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>

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