New issue - ws-tx: term "coordinator" overloaded

["Peter Furniss" <peter.furniss@erebor.co.uk>]

Issue name -- WS-C, WS-AT, WS-BA: Term "Coordinator" overloaded

 

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Target document and draft:

 

Protocol:  Coord, AT, BA

 

Artifact:  spec

 

Draft:

 

Coord spec - cd-01
AT spec  - cd-01
BA spec - cd-01

 

Link to the document referenced:

 

http://www.oasis-open.org/committees/download.php/17311/wstx-wscoor-1.1-spec-cd-01.pdf
http://www.oasis-open.org/committees/download.php/17325/wstx-wsat-1.1-spec-cd-01.pdf
http://www.oasis-open.org/committees/download.php/17302/wstx-wsba-1.1-spec-cd-01.pdf

 

Section and PDF line number:

 

Numerous

 

Issue type:

 

Editorial

 

Related issues:

 

 

 

Issue Description:

 

The term "Coordinator" or "coordinator" is used with three distinct meanings:
 
 A) as a synonym for "coordination service";
 
 B) to describe the logical entity that coordinates all of the participants registered for a transaction;
 
 C) to describe the logical entity that executes a coordination protocol with respect to a single participant.
 
These have different lifecycles and undergo distinct (though sometimes related) state transitions. Distinct terms should be used for each meaning and used consistently across the set of the specifications, to avoid ambiguity and confusion.

 

Issue Details:

 

Meaning A:

 

WS-Coordination explicitly offers "coordinator" as a synonym for "coordination service" (lines 16, 181, 627), and uses the term in that sense in other places (e.g. figure 1, lines 31, 318).

 

This sense is used in WS-BA line 159 and 160 (strictly that is "implementation of a coordination service")

 

An A-Coordinator is a service with an indefinite lifetime, greater than a single coordinated activity and with no defined states.

 

Meaning B:

 

In WS-C the term Coordinator is also used to mean: the entity whose registration EPR and identifier is tranmitted in a CoordinationContext, and which is capable of receiving registrations of multiple participants. ("B-Coordinator"). WS-Coordination sometimes uses the term "coordination context" to refer to this entity (line 514), though usually "coordination context" means the transmissable datatype, as in lines 140-175.

 

In WS-AT, "coordinator" is normally used in this sense (e.g. lines 95, 116, all of section 4.3.3). (In some cases, "coordination service" would be a meaningful alternative, in others not - which indicate it is not a synonym as in sense A).

 

In WS-BA, "coordinator" is clearly of this sense in lines 157 and 158.

 

A B-coordinator is state entity created with the CreateCoordinationContext and ending when all activity is over and it is forgotten (exact details of its termination depend on the coordination type)

 

Meaning C:

 

The term Coordinator is also used in WS-BA to mean: the sub-entity of a B-Coordinator that handles the execution of a protocol with respect to a single participant ("C-Coordinator").

 

The WS-AT does not use "coordinator" in quite this sense - the state tables appear to (but see separate issue) but lines 494-496 distinguish coordinator (sense B) and the state machines.

 

In WS-BA, lines 221-234 use coordinator in sense C (since they refer to the state of a coordinator without regard to other participants) as do the state tables.

 

A C-Coordinator is a state entity created when a Register message is received (if received when B-Coordinator is in appropriate state), and ending when the relationship with the participant is terminated (details depend on coordination type and protocol)

 

 

It might be possible to push the interpretation of coordinator = "coordination service" in many cases, but it would seem unnatural. Understanding "coordinator" to mean sometimes "the continuing coordination service, used by numerous transactions", sometimes "a coordination service's view of a particular transaction" and sometimes "a coordination service's view of the state of a registered relationship with a particular participant service" is not helpful. A state entity should have a name, not be the anonymous view of a state from the perspective of a general entity.

 

 

 

Proposed Resolution:

(obviously more than one way to handle this)

 

A. WS-C: remove all references to "coordinator" that mean A-Coordinator, and replace them with "coordination service".

 

B. WS-C/AT/BA: use the term "Coordinator" for B-Coordinator exclusively.

 

C. WS-AT/BA: use the term "Bilateral Coordinator" for C-Coordinator, e.g. "Bilateral Coordinator View" in describing the coordinator view in a state table title.