activity context

Something we haven't yet got round to discussing in 
much detail is the notion of (business activity) context (c.f. transaction 
context). This is the context information that flows from the initiator and 
between high-level participants (i.e., business objects). We can encode this 
information within the XML, for example. The actual format of the context is 
obviously important for interoperability. If you've had a chance to read my 
previous emails you'll see that it should be possible to support a range of 
different extended transaction models with a single infrastructure, and each of 
these may have a slightly different requirement on the context. So, is it 
possible to have a single context structure that can map to these models? I 
believe so. Using CORBA IDL as an example:

 

struct Context
{
    unsigned 
long actionType;
    long timeout;
    
Coordinator theCoordinator;
    sequence <octet> 
actionId;
    any 
activity_specific_data;
};

 

where:

 

(i) actionType defines the type of model being used 
(so that the rest of the context may be interpreted 
appropriately)

 

(ii) 
timeout is the timeout period associated with the business activity, such that 
if it hasn't completed within this period it will automatically be completed 
with a "failed" semantic (whatever "failed" means will be application 
dependant).

 

(iii) 
theCoordinator is a reference to the coordinator (this may be the root 
coordinator or a subordinate coordinator, depending upon who sent the 
context).

 

(iv) 
actionId is a unique identifier for this business activity.

 

(v) 
activity_specific_data is arbitrary data that is encoded in the context and may 
be interpreted on a per invocation/per model basis.

 

Obviously 
there are other ways in which the context information may be specified and 
encoded. This is just an example. What do people think?

 

What 
I'm hoping to show from this is that the context doesn't have to be complex in 
order to be powerful.

 

Mark.

 

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Dr. Mark Little ()
Transactions Architect, HP 
Arjuna Labs
Phone +44 191 2064538
Fax   +44 191 2064203