1. Convoy Processing in BizTalk Orchestration

2. What is a Convoy?

3. Convoy Definition
A message may contain a field, or set of fields, whose values identify it as a member of a group of related messages, for example a unique PO number, or a SSN. A convoy scenario is one in which:
The values are not known before the arrival of the first message. That is, the first messages "defines" the group.
Succeeding messages in the group may arrive before any further processing or synchronization takes place.
All messages in the group must be processed by the same handler.

4. Scenarios Supported by BizTalk: Parallel Convoy
The messages may be of different types. There is no defined order in which the messages are expected to arrive. The handler accepts them in any order and may process them in parallel.
Clearinghouse example.

5. Parallel Convoy Restrictions
If one of the tasks of a parallel has an activatable receive as the first shape, all of the tasks of that parallel must have an activatable receive as the first shape and all of these receives must initialize at least one correlation.
If a particular correlation is initialized on more than one task of a parallel by a receive, each of the concerned receives must initialize exactly the same correlations.
If a particular correlation is initialized on more than one task of a parallel by a non-activation receive, each one of such receives must also follow (i.e., non-initialized correlation reference) the same correlation set.

6. Scenarios Supported by BizTalk: Uniform Sequential Convoy
The messages are all of the same type from the same party. There is no defined order to the messages. The handler processes them sequentially as delivered.
Streaming example.

7. Scenarios Supported by BizTalk: Non-Uniform Sequential Convoy
The messages, all from the same party, may be of different types; however the order in which the messages are expected to arrive is predefined. The handler processes them in the expected order.
Heath care example.

8. Convoy Set
A Convoy-set for a particular receive shape, is the set of correlation sets that are initialized by another receive shape and followed by this particular receive shape.
Any correlation set that is being followed by a send shape (chronologically) prior to the particular receive shape is not considered as a part of the Convoy-Set.
This caveat in in-place more because of limitation of the current implementation rather than any other semantic concerns. The problem being that given a single service it is impossible to detect whether convoy processing would be required in such cases – it can really be totally determined after looking at the partner service and examining the protocol. This is a useful warning to provide so that the user can examine the program & the protocol and take corrective action. (Warning 4014)

9. Sequential Convoy Semantic Checks
All the correlation sets that constitute a Convoy Set for a particular receive shape must be initialized by one and only one preceding receive shape.
The port for a particular receive shape, that requires convoy processing, must match the port for the receive shape initializing the convoy set.
If a sequential convoy is initialized by an activate receive, then the follower receives cannot be inside a service called from the activated service.

10. Additional Semantic checks for Uniform Sequential Convoys
Message types being received for a particular receive shape, requiring convoy processing, must match the message type for the receive shape initializing the convoy set unless the receive shape is operating on an Ordered Delivery port.
All receives participating in a particular sequential Convoy must follow all the correlation sets that are initialized (or followed) by the initializing receive unless operating on an Ordered Delivery port.
If a sequential convoy is initialized by an activate receive, then the activate receive cannot have a filter expression unless operating on an Ordered Delivery port.

11. Associated Orchestration Build Error Messages
ERROR 2257: if a parallel has an activatable receive then all its' tasks must be activatable
ERROR 2022: a sequential convoy which is initialized by an activate receive may not call or compensate a service with a receive participating in the convoy.
ERROR 2258 : in a sequential convoy receive all correlations must be initialized in a single receive  
ERROR 2259 : in a sequential convoy receive the ports must be identical  
ERROR 2260 : in a sequential convoy receive the messagetypes must be identical unless the port is marked for OrderedDelivery
ERROR 2261 : in a parallel convoy receive the correlations must be identical  
ERROR 2262 : a parallel activate receive convoy must initialize correlations 
ERROR 2263 : in a sequential convoy receive there cannot be an activation filter unless the port is marked for OrderedDelivery
ERROR 2264: in a sequential convoy receive the correlations must be identical unless the port is marked for OrderedDelivery
WARN 4014: convoy processing will not occur -- check your protocol if you were expecting it

12. Questions?