What is gRPC and how does it differ from regular HTTP?

gRPC is a modern framework for remote procedure calls (RPC), developed by Google. It uses HTTP/2 as the transport protocol and Protocol Buffers (protobuf) for data serialization.

Main differences of gRPC from regular HTTP:

• Protocol: gRPC operates over HTTP/2, which provides multiplexing requests, header compression, and a binary transfer protocol, unlike the text-based HTTP/1.1.
• Data format: gRPC uses protobuf — a compact, binary format, whereas regular HTTP often uses JSON or XML.
• Call types: gRPC supports not only request-response but also streaming data in both directions (client-server).
• Performance: thanks to the binary protocol and HTTP/2, gRPC is usually faster and more efficient than REST over HTTP/1.1.

Example of defining a service in protobuf for gRPC:

syntax = "proto3";

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

In C#, code for client and server is generated based on this description for convenient method calls.