Legacy Document

Inside Macintosh: Networking With Open Transport / Part 2 - Open Transport Reference

Chapter 22 - Endpoints Reference / Functions

Functions for Connection-Oriented Transaction-Based Endpoints /

OTCancelRequest

Cancels an outstanding request as defined by a call to the OTSndRequest function.

C INTERFACE

OSStatus OTCancelRequest(EndpointRef ref,
                     OTSequence sequence);

C++ INTERFACE

OSStatus TEndpoint::CancelRequest(OTSequence sequence);

PARAMETERS

ref

The endpoint reference of the endpoint that has sent the request being cancelled.

sequence

A 32-bit value, specifying the transaction ID of the request being canceled. You must specify the same value that you used for the sequence field of the req parameter you passed to the OTSndRequest function. If you specify 0 for this parameter, the provider cancels all outstanding requests for the endpoint. If you specify an invalid sequence number, the provider does nothing.

function result

An error code. See Appendix B.

DISCUSSION

When you make a call to the OTSndRequest function, the endpoint provider allocates memory for internal buffers for this transaction. If you are no longer interested in the transaction, you must tell the endpoint provider by calling the OTCancelRequest function. Explicitly canceling a request allows the provider to free up the memory associated with a transaction request. If the endpoint is acknowledging sends, the provider generates a T_MEMORYRELEASED event for each freed buffer.

If the function completes successfully, it returns the kOTNoErr result; it does not return any other kind of acknowledgment. It is your responsibility to deallocate memory that you have reserved for the address, options, and data buffers associated with the canceled function.

Use OTCancelRequest to cancel an outgoing request; use OTCancelReply to cancel an incoming request.

SEE ALSO

"AppleTalk Reference".

Table 4-4.