Re: partner link assignment

["Antony Miguel" <antony.miguel@scapatech.com>]

Hi,

 

Maybe I can clarify my question here:

 

Lets say I have a partner link P1 and I carry out the following sequence:

 

    1. Copy an endpoint reference into P1 pointing to host H1

    2. Invoke something on the partner link (and therefore host H1)

    3. Copy an endpoint reference into P1 pointing to host H2

    4. Invoke something on the partner link (and therefore host H2)

    5. Copy the first endpoint reference back into P1, pointing to host H1

    6. Invoke something on the partner link (and therefore host H1)

 

In the above sequence, the BPEL engine would have to create a port instance at points 2 and 4.

When point 6 is reached, I would expect the BPEL engine could either re-use the port instance created in 2 or create a new one.

 

My first question is: is this correct?

 

My second question is: if I use a correlation set to correlate points 2 and 6, does this mean the BPEL engine must use the same

port instance in 6 as it did in 2?  Is this the essential purpose of correlation sets - to be associated to a particular port instance?

 

thanks for the help

 

Antony Miguel
Scapa Technologies
antony.miguel@scapatech.com
+44 131 550 1766

----- Original Message -----

From: Antony.Miguel@scapatech.com

To: wsbpel-comment@lists.oasis-open.org

Sent: Thursday, July 08, 2004 4:20 PM

Subject: partner link assignment

Hi,

 

I have another question that I have been struggling to resolve while reading the BPEL specification, hopefully someone can shed some light on it.

 

The basic question is: what does it mean to assign one partner link endpoint to another partner link endpoint?  Is there an example BPEL program somewhere which uses this functionality for something or can someone provide a quick example of a situation in which it could be used?

 

As I understand it (and I don't :) ), roles in a partnerLink just reference one portType each.  Each portType has only one binding so (since the binding is used to create the concrete instances of a portType) assigning one partner link endpoint (role) to another partner link endpoint just means copying one port instance over another port instance (where both instances are equivalent, having been instantiated using the same binding information).  Furthermore, this copying of port instances seems redundant since which port instance is actually used for an invocation etc is determined by the correlation sets associated with a port instance.

 

Do partnerLinks and their endpoint references map to concrete instances of portTypes?  (are partnerLink endpoint references just port instances?)  If so then why are correlation sets necessary? since the port instance to which a invocation refers at runtime is defined by the endpoint reference.

 

If someone has an example BPEL program that demonstrates both correlation sets and partner link assignment, that would be help me a lot.

 

thanks

 

Antony Miguel
Scapa Technologies
antony.miguel@scapatech.com
+44 131 550 1766