gRPC with .NET Core

⚡ gRPC with .NET Core

gRPC (Google Remote Procedure Call) is a high-performance RPC framework that uses HTTP/2 and Protocol Buffers. It's ideal for microservices and real-time communication in .NET Core applications.

gRPC is a modern, high-performance Remote Procedure Call (RPC) framework developed by Google. It is built on HTTP/2 and uses Protocol Buffers (Protobuf) as its Interface Definition Language (IDL) and message serialization format. This approach enables fast, type-safe, and efficient communication between client and server applications, especially in a microservices architecture.

In .NET Core, gRPC is fully integrated and offers features like strong typing, code generation, and streaming capabilities out of the box.

📦 Prerequisites to implemtn in .net Core

• Visual Studio 2022 or VS Code
• .NET Core SDK (3.1 or later)
• gRPC NuGet packages

🧪 Steps to Create a gRPC Service

1. Create a gRPC Project

dotnet new grpc -o GrpcService

2. Define a .proto File

syntax = "proto3";

option csharp_namespace = "GrpcService";

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}
    

3. Implement the Service

public class GreeterService : Greeter.GreeterBase {
    public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context) {
        return Task.FromResult(new HelloReply {
            Message = $"Hello, {request.Name}"
        });
    }
}
    

4. Configure Startup

app.MapGrpcService<GreeterService>();
app.MapGet("/", () => "Use a gRPC client to communicate.");
    

5. Create a gRPC Client

var channel = GrpcChannel.ForAddress("https://localhost:5001");
var client = new Greeter.GreeterClient(channel);
var reply = await client.SayHelloAsync(new HelloRequest { Name = "Shivshanker" });
Console.WriteLine(reply.Message);
    

🧩 Another Example: gRPC Service with .NET Core

1️⃣ Create the gRPC service

Start by creating a new ASP.NET Core gRPC Service project using Visual Studio or the .NET CLI.

2️⃣ Define the service contract with a .proto file

In the Protos folder, the .proto file defines the service methods and message structures. The compiler uses this file to generate the C# server and client code.

Here is an example of a .proto file:

// Protos/greet.proto
syntax = "proto3";

option csharp_namespace = "GrpcGreeter";

package greet;

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}
    

3️⃣ Implement the service

Implement the generated abstract base class Greeter.GreeterBase with your service logic.

4️⃣ Register the gRPC service in Program.cs

Register your service in the application's configuration.

5️⃣ Create and use a client

In a separate project, use the same .proto file to generate a client stub and interact with the service.

⚔️ gRPC vs. REST

Feature	gRPC	REST
Protocol	HTTP/2, which supports multiplexing, header compression (HPACK), and long-lived connections.	Typically HTTP/1.1, with a single request-response per connection, which can be less efficient.
Serialization	Protocol Buffers (Protobuf), a binary format that is faster and more compact than text-based formats.	JSON, a human-readable text format, easier to work with for public APIs but less performant.
API Contract	A contract-first approach using .proto files, which auto-generates strongly-typed clients and servers for various languages.	A resource-oriented approach with no built-in contract, often relying on documentation like OpenAPI/Swagger.
Streaming	Built-in support for four types of streaming: unary (request/response), server streaming, client streaming, and bidirectional streaming.	Unary, or one-way streaming via WebSockets, but not natively for standard REST.
Browser Support	Requires a proxy layer like gRPC-Web for browser support due to its reliance on HTTP/2 features.	Excellent browser support and tool availability.
Developer Experience	Requires tooling to generate code from the .proto file but provides strongly-typed interfaces that prevent runtime errors.	Easy to learn and debug, with a large ecosystem of tools and libraries.

✅ Advantages

• High performance with HTTP/2
• Strongly typed contracts via Protocol Buffers
• Built-in streaming support
• Cross-platform and multi-language support

❌ Limitations

• Not natively supported in browsers
• Requires .proto file management
• Less flexible than REST for dynamic queries

🚀 When to Use gRPC

• High performance, low latency, and efficient communication requirements.
• Microservices and polyglot environments.
• Real-time streaming and internal APIs.
• Mobile and IoT devices that benefit from compact Protobuf messages.

🚫 When Not to Use gRPC

• Browser-accessible or public-facing APIs.
• When human-readable payloads (like JSON) are necessary.
• For broadcasting messages to many clients — use SignalR instead.

💡 Best Practices and Tips

• Reuse gRPC channels for performance.
• Use asynchronous programming with async/await.
• Utilize client factory integration in ASP.NET Core.
• Implement interceptors for cross-cutting concerns (e.g., logging, auth).
• Define deadlines for requests.
• Consider client-side or L7 proxy load balancing.

⚠️ Precautions

• Limited direct browser support.
• Requires careful schema versioning.
• Potential debugging complexity due to binary Protobuf.
• Challenges with traditional L4 load balancing.
• Requires service discovery in microservices architectures.