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author | Jan Tattermusch <jtattermusch@google.com> | 2015-09-28 13:01:03 -0700 |
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committer | Jan Tattermusch <jtattermusch@google.com> | 2015-09-28 13:01:03 -0700 |
commit | 8788e1fd3f962a4131cefa2c2f7e6ca240bfc6b7 (patch) | |
tree | cf45cb04af8253286cf64ea944683ea8a103bf04 /examples | |
parent | 38a0f998189eab2569041330048ad2bd824bb040 (diff) |
remove route guide example text
Diffstat (limited to 'examples')
-rw-r--r-- | examples/csharp/route_guide/README.md | 388 |
1 files changed, 4 insertions, 384 deletions
diff --git a/examples/csharp/route_guide/README.md b/examples/csharp/route_guide/README.md index 155877e62e..a9aa87a83d 100644 --- a/examples/csharp/route_guide/README.md +++ b/examples/csharp/route_guide/README.md @@ -1,386 +1,6 @@ -#gRPC Basics: C# # +#gRPC Basics: C# sample code -This tutorial provides a basic C# programmer's introduction to working with gRPC. By walking through this example you'll learn how to: +The files in this folder are the samples used in [gRPC Basics: C#][], +a detailed tutorial for using gRPC in C#. -- Define a service in a .proto file. -- Generate server and client code using the protocol buffer compiler. -- Use the C# gRPC API to write a simple client and server for your service. - -It assumes that you have read the [Getting started](https://github.com/grpc/grpc/tree/master/examples) guide and are familiar with [protocol buffers] (https://developers.google.com/protocol-buffers/docs/overview). Note that the example in this tutorial only uses the proto2 version of the protocol buffers language, as proto3 support for C# is not ready yet (see [protobuf C# README](https://github.com/google/protobuf/tree/master/csharp#proto2--proto3)). - -This isn't a comprehensive guide to using gRPC in C#: more reference documentation is coming soon. - -## Why use gRPC? - -Our example is a simple route mapping application that lets clients get information about features on their route, create a summary of their route, and exchange route information such as traffic updates with the server and other clients. - -With gRPC we can define our service once in a .proto file and implement clients and servers in any of gRPC's supported languages, which in turn can be run in environments ranging from servers inside Google to your own tablet - all the complexity of communication between different languages and environments is handled for you by gRPC. We also get all the advantages of working with protocol buffers, including efficient serialization, a simple IDL, and easy interface updating. - -## Example code and setup - -The example code for our tutorial is in [examples/csharp/route_guide](.). To download the example, clone this repository by running the following command: -```shell -$ git clone https://github.com/grpc/grpc.git -``` - -All the files for this tutorial are in the directory `examples/csharp/route_guide`. -Open the solution `examples/csharp/route_guide/RouteGuide.sln` from Visual Studio (or Monodevelop on Linux). - -On Windows, you should not need to do anything besides opening the solution. All the needed dependencies will be restored -for you automatically by the `Grpc` NuGet package upon building the solution. - -On Linux (or MacOS), you will first need to install protobuf and gRPC C Core using Linuxbrew (or Homebrew) tool in order to be -able to generate the server and client interface code and run the examples. Follow the instructions for [Linux](https://github.com/grpc/grpc/tree/master/src/csharp#usage-linux-mono) or [MacOS](https://github.com/grpc/grpc/tree/master/src/csharp#usage-macos-mono). - -## Defining the service - -Our first step (as you'll know from [Getting started](https://github.com/grpc/grpc/tree/master/examples)) is to define the gRPC *service* and the method *request* and *response* types using [protocol buffers] (https://developers.google.com/protocol-buffers/docs/overview). You can see the complete .proto file in [`RouteGuide/protos/route_guide.proto`](RouteGuide/protos/route_guide.proto). - -To define a service, you specify a named `service` in your .proto file: - -```protobuf -service RouteGuide { - ... -} -``` - -Then you define `rpc` methods inside your service definition, specifying their request and response types. gRPC lets you define four kinds of service method, all of which are used in the `RouteGuide` service: - -- A *simple RPC* where the client sends a request to the server using the stub and waits for a response to come back, just like a normal function call. -```protobuf - // Obtains the feature at a given position. - rpc GetFeature(Point) returns (Feature) {} -``` - -- A *server-side streaming RPC* where the client sends a request to the server and gets a stream to read a sequence of messages back. The client reads from the returned stream until there are no more messages. As you can see in our example, you specify a server-side streaming method by placing the `stream` keyword before the *response* type. -```protobuf - // Obtains the Features available within the given Rectangle. Results are - // streamed rather than returned at once (e.g. in a response message with a - // repeated field), as the rectangle may cover a large area and contain a - // huge number of features. - rpc ListFeatures(Rectangle) returns (stream Feature) {} -``` - -- A *client-side streaming RPC* where the client writes a sequence of messages and sends them to the server, again using a provided stream. Once the client has finished writing the messages, it waits for the server to read them all and return its response. You specify a server-side streaming method by placing the `stream` keyword before the *request* type. -```protobuf - // Accepts a stream of Points on a route being traversed, returning a - // RouteSummary when traversal is completed. - rpc RecordRoute(stream Point) returns (RouteSummary) {} -``` - -- A *bidirectional streaming RPC* where both sides send a sequence of messages using a read-write stream. The two streams operate independently, so clients and servers can read and write in whatever order they like: for example, the server could wait to receive all the client messages before writing its responses, or it could alternately read a message then write a message, or some other combination of reads and writes. The order of messages in each stream is preserved. You specify this type of method by placing the `stream` keyword before both the request and the response. -```protobuf - // Accepts a stream of RouteNotes sent while a route is being traversed, - // while receiving other RouteNotes (e.g. from other users). - rpc RouteChat(stream RouteNote) returns (stream RouteNote) {} -``` - -Our .proto file also contains protocol buffer message type definitions for all the request and response types used in our service methods - for example, here's the `Point` message type: -```protobuf -// Points are represented as latitude-longitude pairs in the E7 representation -// (degrees multiplied by 10**7 and rounded to the nearest integer). -// Latitudes should be in the range +/- 90 degrees and longitude should be in -// the range +/- 180 degrees (inclusive). -message Point { - int32 latitude = 1; - int32 longitude = 2; -} -``` - - -## Generating client and server code - -Next we need to generate the gRPC client and server interfaces from our .proto service definition. We do this using the protocol buffer compiler `protoc` with a special gRPC C# plugin. - -If you want to run this yourself, make sure you've installed protoc and gRPC C# plugin. The instructions vary based on your OS: -- For Windows, the `Grpc.Tools` and `Google.Protobuf` NuGet packages contain the binaries you will need to generate the code. -- For Linux, make sure you've [installed gRPC C Core using Linuxbrew](https://github.com/grpc/grpc/tree/master/src/csharp#usage-linux-mono) -- For MacOS, make sure you've [installed gRPC C Core using Homebrew](https://github.com/grpc/grpc/tree/master/src/csharp#usage-macos-mono) - -Once that's done, the following command can be used to generate the C# code. - -To generate the code on Windows, we use `protoc.exe` from the `Google.Protobuf` NuGet package and `grpc_csharp_plugin.exe` from the `Grpc.Tools` NuGet package (both under the `tools` directory). -Normally you would need to add the `Grpc.Tools` package to the solution yourself, but in this tutorial it has been already done for you. Following command should be run from the `csharp/route_guide` directory: -``` -> packages\Google.Protobuf.3.0.0-alpha4\tools\protoc -I RouteGuide/protos --csharp_out=RouteGuide --grpc_out=RouteGuide --plugin=protoc-gen-grpc=packages\Grpc.Tools.0.7.0\tools\grpc_csharp_plugin.exe RouteGuide/protos/route_guide.proto -``` - -On Linux/MacOS, we rely on `protoc` and `grpc_csharp_plugin` being installed by Linuxbrew/Homebrew. Run this command from the route_guide directory: -```shell -$ protoc -I RouteGuide/protos --csharp_out=RouteGuide --grpc_out=RouteGuide --plugin=protoc-gen-grpc=`which grpc_csharp_plugin` RouteGuide/protos/route_guide.proto -``` - -Running one of the previous commands regenerates the following files in the RouteGuide directory: -- `RouteGuide/RouteGuide.cs` defines a namespace `examples` - - This contains all the protocol buffer code to populate, serialize, and retrieve our request and response message types -- `RouteGuide/RouteGuideGrpc.cs`, provides stub and service classes - - an interface `RouteGuide.IRouteGuide` to inherit from when defining RouteGuide service implementations - - a class `RouteGuide.RouteGuideClient` that can be used to access remote RouteGuide instances - - -<a name="server"></a> -## Creating the server - -First let's look at how we create a `RouteGuide` server. If you're only interested in creating gRPC clients, you can skip this section and go straight to [Creating the client](#client) (though you might find it interesting anyway!). - -There are two parts to making our `RouteGuide` service do its job: -- Implementing the service interface generated from our service definition: doing the actual "work" of our service. -- Running a gRPC server to listen for requests from clients and return the service responses. - -You can find our example `RouteGuide` server in [RouteGuideServer/RouteGuideImpl.cs](RouteGuideServer/RouteGuideServerImpl.cs). Let's take a closer look at how it works. - -### Implementing RouteGuide - -As you can see, our server has a `RouteGuideImpl` class that implements the generated `RouteGuide.IRouteGuide`: - -```csharp -// RouteGuideImpl provides an implementation of the RouteGuide service. -public class RouteGuideImpl : RouteGuide.IRouteGuide -``` - -#### Simple RPC - -`RouteGuideImpl` implements all our service methods. Let's look at the simplest type first, `GetFeature`, which just gets a `Point` from the client and returns the corresponding feature information from its database in a `Feature`. - -```csharp - public Task<Feature> GetFeature(Point request, Grpc.Core.ServerCallContext context) - { - return Task.FromResult(CheckFeature(request)); - } -``` - -The method is passed a context for the RPC (which is empty in the alpha release), the client's `Point` protocol buffer request, and returns a `Feature` protocol buffer. In the method we create the `Feature` with the appropriate information, and then return it. To allow asynchronous -implementation, the method returns `Task<Feature>` rather than just `Feature`. You are free to perform your computations synchronously and return -the result once you've finished, just as we do in the example. - -#### Server-side streaming RPC - -Now let's look at something a bit more complicated - a streaming RPC. `ListFeatures` is a server-side streaming RPC, so we need to send back multiple `Feature` protocol buffers to our client. - -```csharp - // in RouteGuideImpl - public async Task ListFeatures(Rectangle request, - Grpc.Core.IServerStreamWriter<Feature> responseStream, - Grpc.Core.ServerCallContext context) - { - var responses = features.FindAll( (feature) => feature.Exists() && request.Contains(feature.Location) ); - foreach (var response in responses) - { - await responseStream.WriteAsync(response); - } - } -``` - -As you can see, here the request object is a `Rectangle` in which our client wants to find `Feature`s, but instead of returning a simple response we need to write responses to an asynchronous stream `IServerStreamWriter` using async method `WriteAsync`. - -#### Client-side streaming RPC - -Similarly, the client-side streaming method `RecordRoute` uses an [IAsyncEnumerator](https://github.com/Reactive-Extensions/Rx.NET/blob/master/Ix.NET/Source/System.Interactive.Async/IAsyncEnumerator.cs), to read the stream of requests using the async method `MoveNext` and the `Current` property. - -```csharp - public async Task<RouteSummary> RecordRoute(Grpc.Core.IAsyncStreamReader<Point> requestStream, - Grpc.Core.ServerCallContext context) - { - int pointCount = 0; - int featureCount = 0; - int distance = 0; - Point previous = null; - var stopwatch = new Stopwatch(); - stopwatch.Start(); - - while (await requestStream.MoveNext()) - { - var point = requestStream.Current; - pointCount++; - if (CheckFeature(point).Exists()) - { - featureCount++; - } - if (previous != null) - { - distance += (int) previous.GetDistance(point); - } - previous = point; - } - - stopwatch.Stop(); - - return new RouteSummary - { - PointCount = pointCount, - FeatureCount = featureCount, - Distance = distance, - ElapsedTime = (int)(stopwatch.ElapsedMilliseconds / 1000) - }; - } -``` - -#### Bidirectional streaming RPC - -Finally, let's look at our bidirectional streaming RPC `RouteChat`. - -```csharp - public async Task RouteChat(Grpc.Core.IAsyncStreamReader<RouteNote> requestStream, - Grpc.Core.IServerStreamWriter<RouteNote> responseStream, - Grpc.Core.ServerCallContext context,) - { - while (await requestStream.MoveNext()) - { - var note = requestStream.Current; - List<RouteNote> prevNotes = AddNoteForLocation(note.Location, note); - foreach (var prevNote in prevNotes) - { - await responseStream.WriteAsync(prevNote); - } - } - } -``` - -Here the method receives both `requestStream` and `responseStream` arguments. Reading the requests is done the same way as in the client-side streaming method `RecordRoute`. Writing the responses is done the same way as in the server-side streaming method `ListFeatures`. - -### Starting the server - -Once we've implemented all our methods, we also need to start up a gRPC server so that clients can actually use our service. The following snippet shows how we do this for our `RouteGuide` service: - -```csharp -var features = RouteGuideUtil.ParseFeatures(RouteGuideUtil.DefaultFeaturesFile); - -Server server = new Server -{ - Services = { RouteGuide.BindService(new RouteGuideImpl(features)) }, - Ports = { new ServerPort("localhost", Port, ServerCredentials.Insecure) } -}; -server.Start(); - -Console.WriteLine("RouteGuide server listening on port " + port); -Console.WriteLine("Press any key to stop the server..."); -Console.ReadKey(); - -server.ShutdownAsync().Wait(); -``` -As you can see, we build and start our server using `Grpc.Core.Server` class. To do this, we: - -1. Create an instance of `Grpc.Core.Server`. -1. Create an instance of our service implementation class `RouteGuideImpl`. -3. Register our service implementation by adding its service definition to `Services` collection (We obtain the service definition from the generated `RouteGuide.BindService` method). -2. Specify the address and port we want to use to listen for client requests. This is done by adding `ServerPort` to `Ports` collection. -4. Call `Start` on the server instance to start an RPC server for our service. - -<a name="client"></a> -## Creating the client - -In this section, we'll look at creating a C# client for our `RouteGuide` service. You can see our complete example client code in [RouteGuideClient/Program.cs](RouteGuideClient/Program.cs). - -### Creating a stub - -To call service methods, we first need to create a *stub*. - -First, we need to create a gRPC client channel that will connect to gRPC server. Then, we use the `RouteGuide.NewClient` method of the `RouteGuide` class generated from our .proto. - -```csharp -Channel channel = new Channel("127.0.0.1:50052", Credentials.Insecure) -var client = new RouteGuideClient(RouteGuide.NewClient(channel)); - -// YOUR CODE GOES HERE - -channel.ShutdownAsync().Wait(); -``` - -### Calling service methods - -Now let's look at how we call our service methods. gRPC C# provides asynchronous versions of each of the supported method types. For convenience, -gRPC C# also provides a synchronous method stub, but only for simple (single request/single response) RPCs. - -#### Simple RPC - -Calling the simple RPC `GetFeature` in a synchronous way is nearly as straightforward as calling a local method. - -```csharp -Point request = new Point { Latitude = 409146138, Longitude = -746188906 }; -Feature feature = client.GetFeature(request); -``` - -As you can see, we create and populate a request protocol buffer object (in our case `Point`), and call the desired method on the client object, passing it the request. If the RPC finishes with success, the response protocol buffer (in our case `Feature`) will be returned. Otherwise, an exception of type `RpcException` will be thrown, indicating the status code of the problem. - -Alternatively, if you are in async context, you can call an asynchronous version of the method (and use `await` keyword to await the result): -```csharp -Point request = new Point { Latitude = 409146138, Longitude = -746188906 }; -Feature feature = await client.GetFeatureAsync(request); -``` - -#### Streaming RPCs - -Now let's look at our streaming methods. If you've already read [Creating the server](#server) some of this may look very familiar - streaming RPCs are implemented in a similar way on both sides. The difference with respect to simple call is that the client methods return an instance of a call object, that provides access to request/response streams and/or asynchronous result (depending on the streaming type you are using). - -Here's where we call the server-side streaming method `ListFeatures`, which has property `ReponseStream` of type `IAsyncEnumerator<Feature>` - -```csharp -using (var call = client.ListFeatures(request)) -{ - while (await call.ResponseStream.MoveNext()) - { - Feature feature = call.ResponseStream.Current; - Console.WriteLine("Received " + feature.ToString()); - } -} -``` - -The client-side streaming method `RecordRoute` is similar, except we use the property `RequestStream` to write the requests one by one using `WriteAsync` and eventually signal that no more request will be send using `CompleteAsync`. The method result can be obtained through the property -`ResponseAsync`. -```csharp -using (var call = client.RecordRoute()) -{ - foreach (var point in points) - { - await call.RequestStream.WriteAsync(point); - } - await call.RequestStream.CompleteAsync(); - - RouteSummary summary = await call.ResponseAsync; -} -``` - -Finally, let's look at our bidirectional streaming RPC `RouteChat`. In this case, we write the request to `RequestStream` and receive the responses from `ResponseStream`. As you can see from the example, the streams are independent of each other. - -```csharp - using (var call = client.RouteChat()) - { - var responseReaderTask = Task.Run(async () => - { - while (await call.ResponseStream.MoveNext()) - { - var note = call.ResponseStream.Current; - Console.WriteLine("Received " + note); - } - }); - - foreach (RouteNote request in requests) - { - await call.RequestStream.WriteAsync(request); - } - await call.RequestStream.CompleteAsync(); - await responseReaderTask; -} -``` - -## Try it out! - -Build client and server: - -Open the solution `examples/csharp/route_guide/RouteGuide.sln` from Visual Studio (or Monodevelop on Linux) and hit "Build". - -Run the server, which will listen on port 50052: -``` -> cd RouteGuideServer/bin/Debug -> RouteGuideServer.exe -``` - -Run the client (in a different terminal): -``` -> cd RouteGuideClient/bin/Debug -> RouteGuideClient.exe -``` - -You can also run the server and client directly from Visual Studio. - -On Linux or Mac, use `mono RouteGuideServer.exe` and `mono RouteGuideClient.exe` to run the server and client. +[gRPC Basics: C#]:http://www.grpc.io/docs/tutorials/basic/csharp.html |