Google Cloud Messaging vs MQTT: What are the differences?

<h1>Key Differences Between Google Cloud Messaging and MQTT</h1>

<p>Google Cloud Messaging (GCM) and Message Queuing Telemetry Transport (MQTT) are both popular protocols used for communication in IoT and mobile applications. Here are the key differences between GCM and MQTT:</p>

<h2>1. Payload Limitation:</h2>
<p>GCM has a payload limit of 4KB, while MQTT allows for larger payloads, making it more suitable for applications requiring the transfer of larger chunks of data.</p>

<h2>2. Push vs Publish/Subscribe:</h2>
<p>GCM is principally a push notification service, where the server pushes messages to clients. On the other hand, MQTT follows a publish/subscribe model, enabling bi-directional communication between clients and servers.</p>

<h2>3. Reliability:</h2>
<p>GCM guarantees message delivery with its persistent connection to Google servers, ensuring reliable message delivery. MQTT, however, does not guarantee delivery as it relies on Quality of Service (QoS) levels chosen by the client.</p>

<h2>4. Message Queueing:</h2>
<p>Unlike GCM, MQTT uses a persistent message queue that stores messages until they are successfully delivered to clients, ensuring higher message reliability and durability.</p>

<h2>5. Security:</h2>
<p>GCM provides end-to-end encryption and secure transmission of data using Google's infrastructure, offering robust security measures. MQTT, on the other hand, may require additional security implementations to ensure data confidentiality.</p>

<h2>6. Connection Overhead:</h2>
<p>GCM has a lower connection overhead as it utilizes Google's infrastructure for message delivery, optimizing network resources. MQTT, being a lightweight protocol, may introduce slightly more connection overhead due to its direct client-to-broker communication.</p>

<h2>Summary:</h2>
<p>In summary, Google Cloud Messaging and MQTT differ in terms of payload limitation, communication model, reliability, message queueing, security measures, and connection overhead.</p>