gRPC Website Documentation

gRPC supports an OpenTelemetry plugin that provides metrics designed to help developers:

• Troubleshoot system issues.
• Iterate on and improve system performance.
• Set up continuous monitoring and alerting.

This plugin replaces the previously supported OpenCensus observability framework, which has been sunsetted in favor of OpenTelemetry.

gRPC is a modern, open-source, high-performance Remote Procedure Call (RPC) framework designed to run in any environment. It is optimized for connecting services in and across data centers and is suitable for the 'last mile' of distributed computing (connecting mobile apps, browsers, and IoT devices to backend services).

Main usage scenarios:

• Microservices: Efficiently connecting polyglot services in microservices-style architectures.
• Client-to-Backend: Connecting mobile devices and browser clients to backend services.
• Library Generation: Automatically generating efficient client libraries.

gRPC supports several built-in authentication mechanisms:

• SSL/TLS: Used to authenticate the server and encrypt data. Supports mutual authentication (mTLS) where clients provide certificates.
• ALTS (Application Layer Transport Security): A transport security mechanism available when running on Google Compute Engine or Google Kubernetes Engine (GKE).
• Token-based authentication with Google: A mechanism to attach metadata-based credentials (like OAuth2 tokens) to requests.

Important Security Note: Google credentials should only be used to connect to Google services. Sending a Google-issued OAuth2 token to a non-Google service risks token theft and impersonation.

Token-based authentication must be used in conjunction with SSL/TLS, as most implementations require an encrypted channel to send credentials.

The grpcdebug command-line tool is used to troubleshoot gRPC services by fetching their internal states via the gRPC protocol. It provides a human-friendly interface to browse data from gRPC admin services.

Supported features include:

• Channelz: Inspect statistics such as the number of RPCs sent or failed on a specific gRPC channel.
• Health Checking: Monitor the health status of services.
• CSDS (Admin Services): Inspect address resolution results and dump active xDS configurations used for RPC routing.

gRPC supports client-side implementation on Android using the following languages:

• Java
• Kotlin

Wireshark is a network protocol analyzer that can decode gRPC messages transferred over the network. It uses two specific components for this: the gRPC dissector and the Protocol Buffers (Protobuf) dissector.

Key Capabilities

• Decoding Formats: Supports dissecting gRPC messages serialized in the Protocol Buffers wire format or as JSON.
• RPC Types: Supports unary, server streaming, client streaming, and bidirectional streaming RPC calls.
• Enhanced Dissection: Allows loading .proto files to provide meaningful decodings and supports registering custom subdissectors for byte or string fields.

You can explore real-world applications and case studies of how organizations have adopted gRPC and other CNCF technologies. Key examples include:

• Salesforce: Using gRPC for a unified interoperability strategy.
• Mux: Utilizing cloud-native technology to simplify online video streaming.
• Nulab: Boosting productivity using microservices and Kubernetes.

For a comprehensive list of case studies involving CNCF technologies, visit the CNCF case studies page.

gRPC is a modern, open source remote procedure call (RPC) framework designed for transparent communication between client and server applications.

Key use cases include:

• Low latency, highly scalable, distributed systems.
• Mobile clients communicating with cloud servers.
• Designing new, efficient, and language-independent protocols.
• Layered designs requiring extensions like authentication, load balancing, logging, and monitoring.

Key advantages over raw HTTP/2 binary blobs: gRPC provides high-level features consistently across platforms, such as:

• Application-layer flow-control interaction.
• Cascading call-cancellation.
• Load balancing and failover.

gRPC-Web is a JavaScript client library that allows web applications to communicate directly with gRPC backend services using Protocol Buffers.

Unlike traditional REST architectures where a web app speaks HTTP to a REST API that then translates to gRPC, gRPC-Web enables an end-to-end gRPC pipeline. The client application speaks Protocol Buffers directly to a service proxy (like Envoy), which then communicates with the gRPC backend services. This eliminates the need for manual JSON serialization/deserialization and custom HTTP status code management.

gRPC Reflection is a protocol that allows a gRPC server to declare its exported protobuf-defined APIs over a standardized RPC service. This includes all types referenced by request and response messages.

Benefits

• Automated Tooling: Enables debugging tools like grpcurl and Postman to automatically discover services and types.
• Human-Readable Interaction: Allows clients to encode requests and decode responses in a human-readable format without needing to manually provide .proto files.
• Analogy: It is conceptually similar to serving an OpenAPI (Swagger) document for a REST API.