mqtt
Cloud connectivity for MQTT and AMQP?
The big difference here to point out is : are we speaking about AMQP 0.x or AMQP 1.0. They are two completely different protocols and only the latter is a ISO/IEC standard supported by the main open sources products like ActiveMQ and Artemis brokers, Qpid Proton clients and Qpid Dispatch Router. Products like RabbitMQ support … Read more
What is the maximum message length for a MQTT broker?
It’s not entirely clear what you’re asking here, so I’ll answer both possibilities. The length of the actual topic string is at most 65536 bytes. This is a limit imposed by the mqtt spec, you can’t change it. It is also worth noting that the topic is encoded with utf-8, so you may have less … Read more
Is message order preserved in MQTT messages?
A summary of the message ordering capabilities in MQTT 3.1.1 can be found in the specification itself here. In summary: no guarantees are made about the relative ordering of messages published with different QoS values. (for example, QoS 0 can over take QoS 2 for example as it involves a single packet rather than the … Read more
Can a web browser use MQTT?
Yes, as mentioned in Steve-o’s comment MQTT via websockets is very possible. There are 2 options at the moment IBM’s MQ 7.5 comes with websockets support, you can find details here. The Mosquitto broker has a javascript client with an example running here. To answer your second question lighttpd has a websockets module that can … Read more
When MQTT-SN should be used? How is it different from MQTT?
There are few advantages in MQTT-SN (SN for Sensors Network) over MQTT, especially for embedded devices. Advantages MQTT-SN uses topic ID instead of topic name. First client sends a registration request with topic name and topic ID (2 octets) to a broker. After the registration is accepted, client uses topic ID to refer the topic … Read more
MQTT what is the purpose or usage of Last Will Testament?
LWT messages are not really concerned about detecting whether a client has gone offline or not (that task is handled by keepAlive messages). LWT messages are about what happens after the client has gone offline. The analogy is that of a real last will: If a person dies, she can formulate a testament, in which … Read more
Basic Steps for Using MQTT in android
You need: an MQTT broker which runs on the server side. This could be something like the mosquitto broker which is Open Source. an MQTT client library which you include in your Android app, enabling your app to connect, subscribe, and publish messages. There are a number of Java options listed at http://mqtt.org/software to come … Read more
MQTT vs. XMPP Which Should I Choose? [closed]
It depends on what you are trying to do and what hardware you are running. MQTT has very low keep-alive traffic. XMPP is a an IM protocol, and has a much, much higher overhead in handling presence messages between all the clients. If you have a small memory footprint constraint, then having to handle the … Read more
What is the difference between MQTT broker and Apache Kafka
The main motive behind Kafka is scalability. MQTT is a protocol with public specification for lightweight client / message broker communications, allowing publish/subscribe exchanges. Multiple implementations of client libraries and brokers (Mosquitto, JoramMQ…) exist and are virtually compatible. MQTT just specifies the transport, and vaguely the application part (i.e. how data is handled and possibly … Read more