I have created my own IConnectionIdGenerator implementation which for simpicty in my webforms application names the client connection Id by the EmailAddress.ToL
Yes thats perfect, I came to a simlar conclusion.
I also trying to think of a way to make client broadcast messages to the same email address group unique to the current url (so a progress bar on one page does not also update a progress bar on another)
I will either make extend the group id to be something like emailAddress + currentURL so its just a combination of the two strings. However that would make any global site broadcasts (to all urls) difficult to do unless there is a way of getting the groups collection and parsing out the email addresses and sending the message to each email address + url combination.
It may be better if I just tag on some client side check and send a progress bar Id as a parameter that is unique to the progress bar on the page that is ment to be updated.