National Instruments 320682C

Chapter 7 TCP Library

Return Value

status integer Refer to error codes in

Table 7-3.

Parameter Discussion

serverCallbackFunction is the name of the function to be called to process client requests.

The callback function must be of the following form:

int (*tcpFuncPtr) (int handle, int xType, int errCode,

void *callbackData)

The xType parameter specifies the type of message received from the server. The server

callback function can receive the following transaction types.

TCP_CONNECT

TCP_DISCONNECT

TCP_DATAREADY

The errCode parameter is used only when the transaction type is TCP_DISCONNECT.

The following describes each transaction type.

TCP_CONNECT—The transaction type is received when a client is requesting a connection.

TCP_DISCONNECT—Received when a client is requesting the termination of a connection, or

when a connection is being terminated due to an error. If the connection is terminated due to an

error, the errCode parameter contains a negative error code. Refer to Table 7-3 for the list of

error codes.

TCP_DATATREADY—Received when the client has sent data via TCP to the server. Your

program, acting as the server, should call ServerTCPRead to obtain the data.

The server callback function should return TRUE if the request is successful. Otherwise, the

function should return FALSE.

Note: Server callback should be short and should return as soon as possible.

callbackData is a four-byte value that will be passed to the callback function each time it is

called for this server.