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Hi Frank,
when I wrote the library, it seemed to make sense to enforce the
setting of the message arrived callback, to make sure any incoming
messages were handled. There are some servers where a message
can be sent to the client unsolicited, without a subscription.
This isn't standard MQTT behaviour of course, although I'm not
sure that the spec actually forbids it.
I'm not strongly attached to my decision to return an error if you
don't set message arrived when calling setCallbacks, so I would be
happy to change it.
Ian
On 09/01/15 17:43, Frank Pagliughi wrote:
Hello Ian, and all,
In the latest Paho C Async library, the publish example,
MQTTAsync_publish.c, sets the callbacks as so (~line 126):
MQTTAsync_setCallbacks(client, NULL, connlost, NULL,
NULL);
As makes sense with a publish-only client, it sets the 4th
parameter for a "message arrived" callback to NULL.
The implementation of the MQTTAsync_setCallbacks function,
however, rejects the NULL value for message arrived (ma)
parameter, in MQTTAsync.c (~line 1719):
if (m == NULL || ma == NULL ||
m->c->connect_state != 0)
rc = MQTTASYNC_FAILURE;
else
...
Which of these should be the correct behavior? I'm guessing that
the library should accept a NULL value for the callback (?).
Thanks,
Frank
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