Hi @Shohil_Sethia,
Using the REST API is the way to go. Querying the Camunda database all by yourself will be a painful experience if you are planning to build a real-world application. If you want to save the REST API access, you could consider using an embedded process engine that hits the Camunda database directly.
It appears that you are at the start of a project. Based on your last question I think that you already tried using the REST API but are struggling. I also have the feeling that these struggles come from the complexity of your application architecture (frontend, backend, Camunda integration, server/proxy setup). Note that we are not able to assist with sorting such general issues out as this is a very time-consuming task. We prefer to invest this time in developing new Camunda features that all users benefit from.
As a general advice, try to make a step back and understand each of the components on their own. For example regarding Camunda REST API integration and proxies/CORS, write a minimal (non-angular, non-custom backend) Javascript application that works. If you get this working, add the other components one-by-one in. If something breaks in that process, try to understand how your setup has changed and in which component you’ll have to change something.
Cheers,
Thorben