Remote Procedure Call (RPC) is a protocol that one program can use to request a service from a program located on another computer or in a different part of the same computer’s operating system. It allows programs to execute procedures (subroutines) in a remote address space, as if they were local procedures without the programmer explicitly coding the details for remote communication.

Here’s how RPC works:

Client-Server Architecture: RPC typically involves a client-server architecture. The client program sends a request to the server program, and the server processes the request and sends back a response.

Procedure Calls: From the perspective of the client program, it makes procedure calls that appear to be local. These calls are actually RPC calls.

Marshalling: When the client makes a procedure call, the parameters and request information are marshaled (serialized) into a format that can be transmitted over a network.

Transmission: The marshaled request is transmitted to the server program, which resides on a remote computer.

Unmarshalling: The server program receives the request, unmarshals (deserializes) the data, and processes the request by invoking the appropriate procedure.

Processing: The server executes the requested procedure with the provided parameters and generates a response.

Marshalling (Again): The server marshals the response data into a format suitable for network transmission.Transmission (Again): The response is sent back to the client program.

Unmarshalling (Again): The client receives the response, unmarshals the data, and retrieves the result.

Procedure Completion: The client program continues its execution with the result of the remote procedure call.

RPC allows programs to communicate and collaborate across a network, making it a fundamental technology for distributed computing. It abstracts the complexities of network communication, making it easier for developers to build distributed systems and services. RPC can be used in various contexts, including client-server applications, microservices architectures, and inter-process communication (IPC) within a single machine or between machines.

Different RPC frameworks and protocols exist, including gRPC, XML-RPC, and JSON-RPC, each with its own features and use cases. The choice of RPC technology depends on factors such as performance, language support, and the specific requirements of the application being developed.