.NET Server Setup

Host IonPath services in an ASP.NET Core application with dependency injection, RPC endpoint mapping, and interceptors.

Basic Setup

var builder = WebApplication.CreateBuilder(args);

// Register IonPath protocol services
builder.Services.AddIonProtocol(options =>
{
    options.WithTransport<MyAppTransport>();
});

// Register your service implementations
builder.Services.AddScoped<IUserService, UserServiceImpl>();

var app = builder.Build();

// Map all IonPath RPC endpoints
app.MapRpcEndpoints();

app.Run();

Implementing a Service

Implement the generated interface (IServiceName) and register it with DI:

public class UserServiceImpl : IUserService
{
    private readonly IDbContext _db;

    public UserServiceImpl(IDbContext db) => _db = db;

    public async Task<User> GetUser(
        uint spaceId,  // base arg
        uint userId,   // method arg
        CancellationToken ct)
    {
        return await _db.Users
            .Where(u => u.SpaceId == spaceId && u.Id == userId)
            .FirstAsync(ct);
    }
}

Base arguments and method arguments are flattened into the method signature. A CancellationToken is automatically passed for request cancellation.

Streaming Methods

Server-streaming methods return IAsyncEnumerable<T>:

public async IAsyncEnumerable<User> WatchUpdates(
    uint spaceId,
    [EnumeratorCancellation] CancellationToken ct)
{
    await foreach (var update in _updates.ReadAllAsync(ct))
    {
        if (update.SpaceId == spaceId)
            yield return update;
    }
}

Interceptors

Interceptors provide cross-cutting concerns (logging, metrics, auth) around method execution:

builder.Services.AddIonProtocol(options =>
{
    options.AddInterceptor<LoggingInterceptor>();
    options.AddInterceptor<MetricsInterceptor>();
});

Interceptors execute in registration order. They receive the execution context and can inspect/modify the request, response, or error.

Ticket-Based Authentication

IonPath uses ticket-based authentication instead of standard HTTP headers. Configure the ticket exchange:

builder.Services.AddIonProtocol(options =>
{
    options.WithTicketExchange<JwtTicketExchange>();
});

The IIonTicketExchange interface validates tickets and returns the associated identity. For WebSocket, the ticket is passed via the subprotocol header; for HTTP, via a custom header.

OpenTelemetry

IonPath instruments method calls with OpenTelemetry spans and metrics via the Instruments class:

// Automatically creates spans for each RPC method call:
// ion.rpc.{service}.{method}
// With attributes: ion.service, ion.method, ion.status