MQTT vs. HTTP: When to Use & Which one to use?

MQTT vs. HTTP

HTTP – Hyper-Text Transfer Protocol which is a widely used protocol to handle the data between client and server.

Past few years most of you might hear about MQTT which is gaining its momentum particularly in the field IoT devices and their development.

MQTT

HTTP:

Design and Messaging

HTTP is document-centric whereas MQTT is data-centric. HTTP is a request-response protocol that is not so fair for the mobile devices. Coming to the data transfer, we can consider the HTTP can handle the better data payload between client and server, but for MQTT – specialty is light weightiness like it can transfer the data as a byte array that serves as publish/subscribe model.

Hence, MQTT is mainly considered to use for resource-constrained devices. Usage of MQTT protocol in small devices that include mobile devices will help save the battery.

These things apart, a kind of publish/subscribe model that enables the independent existence of the functionality so that the whole system will not at risk when something goes down or out of order.

Speed and Delivery

It was understood that MQTT throughput is 93 times faster than the Hyper-Text Transfer Protocol. Also MQTT would ensure the high delivery rates when compared to HTTP.

Quality of services is of 3 types:

1. At most one: These levels of Quality will guarantee the best delivery.

2. at least once: This level of Quality will ensure that a message will be delivered at least once. But there is always a chance the message can be delivered more than once.

3. Exactly once: This level of Quality will guarantee that each message is received only once by the end system.

What if there is an unexpected disconnection of a client?

MQTT Protocol will send messages to all subscribed clients from a broker and there will be an immediate status update for a newly subscribed client.

HTTP Protocol does not have support for this.

Complexity and Message Size:

HTTP protocol contains longer headers along with messages they hold.

• General headers
• Request headers
• Response headers
• Entity headers

MQTT specifications are short and simple that holds short message header of size 2 bytes.

• CONNECT
• PUBLISH
• SUBSCRIBE
• UNSUBSCRIBE
• DISCONNECT

Bottom-line:

MQTT Protocol is robust even in the cases of intermittent connectivity. It is quite efficient in the cases of faster response time, throughput, and bandwidth usage.

HTTP is also unique in the way it behaves. But, MQTT is most suggestible when you are working with IoT services.