Questions tagged [publish-subscriber]

For questions based on the publish-subscribe design pattern, especially when referring to questions about any protocol that implements this pattern. If your question is about a specific protocol (e.g. MQTT) or a specific service (e.g. PubNub), use that tag instead, and use this tag only where you need to ask generically.

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How to handle the connection in MQTT using Paho

I've managed to connect to my Mosquitto broker of Paho MQTT JS client. However, the client disconnects inmediately after completing the connection. Before it worked now I'm testing it doesn't work. ...
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2 answers
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Determine state before publish

I have a mosquitto MQTT broker on a Raspberry Pi. I have some topics from a client in this format SolutionCommand/state as an array 110001. In other hand I can invoke some publish topics like ...
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4 votes
2 answers
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MQTT subscriber connection

I understand an MQTT client publishes data to a topic after connect message. I am not sure how an MQTT client subscribing to a topic get updated when there is a publish to that topic. Is it the ...
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2 votes
0 answers
762 views

How to take data from multiple BLE devices into a central device simultaneously?

Firstly, I am very beginner in BLE domain. I have very little knowledge about it. I have Adafruit Feather 32u4 Bluefruit LE module. I want to do a project where multiple BLE peripheral devices ...
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use Gsm Sim800L To Publish data using MQtt [closed]

I have a Module Gsm Sim800L and I must Publish Data to a nodeRed Server Of IBM Bluemix. I used the library (Arduino MQTT Library for SIM800 GSM Modem) at this Link : https://elementztechblog....
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1 answer
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Are MQTT Brokers able to retain/cache some data for a certain amount of time and then send to the subscribers?

I currently have a Mosquitto MQTT Broker on which some IoT Nodes publish their information on a specific topic. I have an instance of Telegraf from InfluxData running that subscribes to this topic and ...
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1 answer
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How to setup local MQTT in Bridge REMAP remote topics

I am trying to setup MQTT bridge, where I want to publish all local topic to remote, but subscribe only certain remote topic which matches wild card and remap to local broker Here is the config ...
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7 votes
2 answers
3k views

MQTT multiple topics vs. bigger payload

I am wondering about best practices of topic naming and payload design of mqtt messages. Is it better to have multiple and long topic names instead and a bigger payload or short topic name with ...
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6 votes
1 answer
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node-red - Units of work

I have a MQTT Input node that kicks of database operations (SELECT and INSERT) for PostgreSQL database. The database operations are done with node-contrib-postgres-multi.Since these operations are ...
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5 votes
1 answer
7k views

mosquitto - persistence configuration options

I want to understand the persistence related options in Mosquitto as described here. To begin with, do these options apply only in case of QoS > 0 and/or retained messages? persistence If true, ...
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9 votes
2 answers
630 views

AWS IoT implementation on a low end controller like Atmega328, nrf51822?

I have been using AWS IoT implemented in a RPi for a while. I was wondering if I could use a controller like Atmega328 or some NRF based controllers or STM32 to publish and subscribe to AWS IoT MQTT ...
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5 votes
1 answer
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Can multiple subscribers subscribe to the same topic from AWS IoT?

Just like what the question asks, can multiple subscribers subscribe to the same topic reading the same message from AWS IoT?
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8 votes
2 answers
15k views

List clients subscribed to a certain topic in Mosquitto server

So that is the general question, but I'll provide the scenario here. I'm running Mosquitto server to provide mqtt comm between esp relay modules (Sonoff from Itead) and Home Assistant. Most of the ...
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16 votes
7 answers
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What IoT services are available for storing/sending/publishing generic data in the cloud?

What IoT services are available for storing/sending/publishing (and opposite operations) generic small amount of data in the cloud? I am looking, for example, for a service where a device could store ...
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  • 269
7 votes
1 answer
149 views

Do protocols based on the publish-subscribe pattern negate the benefits of mesh networks?

Protocols that are modelled on the publish-subscribe pattern such as MQTT and AMQP require a centralised message broker to co-ordinate messages being sent and received. This does not pose much of a ...
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16 votes
3 answers
195 views

Is the Subscriber-Publisher pattern applicable also to actuators?

There are tons of tutorials on the web, especially with RabbitMQ, on how to publish sensor data; for example, temperature, humidity, etc. Just publish the value to a message queue and anybody can ...
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