Question

One of our ‘frontend’ developers keeps requesting from us backend developers that the backend notifies all connected clients (it’s a client/server environment) of changes to objects. As in: whenever one user makes a change, all other connected clients must be notified immediately of the change.

At the moment our architecture does not have a notification system of that kind and we don’t have a sort of pub/sub model for explicitly chosen objects (e.g. the one the frontend is currently implementing).. which would make sense in such a usecase imho, but obviously requires extra implementation.

However, I thought frontends typically check for locks for concurrently existing user changes on the same object and rather pull for changes / load on demand and in the background rather than the backend pushing all changes to all clients for all objects constantly.. which seems rather excessive to me.

However, it’s being argumented that e.g. the MS Entity Framework does in fact publish (INotify)PropertyChanged not only for local changes, but for all such changes including other client connections, but I have found no proof or details regarding this.

Can anyone shed some light into this? Do other e.g. ORMs etc provide broadcasted (INotify)PropertyChanged events on entities?

Answer 1

These notifications are purely local notifications of the OnChange += SomeHandler variety. What you are requesting seems to be what the new Reactive Extensions library is introducing with .NET 4. Still, even with Rx, such notifications would not be automagic; some amount of handling of the pub/sub notification would be required.