ct_sendpassthru

Send a Tabular Data Stream (TDS) packet to a server.

CS_RETCODE ct_sendpassthru (cmd, sendptr)
 
CS_COMMAND     *cmd;
CS_VOID               *sendptr;

sendptr: A pointer to a buffer containing the TDS packet to be sent to the server.

ct_sendpassthru returns the following values:

**Table 3-59: ct_sendpassthru return values**
Return value	Meaning
CS_PASSTHRU_MORE	Packet sent successfully; more packets are available.
CS_PASSTHRU_EOM	Packet sent successfully; no more packets are available.
CS_FAIL	The routine failed.
CS_CANCELLED	The routine was cancelled.
CS_PENDING	Asynchronous network I/O is in effect.See “Asynchronous programming”.
CS_BUSY	An asynchronous operation is already pending for this connection. See “Asynchronous programming”.

TDS is a communications protocol used for the transfer of requests and request results between clients and servers. Under ordinary circumstances, non-gateway applications do not have to deal with TDS, because Client-Library manages the data stream.
ct_recvpassthru and ct_sendpassthru are useful in gateway applications. When an application serves as the intermediary between two parties (such as a client and a remote server, or two servers), it can use these routines to pass the TDS stream from one server to the other, eliminating the process of interpreting the information and re-encoding it.
ct_sendpassthru sends a packet of bytes from the *sendptr buffer. Most commonly, sendptr will be *recvptr as returned by srv_recvpassthru. sendptr can also be the address of a user-allocated buffer containing the packet to send.
Default packet sizes vary by platform. On most platforms, a packet has a default size of 512 bytes. A connection can change its packet size through ct_con_props.
ct_sendpassthru returns CS_PASSTHRU_EOM if the TDS packet in the buffer is marked EOM (End Of Message). If the TDS packet is not marked EOM, ct_sendpassthru returns CS_PASSTHRU_MORE.
A connection which is being used for a passthrough operation cannot be used for any other Client-Library function until CS_PASSTHRU_EOM has been received.