POLL

The user program issues the POLL request to complete and retrieve the results from a prior SCMD request.

The POLL request is rejected if a prior subcommand is not in-progress. That is, a prior SCMD or POLL request must have returned the status code FCAI-Status-InProgress; otherwise, the current POLL request returns FCAI-IE-NotInProgress.

Issuing an SCMD request in no-wait mode enables you to perform other program functions while the subcommand is running. While you are performing these functions, the FTP client might be writing a large amount of data to the interface.

Guideline: Avoid large intervals of time between POLL requests. Large time intervals can cause a pipe overflow and lead to an error or a wait in the client until the results from the subcommand are retrieved.

Each POLL request copies up to 32 KB of data from the client to the interface buffer even if the subcommand has not yet completed. The actual amount that is returned depends upon the size of the output, the timing of the request, and how much space is available in the current part of the interface buffer.

See GETL for a discussion of the interface buffer. See FCAI_PollWait: Specifying a wait time before POLL for more information about managing POLL requests.