Remote Procedure Calls

RPC stands for Remote Procedure Calls. It is a programming model built on top of request-response network protocols. Issuing an RPC in a client amounts to invoking a procedure from application code. For a server, servicing an RPC amounts to implementing a procedure with a particular signature.

In the client, the objects that expose these procedures are called stubs. When application code invokes a procedure on a stub, the stub translates the arguments into bytes and then sends a request to the server, the contents of which are the serialized arguments. When it gets back a response from the server, it translates the bytes into a result value, which is then returned back to the application code that called it.

In the server, the objects that expose these procedures are service implementations. The server machinery receives the request, translates the bytes back into procedure arguments, and then invokes a procedure on the service implementation, passing it those arguments. The service implementation performs its business logic and then returns a result, either a value on success or an error code on failure. (In some RPC implementations, servers can return both values and an error code). The server machinery then translates this result into bytes, which then become the response that is sent back to the client.

RPC is not a new programming idiom: proposals for remote procedure call semantics were written in the 70’s, and practical RPC implementations appeared in the 80’s, such as the Network File System (NFS).

gRPC is a cross-platform RPC system that supports a wide variety of programming languages. It excels at providing high performance and ease of use, to greatly simplify the construction of all types of distributed systems.