RPC

Remote procedure call (RPC) is a communication paradigm that enables a program to invoke a procedure on a different address space, typically on another machine, as if it were a local call. This abstraction hides the details of the underlying network, data serialization, and marshalling from the caller, presenting a simple function-like interface. RPC is widely used in distributed systems to enable modular services and transparent inter-process communication.

An RPC system typically involves client and server components: client-side stubs marshal the caller's arguments into a message, send it over a transport (for example TCP), and await a reply; the server unpacks the request, invokes the requested procedure on the server, and returns results. Implementations differ in the interface description language (IDL), serialization format, and transport. Classic examples include ONC/RPC and DCE/RPC; modern frameworks include gRPC (HTTP/2 and protocol buffers), Apache Thrift, JSON-RPC and XML-RPC over HTTP.

RPC design raises considerations about performance, reliability, and security. Network latency and serialization overhead are factors; asynchronous or streaming RPC can mitigate some latency. Security relies on authentication, encryption (e.g., TLS), and proper access control. RPC interfaces require careful versioning and compatibility management to avoid breaking clients. RPC is commonly used in microservices, cloud services, and distributed systems, offering abstraction and language-agnostic interfaces but potentially increasing coupling and rollout complexity compared with REST or event-driven patterns.