Your comments

Is MQTT supported for Server?

You can download OpenHAB installation from and install it on any Windows-based PC. Then download Demo Setup from the same page - it will create demo Smart Home Items, which you can play with. REST API should be working in this configuration by default.
Can you provide some examples, of how you did it?
I could send commands using GET request, but POST or PUT do not work.
Also interesting how you to get updates of item statuses.