Before asking my question, I would like to note that I have made some research for similar posts and I have not been able to find a clear answer so I decided to write my question in here.
I am trying to improve my Restful services by applying the best practices. I noticed that I found specific user information by username/userId under the most of the endpoints that I created. Generally, I need to find the user identity first for the rest of the processing, (to get user-related resource). I consider caching user data but in this case I am afraid of violating REST principles.
Do I have to re-identify the user every time the server receives a request to continue providing my service as a Restful service? or Can I use cache (user model in my case) to send a faster response to the request sender?