c# - Publish/Subscribe pattern using OperationContext.Current.GetCallbackChannel<T>() -

i have wcf service implements callback pattern shown in msdn documentation. binding: wsdualhttpbinding. works fine.

as can see in example paragraph, "callback channel" (so, server client) using code:

operationcontext.current.getcallbackchannel<t>() 

i used callback pattern implement publish/subscribe mechanism. this, store every "callback channel" list , use contact subscribers when publish event fires. clients can subscribe service, calling specific procedure. after tests, seems work fine.

however, have questions: right way , use "callback channels"? there expiration time of channels? there limits in implementation? getcallbackchannel method have limits (i.e. how works, exactly)? subscribers dynamic clients, server have when subscriber breaks down?

i work first time callback , publish/subscribe model, need guidelines.