[DFDL-WG] Fw: DFDL Discriminator - Question from Ruth
Tim Kimber
KIMBERT at uk.ibm.com
Thu Nov 18 08:27:07 CST 2010
I think the rule should be 'at most one discriminator on an element or
group'. If you have more than one discriminator then you have to define
what happens if some of them pass and the others fail.
regards,
Tim Kimber, Common Transformation Team,
Hursley, UK
Internet: kimbert at uk.ibm.com
Tel. 01962-816742
Internal tel. 246742
From: Stephanie Fetzer <sfetzer at us.ibm.com>
To: dfdl-wg at ogf.org
Date: 18/11/2010 13:17
Subject: [DFDL-WG] Fw: DFDL Discriminator - Question from Ruth
Sent by: dfdl-wg-bounces at ogf.org
All:
On the DFDL WG call 17NOV2010 my concern was that this rule was added
'recently' but on closer review I see that it was just changed a bit
("discriminators" changed to "dfdl:discriminators"). Ruth, Alan and I are
all in agreement that this rule is a throwback to an earlier
discrimination schema and needs to be removed.
The proposal is to remove the following from the spec:
In section 7.4 : "There can be at most one dfdl:discriminator within a
sequence group. It is a schema definition error if there is more than one
dfdl:discriminator annotation that applies to a single sequence group
I'm sending this email out with two purposes:
1. Does anyone disagree and believe that this rules is still relevant?
2. Is this change critical enough to amend the final spec or publish
some form of errata to the specification? And if so, what is our next
step?
Regards,
Stephanie Fetzer
WebSphere Transformation Extender (WTX)
Industry Packs - Architect
----- Forwarded by Stephanie Fetzer/Charlotte/IBM on 11/18/2010 07:54 AM
-----
From:
Alan Powell/UK/IBM at IBMGB
To:
Stephanie Fetzer/Charlotte/IBM at IBMUS
Cc:
Ruth Wiegand/Boca Raton/IBM at IBMUS, Steve Hanson/UK/IBM at IBMGB
Date:
11/17/2010 05:55 AM
Subject:
Re: DFDL Discriminator - Question from Ruth
Stephanie
I think you are correct. That statement is probably left over from when
the discriminator confirmed the existence of a parent.
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 at uk.ibm.com
From: Stephanie Fetzer/Charlotte/IBM at IBMUS
To: Steve Hanson/UK/IBM at IBMGB, Alan Powell/UK/IBM at IBMGB
Cc: Ruth Wiegand/Boca Raton/IBM at IBMUS
Date: 16/11/2010 20:42
Subject: DFDL Discriminator - Question from Ruth
Steve/Alan:
Was just talking with Ruth about the discriminators and I think we've got
something in the spec that we may need to remove in this area. Let me
talk this out here first to see if perhaps I've remembered something
incorrectly.
In section 7.4 we have: "There can be at most one dfdl:discriminator
within a sequence group. It is a schema definition error if there is more
than one dfdl:discriminator annotation that applies to a single sequence
group"
This makes perfect sense in WTX. In WTX an identifier is placed on a
component of a group. Then the identifier is proven to exist the parent
exists. Allowing only one per the sequence is necessary in this scheme.
In DFDL we place the discriminator on the component being discriminated.
So we have a rule that points to ones children such as ..if present child2
then I exist.
I can not see how the 'one per sequence' gets us anything in CT in most
cases. We can't mean that only one of the parents in a sequence can
contain a discriminator. In EDI each segment in a loop can have a
discriminator. As we are using a rule at the parent it would be difficult
(and not very useful) to restrict the rule to referencing only one child.
So I'm confused - and I've confused Ruth.
Can we take five minutes from the WG call to straighten me back out again
please?
Regards,
Stephanie Fetzer
WebSphere Transformation Extender (WTX)
Industry Packs - Architect
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