Multiple event receivers with a list

Question

Hi All,
If there are two item event receivers attached with a list and event is cancelled by event receiver that trigger first, will second event receiver be invoked? As per my understanding that second event receiver will not be invoked.
I have a requirement where in case first event receiver cancel the event, second event recever should still be invoked.
do anyone has any idea aroound it?
Regards Amit

Answer 1

Hi, Amit KM.
http://msdn.microsoft.com/en-us/library/gg749858.aspx
Notice the following details:
Synchronous event receivers are called in sequential order based on the sequence number specified during event binding. This applies to both Before and After synchronous events.
Asynchronous After event receiver threads are initiated in sequential order based on the sequence number. However, there is no guarantee that they will finish in that same order.
An asynchronous After event can start at any time after its associated user action is performed. It may start before, at the same time as, or after the Web request is completed.
After a user initiates an action in the SharePoint user interface, and before SharePoint Foundation executes the user action, the synchronous Before events are raised. If there are multiple synchronous Before events, they are raised in the order specified
by their sequence number. Similarly, synchronous After events are raised after SharePoint Foundation executes the user action. These, too, are raised in the order specified by sequence number. As you can see, all synchronous events are processed in the same
thread as that in which the user action occurs.
Asynchronous After events, however, are processed on secondary threads.
So you're completely right that if the first event receiver has cancelled the operation, the second event receiver will never been executed.
In your case if you want second event receiver(B) to be invoked regardless of the first event receivers'
(A) result you can easily swap the sequence numbers for those event receivers.
Event Receiver Sequence          
The event receiver sequence specifies the order in which an event receiver is executed in cases where an event triggers multiple event receivers. For example, if you have two
ItemAdded event receivers bound to the same list (one from Assembly "1" and the other from Assembly "2"), the event receiver that is bound with a lower sequence number is executed first. A practical example is adding an event receiver to a
system list that already has a system event receiver bound to it. In that case, you assign the new event receiver a higher sequence number.
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<Receivers ListUrl="Lists/Tasks">
<Receiver>
<Assembly>MyReceiverAssembly, Version=1.0.0.0, Culture=Neutral,
PublicKeyToken=12e5e5525fb3d28a</Assembly>
<Class>MyReceiverAssembly.MyReceiverClass</Class>
<Type>ItemAdded</Type>
<Name>My ItemAdded Event Receiver</Name>
<Synchronization>Synchronous</Synchronization>
<SequenceNumber>1000</SequenceNumber>
</Receiver>
</Receivers>
</Elements>
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