SQL/MX Queuing and Publish/Subscribe Services

Embedded SQL Examples
HP NonStop SQL/MX Queuing and Publish/Subscribe Services—523734-002
3-2
Stream Access
Stream Access
The stream access mode enables applications to access regular tables as continuous
data streams. The stream access mode first does a regular scan of the table. Then, if
all available rows have been retrieved, the stream access mode causes fetch
operations to wait (block) instead of returning the end-of-data condition.
This program illustrates the stream access mode with no embedded DELETE or
UPDATE operation:
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#include <stdio.h>
#include <string.h>
long StreamParcels()
{
EXEC SQL BEGIN DECLARE SECTION;
int destination;
int origin;
int seqnbr;
long SQLCODE;
EXEC SQL END DECLARE SECTION;
EXEC SQL WHENEVER SQLERROR GOTO EndOfProcessing;
/* Routes incoming parcels to their destination */
EXEC SQL DECLARE arrivals CURSOR FOR
SELECT destination, origin, seqnbr
FROM (SELECT * FROM STREAM(inbox)) AS inbox;
EXEC SQL OPEN arrivals;
/* Wait for newly arrived parcels and notify receivers */
while (1) {
/* Fetch notifications */
EXEC SQL FETCH arrivals
INTO :destination,:origin,:seqnbr;
printf("\nDestination:%d Origin:%d "
"Sequence Number:%d",
destination, origin, seqnbr);
/* Route package, notify receivers */
routePackage(seqnbr, destination, origin);
}
EndOfProcessing:
EXEC SQL WHENEVER SQLERROR GOTO EndError;
EXEC SQL CLOSE arrivals;
EndError:
return SQLCODE;
}
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