REST

Representational State Transfer (ReST or REST) follows a structured approach and necessitates that developers clearly organize their resources using universal resource identifiers (URIs). REST APIs follow the conventional CRUD philosophy, meaning that requests interact with HTTP resources (application layer protocol) via GET, POST, PUT, or DELETE operations to interact with databases and external services. REST contracts are linked to hostnames, paths, HTTP methods, headers, request bodies, response bodies, and more.

RPC

Remote Procedure Call (RPC) is geared towards running remote workloads as if they’re initiated locally. RPC allows users to tap into services running within external networks. A client program requests a service from the provider program (the “server”). Users can perform multiple procedural calls simultaneously thanks to multi-threading, even though these calls are synchronous.

RPC relies on an intermediary, a communicative link called an interface definition language (IDL). IDLs are essential for powering this RPC communication between machines running different operating systems or those using different languages.

Google developed gRPC to patch RPC’s weaknesses. New features have included interoperability, HTTP/2 support, and Protocol Buffers support. Additionally, another alternative called distributed remote procedure call (DRPC) recently arrived as a lightweight option.

RPC is an older approach to API design, and thus relies on UDP or TCP (transport-layer protocols) to work properly. Accordingly, RPC can work using either connection-oriented or connectionless protocols. Once a call is made in RPC, the calling environment is suspended while the process is handed over to the server and then executed. Once that procedure is finished, the results are shipped back to the client. This is the query-response loop. RPC, therefore, excels in applications where control alternates between both parties. Execution in these implementations occurs synchronously.

When to use?

RPC and REST have evolved considerably since their debut, and while each is useful, they’re functionally unique in significant ways. Each has its own use cases, but both RPC and REST may be used together. The most fundamental difference is that RPC was designed for actions, while REST is resource-centric. Alternatively, REST is ideal for domain modeling and handling large quantities of data. custom contracts make RPC ideal for IoT applications — especially low-powered ones — where REST might otherwise struggle due to resource consumption. Conversely, REST truly excels in hypermedia-dependent scenarios. It can group many different resources together and serve them in the appropriate format to users. While RPC hides the network communication processes from the user, REST uses resources to abstract information.