Defined tokens - feature request

[alanlit]

When creating a callback my client has to wait to receive the token (so it can possibly cancel later). If I could supply the token in the setup call, I would not have to wait.(Of course there might be race conditions if I try to cancel quickly, or the setup call might fail - but both of these I would handle on my end). Note that since you cancel by supplying both the original URL and the token this would cause no problems if two independent clients supplied the same token, and likewise if my client supplied a duplicate live token I would just handle some error return.

My use case can involve the wholesale creation of lots of callbacks for lots of users and getting the setup off the user's thread would be really useful.

Thoughts ?

Alan