Message callback routines and ct_diag return Client-Library and server messages in CS_CLIENTMSG and CS_SERVERMSG structures. In the CS_CLIENTMSG structure, the message text is stored in the msgstring field. In the CS_SERVERMSG structure, the message text is stored in the text field. Both msgstring and text are CS_MAX_MSG bytes long.
If a message longer than CS_MAX_MSG - 1 bytes is generated, Client-Library’s default behavior is to truncate the message. However, an application can use the CS_NO_TRUNCATE property to instruct Client-Library to “sequence” long messages instead of truncating them.
When Client-Library is sequencing long messages, it uses as many CS_CLIENTMSG or CS_SERVERMSG structures as necessary to return the full text of a message. The message’s first CS_MAX_MSG bytes are returned in one structure, its second CS_MAX_MSG bytes in a second structure, and so forth.
Client-Library null terminates only the last chunk of a message. If a message is exactly CS_MAX_MSG bytes long, the message is returned in two chunks: the first contains CS_MAX_MSG bytes of the message and the second contains a null terminator.
If an application is using callback routines to handle messages, Client-Library calls the callback routine once for each message chunk.
If an application use ct_diag to handle messages, it must call ct_diag once for each message chunk.
The SQLCA, SQLCODE, and SQLSTATE structures do not
support sequenced messages. An application cannot use these structures
to retrieve sequenced messages. Messages that are too long for these
structures are truncated.
Operating system messages are reported in the osstring field of the CS_CLIENTMSG structure. Client-Library does not sequence operating system messages.
For more information on sequenced messages, see the “Error and Message Handling” topics page in the Open Client Client-Library/C Reference Manual.
