I want to know Does Solace supports plain HTTP, using MQTT Protocol?
Solace supports MQTT via WebSockets and via TCP.
A key advantage of Solace Web Messaging over standard HTTP is that it allows server based applications in a datacenter to asynchronously send real-time updates to browser and mobile applications over a web infrastructure. Web transport techniques (known as Comet, Long Polling, HTTP Streaming, HTTP Push, and WebSockets) are used by the event broker and Web messaging APIs to provide asynchronous updates to HTTP client applications.
However, Solace Web Messaging provides far more than this. It provides a complete topic-based, publish/subscribe messaging fabric with ubiquitous reach between browser/mobile applications and server applications without needing any other infrastructure or bridging software. No web streamers, no web servers, no gateways to integrate with other messaging systems.