W3C home > Mailing lists > Public > public-ws-chor@w3.org > March 2005

Re: toRole and fromRole names and type references and similar.

From: Gary Brown <gary@enigmatec.net>
Date: Mon, 21 Mar 2005 13:00:31 -0000
Message-ID: <00a301c52e15$fa44f020$0200a8c0@LATTITUDEGary>
To: "Tony Fletcher" <tony_fletcher@btopenworld.com>, <public-ws-chor@w3.org>
MessageHi Tony,

I still need a concrete example, as I don't see what is missing from the current CDL spec. What you are suggesting seems to be adding more content to a choreography definition without adding more value - I'm sorry but at the moment I don't understand the problem you are trying to solve.

If you are objecting to the fact that we have role types, but no instances, then possibly the problem is that we have "role types". Maybe we should just have "roles" - i.e. a participant plays a set of roles, and a relationship provides an association between two roles. Likewise, a relationship instead of a relationshipType.

Regards
Gary
  ----- Original Message ----- 
  From: Tony Fletcher 
  To: 'Gary Brown' ; public-ws-chor@w3.org 
  Sent: Monday, March 21, 2005 12:46 PM
  Subject: RE: toRole and fromRole names and type references and similar.


  Dear Gary,

  Thank you for your response.  The intent was not role instances but rather instances of roleTypes - which is a role!

  That is the point I am making.  At present we set up the participantType, roleType and ChannelType definitions, but then each time we use a role we have to give it a name and say what type it is.  If you look towards the bottom of my mail you will see I have suggested adding a roleAssignments element where one could say what roles the choreography used give them names and say what type they were and then we could just use the role name and omit the type reference elsewhere.
  <roleAssignments name="ncname" ">

     <roleAssignment role name="ncname" roleType="qname" />+

  </roleAssignments>


  Maybe even better would be to have an element where one assigned a name to a participant and said what type it was and gave names to each role in that participant - we define participantTypes at present but never seem to use participants (of a given type).

  So we would then have:
  <participantType name="ncname">

     <roleType typeRef="qname" />+

  </participantType>

  and something like
  <participant name="ncname" typeRef="qname">

     <role name="ncname" typeRef="qname" />+

  </participantType>

  where the typeRef of the participant needs to match an 'ncname' of a participantType and the typeRef (s) of the role(s) need to match the corresponding 'ncname'(s) of a roleType contained in that participantType.

  Best Regards     Tony
  A M Fletcher
  Home: 35, Wimborne Avenue, IPSWICH  IP3  8QW
  Tel: +44 (0) 1473 729537   Mobile: +44 (0) 7801 948219
   amfletcher@iee.org       (also tony_fletcher@btopenworld.com)

  -----Original Message-----
  From: Gary Brown [mailto:gary@enigmatec.net] 
  Sent: 21 March 2005 08:57
  To: Tony Fletcher; public-ws-chor@w3.org
  Subject: Re: toRole and fromRole names and type references and similar.


  Hi Tony,

  I am not sure why we need the name and type reference, can you give a concrete example? As we don't have the concept of role instances, I would assume that a single attribute (whether called name or type ref) would be sufficient.

  Regards
  Gary
    ----- Original Message ----- 
    From: Tony Fletcher 
    To: public-ws-chor@w3.org 
    Sent: Saturday, March 19, 2005 11:04 PM
    Subject: toRole and fromRole names and type references and similar.


    Dear Colleagues,

    In trying to sort out roletypes from roles for issues 1018 and 1018
    I wonder if we should not change the interaction syntax defined in 2.5.2.3 from
                                                         Interaction Syntax
    The syntax of the <emph>interaction</emph> construct is:



    <interaction  name="ncname"

                  channelVariable="qname"

                  operation="ncname"

                  align="true"|"false"?

                  initiate="true"|"false"? >

     

       <participate  relationshipType="qname"

                     fromRole="qname" toRole="qname" />

     

       <exchange  name="ncname"

                  informationType="qname"?|channelType="qname"?

                  action="request"|"respond" >

         <send      variable="XPath-expression"? 

                    recordReference="list of ncname"?   

                    causeException="true"|"false"? />

         <receive   variable="XPath-expression"? 

                    recordReference="list of ncname"? 

                    causeException="true"|"false"? />

       </exchange>*

     

       <timeout  time-to-complete="XPath-expression"

                 fromRoleRecordReference="list of ncname"?

                 toRoleRecordReference="list of ncname"? />?

     

       <record  name="ncname"

                when="before"|"after"|"timeout"

                causeException="true"|"false"? >

         <source  variable="XPath-expression"? | expression="Xpath-expression"? />

         <target  variable="XPath-expression" />

       </record>*

    </interaction>

    to
                                                         Interaction Syntax
    The syntax of the <emph>interaction</emph> construct is:



    <interaction  name="ncname"

                  channelVariable="qname"

                  operation="ncname"

                  align="true"|"false"?

                  initiate="true"|"false"? >

     

       <participate  relationshipType="qname"

                     fromRole="ncnameqname" fromRoleType="qname"

                     toRole="ncnameqname" toRoleType="qname"

       />

     

       <exchange  name="ncname"

                  informationType="qname"?|channelType="qname"?

                  action="request"|"respond" >

         <send      variable="XPath-expression"? 

                    recordReference="list of ncname"?   

                    causeException="true"|"false"? />

         <receive   variable="XPath-expression"? 

                    recordReference="list of ncname"? 

                    causeException="true"|"false"? />

       </exchange>*

     

       <timeout  time-to-complete="XPath-expression"

                 fromRoleRecordReference="list of ncname"?

                 toRoleRecordReference="list of ncname"? />?

     

       <record  name="ncname"

                when="before"|"after"|"timeout"

                causeException="true"|"false"? >

         <source  variable="XPath-expression"? | expression="Xpath-expression"? />

         <target  variable="XPath-expression" />

       </record>*

    </interaction>


    That is that we should give the roles names as well as showing what type the correspond to.

    Similarly for perform.  Should we not change
    <perform  choreographyName="qname" 

              choreographyInstanceId="XPath-expression"? >

       <bind  name="ncname">

         <this variable="XPath-expression" role="qname"/>

         <free variable="XPath-expression" role="qname"/>

       </bind>*

       Choreography-Notation?

    </perform>

    to
    <perform  choreographyName="qname" 

              choreographyInstanceId="XPath-expression"? >

       <bind  name="ncname">

         <this variable="XPath-expression" role="ncname" roleTypeRef="qname"/>

         <free variable="XPath-expression" role="ncname" roleTypeRef="qname"/>

       </bind>*

       Choreography-Notation?

    </perform>


    I propose to change the syntax of assign from
     

    <assign  roleType="qname">

       <copy  name="ncname" causeException="true"|"false"? >

          <source  variable="XPath-expression"?|expression="Xpath-expression"? />

          <target  variable="XPath-expression" />

       </copy>+

    </assign>

    to
     

    <assign  role="ncname" roleType="qname">

       <copy  name="ncname" causeException="true"|"false"? >

          <source  variable="XPath-expression"?|expression="Xpath-expression"? />

          <target  variable="XPath-expression" />

       </copy>+

    </assign>


    I propose to change the syntax for noAction from 
     

    <noAction roleType="qname? />

     

    to 
     

    <noAction role="ncname"? roleType="qname"? />

     



    although having one place in a choreography where we say what roles are involved and what the type of each role is would probably be better then doing it in several places like this and having to check consistency.  Perhaps something like
    <roleAssignments name="ncname" ">

       <roleAssignment role name="ncname" roleType="qname" />+

    </roleAssignments>


    then noAction would become
    <noAction role="ncname"? />


    and similar elsewhere.




    Best Regards     Tony
    A M Fletcher

    Cohesions  (TM)

    Business transaction management software for application coordination       www.choreology.com

    Choreology Ltd., 68 Lombard Street, London EC3V 9LJ     UK
    Tel: +44 (0) 1473 729537   Mobile: +44 (0) 7801 948219
    tony.fletcher@choreology.com     (Home: amfletcher@iee.org)
Received on Monday, 21 March 2005 13:00:53 UTC

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