Grpc.Net.Client.Web

The .NET gRPC client can be configured to make gRPC-Web calls. This is useful for Blazor WebAssembly apps, which are hosted in the browser and have the same HTTP limitations of JavaScript code. Calling gRPC-Web with a .NET client is the same as HTTP/2 gRPC. The only modification is how the channel is created.

To use gRPC-Web:

• Add a reference to the Grpc.Net.Client.Web package.
• Ensure the reference to Grpc.Net.Client package is 2.29.0 or greater.
• Configure the channel to use the GrpcWebHandler:

var channel = GrpcChannel.ForAddress("https://localhost:5001", new GrpcChannelOptions { HttpHandler = new GrpcWebHandler(new HttpClientHandler()) }); var client = new Greeter.GreeterClient(channel); var response = await client.SayHelloAsync(new HelloRequest { Name = ".NET" });

The preceding code:

• Configures a channel to use gRPC-Web.
• Creates a client and makes a call using the channel.

GrpcWebHandler has the following configuration options:

• InnerHandler: The underlying HttpMessageHandler that makes the gRPC HTTP request, for example, HttpClientHandler.
• GrpcWebMode: An enumeration type that specifies whether the gRPC HTTP request Content-Type is application/grpc-web or application/grpc-web-text.
  • GrpcWebMode.GrpcWeb configures content to be sent without encoding. Default value.
  • GrpcWebMode.GrpcWebText configures content to be base64 encoded. Required for server streaming calls in browsers.