[fpc-pascal] Sending Hex codes over TCP/IP

[Tony Whyman]

A TCP connection is no more than a pair of byte streams - one in each direction. You have to define your own structure for each byte stream and the procedures for use i.e. a protocol. lt will be easier if you can use a standard protocol such as http. An http POST is one way to send an array of bytes to a server and to receive a response.
if you want to define your own protocol then you could send your array of bytes as an integer length followed by the bytes encoded one after the other. If you want your protocol to be platform independent then be careful to define the bit order (little endien or big endien) and how multibyte integers are encoded (low order byte first or high order byte first).Your protocol could be as simple as one side iniiates a connection, sends a byte count followed by the byte array. The receiver, once it has received all bytes (as given by the byte count) processes the data and then returns the response preceded by a byte count. Of course your application may be more complex than that, which is why protocol design is such an interesting problem.
-------- Original message --------From: James Richters via fpc-pascal <fpc-pascal at lists.freepascal.org> Date: 11/09/2020  21:59  (GMT+00:00) To: 'FPC-Pascal users discussions' <fpc-pascal at lists.freepascal.org> Cc: James Richters <james at productionautomation.net> Subject: [fpc-pascal] Sending Hex codes over TCP/IP I'm trying to figure out how to send and receive Arrays of Bytes or perhaps a buffer of hex codes over TCP/IP,  but everything I find seems to want to send and receive strings.  Can someone please point me in the right direction on how to do this?	Basically I want to make a connection to an IP address at a specific port and then send some bytes to the server then get some bytes back from the server.  The data sent is just hexadecimal and it can't be followed by linefeeds or carriage returns, and I want to just receive the bytes back into a buffer of some sort so I can look at it one byte at a time.  I prefer some kind of array of bytes so I can just access the bytes with elements of the array.  I've been going round and round trying to figure this out.  Any help is greatly appreciatedJames_______________________________________________fpc-pascal maillist  -  fpc-pascal at lists.freepascal.orghttps://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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