I was able to load mqtt extension in thingworx composer
And also added a new thing called TestMQTT and added property called msg.
The idea is to get message from application and show it in msg
I have also created topic called topicmasg.
And I tried to connect from using mqtt client from my machine and I got this error
:~ sundar$ mosquitto_pub -h http://22.214.171.124:1883/Thingworx/Things/TestMQTT/msg -t topicmsg -m sundar
Unable to connect (Lookup error.).