I'm a developer working at Toss who has also participated in and helped with lectures. You absolutely must know about RPC communication. Many people say they've implemented MSA by simply implementing it with HTTP, but honestly, I don't agree with that. In fact, when I went to interviews in the past, whenever MSA architecture came up, they would invariably ask questions about RPC as well, which shows that RPC communication in MSA is one of the extremely important elements in terms of resource optimization and management. I hope this lecture will be of great help to you.