Darren Govoni <dar...@ontrenet.com> writes: >>From what I learned in other posts, the dataReceived(self, data): in the > Echo server > will get called with out-of-order data/bytes from the client. Of course, > I could be misinformed, > but what I understood before was that in this type of Protocol, I would > have to re-order > and re-assemble the bytes. And I'm trying to avoid that, since of > course, TCP already does it.
Data being received out of order can't happen, as long as the Protocol is layered on top of TCP, since as you say, TCP already provides that guarantee. The dataReceived() method is really just how the data being received from TCP is handed to the Protocol object. UDP can be out of order, as it provides very few guarantees above and beyond IP itself. But I'm not sure you can layer an IProtocol over UDP with Twisted. There is a general issue where you may receive the data in differently sized chunks in dataReceived() than it might have been transmitted originally, which is a common source of confusion to people new to stream protocols, so perhaps you were thinking of that issue? The stream nature (and possibility for early disconnect from the client) is why having some internal length information for bulk transfers is sensible. For your original question, I was going to suggest an older posting of mine for a similar situation where I needed a bulk upload to augment a PB-based server, but it appears that you've located it in the archives yourself. > But like I said, I could have been misinformed because it seems pretty > basic to write 1,2,3 > to a server and have it received 1,2,3, guaranteed. Yes - TCP guarantees that what you transmit at one end will be received in order at the other end or not at all (e.g., outages, disconnects, etc...). It has a weaker guarantee in terms of no corruption, but one that is, in combination with typical link layer protections, generally more than sufficient for the vast majority of connections using it each day. -- David _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
