Tim's presentation is insightful. Highlights (actually it's all good so this is most of the presentation): - Use plain text if... you possibly can. - JSON issues: Watch out for extensibility. - Use JSON if... The expected lifetime of the data is short. - Use XML if... your data is document flavoured or you're worried about i18n, extensibility or reusability. - Inventing New XML Languages: - Time-consuming. - Bureaucratic. - Difficult. - Unpleasant. - Includes complex software development as a sub-task. - Usually fails. - ... so try not to! - Some Good XML Languages - XHTML - DocBook - ODF - Atom - XMPP - UBL - RDF - Design Issue: Model vs. Syntax - “What matters is getting the data model right. The syntax is ephemeral.” vs - “The bits on the wire are the only reality.” - Design Issue: Minimalism vs. Completeness - “Let’s solve the whole problem.” - “Minimum progress required to declare victory.” - XML Schema Definitions (XSD): - Hard to understand, hard to implement, hard to interoperate. - One of the reasons why the SOA/WS-* project is sinking. - XML Extensibility: Three Options - No changes. - Must-Understand policy (e.g. as in SOAP). - Must-Ignore policy (e.g. as in Atom). Morals of the story (IMO): - Bend over backwards to use plain text (if we can) - JSON is more interesting for RPC than ROA (Resource Oriented Architecture) - Avoid inventing new [XML] languages at all costs - 6 of the 7 "good" XML languages have already come up in the context of OCCI (NFI what UBL is) - Model and bits-on-the-wire are both important to us - RELAX NG and XPath is a GoodThing™ - For XML extensibility ignore that which you don't understand (ala Atom) - Solve as much of the problem as we need to now but provide for extensibility later Sam ---------- Forwarded message ---------- From: Tim Bray <tbray@textuality.com> Date: 2009/5/27 Subject: Re: Structured data over TCP? To: Patrik Fältström <patrik@frobbit.se> Cc: apps-discuss@ietf.org 2009/5/26 Patrik Fältström <patrik@frobbit.se>:

Do Apps Area have any general feeling about this?

I was going to start typing in a lengthy answer but then I remembered I gave a tutorial at IETF70 on the choice of data formats for use in Internet Protocols. It's centered around XML but I think covers many of the other issues that have come up in this. Available for your reading pleasure at http://www.tbray.org/tmp/IETF70.pdf -Tim _______________________________________________ Apps-Discuss mailing list Apps-Discuss@ietf.org https://www.ietf.org/mailman/listinfo/apps-discuss