May 2013 - dfdl-wg - lists.ogf.org

Implementation limits
by Steve Hanson 11 Jul '13

11 Jul '13

Just checking - did we close on this? Regards Steve Hanson Architect, Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 21/01/2013 18:38 ----- From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> To: Steve Hanson/UK/IBM@IBMGB, Cc: dfdl-wg(a)ogf.org Date: 19/11/2012 21:08 Subject: Re: [DFDL-WG] proposed clarification/narrowing - no twos-complement decimal, integer or nonNegativeInteger Do we have a section where this goes? There are lots of implied implementation limits. Maximum string length? Maximum hexbinary length? Maximum number of packed digits in various numbers. Maximum length of a delimiter? Maximum length of a fixed attribute? Maximum length of a pattern regex expression? Maximum length of a regular expression? There's also limits on buffering of data for unparsing, etc. There's also limits on lookahead/speculation. I.e., how far an implementation is willing to speculate forward. etc. For some types these are clear: e.g., binary xs:int is 32 bits max. Do we need a numbered section on implementation specific limits. 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

3 4

escapeKind clarifications needed.
by Mike Beckerle 31 May '13

31 May '13

When escapeKind='escapeBlock' we only use the escapeEscapeCharacter if needed to escape the block end. We don't use the escapeCharacter at all. So, is it an error if escapeKind='escapeBlock' and you define a value for escapeCharacter in the same dfdl:escapeScheme? Such property cannot be inherited by scope, so since escapeBlock kind doesn't use the escapeCharacter, this can only be either an error, or silently ignored, or ignored with a warning. An error is the best choice from a language design perspective. -- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com

2 1

Fwd: [dfdl] initiatedContent w/o initiators
by Mike Beckerle 31 May '13

31 May '13

Forgot to copy the workgroup. ---------- Forwarded message ---------- From: Mike Beckerle <mbeckerle.dfdl(a)gmail.com> Date: Fri, May 31, 2013 at 1:32 AM Subject: Re: [DFDL-WG] [dfdl] initiatedContent w/o initiators To: "Garriss Jr., James P." <jgarriss(a)mitre.org> You need two nested choices. Only the inner one uses initiated content. <xsd:choice> <xsd:choice dfdl:initiatedContent="yes"> <xsd:element ref="Date"/> <xsd:element ref="From"/> <xsd:element ref="MessageId"/> <xsd:element ref="Subject"/> </xsd:choice>  <xsd:sequence dfdl:hiddenGroupRef="UnwantedHeadersGroup"/> </xsd:choice> On Thu, May 30, 2013 at 2:49 PM, Garriss Jr., James P. <jgarriss(a)mitre.org>wrote: > Spec says:**** > > ** ** > > It is a schema definition error if any children have their dfdl:initiator > property set to the empty string.**** > > ** ** > > Does that include a sequence with a hiddenGroupRef?**** > > ** ** > > For example, part of a schema for email headers is this:**** > > ** ** > > > <xsd:choice dfdl:initiatedContent="yes">**** > > > <xsd:element ref="Date"/>**** > > > <xsd:element ref="From"/>**** > > > <xsd:element ref="MessageId"/>**** > > > <xsd:element ref="Subject"/>**** > > > **** > > > <xsd:sequence dfdl:hiddenGroupRef="UnwantedHeadersGroup"/>**** > > > </xsd:choice>**** > > ** ** > > Date, From, and the other headers are all elements with initiators, but > UnwantedHeadersGroup does not have an initiator (because I don’t know it a > priori). **** > > ** ** > > Should this throw an error in a DFDL implementation? I suspect it should, > though I hope it shouldn’t.**** > > -- > dfdl-wg mailing list > dfdl-wg(a)ogf.org > https://www.ogf.org/mailman/listinfo/dfdl-wg > -- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com -- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com

2 3

Better way to model "empty"?
by Garriss Jr., James P. 31 May '13

31 May '13

A return path email header can take two forms: 1. Plain email form: Return-path: <steve(a)tresys.com> 2. Empty form: Return-path: <> I've found 2 different ways to model this: #1 - with a choice <xsd:choice> <xsd:element name="Empty" type="xsd:string" dfdl:lengthKind="explicit" dfdl:length="0"/> <xsd:element name="PlainEmail" type="PlainEmail"/> </xsd:choice> #2 - with min/maxOccurs <xsd:element name="PlainEmail" type="PlainEmail" minOccurs="0" maxOccurs="1" dfdl:occursCountKind="implicit"/> When I'm faced with selecting one of these implementations over another, how do I think? What criteria should I be using? Is there another, better way that I haven't even thought of? TIA

2 1

Re: [DFDL-WG] [dfdl] initiatedContent w/o initiators
by Garriss Jr., James P. 31 May '13

31 May '13

Thanks for the help, Mike. I understand what you want me to do, but not why. After all, the code I have works great on all the test data I've thrown at it. Please explain how this is different from the schema code I have and why it is better. TIA. From: Mike Beckerle [mailto:mbeckerle.dfdl@gmail.com] Sent: Friday, May 31, 2013 1:33 AM To: Garriss Jr., James P. Subject: Re: [DFDL-WG] [dfdl] initiatedContent w/o initiators You need two nested choices. Only the inner one uses initiated content. <xsd:choice> <xsd:choice dfdl:initiatedContent="yes"> <xsd:element ref="Date"/> <xsd:element ref="From"/> <xsd:element ref="MessageId"/> <xsd:element ref="Subject"/> </xsd:choice>  <xsd:sequence dfdl:hiddenGroupRef="UnwantedHeadersGroup"/> </xsd:choice> On Thu, May 30, 2013 at 2:49 PM, Garriss Jr., James P. <jgarriss(a)mitre.org<mailto:jgarriss@mitre.org>> wrote: Spec says: It is a schema definition error if any children have their dfdl:initiator property set to the empty string. Does that include a sequence with a hiddenGroupRef? For example, part of a schema for email headers is this: <xsd:choice dfdl:initiatedContent="yes"> <xsd:element ref="Date"/> <xsd:element ref="From"/> <xsd:element ref="MessageId"/> <xsd:element ref="Subject"/>  <xsd:sequence dfdl:hiddenGroupRef="UnwantedHeadersGroup"/> </xsd:choice> Date, From, and the other headers are all elements with initiators, but UnwantedHeadersGroup does not have an initiator (because I don't know it a priori). Should this throw an error in a DFDL implementation? I suspect it should, though I hope it shouldn't. -- dfdl-wg mailing list dfdl-wg(a)ogf.org<mailto:dfdl-wg@ogf.org> https://www.ogf.org/mailman/listinfo/dfdl-wg -- Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com<http://www.tresys.com>

1 0

emptyValueDelimiterPolicy clarification
by Garriss Jr., James P. 31 May '13

31 May '13

This property specifies whether the initiator/terminator much be present if the element is empty. But the mere presence of this property does not specify that the element can be empty, right? IOW, I still have to describe that the element can be empty. That right?

2 1

[dfdl] initiatedContent w/o initiators
by Garriss Jr., James P. 30 May '13

30 May '13

Spec says: It is a schema definition error if any children have their dfdl:initiator property set to the empty string. Does that include a sequence with a hiddenGroupRef? For example, part of a schema for email headers is this: <xsd:choice dfdl:initiatedContent="yes"> <xsd:element ref="Date"/> <xsd:element ref="From"/> <xsd:element ref="MessageId"/> <xsd:element ref="Subject"/>  <xsd:sequence dfdl:hiddenGroupRef="UnwantedHeadersGroup"/> </xsd:choice> Date, From, and the other headers are all elements with initiators, but UnwantedHeadersGroup does not have an initiator (because I don't know it a priori). Should this throw an error in a DFDL implementation? I suspect it should, though I hope it shouldn't.

1 0

DFDL support for XML schema elements or attributes
by Alonza Mumford 30 May '13

30 May '13

I've looked over the DFDL 1.0 specification and I have a few questions regarding the inclusion of certain XML Schema elements or attributes. Does anyone know as to whether the following elements are supported in DFDL 1.0: - xs:extension - xs:list - xs:all - xs:any - xs:anyAttribute - xs:field - xs:key - xs:keyref - xs:selector - xs:unique Does anyone know as to whether the following elements are supported in DFDL 1.0: - xs:abstract - xs:attributeFormDefault - xs:base - xs:block - xs:blockDefault - xs:fixed - xs:mixed - xs:processContents Thanks, Alonza

2 1

OGF DFDL WG Call Minutes 2013-05-28
by Steve Hanson 29 May '13

29 May '13

Please find minutes from the above call on Redmine at http://redmine.ogf.org/dmsf_files/13080?download= Errata document is now at v013 here: http://redmine.ogf.org/dmsf_files/8104?download= Action 140 errata addendum at v001 here: http://redmine.ogf.org/dmsf_files/13017?download= Regards Steve Hanson Architect, IBM DFDL, Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848

1 0

dfdl:calendarLanguage - should allow an expression?
by Steve Hanson 29 May '13

29 May '13

DFDL has the design point that the combination of schema & data should give the same result regardless of locale and/or machine. To create a schema that does vary across locale or machine requires the user deliberately to use expressions for the relevant DFDL properties (encoding, decimal separator, etc) and parameterise the schema, using either built-in DFDL variables or user-defined variables. However the dfdl:calendarLanguage property is only defined as a String, I think it should also allow an expression as otherwise a schema is tied to a particular locale for it's calendar language support. Regards Steve Hanson Architect, IBM Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh(a)uk.ibm.com tel:+44-1962-815848 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

2 2