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Re: [paho-dev] MQTT C asynchronous token


I've raised a bug to track this item:

We're creating new web pages for each of the clients.  I've put one together for the C++ client:  If you have any changes you'd like me to make, let me know.


On 04/23/2014 07:22 PM, Frank Pagliughi wrote:
Hello Ian, and all,

I'm trying to wrap up the next rev of the C++ library, and have one nagging issue that I believe I inquired about last time. In the C library, the MQTTAsync_send() and MQTTAsync_sendMessage() functions claim:
An MQTTAsync_token is issued when this function returns successfully.
I can't find how to get this MQTTAsyncToken value until the callback which happens after the message is delivered.

The problem is that, like the Java client, the C++ client has a publish() function which returns a token, and that token is supposed to know the message ID of the outgoing packet. It is reported via:
int     itoken::get_message_id();
So, to implement this I need the Message ID (MQTTAsyncToken) as soon as the message is queued - before returning from the publish() function.

It seems that the latest version of the ...err... asynchronous mode of the synchronous library has everything I would need to publish messages, since the publish functions take a pointer to an MQTTClient_deliveryToken
int MQTTClient_publish(MQTTClient handle, char *topicName, int payloadlen,
                       void *payload, int qos, int retained,

                       MQTTClient_deliveryToken *dt)
That would be perfect!  I would switch over to the synchronous library, but there are not corresponding asynchronous  versions of connect() and disconnect().

If those existed, I (we?) wouldn't need the asynchronous library at all.


Ian Craggs                          
icraggs@xxxxxxxxxx                 IBM United Kingdom
Committer on Paho, Mosquitto

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