cwbDQ_AsyncRead

Use the cwbDQ_AsyncRead command.

Purpose

Read a record from the IBM i data queue object that is identified by the specified handle. The AsyncRead will return control to the caller immediately. This call is used in conjunction with the CheckData API. When a record is read from a data queue, it is removed from the data queue. If the data queue is empty for more than the specified wait time, the read is aborted, and the CheckData API returns a value of CWBDQ_TIMED_OUT. You may specifying a wait time from 0 to 99,999 (in seconds) or forever (-1). A wait time of zero causes the CheckData API to return a value of CWBDQ_TIMED_OUT on its initial call if there is no data in the data queue.

Syntax

 
unsigned int CWB_ENTRY cwbDQ_AsyncRead(
                             cwbDQ_QueueHandle   queueHandle,
                             cwbDQ_Data          data,
                             signed long         waitTime,
                             cwbDQ_ReadHandle   *readHandle,
                             cwbSV_ErrHandle     errorHandle);

Parameters

cwbDQ_QueueHandle queueHandle - input: Handle that was returned by a previous call to the cwbDQ_Open function. This identifies the IBM i data queue object.
cwbDQ_Data data - input: The data object to be read from the IBM i data queue.
signed long waitTime - input: Length of time in seconds to wait for data, if the data queue is empty. A wait time of -1 indicates to wait forever.
cwbDQ_ReadHandle * readHandle - output: Pointer to where the cwbDQ_ReadHandle will be written. This handle will be used in subsequent calls to the cwbDQ_CheckData API.
cwbSV_ErrHandle errorHandle - output: Any returned messages will be written to this object. It is created with the cwbSV_CreateErrHandle API. The messages may be retrieved through the cwbSV_GetErrText API. If the parameter is set to zero, no messages will be retrieved.

Return Codes

The following list shows common return values.

CWB_OK: Successful completion.
CWBDQ_INVALID_TIME: Invalid wait time.
CWBDQ_INVALID_QUEUE_HANDLE: Invalid queue handle.
CWBDQ_INVALID_SEARCH: Invalid search order.

Usage

This function requires that you have previously issued the following APIs:

cwbDQ_Open or cwbDQ_OpenEx
cwbDQ_CreateData