[DFDL-WG] dfdl:sequence and othe rspecialized annotations - RE: Reducing the number of DFDL properties.

Mon Mar 2 19:19:22 CST 2009

Folks,

I wanted to remind everyone the purpose of dfdl:sequence and the other
specialized annotations.

The point of these is to allow a XSD for dfdl annotations to provide some
value in the following way:

1.	

	Get an XSD-aware XML Editor (e.g., Altova XML Spy).
2.	

	Plug into it the XSD for dfdl annotations.
3.	

	Start editing a DFDL Schema.
4.	

	When you type dfdl:sequence instead of dfdl:format, based on the
schema (for DFDL annoataions) information, Altova XML Spy will give you
pulldown lists and graphical prompting which will show you only the relevant
properties.
5.	

	If you type dfdl:format you get all the properties, little help for
narrowing down the list.

The whole point: cheap and easy tooling to help author DFDL schemas.

This is why these were moved to a later section of the document. They're not
needed for the DFDL language per se. They're just there to enable this
tooling. Symantically, they mean exactly what dfdl:format means. We could
just completely avoid mention of them until that point in the spec., which
would perhaps remove the issues of confusion as mentioned by Dave Glick. 

Here's the reason why we might want to remove them anyway: Too many
properties are applicable to these things. Since everything can have text
represetnation, and text representation requires a whole bunch of
properties, you get a long list of properties for a dfdl:sequence. Not a
short list of separator/terminator type properties only. Every property that
affects text and character sets applies. Given this, the value of these
things gets somewhat diluted.

I can go either way with this particular item. At minimum we should reserve
all symbols in the dfdl namespace. I think Suman is right that if we don't
specify these, then people will create them in various non-standard ways.

  _____  

From: dfdl-wg-bounces at ogf.org [mailto:dfdl-wg-bounces at ogf.org] On Behalf Of
Steve Hanson
Sent: Monday, March 02, 2009 6:45 PM
To: Suman Kalia
Cc: dfdl-wg at ogf.org
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 at uk.ibm.com
Phone (+44)/(0) 1962-815848 

Suman Kalia <kalia at ca.ibm.com> 

02/03/2009 22:02 

To
Steve Hanson/UK/IBM at IBMGB 

cc
dfdl-wg at ogf.org, "Dave Glick" <dglick at 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.h
tml>
http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.ht
ml

Tel : 905-413-3923  T/L  969-3923
Fax : 905-413-4850 T/L  969-4850
Internet ID : kalia at ca.ibm.com 

From: 	Steve Hanson <smh at uk.ibm.com> 

To: 	Suman Kalia/Toronto/IBM at IBMCA 

Cc: 	dfdl-wg at ogf.org, "Dave Glick" <dglick at 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 at uk.ibm.com
Phone (+44)/(0) 1962-815848 

Suman Kalia <kalia at ca.ibm.com> 
Sent by: dfdl-wg-bounces at ogf.org 

02/03/2009 16:25 

To
"Dave Glick" <dglick at dracorp.com> 

cc
dfdl-wg at ogf.org, dfdl-wg-bounces at 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.h
tml>
http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.ht
ml

Tel : 905-413-3923  T/L  969-3923
Fax : 905-413-4850 T/L  969-4850
Internet ID : kalia at ca.ibm.com 
From: 	"Dave Glick" <dglick at dracorp.com> 

To: 	"Alan Powell" <alan_powell at uk.ibm.com>, <mbeckerle.dfdl at gmail.com> 

Cc: 	dfdl-wg at 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  |   <mailto:dglick at dracorp.com> dglick at dracorp.com  |
703.299.0700 x212
Data Research and Analysis Corp.  |   <http://www.dracorp.com/>
www.dracorp.com 

  _____  

From: dfdl-wg-bounces at ogf.org [ <mailto:dfdl-wg-bounces at ogf.org>
mailto:dfdl-wg-bounces at ogf.org] On Behalf Of Alan Powell
Sent: Monday, March 02, 2009 11:03 AM
To: mbeckerle.dfdl at gmail.com
Cc: dfdl-wg at 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 at uk.ibm.com  
Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898 

From: 	"Mike Beckerle" <mbeckerle.dfdl at gmail.com> 

To: 	Alan Powell/UK/IBM at IBMGB 

Cc: 	<dfdl-wg at 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. 

  _____  

From: Alan Powell [ <mailto:alan_powell at uk.ibm.com>
mailto:alan_powell at uk.ibm.com] 
Sent: Thursday, February 26, 2009 12:22 PM
To: mbeckerle.dfdl at gmail.com
Cc: dfdl-wg at 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 at 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. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU 

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  _____  

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. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU 

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