CStoreSCP - How to raise an event on received CStore request?

[captainstark]

Hi,
I'm using the StoreScp as provided by sample code at https://github.com/fo-dicom/fo-dicom-samples/tree/master/Core/C-Store%20SCP

Instead of writing a DICOM file on every received C-STORE request I simply want to extract some data from the incoming data set and raise an event for registered listeners.

But when creating the SCP from my main code as suggested in the sample

var server = DicomServerFactory.Create<StoreScp>(port)

I have no access to the actual StoreScp instance to register with such an event.

Is there any reference implementation or hint how to do this?

Thanks a lot.

[gofal]

it is because of the nature how tcp-connections work. the server is waiting in the background-task for incomming requests. and there might be several connections at the same time.
So the instances of StoreScp will be created by the server whenever a new connection was established.
So you have to design it the other way round: you need to have a public available method that implement the event-handler. And then in the StoreScp class in the method OnCStoreRequest the instance will invoke this method.

[captainstark]

Thanks for clarification. This is exactly how I did it. Only issue was how to inject a reference of the actual handler into StoreScp instance. The only option I found was to use the userState argument of the Create method.

DicomServerFactory.Create<StoreScp>(port, userState: this);

The actual StoreScp instance can access this from OnCStoreRequestAsync as follows:

DicomImporter? dicomImporter = this.UserState as DicomImporter;
dicomImporter?.OnInstanceReceived(request);

Any better suggestion appreciated.

[gofal]

This is basically the idea of the UserState property of type Object. With that you can pass certain instances, theoretically if you have several DicomServer-instances running of your StoreScp, then you can pass different instances per DicomServer.

Other aproaches could be, that you have a static message sink where your StoreScp instances inject some messages after an instance was received.
Or when using dependency injection, you could register an instance of such an DicomImporter and your StoreScp resolves this instance from DI-Container.