Prevent saga id from being changed

[ramonsmits]

If a modification of the Saga Id then an exception will be thrown

A modification of IContainSagaData.Id has been detected. This property is for infrastructure purposes only and should not be modified. SagaType: TheSagaType

In a response to a question of mine in the mailinglist it seems that you should not change the saga id. Although I'm not exactly sure why this is inappropriate as often you already use guids for identification and this unnecessarly uses more storage and creates an additional index which is not required as the primary key is already having a clustered index.

Although it works I also found a scenario where it can cause issues. When two different saga types within the same service share the same ID and both are using timeouts then a timeout belong to just one of these saga types.

You could also say that a timeout which refers to a saga should not only be identified by its key but also by its type.

But, my guess is that changing the key should either be prevented (making the setter internal or ) or be checked for modification after the saga has been invoked.

[ramonsmits]

Also, if IT IS allowed to change the saga id then maybe it should not be allowed that the id is Guid.Empty so SagaDispatcherFactory validates this.