What explains the protobuf restriction to use only over the HTTP/2 protocol?

gRPC, which uses Protocol Buffers (protobuf) for data serialization, is built on top of HTTP/2 due to several key advantages of this protocol:

• Multiplexing streams: HTTP/2 allows multiple requests and responses to be transmitted simultaneously over a single TCP connection without blocking, enhancing performance.
• Bidirectional streaming: HTTP/2 supports bidirectional streaming, which is important for gRPC, where the client and server can exchange messages in real-time.
• Header compression: HTTP/2 uses efficient header compression, reducing overhead.

Thus, the limitation of protobuf (in the context of gRPC) to use HTTP/2 is related to the need to leverage the capabilities of this protocol for efficient, fast, and bidirectional communication between services.