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From Sanjaya Amarasekera <cron...@yahoo.com>
Subject Re: WS-Business Activity Specification Implementation for Apache Kandula2
Date Wed, 27 Dec 2006 06:45:18 GMT
Hi Everybody, 
   
  I have implemented all WS Coordination, AT and BA Specifications on .Net platform. However,
my design is technology independent and it can be easily implemented on any platform. If anyone
is interested i can send the source code. 
   
  CC Bimalee:  feel free to contact me for any assistance.
   
  CC Hannes:  I doubt the appropriateness of WS-Business Activity Initiator protocol. In BA
scenario, the initiator itself becomes the coordinator. In contrast to AT Specification, the
abstract nature of the BA Specification allows the Initiator to decide the coordination logic.
In such situations where the coordination logic resides within the Initiator application (eg:
workflow engines), it is highly unlikely to use an external coordinator. 
   
  However, I agree the fact that the introduction of a WS-Business Activity Initiator protocol
is possible and it is in accordance with the BA Specification. 
   
  When the Initiator ad Coordinator becomes two different entities, the Initiator requires
to know the status information of all the participants (which coordinator possesses) and the
coordinator need to know the coordination logic (which Initiator possesses).  Therefore, such
a new protocol should be capable of exchanging all the information (these information could
be application specific as well) between the Coordinator and the Initiator.
   
  Considering the amount of information exchange, it is very important to reduce the transportation
overheads/ delays. Usage of a new WS-Business Activity Initiator protocol will require this
communication to happen by means of Web service requests/ responses which is costly. 
   
  The question arises is that considering the usage scenarios of BA such as workflow engines,
whether is it necessary to separate the Coordinator from Initiator bearing the aforementioned
overheads and difficulties. 
   
  In my implementation I have made the Coordinator and Initiator to be a single entity and
the coordination logic to be part of the application code. The coordination rules for each
Coordination Type (Mixed outcome and Atomic outcome) is managed outside the application code
and hence, the application is free from unnecessary burdens.  
   
  However, there can be scenarios where the existence of an independent trusted Coordinator
is essentials. My implementation supports such scenarios by encapsulating the coordination
logic within the Coordinator and allowing it to run independently. In such scenarios, participants
can join the business activity using participant protocols defined in BA Specification.  

     
  Regards
  Sanjaya
   
   
   

  Hi Bimalee,


> In the mailing list we have seen that there are some people who have 
> already implemented this specification. It would be a great if they can 
> share their experiences with us.

Georg and I have more or less completed the WS-BA implementation for 
Kandula 1. We are currently working on a "real world" demonstration 
application to include with the source code and hope that this will help 
mature our code to have it released to the public.


As the WS-BA specification does not include the initiator<-->coordinator 
interface we defined a new "WS-Business Activity Initiator" protocol to 
fill this gap. Unfortunately we are still waiting for our univiersity's 
approval to publish it, but are looking forward to get it in the next week.


As to Kandula 2: if you don't want to do a complete rewrite of 
everything, all you need to do was to insert the WS-BA hooks to the 
existing WS-BA implementation into the kandula 2 core.
The WS-BA implementation Georg and I did does not require a specific 
axis implementation, I guess with some minor tweaks it should also run 
on Axis 2.


Best regards and season's greetings,

-hannes



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