4.3 KiB
| title | author | description | monikerRange | ms.author | ms.date | uid |
|---|---|---|---|---|---|---|
| gRPC services with C# | juntaoluo | Learn the basic concepts when writing gRPC services with C#. | >= aspnetcore-3.0 | johluo | 07/03/2019 | grpc/basics |
gRPC services with C#
This document outlines the concepts needed to write gRPC apps in C#. The topics covered here apply to both C-core-based and ASP.NET Core-based gRPC apps.
proto file
gRPC uses a contract-first approach to API development. Protocol buffers (protobuf) are used as the Interface Design Language (IDL) by default. The *.proto file contains:
- The definition of the gRPC service.
- The messages sent between clients and servers.
For more information on the syntax of protobuf files, see the official documentation (protobuf).
For example, consider the greet.proto file used in Get started with gRPC service:
- Defines a
Greeterservice. - The
Greeterservice defines aSayHellocall. SayHellosends aHelloRequestmessage and receives aHelloReplymessage:
Add a .proto file to a C# app
The *.proto file is included in a project by adding it to the <Protobuf> item group:
C# Tooling support for .proto files
The tooling package Grpc.Tools is required to generate the C# assets from *.proto files. The generated assets (files):
- Are generated on an as-needed basis each time the project is built.
- Aren't added to the project or checked into source control.
- Are a build artifact contained in the obj directory.
This package is required by both the server and client projects. The Grpc.AspNetCore metapackage includes a reference to Grpc.Tools. Server projects can add Grpc.AspNetCore using the Package Manager in Visual Studio or by adding a <PackageReference> to the project file:
Client projects should directly reference Grpc.Tools alongside the other packages required to use the gRPC client. The tooling package isn't required at runtime, so the dependency is marked with PrivateAssets="All":
Generated C# assets
The tooling package generates the C# types representing the messages defined in the included *.proto files.
For server-side assets, an abstract service base type is generated. The base type contains the definitions of all the gRPC calls contained in the .proto file. Create a concrete service implementation that derives from this base type and implements the logic for the gRPC calls. For the greet.proto, the example described previously, an abstract GreeterBase type that contains a virtual SayHello method is generated. A concrete implementation GreeterService overrides the method and implements the logic handling the gRPC call.
For client-side assets, a concrete client type is generated. The gRPC calls in the .proto file are translated into methods on the concrete type, which can be called. For the greet.proto, the example described previously, a concrete GreeterClient type is generated. Call GreeterClient.SayHelloAsync to initiate a gRPC call to the server.
By default, server and client assets are generated for each *.proto file included in the <Protobuf> item group. To ensure only the server assets are generated in a server project, the GrpcServices attribute is set to Server.
Similarly, the attribute is set to Client in client projects.