2. dfdl:hidden There has been some discussion on whether the 'hidden' global group should be indicated in some way. Option A: Leave the DFDL specification unchanged, in which case we must expose the internal DFDL constructs to the user of the DFDL editor. That means the following: - to make a group member hidden, a local group and a global group must be created to represent the hidden item. This is a refactoring operation. - to make the UI consistent, the global group needs to be exposed as a first-class modelling construct. That means that it appears along with local element/element ref/local group/group ref in any context where the user is dealing with group members. There are more details of what the editor needs to do in Steve's comments on the first note in this chain. Option B: Make one change to the DFDL specification, to make it possible for a DFDL editor to present dfdl:hidden as a simple flag on any group member The change is to put a DFDL annotation on the global sequence group that contains the hidden items. This would allow the DFDL editor to distinguish these global groups from the real ones that belong to the user's schema. This allows a hidden item to be represented by a pair of *internal* groups, both of which have a dfdl:annotation. One is local, and appears where the hidden item used to appear, The other is global and is referenced by the local one. They are created and deleted as pairs whenever an item is hidden or un-hidden. 3. dfdl:discriminator : the 'message' attribute >From Tim: I remembered the reason why I thought this was a good idea. Consider the situation where someone is generating their DFDL schema from meta-data. The model is large, and consists of many references to global structures. Each global structure ( e.g. an HL7 segment ) is identified in a particular way. Sometimes the segment is required, sometimes it is not. Sometimes it occurs as a child of a choice group, and sometimes not. Regardless, it is highly likely that the segment will be identified in the same way wherever it occurs. A natural decision for the modeler would be to create a dfdl:discriminator on all references to the segement, even if the ref is not under a point of uncertainty. It's harmless, and it carries no performance penalty. If we disallow the "message" attribute, it will force the modeler to put in extra logic to work out whether the ref is under a POI, and generate an assert/discriminator as appropriate. I'd be interested to know what Steph thinks about this - I think I've heard her say that she sometimes uses discriminators where an assert would have done the job, just to maintain consistency throughout the model. Current Actions: No Action 066 Investigate format for defining test cases 25/11:IBM to see if it is possible to publish its test case format. 04/12: no update ... 17/02: IBM is willing in principle to publish the test case format and some of the test cases. May need some time to build a 'compliance suite' 24/03: No progress 03/03: Discussions have been taking place on the subset of tests that will be provided. 10/03: work is progressing 17/03: work is progressing 31/03: work is progressing 14/04: And XML test case format has been defined and is being tested. 21/04. Schema for TDML defined. Need to define how this and the test cases will be made public 05/05: Work still progressing 12/05: Work still progressing 02/06: Work still progressing on technical and legal considerations ... 21/07: work continues 085 ALL: publicize Public comments phase to ensure a good review.. 14/04: see minutes 21/04: Press release, OMG and other standards bodies. 05/05: Alan and Steve H have contacted other standards bodies. Will ask them to add comments on spec 15/05: still no public comments 02/06: No public comments 16/06: Public comments period has ended with no external comments. Alan had posted changes made in draft 041. Steve suggested send a note to the WG highlighting these changes. Steve also suggested requesting an extension as other IBM groups may review. We discussed whether this was necessary as changes will need to be made during the implementation phase anyway. Alan to ask OGF what the process is for changes post public comment. 23/06: Still no comments. Alan will contact OGF to understand the rest of the process. 30/06: Alan has emailed Joel asking what the process is now public comment period is over andcan we update the published version with WG updates. No response yet. 07/07: No response. Alan will chase up 14/07: No response from Joel. Sent email to Greg Newby by no response. 21/07: Still no response. 086 AP: Nils and Defaults during unparsing - update table 31/03: TK to documetn use cases for parsing 14/04: Investigate new property to control empty string behaviour. 21/04: After investigation a new property is not required. New rules developed and tables updated. Need examples of complexTypes to confirm tables apply. Review Nils, defaulting spec section. 05/05: Discussed defaulting complex elements. Tables updated but need to add terminator. SH; to confirm WMD behaviour when infoset item has no value on unparsing Need to describe defaulting choices. 15/05: More discussion. Alan updating sections 26/05: Discussed draft updates. Stephanie to confirm asserts do not make an element required. Alan will update draft.. All: review rest of draft. 02/06: Alan updated description. Please review. Discussed Stephanie's example using discriminators. Decided no changes needed. 16/05: went through Steves comments. Steve to update draft. 23/06: Steve's updates to the rules discussed. See minutes. Rest of document needs updating. 30/06: Discussed Alans updates. Some corrections. Alan will send out updated copy for review before next call. 07/07: Discussed Alan updates and Tim and Steve's comments. Still some corrections and updates. 14/07: Discussed Alan updates (v9) Still some corrections and updates. 21/07: Discussed Draft 10. Shouldn't mention input/outputValueCalc in this section. Mention defaulting in calculated values section. Move details of nilValue from nilKind property. 099 Splitting the specification in simpler sections. 07/07: Steve sent a proposal but not discussed. Alan will arrange a separate call. 14/07:Discussed Steve's proposal and Suman's and Alan's comments. Need to add choice, validation, facets. Also how does an implementation declare which subsets it supports. Suggested levels and/or profiles. Steve highlighted a problem when a DFDL schema from an implementation of just the core functions was moved to a full DFDL implementation what should happen about the missing properties. Does the full implementation need to be aware of subsets of functions? Should it raise a schema definition error for use of a function not in the subset. 21/07: no progress 101 Semantics of 'fixed' 21/07: Discussed whether not matching the 'fixed' value should be a validation error or processing error. Decided that for consistency it should be a validation error. It would be useful however to avoid having to duplication of facet information in an assert which could become unwieldy for, say, a large enumeration. Suggestions - a parser option that 'converted all validation errors to processing errors' - a dfdl expression function that 'applied all facets' or 'applied specific facet' to a particular element. Stephanie will produce some examples of how this could be used. 102 Clarify the specification of error reporting from a DFDL processor - section 2.3 needs to be updated 21/07: Section is not clear. Alan will update. 103 Asserts and discriminators - specify the scope of forward references. Must be downward-only. The expression must be resolvable by the time the component on which it is positioned goes out of scope - otherwise it is a processing error. 21/07: Agreed 104 Expressions Discuss error behaviour when evaluating an expression in various contexts - All properties: wrong type returned : schema definition error exception when evaluating expression : schema definition error referenced variables/paths not available : schema definition error - Properties which allow a forward reference referenced variables/paths not available : no error. DFDL processor continues processing until the expression result is available, then acts on the result. 21/07: Steve stated the current definition that returning the incorrect type was a schema definition error and everything else was a processing error. 107 teston/testoff dfdl expression functions. Are these functions still needed. They were introduced to allow individual bits to be set in a byte. Steve to look at TLog and ISO 8583 formats that use existence flags to see if they are still required. Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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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DFDL V1 draft 42 is available
by Alan Powell 30 Jul '10

30 Jul '10

DFDL V1 draft 42 is available from gridforge. http://forge.gridforum.org/sf/docman/do/downloadDocument/projects.dfdl-wg/d… Revision History Latest entry at the top please Version Author/ Contributor History Date(yyyy-mm-dd) 042 Alan Powell Rename leadingSkipBytes and trailingSkipBytes to leadingSkip and TrailingSkip to allow either to be bytes or bits. Removed restrictons on alignmentUnits Clarified trailingSkip when dfdl:lengthKind is delimited or endOfParent Removed timing from dfdl:assert. Expression for dfdl:assert and dfdl:discriminator may only refer to previous or child elements. Clarified when expression must be evaluated. Clarified defaulting arrays and separatorPolicy 'required' Improved description of xxpadCharacter Changed choicekind enumerations. Added choiceLengthKind Corrected syntax of expression predicates Allow packed or bcd calendars to be delimited Clarified that outputValueCalc ignores infoset. Other minor changes. Property expressions must not contain forward references. Improved descriptions of property types and corrected some properties. Significant update to Nils and defaults sections. Dropped dfdl:nilIndicatorPath and dfdl:nilIndicatorIndex dfdl:missingValueInitiatorPolicy applies to dfdl:element, dfdl:simpleType, dfdl:sequence, dfdl:choice, dfdl:group 2010-07-28 Regards Alan Powell Development - MQSeries, Message Broker, ESB IBM Software Group, Application and Integration Middleware Software ------------------------------------------------------------------------------------------------------------------------------------------- IBM MP211, Hursley Park Hursley, SO21 2JN United Kingdom Phone: +44-1962-815073 e-mail: alan_powell(a)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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