@Shohil_Sethia, so unsupported format error means that you are most likely getting 404 on tomcat while sending request to your path and tomcat replies to you with standard page, which is not a JSON but a text.
Apart from that I would like to make sure that you understand following concept, given that
- node+express - server side code which serves content for your frontend (AngularJS)
- frontend (AngularJS) executed in users browser
In general it is not a problem to send requests from one backend system to another, i.e. from your express server to camunda server. But there is a problem when user does that from his browser. This is why a clean solution would be for browser to request your express server, which will then proxy request to camunda.
Does that help you?
Askar.