Building High-Performance APIs with gRPC in .NET Core 9
Building High-Performance APIs with gRPC in .NET Core 9
Introduction
gRPC (Google Remote Procedure Call) is a high-performance, open-source RPC framework designed for efficient communication between services. It offers faster response times, low bandwidth usage, and strongly typed contracts, making it a great alternative to REST APIs for microservices and real-time applications.
In this article, we will explore how to set up and use gRPC in .NET Core 9, covering key concepts, implementation steps, and best practices.
---
Why Use gRPC?
✔ High Performance: Uses HTTP/2 for multiplexing, compression, and lower latency.
✔ Strong Typing: Uses Protocol Buffers (Protobuf) instead of JSON, ensuring data integrity.
✔ Streaming Support: Supports unary, client-streaming, server-streaming, and bi-directional streaming.
✔ Better Efficiency: Uses binary serialization (Protobuf), reducing payload size compared to JSON.
✔ Language Agnostic: Supports multiple languages like C#, Java, Python, and Go.
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Setting Up gRPC in .NET Core 9
Step 1: Create a gRPC Project
Open a terminal and run:
dotnet new grpc -n GrpcServiceDemo
cd GrpcServiceDemo
dotnet build
This will create a gRPC service project with the following structure:
GrpcServiceDemo/
│── Protos/
│ └── greet.proto
│── Services/
│ └── GreeterService.cs
│── appsettings.json
│── Program.cs
│── Startup.cs (for older versions)
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Step 2: Define a gRPC Service (Protobuf File)
Inside the Protos folder, open greet.proto and define the service:
syntax = "proto3";
option csharp_namespace = "GrpcServiceDemo";
service Greeter {
rpc SayHello (HelloRequest) returns (HelloReply);
}
message HelloRequest {
string name = 1;
}
message HelloReply {
string message = 1;
}
Explanation:
Defines a Greeter service with a single method SayHello().
HelloRequest is the input message containing a name field.
HelloReply is the response message containing a message field.
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Step 3: Implement the gRPC Service in C#
Open Services/GreeterService.cs and modify it:
using System.Threading.Tasks;
using Grpc.Core;
using GrpcServiceDemo;
public class GreeterService : Greeter.GreeterBase
{
public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context)
{
return Task.FromResult(new HelloReply
{
Message = $"Hello, {request.Name}!"
});
}
}
Explanation:
Greeter.GreeterBase is generated from greet.proto and provides the base class.
SayHello() implements the gRPC method, responding with a greeting message.
---
Step 4: Configure gRPC in .NET Core 9
Modify Program.cs:
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddGrpc();
var app = builder.Build();
app.MapGrpcService<GreeterService>();
app.MapGet("/", () => "gRPC Service is running. Use a gRPC client to communicate.");
app.Run();
Key Points:
✔ Registers gRPC services using builder.Services.AddGrpc().
✔ Maps the GreeterService using app.MapGrpcService<GreeterService>().
✔ Adds a fallback endpoint for browser requests.
---
Step 5: Running the gRPC Server
Run the application:
dotnet run
By default, gRPC will run on https://localhost:5001.
---
Creating a gRPC Client in .NET Core 9
To test the gRPC service, let's create a gRPC client.
Step 1: Create a .NET Console App
dotnet new console -n GrpcClientDemo
cd GrpcClientDemo
dotnet add package Grpc.Net.Client
dotnet add package Google.Protobuf
dotnet add package Grpc.Tools
---
Step 2: Add Protobuf Reference
Modify GrpcClientDemo.csproj to include:
<ItemGroup>
<Protobuf Include="../GrpcServiceDemo/Protos/greet.proto" GrpcServices="Client" />
</ItemGroup>
This will auto-generate the client classes from the Protobuf file.
---
Step 3: Implement the gRPC Client
Modify Program.cs:
using System;
using System.Threading.Tasks;
using Grpc.Net.Client;
using GrpcServiceDemo;
class Program
{
static async Task Main(string[] args)
{
using var channel = GrpcChannel.ForAddress("https://localhost:5001");
var client = new Greeter.GreeterClient(channel);
var request = new HelloRequest { Name = "John" };
var response = await client.SayHelloAsync(request);
Console.WriteLine("Server Response: " + response.Message);
}
}
Explanation:
✔ GrpcChannel.ForAddress() creates a secure connection to the gRPC server.
✔ GreeterClient calls the SayHello() method.
✔ The response is displayed in the console.
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Step 4: Run the gRPC Client
Start the server first:
cd GrpcServiceDemo
dotnet run
Then, run the client in another terminal:
cd GrpcClientDemo
dotnet run
Output:
Server Response: Hello, John!
---
gRPC Streaming in .NET Core 9
gRPC supports streaming, allowing efficient real-time data transfer.
Example: Server Streaming
Modify greet.proto:
service Greeter {
rpc SayHelloStream (HelloRequest) returns (stream HelloReply);
}
Modify GreeterService.cs:
public override async Task SayHelloStream(
HelloRequest request,
IServerStreamWriter<HelloReply> responseStream,
ServerCallContext context)
{
for (int i = 0; i < 5; i++)
{
await responseStream.WriteAsync(new HelloReply
{
Message = $"Hello {request.Name}, message {i + 1}"
});
await Task.Delay(1000);
}
}
Modify Program.cs in the client:
using var channel = GrpcChannel.ForAddress("https://localhost:5001");
var client = new Greeter.GreeterClient(channel);
using var call = client.SayHelloStream(new HelloRequest { Name = "John" });
await foreach (var response in call.ResponseStream.ReadAllAsync())
{
Console.WriteLine("Received: " + response.Message);
}
Now, the client will receive multiple messages asynchronously from the server.
---
Conclusion
gRPC in .NET Core 9 is a powerful tool for building high-performance, scalable, and real-time APIs. It outperforms REST in scenarios requiring low latency, real-time streaming, and strongly typed contracts.
Key Takeaways:
✔ gRPC is faster and more efficient than REST.
✔
Uses Protocol Buffers (Protobuf) for compact, strongly typed data exchange.
✔ Supports unary, streaming, and bi-directional communication.
✔ Ideal for microservices, IoT, and real-time applications.
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