Mike

Am I allowed to put DFDL properties on the new simple type, or is the new type considered to be a built-in type? I think the latter is clearer and simpler to implement. Support for 'clob' would then just add a new simple type restriction 'dfdlx:clob'.

Assuming that the feature makes it into a future DFDL 2.0, the schema containing the 'blob' simple type would then be in the standard DFDL namespace. That's the first example of such a schema, as this is the first time we are extending base XML Schema as opposed to defining annotations. If the new type is considered a built-in type, then this schema should be part of the DFDL 2.0 standard and read-only.

Any thoughts on allowing the specification of the filename via DFDL property rather than API call?

Presumably I could create a local restriction of 'dfdlx:blob'? One motivation for so doing would be to validate the length or content of my binary data. There's a problem with that though - validation works against the infoset, so the allowable facets are those applicable to xs:anyUri and would be applied to the file name, not the binary data. It also means that dfdl:lengthKind 'implicit' can't be used. I don't see a way round this.

Regards

Steve Hanson

IBM Hybrid Integration, Hursley, UK
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
smh@uk.ibm.com
tel:+44-1962-815848
mob:+44-7717-378890
Note: I work Tuesday to Friday

From: Mike Beckerle <mbeckerle.dfdl@gmail.com>
To: DFDL-WG <dfdl-wg@ogf.org>
Date: 12/07/2019 18:14
Subject: [DFDL-WG] BLOB - binary large object proposal - updated
Sent by: "dfdl-wg" <dfdl-wg-bounces@ogf.org>

This concept, ,which has been discussed before, is in high demand in the Daffodil user community to enable DFDL to be used to parse image file formats.
The use case is to provide uniform image-metadata access without getting bogged down in the large byte-array that makes up most of the file and would be very large (and pointless) if rendered into XML or JSON.

So our proposal, (which will get turned into an official Experimental feature document), has been simplified and revised and is described here:

https://cwiki.apache.org/confluence/display/DAFFODIL/Proposal%3A+Binary+Large+Objects

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
-- 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