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Related issues

A profile of MIME

One of the weaknesses of XML is that it is not particularly suitable for conveying non-textual content.

Of course, techniques exist to encode binary data in an XML document, but these are, at best, unnecessarily wasteful of space and bandwidth when transferring large amounts of data (e.g. photographic images).

This problem has been recognized, and specifications [11][12] have been prepared to address the problems.

An alternative approach, compatible with [12], would be to utilize an existing, widely-used specification, viz MIME.  Considering an proferred design alternative, the DIME specification provides:

  • message framing (delimiting)
  • message chunking
  • payload type labelling
  • payload instance identification
  • aggregation of logically related document components
  • additional metadata

Which to me all look very much like existing MIME capabilities.  The main differences I see are:

  • DIME is designed on the assumption of a binary carrier capability, and
  • DIME allows URIs to be used as well as MIME content-type values for payload type tagging
  • content delimiting by byte counting rather than boundary string or end-of-stream detection

I suggest that a simplified MIME profile could provide pretty much the same capabilities, but also be accessible to vast numbers of existing applications, using:

  • Content-type, Content-type-encoding and Content-ID headers,
  • default 8-bit content transfer encoding, and
  • multipart/related, message/partial (for chunking, if required), and simple content-types

[11] Direct Internet Message Encapsulation (DIME), Henrik Frystyk Nielsen, Henry Sanders, Russell Butek, Simon Nash, 17 June 2002,   http://www.ietf.org/internet-drafts/draft-nielsen-dime-02.txt .

[12] SOAP 1.2 Attachment Feature, Henrik Frystyk Nielsen, Hervé Ruellan, W3C Working Draft 24 September 2002, http://www.w3.org/TR/soap12-af .

[13] See also: Cover Pages, Technology Reports, Direct Internet Message Encapsulation (DIME), http://xml.coverpages.org/dime.html .

[14] See also: SOAP Messages with Attachments, John J. Barton, Satish Thatte, Henrik Frystyk Nielsen, W3C Note 11 December 2000,   http://www.w3.org/TR/SOAP-attachments .