Awesome news - really love mosquitto and belief the new V1.4 & (websock) is going to make things really awesome for powerful web-based integration. I can already see using say AWS's ELB with SSL on say port 8883 terminated to port 1883 adding port 443 to port ___ for web-sock can really allow secure way of allowing MQTT over SSL and secure web-sockets
From my side, for future options in mosquitto
1. Think handling load is key for the IoT ....if we can get say 250 000 concurrent connections on a single server that would really help - 500 000 would be epic
2. Integration with other brokers like Kafka, RabbitMQ for passing MQTT to say AMQP - bridge but more on code level - allowing routing/transformation
3. Second the idea of offloading message to databases like postgress, mongo, cassandra would very handy
4. BIG options is router - allowing device to be route to dedicated mosquitto broker - diff to clustering :)...clustering is complex, routing is easy
5. Rules engine for routing in-comming message
6. MONITORING options - keeping an eye on load and troughput for tests and support
Overall I LOVE Mosquitto - hats of to Roger for a rock solid broker and belief V1.4 and future releases will continue to shine with more awe-inspiring options making IoT easier and a reality for hobby to companies all around the globe
Keep up the epic work
Warm regards
Izak Smit
PHP2ASP
South Africa