commit | 3fcd20fb5aaa920afd8ab8fccaccb5ea7371b02b | [log] [tgz] |
---|---|---|
author | Jon Skeet <jonskeet@google.com> | Fri Jul 08 14:38:39 2016 +0100 |
committer | Jon Skeet <jonskeet@google.com> | Fri Jul 15 07:09:54 2016 +0100 |
tree | a20952fa93374e362ca57dcda15a3c4fc61e10ac | |
parent | 9b45afbbc52977fc0c5a820c2eb2fb7276335822 [diff] |
Overhaul how the native extension is found, loaded and used The goal of this is to fix #7230. The changes here are: - The layout in the nuget package; the files are now in `/runtimes/{os}/native/{library}` - The filename of each library, which now includes the architecture, e.g `grpc_csharp_ext.x64.dll` - The targets file used to copy those files in msbuild-based projects; note that we now don't build up a folder structure. - The way the functions are found Before this change, on Linux and OSX we used to find library symbols manually, and use DllImport on Windows. With this change, the name of the library file changes based on architecture, so `DllImport` doesn't work. Instead, we have to use `GetProcAddress` to fetch the function. This is further convoluted by the convention on Windows-x86 to prefix the function name with `_` and suffix it based on the stack size of the arguments. We can't easily tell the argument size here, so we just try 0, 4, 8...128. (128 bytes should be enough for anyone.) This is inefficient, but it's a one-time hit with a known number of functions, and doesn't seem to have any significant impact. The benefit of this in code is we don't need the DllImports any more, and we don't need to conditionally use `FindSymbol` - we just use it for everything, so things are rather more uniform and tidy. The further benefit of this is that the library name is no longer tied to a particular filename format - so if someone wanted to have a directory with the libraries for every version in, with the version in the filename, we'd handle that just fine. (At least once Testing: - Windows: - Console app under msbuild, dotnet cli and DNX - ASP.NET Classic under msbuild - ASP.NET Core (still running under net451) - Ubuntu 16.04 - Console app under dotnet cli, run with dotnet run and mono - OSX: - Console app under dotnet cli, run with dotnet run and mono Under dotnet cli, a dependency on `Microsoft.NETCore.Platforms` is required in order to force the libraries to be copied. This change does *not* further enable .NET Core. It attempts to keep the existing experimental .NET Core project files in line with the msbuild files, but I expect further work to be required for .NET Core, which has a different build/publication model.
Copyright 2015 Google Inc.
#Documentation
You can find more detailed documentation and examples in the doc and examples directories respectively.
#Installation & Testing
See INSTALL for installation instructions for various platforms.
See tools/run_tests for more guidance on how to run various test suites (e.g. unit tests, interop tests, benchmarks)
#Repository Structure & Status
This repository contains source code for gRPC libraries for multiple languages written on top of shared C core library [src/core] (src/core).
Libraries in different languages are in different states of development. We are seeking contributions for all of these libraries.
Language | Source | Status |
---|---|---|
Shared C [core library] | [src/core] (src/core) | Beta - the surface API is stable |
C++ | [src/cpp] (src/cpp) | Beta - the surface API is stable |
Ruby | [src/ruby] (src/ruby) | Beta - the surface API is stable |
NodeJS | [src/node] (src/node) | Beta - the surface API is stable |
Python | [src/python] (src/python) | Beta - the surface API is stable |
PHP | [src/php] (src/php) | Beta - the surface API is stable |
C# | [src/csharp] (src/csharp) | Beta - the surface API is stable |
Objective-C | [src/objective-c] (src/objective-c) | Beta - the surface API is stable |
See MANIFEST.md for a listing of top-level items in the repository.
#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 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.
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.
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
).
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).
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.