Yes I can see the use-case for use during unparsing when asserts can not be used. Will add to agenda for future WG call.

Regards

Steve Hanson
IBM Integration Bus, Hursley, UK
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
smh@uk.ibm.com
tel:+44-1962-815848
mob:+44-7717-378890

From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: "dfdl-wg@ogf.org" <dfdl-wg@ogf.org>
Date: 14/06/2016 17:10
Subject: Re: [DFDL-WG] still no need for fn:error
Sent by: "dfdl-wg" <dfdl-wg-bounces@ogf.org>

I want to re-open the discussion of fn:error.

Previously we said it was not needed because an assert could be used.

However, we've now run into where we want to cause an error, during unparsing, during outputValueCalc.

<xs:element name="Protocol" type="pcap:bit" dfdl:length="8"
           dfdl:outputValueCalc="{
           if (fn:exists(../../pcap:ICMPv4)) then 1
           else if (fn:exists(../../pcap:TransportLayer/pcap:TCP )) then 6
           else if (fn:exists(../../pcap:TransportLayer/pcap:UDP )) then 17
           else -1 }"/>

That -1 at the end. That's an error case. We really want fn:error("Unrecognized protocol.")

We can't change to a dfdl:assert, because assertions aren't evaluated when unparsing.

Comments?

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy

On Thu, Jul 25, 2013 at 9:16 AM, Mike Beckerle <mbeckerle.dfdl@gmail.com> wrote:
Respin of this example:

Here's the example as suggested by Jonathan of how to issue an error that I previously was suggesting needed fn:error. I'm convinced this is sufficient and we can avoid the need for fn:error now.

<xs:element name="magic_number" type="ex:uint32" dfdl:byteOrder="bigEndian">
<xs:annotation>
<xs:appinfo source="http://www.ogf.org/dfdl/">
     <dfdl:assert
       test="{ (xs:unsignedInt(.) eq dfdl:unsignedInt('xa1b2c3d4')) |
       (xs:unsignedInt(.) eq dfdl:unsignedInt('xd4c3b2a1')) }"
       message="{ fn:concat(
                     'Magic number ',
                     dfdl:hexBinary(dfdl:unsignedInt(.)),
   ' was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian).' }" />
   <dfdl:setVariable ref="ex:bOrd">{ xs:unsignedInt(.) }<dfdl:setVariable>
</xs:appinfo>
</xs:annotation>
</xs:element>

On Wed, Jul 24, 2013 at 11:58 AM, Steve Hanson <smh@uk.ibm.com> wrote:
Mike, I think you meant:

       test="{ (xs:unsignedInt(.) eq dfdl:unsignedInt('xa1b2c3d4')) |
       (xs:unsignedInt(.) eq dfdl:unsignedInt('xd4c3b2a1')) }"

Regards

Steve Hanson
Architect, IBM Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh@uk.ibm.com
tel:+44-1962-815848

From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: dfdl-wg@ogf.org,
Date: 24/07/2013 16:46
Subject: [DFDL-WG] still no need for fn:error
Sent by: dfdl-wg-bounces@ogf.org

Here's the example as suggested by Jonathan of how to issue an error that I previously was suggesting needed fn:error. I'm convinced this is sufficient and we can avoid the need for fn:error now.

<xs:element name="magic_number" type="ex:uint32" dfdl:byteOrder="bigEndian">
<xs:annotation>
<xs:appinfo source="http://www.ogf.org/dfdl/">
     <dfdl:assert
       test="{ (xs:unsignedInt(.) eq dfdl:unsignedInt('xa1b2c3d4')) |
       (xs:unsignedInt(.) eq dfdl:unsignedInt('xd4c3b2a1')) }"
       message="{ fn:concat(
                     'Magic number ',
                     dfdl:hexBinary(dfdl:unsignedInt(.)),
   ' was not 0xA1B2C3D4 (for bigEndian) or 0xD4C3B2A1 (for littleEndian).' }" />
   <dfdl:setVariable ref="ex:bOrd">{ xs:unsignedInt(.) }<dfdl:setVariable>
</xs:appinfo>
</xs:annotation>
</xs:element>

--
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com-- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg

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--
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com

-- dfdl-wg mailing list dfdl-wg@ogf.org https://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