Swift gRPC
This repository contains an experimental Swift gRPC API and code generator.
It is intended for use with Apple's
swift-protobuf
support for Protocol Buffers. Both projects contain
code generation plugins for protoc, Google's
Protocol Buffer compiler, and both contain libraries
of supporting code that is needed to build and run
the generated code.
APIs and generated code is provided for both gRPC clients and servers, and can be built either with Xcode or the Swift Package Manager. Support is provided for all four gRPC API styles (Unary, Server Streaming, Client Streaming, and Bidirectional Streaming) and connections can be made either over secure (TLS) or insecure channels.
The Echo example provides a comprehensive demonstration of currently-supported features.
Swift Package Manager builds may also be made on Linux systems. Please see DOCKER.md and LINUX.md for details.
CocoaPods integration
Swift gRPC is currently available from CocoaPods.
To integrate, add the following line to your Podfile:
pod 'SwiftGRPC'
Then, run pod install from command line and use your project's generated
.xcworkspace file.
Manual integration
When not using CocoaPods, Swift gRPC includes vendored copies of the gRPC Core library and BoringSSL (an OpenSSL fork that is used by the gRPC Core). These are built automatically in Swift Package Manager builds.
After building your project, add the generated
SwiftGRPC.xcodeproj to your project, and add build dependencies
on BoringSSL, CgRPC, and SwiftGRPC.
Please also note that your project will need to include the
SwiftProtobuf.xcodeproj from
Swift Protobuf and
the source files that you generate with protoc/plugins.
See Echo for a working Xcode-based example, and don't hesitate to file issues if you find any problems.
Usage
The recommended way to use Swift gRPC is to first define an API using the Protocol Buffer language and then use the Protocol Buffer Compiler and the Swift Protobuf and Swift gRPC plugins to generate the necessary support code.
Getting the plugins
Binary releases of protoc, the Protocol Buffer Compiler, are
available on GitHub.
To build the plugins, run make in the main directory.
This uses the Swift Package Manager to build both of the necessary
plugins: protoc-gen-swift, which generates Protocol Buffer support code
and protoc-gen-swiftgrpc, which generates gRPC interface code.
Using the plugins
To use the plugins, protoc and both plugins should be in your
search path. Invoke them with commands like the following:
protoc <your proto files> \
--swift_out=. \
--swiftgrpc_out=.
By convention the --swift_out option invokes the protoc-gen-swift
plugin and --swiftgrpc_out invokes protoc-gen-swiftgrpc.
Parameters
To pass extra parameters to the plugin, use a comma-separated parameter list separated from the output directory by a colon.
| Flag | Values | Default | Description |
|---|---|---|---|
Visibility |
Internal/Public |
Internal |
ACL of generated code |
Server |
true/false |
true |
Whether to generate server code |
Client |
true/false |
true |
Whether to generate client code |
TestStubs |
true/false |
false |
Whether to generate test stub code |
Example:
$ protoc <your proto> --swiftgrpc_out=Client=true,Server=false:.
Building your project
Most grpc-swift development is done with the Swift Package Manager.
For usage in Xcode projects, we rely on the swift package generate-xcodeproj
command to generate an Xcode project for the grpc-swift core libraries.
The top-level Makefile uses the Swift Package Manager to generate an Xcode project for the SwiftGRPC package:
$ make
This will create SwiftGRPC.xcodeproj, which you should
add to your project, along with setting the necessary build dependencies
mentioned above.
Low-level gRPC
While the recommended way to use gRPC is with Protocol Buffers and generated code, at its core gRPC is a powerful HTTP/2-based communication system that can support arbitrary payloads. As such, each gRPC library includes low-level interfaces that can be used to directly build API clients and servers with no generated code. For an example of this in Swift, please see the Simple example.
Having build problems?
grpc-swift depends on Swift, Xcode, and swift-protobuf. We are currently testing with the following versions:
- Xcode 9.1
- Swift 4.0
- swift-protobuf 1.0.3
License
grpc-swift is released under the same license as gRPC, repeated in LICENSE.
Contributing
Please get involved! See our guidelines for contributing.