How to fetch a Test Plan using test case in RQM via Rest or OSLC API?
One answer
Use OSLC Query - there's some examples of query for DOORS Next here https://jazz.net/library/article/1197
You'll have to adapt the discovery to QM but it's basically the same steps to find the query capability, and to use it.
EWM projects have specific query capabilities for test case, test plan, test suite and many other types of resource.
The EWM application itself also provides query capabilities for Component and Configuration, i.e. across all projects - you'd scope these - e.g. using oslc.where specifying a project area - to avoid excessive load on the server.
Also, search this forum, there are other questions about OSLC Query which may have useful answers. For example https://jazz.net/forum/questions/277398/rqm-oslc-query-or-rest-api-to-get-latest-baselines-from-stream