How to rollback an NHibernate Transaction within NServiceBus

It's my understanding we have essentially 2 kinds of exc开发者_如何学JAVAeptions when using NServiceBus.

Environmental : Meaning any required component is not currently available. Usually resulting in a full rollback of the transaction. This is the description I see behind the rollback within NServiceBus Documentation (Including putting the message back on the bus - which sounds fantastic). How do I do this?

Validation : A message is being processed that cannot succeed because of business logic, rules, etc. Where in I want to rollback all database interaction but there's no value in keeping the command in the queue. In which case I just want to roll back the NHibernate section of the transaction - not the MSMQ portion. How do I do this? Typically I would perform validation before any single message is processed but when you have multiple messages bound together into a single transaction and you want to roll them all back this isn't possible via pre-validation.

My assumption is either the answer is insanely obvious and I've overlooked it or what I'm trying to do isn't possible (in regards to the Validation exception).

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NSB takes care of getting the message out of the way by moving it to an error queue(v2.5). In v3 this functionality is enhanced and will give you more options to handle faults(DB, custom, etc.). The error queue is configured in your app.config.

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In my experience, it's easiest (and probably also more appropriate) to ensure that messages have a very high probability that they can succeed when they participate in a distributed transaction.

Therefore, most validation logic should already have been carried out when you dispatch the command message, and rollback is reserved for the truly exceptional case.

If your client cannot perform the validation, maybe you should insert a validation service in front of your current service. This validation service could route invalid command messages somewhere else before they reach the real service.

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Thank you for your answers. I believe the answer lies somewhere between the two.

We are unfortunately unable to implement a validation service but we've simply added better upfront validation to the message processing logic.

Unfortunately until we get to v3 we are currently unable to use the Error Queue as we are utilizing the message response functionality to alert integrators of issues with their messages. And throwing an unhandled error prevents any responses from being generated.