RE: [xml-dev] REST, SOAP, Speech Acts and the mustUnderstand model of SOA communications (was: Re: What Does SOAP/WS Do that A REST System Can't?)

["Michael Kay" <mike@saxonica.com>]

Not to mention

xml:mustUnderstand="7": receiver may misunderstand. This is also very common
in eCommerce.

Michael Kay
http://www.saxonica.com/
 

> -----Original Message-----
> From: Peter Rodgers [mailto:pjr@1060.org] 
> Sent: 01 April 2005 11:55
> To: sean.mcgrath@propylon.com
> Cc: xml-dev@lists.xml.org
> Subject: Re: [xml-dev] REST, SOAP, Speech Acts and the 
> mustUnderstand model of SOA communications (was: Re: What 
> Does SOAP/WS Do that A REST System Can't?)
> 
> You forgot:
> 
> xml:mustUnderstand="6" - reciever must understand each and 
> every meaning 
> of the message both explicit and by inference from supporting 
> metadata 
> for example, the timestamp of the message.
> 
> 
> Sean McGrath wrote:
> > Whatever about the pros and cons of REST versus SOAP, I think it is
> > abundantly clear that the mustUnderstand model [1] is a key 
> concept in
> > developing loosely coupled systems that can evolve independently.
> > 
> > I would like to suggest that the mustUnderstand model is 
> sufficiently
> > important that it should be added to the xml namespace alongside
> > xml:space and xml:lang.
> > 
> > I'm a big fan of conceptualising XML message exchange in terms of
> > Speech Acts[2]. To make the most of the power of this abstraction, I
> > think it is necessary to extend the coarse boolean mustUnderstand
> > model into a more fine grained model that matches the way 
> speech acts
> > are used in the real world.
> > 
> > I would like to suggest that xml:mustUnderstand be an 
> enumeration with
> > a number of positive integer values, the semantics of 
> which, should be
> > part of the specification. I can think of five.
> > 
> > Additions/comments on these welcome:
> > 
> > 
> > xml:mustUnderstand="0" - It is permissable for the recipient to not
> > understand the message fragment. No specific directions about the
> > speech act semantics in this case.
> > 
> > xml:mustUnderstand="1" - The message fragment must be understood,
> > otherwise the conversation must fail.
> > 
> > xml:mustUnderstand="2" - reciever must claim to understand, 
> even if it
> > does not. The sender should have not be able to tell whether or not
> > the receiver really understands or is simply claiming to
> > understand. This is particularly useful in the service industries.
> > 
> > xml:mustUnderstand="3" - receiver may at first issue one or more
> > failure responses indicating that it does not understand the message
> > fragment. Then, without any action from the sender other 
> than retries,
> > the receiver begins to understand the message fragment. 
> This has many
> > applications in the political arena.
> > 
> > xml:mustUnderstand="4" - reciever may claim to understand 
> the message
> > fragment one or more times and then begin issuing failure
> > responses. The failure responses should indicate that the 
> message was
> > never understood and assert that the receivers behavior has been
> > consistent in this regard all along. This has many 
> applications in the
> > media and in academia.
> > 
> > xml:mustUnderstand="5" - reciever may claim not to understand but,
> > unknown to the sender, may act upon the message fragment. This has
> > many applications in e-commerce.
> > 
> > 
> > Thoughts?
> > 
> > Sean
> > seanmcgrath.blogspot.com
> > 
> > [1]
> > 
> http://www.pacificspirit.com/blog/2004/07/27/dare%20versioning
> %20extensibility%20article%20comparison 
> > 
> > 
> > [2]
> > 
> http://www.manageability.org/blog/stuff/the-restfulness-of-spe
> ech-acts/view
> > 
> > 
> > 
> > 
> > 
> > 
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