gRPC

gRPC is an open-source remote procedure call (RPC) framework developed by Google for efficient inter-service communication. It uses HTTP/2 as the transport protocol and Protocol Buffers (protobuf) as the interface definition language and message format, enabling compact binary payloads, multiplexed streams, and efficient flow control between clients and servers.

Service interfaces are declared in .proto files, which define service methods and the corresponding request and response message types. Generate language-specific client and server stubs for multiple programming languages, supporting four RPC styles: unary (single request, single response), server streaming (single request, stream of responses), client streaming (stream of requests, single response), and bidirectional streaming (two streams).

History and ecosystem: gRPC was announced by Google in 2015 and released as open source. It joined the Cloud Native Computing Foundation (CNCF) as a sandbox project in 2016 and progressed to graduation in 2020. The project has a broad ecosystem, including gRPC-Web for browser clients and gRPC-Gateway to map RESTful JSON APIs to gRPC services.

Architecture and features: HTTP/2 enables multiplexed calls over a single connection, header compression, and server push; Protobuf ensures efficient serialization. gRPC provides built-in support for authentication, TLS, deadlines, and retries, as well as pluggable credentials, load balancing, tracing, health checks, and timeouts. It is designed for polyglot environments with language bindings for C++, Java, Python, Go, C#, Node.js, Ruby, PHP, Dart, Objective-C, and more.

Use cases and limitations: gRPC is popular for microservices and cloud-native architectures that require low-latency, streaming, and strong typing. Limitations include less human-readability of payloads, reliance on generated code, and the need for proxies or bridges for browser or legacy HTTP tooling.