Any thoughts on this? Note one correction below. ---------------------------------------------------- We discussed this on the call yesterday as minuted by Alan. I missed xsd:any from the table in the mail below, so that's added. Specialized annotations may help alleviate something that has been noted by folk at IBM when creating DFDL schemas. If using dfdl:format on complex types to set properties, it is usually to default values for the elements of the complex type. But the first thing following the complex type is the model group (sequence, choice) so any properties with the same name have to be explicitly set. That's all working as designed but it is a common mistake to forget to do this. The cause is having properties with the same name on both sequence and element. Having specialized annotations provides a way round this by allowing the introduction of 'parallel' scoping. <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:defineFormat> <dfdl:sequence terminator="$" ... /> <dfdl:element terminator="%" ... /> <dfdl:simpleType ... /> <dfdl:choice ... /> <dfdl:any ... /> </dfdl:defineFormat> </xs:appinfo></xs:annotation> <xs:complexType name="myType"> <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:complexType> <dfdl:sequence lengthKind="implicit" ... /> <dfdl:element lengthKind="delimited" ... /> </dfdl:complexType> </xs:appinfo></xs:annotation> <xs:sequence> <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:sequence ... /> </xs:appinfo></xs:annotation> <xs:element name="el1" type="xs:string"> <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:element ... /> </xs:appinfo></xs:annotation> </xs:element> <xs:element name="el2" type="xs:string"> <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:element ... /> </xs:appinfo></xs:annotation> </xs:element> <xs:element name="el3" type="xs:string"> <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:element ... /> </xs:appinfo></xs:annotation> </xs:element> </xs:sequence> </xs:complexType> This makes it very clear which properties are going to be used where and allows separate defaults to be set up for different kinds of xsd object. But there are a couple of problems with this. 1) What does this mean? <xs:complexType name="myType" dfdl:lengthKind="implicit" ... > Possible answers: a) We don't allow short form on xs:complexType. b) Short form applies to all DFDL specializations c) Short form applies to one specific DFDL specialization, eg, dfdl:element. Personally I think a) would be a shame and a loss of convenience; c) is too arbitrary; b) looks the most sensible, but opens up another question, namely whether this equivalent is also allowed. <xs:complexType name="myType"> <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:complexType lengthKind="delimited"> <dfdl:sequence lengthKind="implicit" ... /> <dfdl:element lengthKind="delimited" ... /> </dfdl:complexType> </xs:appinfo></xs:annotation> 2) I am forced to set common properties in multiple places. <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:defineFormat> <dfdl:sequence encoding="UTF-8" ... /> <dfdl:element encoding="UTF-8" ... /> <dfdl:simpleType encoding="UTF-8" ... /> <dfdl:choice encoding="UTF-8" ... /> <dfdl:any encoding="UTF-8" ... /> </dfdl:defineFormat> </xs:appinfo></xs:annotation> But we could also allow this, and say that dfdl:format applied to all xsd objects. Note that this is consistent with 1) b) above, <xs:annotation><xs:appinfo source=”http://www.ogf.org/dfdl/”> <dfdl:defineFormat> <dfdl:format encoding="UTF-8" ... /> <dfdl:sequence ... /> <dfdl:element ... /> <dfdl:simpleType ... /> <dfdl:choice ... /> <dfdl:any ... /> </dfdl:defineFormat> </xs:appinfo></xs:annotation> We should also bear in mind when deciding all this that we do already provide one other facility which provides a form of parallelism. <dfdl:format ref=”reusableDef"... /> So I can already create a set of annotations applicable to a specific kind of xsd object and reuse that via the dfdl:ref attribute. Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh@uk.ibm.com Phone (+44)/(0) 1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 12/03/2009 10:00 ----- Steve Hanson/UK/IBM 09/03/2009 16:10 To DFDL Working Group cc Subject Fw: [DFDL-WG] dfdl:sequence and other specialized annotations Although it was minuted in last week's call that we decided to drop specialised annotations, I don't actually recall that was decision on the call. The proposal below is in accordance with the suggestion by Martin, and echoed by Dave, that we have only specialised annotations for xsd objects. Schema object DFDL annotation allowed Notes Schema declaration dfdl:format Only within an enclosing dfd:defineFormat. Element declaration dfdl:element Just those properties allowed on elements Element reference dfdl:element Just those properties allowed on elements. Overrides dfdl:element properties on global element Complex type definition dfdl:complexType Full dfdl:format properties. For scoping purposes only. Simple type definition dfdl:simpleType Just those properties allowed on simple types. Sequence declaration dfdl:sequence Just those properties allowed on sequences. Choice declaration dfdl:choice Just those properties allowed on choices. Group reference dfdl:group Just those properties allowed on sequence/choice. Overrides dfdl:sequence/dfdl:choice properties on global group sequence/choice model group Wildcard element dfdl:any Just those properties allowed on wildcard elementsv An alternative as I previously wrote is to allow dfdl:sequence and dfdl:choice on a group reference. Group reference (to sequence group) dfdl:sequence Just those properties allowed on sequence/choice. Overrides dfdl:sequence properties on global group model sequence group Group reference (to choice group) dfdl:choice Just those properties allowed on sequence/choice. Overrides dfdl:choice properties on global group model choice group Although this does not look as good visually, it is worth bearing in mind section 22.2 of the spec: 22.2 Group Reference A copy of the definition referenced by a group reference is substituted inline for its declaration while combining any DFDL format annotation elements associated with it as given in Section 10.5. (TBD: xref to scoping?) Processing then proceeds as for an anonymous group declaration. Note: The use of specialised annotations relies on the removal of something that we had talked about but not yet reflected in the spec - dfdl:format on global xsd:group definitions. The idea of allowing this came about fairly recently when we changed the rules for hidden objects. I was unhappy that embedded hidden xsd objects within DFDL annotations would make them invisible to a schema validator, so dfdl:hidden was changed to be a reference to a global group containing the hidden objects. I suggested that we could also put scoping annotations on global groups to support scoping within the hidden construct, it seemed a good idea at the time, but it was not fully explored. Thinking it through, because the global group effectively disappears when the reference is resolved, then so does its annotations. I'm therefore happy to retract scoping annotations on global groups if it makes specialised annotations work. Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh@uk.ibm.com Phone (+44)/(0) 1962-815848 From: Steve Hanson/UK/IBM@IBMGB To: Suman Kalia <kalia@ca.ibm.com> Cc: dfdl-wg@ogf.org Date: 02/03/2009 23:45 Subject: Re: [DFDL-WG] Reducing the number of DFDL properties. Suman A DFDL annotation on a group reference overrides a DFDL annotation on the content of the model group (ie, sequence, choice), not a DFDL annotation on the global group. It allows you to override the sequence/choice properties at point of use. The DFDL annotation on a global group is like that on a complex type - it is a scoping construct only. Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh@uk.ibm.com Phone (+44)/(0) 1962-815848 Suman Kalia <kalia@ca.ibm.com> 02/03/2009 22:02 To Steve Hanson/UK/IBM@IBMGB cc dfdl-wg@ogf.org, "Dave Glick" <dglick@dracorp.com> Subject Re: [DFDL-WG] Reducing the number of DFDL properties. I can see where you are coming from and I agree with most of your proposal except putting dfdl:sequence, dfdl:choice , dfdl:all on group references as it does not give the right optics.. From consistency point of view, the references (group and element references) should have the equivalent/same set of annotations that can appear on the referenced artifacts. Suman Kalia IBM Toronto Lab WMB Toolkit Architect and Development Lead WebSphere Business Integration Application Connectivity Tools http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.ht... Tel : 905-413-3923 T/L 969-3923 Fax : 905-413-4850 T/L 969-4850 Internet ID : kalia@ca.ibm.com From: Steve Hanson <smh@uk.ibm.com> To: Suman Kalia/Toronto/IBM@IBMCA Cc: dfdl-wg@ogf.org, "Dave Glick" <dglick@dracorp.com> Date: 03/02/2009 12:45 PM Subject: Re: [DFDL-WG] Reducing the number of DFDL properties. If I recall, one reason for having the specialised elements was so that the content of the annotations could be more tightly validated by the schema-for-dfdl xsd. However, the problem with the specialised annotations is that we do not provide them for all circumstances. For example, the spec allows me to use dfdl:sequence on an xs:sequence but not an xs:group reference to a global xs:group with compostion xs:sequence. Nor does it allow me to use a specialised element on xs:simpleType or xs:restriction. So as it stands, validation would not be fool-proof anyway. I think we must either ditch specialisations, or mandate the use of specialisations on the corresponding schema objects. The latter is more workable now we have changed the scoping rules so that scoping of dfdl properties can only be done from complex type or schema level, as below. But it does mean that dfdl annotations are less flexible. dfdl;defineFormat => dfdl:format xs:complexType => dfdl:format xs:group => dfdl:format xs:sequence or xs:group ref to a global group with xs:sequence => dfdl:sequence xs:choice or xs:group ref to a global group with xs:choice => dfdl:choice xs:element or xs:element ref => dfdl:element xs:any => dfdl:any xs:simpleType, xs:restriction => dfdl:simpleType In other words, you use dfdl:format when you are scoping properties, you must use specialised annotation for specific objects. Regards Steve Hanson Programming Model Architect WebSphere Message Brokers Hursley, UK Internet: smh@uk.ibm.com Phone (+44)/(0) 1962-815848 Suman Kalia <kalia@ca.ibm.com> Sent by: dfdl-wg-bounces@ogf.org 02/03/2009 16:25 To "Dave Glick" <dglick@dracorp.com> cc dfdl-wg@ogf.org, dfdl-wg-bounces@ogf.org Subject Re: [DFDL-WG] Reducing the number of DFDL properties. I am not sure what kind of confusion or redundancy is caused by these specialized annotations. In the absence of these specialized annotations, you will have to go through plethora of annotations and determine which ones are applicable for sequence , choice, all, elements etc.. The danger is we don't have these levels of abstractions, then number of folks (specifically implementers) would build them anyway and then we will have to contend with incompatible abstractions.. Suman Kalia IBM Toronto Lab WMB Toolkit Architect and Development Lead WebSphere Business Integration Application Connectivity Tools http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.ht... Tel : 905-413-3923 T/L 969-3923 Fax : 905-413-4850 T/L 969-4850 Internet ID : kalia@ca.ibm.com From: "Dave Glick" <dglick@dracorp.com> To: "Alan Powell" <alan_powell@uk.ibm.com>, <mbeckerle.dfdl@gmail.com> Cc: dfdl-wg@ogf.org Date: 03/02/2009 11:16 AM Subject: Re: [DFDL-WG] Reducing the number of DFDL properties. Alan/Mike, I agree with this – one of my complaints with v033 was that these specialized annotation elements just added confusion and redundancy. Dave --- David Glick | dglick@dracorp.com | 703.299.0700 x212 Data Research and Analysis Corp. | www.dracorp.com From: dfdl-wg-bounces@ogf.org [mailto:dfdl-wg-bounces@ogf.org] On Behalf Of Alan Powell Sent: Monday, March 02, 2009 11:03 AM To: mbeckerle.dfdl@gmail.com Cc: dfdl-wg@ogf.org Subject: Re: [DFDL-WG] Reducing the number of DFDL properties. Mike Thanks Can I also suggest dropping the dfdl:sequence, dfdl:choice, dfdl:element and dfdl:any specialized annotations and just have dfdl:format. Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell@uk.ibm.com Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898 From: "Mike Beckerle" <mbeckerle.dfdl@gmail.com> To: Alan Powell/UK/IBM@IBMGB Cc: <dfdl-wg@ogf.org> Date: 28/02/2009 19:38 Subject: RE: Reducing the number of DFDL properties. If a property is redundant, I'm in favor of dropping it. If a property adds generality that we don't have a use case for, I'm in favor of dropping it. I am happy to drop type substitution from v1.0. It's a convenience that can be achieved a different way. E.g., if you really want "float" to mean "float in my particular binary representation", then just put a type definition with DFDL annotations in a different namespace, and when you write your DFDL schema, arrange for the default namespace to pick it up from your namespace, and not xs:float. <xs:element name="myElement" type="float"/> <!-- float here is myNamespace:float which can have DFDL annotations on it --> <xs:element name="anotherElem" type="xs:float"/> <!-- explicitly xs:float without further adornment --> If you want the XSD unadorned "float" type, be explicit and use "xs:float". Voila - no loss of flexibility, equal textual convenience. I think that would satisfy the community that really wanted very compact "slideware acceptable" schemas. This is the same group that wants short-form annotations as well. Mike Beckerle | OGF DFDL WG Co-Chair | CTO | Oco, Inc. Tel: 781-810-2100 | 100 Fifth Ave., 4th Floor, Waltham MA 02451 | mbeckerle.dfdl@gmail.com From: Alan Powell [mailto:alan_powell@uk.ibm.com] Sent: Thursday, February 26, 2009 12:22 PM To: mbeckerle.dfdl@gmail.com Cc: dfdl-wg@ogf.org Subject: Reducing the number of DFDL properties. Mike A number of people at IBM have become concerned at the number of properties in DFDL and have identified a number of 'usability' properties that could be dropped. They feel that we should be simplifying the properties wherever possible and not introducing multiple ways of doing the same function without very good reason. The following are offered for consideration. 1. lengthKind='nullterminated' This is just shorthand for lengthKind=delimited and terminator='%Null'. It was felt this this is not even the most common terminator so why have a special case? 2. trimKind It is felt that there aren't any cases when you would want to pad but not trim and vice versa so make padKind control both. 3. typeSubstitution. Is this needed in DFDL v1? Can you consider these before the call next week Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell@uk.ibm.com Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898 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 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. 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