Re: [lwip-users] MQTT: Matching data to topic for InPub?

[Luciano Moretti]

In the section for MQTT_MSG_TYPE_PUBLISH the topic isn't stored into the client->inpub_arg,  so wouldn't be available through the arg pointer on the other side.

Thanks,

Luciano

On Fri, Jul 2, 2021 at 2:41 AM goldsimon@gmx.de <goldsimon@gmx.de> wrote:

Am 01.07.2021 um 22:28 schrieb Luciano Moretti:
> Hi:
> Looking at getting MQTT working and while Outgoing Publishes and
> Subscription Requests are working I have a question trying to resolve
> the Incoming Publishes. The MQTT client uses 2 callbacks to split the
> Incoming Publish: The mqtt_incoming_publish_cb_t() and
> the mqtt_incoming_data_cb_t(). Looking at the MQTT Client code a single
> MQTT_MSG_TYPE_PUBLISH packet comes into the mqtt_message_recieved()
> function and gets split between the two callbacks. Why is this split
> instead of sending the topic+data in one callback?

I cannot really answer this. It's just the way the author wrote the code...

> If we have multiple
> subscriptions is it guaranteed that we'll receive an incoming Topic
> callback, then the matching incoming data callback? I think this is the
> case as we're in a single-threaded RAW API context.

>From my knowledge of the code, this is guaranteed, yes. Reading the
code, you cannot identify the topic from the 'arg' parameter, or can you?

Regards,
Simon

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