Writing "hello\3\0" to a socket returns 0x03. What is this and is that expected?

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I’m working with some legacy code which communicates with a KDB server via IPC.

The start of each connection, from the client side, sends the string “hello\3\0”. “\3” appears to be the ASCII character for end of message.

If this string is sent to a KDB instance, it will return 0x03, and nothing more. Or at least this is the behavior I observe.

I checked the KDB datatypes documentation and could not find anything for 0x03. I might be looking in the wrong place here, it’s possible this value (0x03) has nothing to do with the datatypes.

Does anyone know if this is the expected behavior and what the value 0x03 means?

1 Answer

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Interprocess communication | Developing | kdb+ and q documentation - kdb+ and q documentation

After a client has opened a socket to the server, it sends a null-terminated ASCII string "username:password\N" where \N is a single byte which represents the client’s capability with respect to compression, timestamp|timespan and UUID, e.g. "myname:mypassword\3" .

Thank you for this, I must have missed this part of the docs. I'm not sure about the following however. If the server accepts the credentials, it sends a single-byte response which represents the common capability. What does this mean?

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From the link: "If the server accepts the credentials, it sends a single-byte response which represents the common capability."

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