Handling Data During a Session
An application can both read from and write data to another application during
a session. Use the PPCRead function during a session to read incoming blocks of data from another application.
Once a session is initiated, you should have a PPCRead function pending. You can issue a PPCRead function from inside a completion routine. This provides you with immediate notification if an error condition arises or the session
closes.
The blockCreator, blockType, and userData fields are returned for the block
you are reading. (These fields are set by the PPCWrite function.) To determine whether there is additional data to be read, check the more field.
This field is FALSE to indicate the end of a message block. The following program illustrates how you use the PPCRead function to read data during a session.
// Using the PPCRead function to read data during a session
// Assuming inclusion of MacHeaders
#include <PPCToolBox.h>
// Prototype your routine like this prior to calling it
OSErr MyPPCRead(PPCReadPBPtr thePPCReadPBPtr,
)
{
thePPCReadPBPtr->ioCompletion = NULL;
// from the PPCStart function or the PPCInform function:
thePPCReadPBPtr->sessRefNum = theSessRefNum;
thePPCReadPBPtr-> bufferLength = theBufferLength;
thePPCReadPBPtr-> bufferPtr = theBufferPtr;
}
You should make any calls to PPCRead asynchronously. You can provide a completion routine that will be called when the PPCRead function has completed, or you can poll the ioResult field of the PPC parameter block to
completion routine can issue another asynchronous PPC Toolbox call or set global variables. If another PPC Toolbox call is made from a completion routine, then the PPCRead function must use a record of data type The following program illustrates a function that can be used to poll the
ioResult field of a record of data type PPCReadPBRec. The function returns completed.
// Polling the ioResult field to determine if a PPCRead function has completed
// Assuming inclusion of MacHeaders
#include <PPCToolBox.h>
// Prototype your polling routine like this prior to calling it
Boolean MyReadComplete(PPCReadPBPtr thePPCReadPBPtr, OSErr *err) {
// Error result gets value of ioResult
*err = thePPCReadPBPtr->ioResult;
// Return false if error is 1.
return !*err;
}