Issue 013 - WS-C: Remove fault 4.5 ContextRefused

["Peter Furniss" <peter.furniss@choreology.com>]

This is hereby declared to be ws-tx Issue 013.

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Issue name -- WS-C: Remove fault 4.5 ContextRefused

Owner:  Alastair Green [mailto:alastair.green@choreology.com] 
 
Target document and draft:
 
Protocol:  Coord

Artifact:  spec / schema

Draft:
 
Coord spec working draft uploaded 2005-12-02
WS-Coordination schema contributed by input authors, not yet uploaded 
to Working Drafts folder
 
Link to the document referenced:
 
http://www.oasis-open.org/committees/download.php/15738/WS-Coordination-
2005-11-22.pdf

Section and PDF line number:
 
 Section 4.5 "Context Refused", ll. 451-459
 
 
Issue type: Design
 
 
Related issues:
 
 Issue 003 - WS-C: Appropriate categories of fault
 
 
Issue Description:
 
ContextRefused fault relates to application protocol behaviour which 
should not be specified by WS- Coordination.
 
 
Issue Details:
 
 [This issue stems from Choreology Contribution issue TX-19.]
 
Faults in WS-C should be divided into only two categories: those which
apply 
to the process of context creation and registration (or which apply to
the misuse of the 
conversational channel created by
registration), and those which are basic faults available to all 
coordination protocols.
 
ContextRefused is a fault that relates to an application protocol (an 
exchange between two applications that are attempting to establish 
agreed use of a distributed coordination protocol). Such protocols 
should define their own messages and faults.
 
The preamble of this fault (l1. 452-453) states:
 
 "This fault is sent to a coordinator to indicate that the endpoint 
 cannot accept a context which it was passed:"

This description evokes the problem perfectly. An application 
communicates a context (by some means) to a service. The service 
decides that it does not wish to register any participants. This 
decision may be important, or unimportant, to the original propagator 
of the context.
 
Example A: in an auction, the context has been posted on a secure 
website, accessible by registered bidders. The fact that registered 
bidder 43 is not interested in making an offer
is uninteresting to the auction site.
 
Example B: a client knows that he cannot proceed with a 
three-component trade unless at least one service for
each component has registered. The client-service contract 
states that 
the service will either send a quote or
will send a not-interested message, to ensure rapid conclusion of the 
transaction.

Example C: same scenario as B, but the client simply tracks inbound 
quotes, and decides when he has sufficient to proceed to make a choice 
and conclude the transaction.
 
Examples A and C do not require the semantic "not-interested" to be
communicated: the semantic is not
generally needed, therefore. Example B requires the semantic to be 
communicated from service to client, but not from the service to the
Coordinator. We cannot assume that the 
Coordinator has any interest in presence or
absence of particular participants, or their number ("checking"). 
Indeed, products implementing protocols such
as WS-AT and WS-BA typically leave checking issues in the 
hands of the application.  
 
These kinds of communications are the property of specific application
protocols 
(or perhaps, of some future coordination protocols) but not of a
general-purpose 
coordination framework.
 
 
Proposed Resolution:
 
Remove ll. 451-459 of the specification.
Remove l. 100 of the schema document.