Multiple topics callbacks on single subscriber [14483]

[paulbkeelp]

We have a central subscriber application that need to subscribe 10+ Topics

For single Topic subscription all pretty much easy, we can call Init() all the default stuff and call the below callbacks
SubListener::on_subscription_matched
SubListener::on_data_available

If we have an application that need to subscribe 10+ Topics. How to acheive this easily - any examples please ?
SubListener::on_subscription_matched
SubListener::on_data_available

how to listen on multiple callbacks (multiple topics) on on_data_available. I see on MQTT we can register the callback on a topics. are there a simililar way please ?

[JLBuenoLopez]

Hi @paulbkeelp,

Using DDS you will need to create a specific DataReader for each Topic, as create_datareader requires the Topic as mandatory argument. Therefore, each DataReader is bound to a single Topic since its creation. These DataReaders can be created within the same Subscriber.

In order to be notified of data reception, you can use either the on_data_on_readers callback defined by the SubscriberListener or attach the same DataReaderListener to every DataReader.

I hope this information helps with your use case!

[paulbkeelp]

@JLBuenoLopez-eProsima Glad for your input. I will try that and Keep you updated.
Many Thanks

[zixuan-su]

hello, I'm having the same problem，do you solve it?

[EduPonz]

Hi @zixuan-su ,

To which problem are you referring? In DDS, each DataReader receives data from 1 topic, so you get callbacks each time any DataWriter publishes data on that topic. If you want to listen for data over different topics, you need several DataReaders (on per topic). What @JLBuenoLopez-eProsima is suggesting is a convenience to get a notification whenever any DataReader receives data, so that application can call to read/take on the appropriate one.

[zixuan-su]

Hi @zixuan-su ,

To which problem are you referring? In DDS, each DataReader receives data from 1 topic, so you get callbacks each time any DataWriter publishes data on that topic. If you want to listen for data over different topics, you need several DataReaders (on per topic). What @JLBuenoLopez-eProsima is suggesting is a convenience to get a notification whenever any DataReader receives data, so that application can call to read/take on the appropriate one.

thanks， I have solved it!