As a simplification, you may want to think of the processing of network data the same way as reading a file while some other process is writing to it.

You cannot determine without some protocol when a "block" of data is complete. The common solutions to this problem are:

a) the above mentioned "end of block" marker. In the case of a line-based protocol, the newline character serves as an end-of-block marker. This is especially useful if its inefficient to know the length of a block in advance (usually, because the block is large and takes a long time to compute). And line-based protocols are just nice to read for humans, which can also be a big help in analyzing any problems.

b) prefix the block with its length. HTTP for instance provides a mechanism for this using the content-length header. Many binary protocols work the same way. When possible, this gives a few advantages over end-of-block markers; the client will know how much memory to allocate for the incoming data, and it can make it easier to pass the data on without any additional processing.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

In reply to Re: How can I determine the server is waiting for input in POE::Wheel::ReadWrite? by Joost
in thread How can I determine the server is waiting for input in POE::Wheel::ReadWrite? by woosley

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