Re: [DFDL-WG] still no need for fn:error

14 Jun 2016

      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
<http://www.ogf.org/About/abt_policies.php>

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/*
<http://www.ogf.org/dfdl/dfdl-1.0/>">
     <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* <http://www.ogf.org/dfdl/>
IBM SWG, Hursley, UK
*smh@uk.ibm.com* <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/*
<http://www.ogf.org/dfdl/dfdl-1.0/>">
     <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* <http://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
--
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com