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gerrit-public.fairphone.software / platform / external / grpc-grpc / 5e9757bf0f8ada75068038c3e29d8b1e875d2ce3
commit5e9757bf0f8ada75068038c3e29d8b1e875d2ce3[log] [tgz]
authorStanley Cheung <stanley.cheung@gmail.com>Thu May 28 09:51:08 2015 -0700
committerStanley Cheung <stanley.cheung@gmail.com>Thu May 28 09:51:08 2015 -0700
treec3bcfe80e31ed89b15d625299bf9a72dba2f4c4c
parent46a36d7cab42c1e6adad44a7760d5e6726a50b0b [diff]
parent241563b00301c68e306c4c1662149f131b22a15c [diff]
Merge pull request #1773 from donnadionne/test-log

Adding 2 helper build scripts to allow docker images to be built
tree: c3bcfe80e31ed89b15d625299bf9a72dba2f4c4c
  1. doc/
  2. etc/
  3. examples/
  4. include/
  5. src/
  6. templates/
  7. test/
  8. third_party/
  9. tools/
  10. vsprojects/
  11. .clang-format
  12. .editorconfig
  13. .gitignore
  14. .gitmodules
  15. .travis.yml
  16. BUILD
  17. build.json
  18. CONTRIBUTING.md
  19. gRPC.podspec
  20. INSTALL
  21. LICENSE
  22. Makefile
  23. PATENTS
  24. README.md
README.md

Build Status Coverage Status

gRPC - An RPC library and framework

Copyright 2015 Google Inc.

#Documentation

You can find more detailed documentation and examples in the grpc-common repository.

#Installation

See grpc/INSTALL for installation instructions for various platforms.

#Repository Structure

This repository contains source code for gRPC libraries for multiple languages written on top of shared C core library [src/core] (src/core).

  • C++ source code: [src/cpp] (src/cpp)
  • Ruby source code: [src/ruby] (src/ruby)
  • NodeJS source code: [src/node] (src/node)
  • Python source code: [src/python] (src/python)
  • PHP source code: [src/php] (src/php)
  • C# source code: [src/csharp] (src/csharp)
  • Objective-C source code: [src/objective-c] (src/objective-c)

Java source code is in [grpc-java] (http://github.com/grpc/grpc-java) repository. Go source code is in [grpc-go] (http://github.com/grpc/grpc-go) repository.

#Current Status of libraries

Libraries in different languages are in different state of development. We are seeking contributions for all of these libraries.

  • shared C core library [src/core] (src/core) : Early adopter ready - Alpha.
  • C++ Library: [src/cpp] (src/cpp) : Early adopter ready - Alpha.
  • Ruby Library: [src/ruby] (src/ruby) : Early adopter ready - Alpha.
  • NodeJS Library: [src/node] (src/node) : Early adopter ready - Alpha.
  • Python Library: [src/python] (src/python) : Early adopter ready - Alpha.
  • PHP Library: [src/php] (src/php) : Pre-Alpha.
  • C# Library: [src/csharp] (src/csharp) : Pre-Alpha.
  • Objective-C Library: [src/objective-c] (src/objective-c): Pre-Alpha.

#Overview

Remote Procedure Calls (RPCs) provide a useful abstraction for building distributed applications and services. The libraries in this repository provide a concrete implementation of the gRPC protocol, layered over HTTP/2. These libraries enable communication between clients and servers using any combination of the supported languages.

##Interface

Developers using gRPC typically start with the description of an RPC service (a collection of methods), and generate client and server side interfaces which they use on the client-side and implement on the server side.

By default, gRPC uses Protocol Buffers as the Interface Definition Language (IDL) for describing both the service interface and the structure of the payload messages. It is possible to use other alternatives if desired.

###Surface API Starting from an interface definition in a .proto file, gRPC provides Protocol Compiler plugins that generate Client- and Server-side APIs. gRPC users typically call into these APIs on the Client side and implement the corresponding API on the server side.

Synchronous vs. asynchronous

Synchronous RPC calls, that block until a response arrives from the server, are the closest approximation to the abstraction of a procedure call that RPC aspires to.

On the other hand, networks are inherently asynchronous and in many scenarios,
it is desirable to have the ability to start RPCs without blocking the current thread.

The gRPC programming surface in most languages comes in both synchronous and asynchronous flavors.

Streaming

gRPC supports streaming semantics, where either the client or the server (or both) send a stream of messages on a single RPC call. The most general case is Bidirectional Streaming where a single gRPC call establishes a stream where both the client and the server can send a stream of messages to each other. The streamed messages are delivered in the order they were sent.

#Protocol

The gRPC protocol specifies the abstract requirements for communication between clients and servers. A concrete embedding over HTTP/2 completes the picture by fleshing out the details of each of the required operations.

Abstract gRPC protocol

A gRPC RPC comprises of a bidirectional stream of messages, initiated by the client. In the client-to-server direction, this stream begins with a mandatory Call Header, followed by optional Initial-Metadata, followed by zero or more Payload Messages. The server-to-client direction contains an optional Initial-Metadata, followed by zero or more Payload Messages terminated with a mandatory Status and optional Status-Metadata (a.k.a.,Trailing-Metadata).

Implementation over HTTP/2

The abstract protocol defined above is implemented over HTTP/2. gRPC bidirectional streams are mapped to HTTP/2 streams. The contents of Call Header and Initial Metadata are sent as HTTP/2 headers and subject to HPACK compression. Payload Messages are serialized into a byte stream of length prefixed gRPC frames which are then fragmented into HTTP/2 frames at the sender and reassembled at the receiver. Status and Trailing-Metadata are sent as HTTP/2 trailing headers (a.k.a., trailers).

Flow Control

gRPC inherits the flow control mechanisms in HTTP/2 and uses them to enable fine-grained control of the amount of memory used for buffering in-flight messages.