TCP通信などにおけるデータフォーマットに関して、<CR><LF>や<STX><ETX>などの使用について疑問に思った。
以下を見つけた。
Three standard message formats are provided for this purpose; you can also provide code for your own custom format.
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The first of the three standard formats is length-header, in which case a 4 byte length header precedes the data;
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The second is stx-etx in which the message data is preceded by an STX (0x02) character and terminated with an ETX (0x03) character.
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The third is crlf in which the message is terminated with a carriage return and line feed (\r\n).
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The length-header format can also handle binary data. The other two formats can only handle text data (specifcally, data that does not contain characters 0x02 and 0x03 for stx-etx and 0x0d and 0x0a for crlf). This limitation can be avoided by appropriate character escaping techniques in the application layer.