On 01/06/11 08:05, Justin Uberti wrote:
Background: I had a discussion with a coworker who wanted to have a single API to both streaming and datagram service; I believe it makes more sense to define an API to a datagram service and an API to a streaming service separately - the big argument for PseudoTCP is the client-to-client connection case, where one often finds that UDP works and TCP doesn't.
I had been thinking the datagram and streaming services should use a single API - much of the API ends up being the same, and that's how BSD sockets work. There are a few differences for streaming services, but they are mostly (entirely?) additive (flow control being the main one).
The huge difference is that a streaming API gives you a sequence of bytes, in strict order, while a datagram API gives you a (not necessarily ordered) sequence of datagrams. Each datagram is guaranteed to be treated as an unit, but order is not preserved. There is no guarantee about block boundaries in a stream (you have to create them yourself if you want them), but order is strictly preserved. For most of the rest of the functions, the APIs can (and should) be the same, but the sending and reception of data is different. Harald