ASP.NET Core namespace resolution

The ASP.NET Core client provides namespace resolution designed for multi-tenant web applications. It integrates with HTTP context and offers built-in resolvers for common request patterns.

If your multi-tenant setup is based on Arc Tenancy, you can map the current tenant to a namespace. See Arc Tenancy.

Built-in resolvers

HTTP header resolution (default)

The default resolver reads the namespace from an HTTP header. Configure it through ChronicleAspNetCoreOptions:

builder.Services.Configure<ChronicleAspNetCoreOptions>(options =>
{
    options.EventStore = "my-event-store";
    options.NamespaceHttpHeader = "x-cratis-tenant-id"; // Default value
});

builder.Services.Configure<ChronicleAspNetCoreOptions>(options =>
    options.EventStore = "my-event-store"
           .WithHttpHeaderNamespaceResolver("x-cratis-tenant-id"));

When the header is present, its value becomes the namespace for the request. If the header is missing, the default namespace is used.

Subdomain resolution

The subdomain resolver extracts the namespace from the request host (for example, tenant1.example.com).

builder.Services.Configure<ChronicleAspNetCoreOptions>(options =>
    options.EventStore = "my-event-store"
           .WithSubdomainNamespaceResolver());

Custom resolvers

You can configure a custom resolver either by type (DI) or by instance:

builder.Services.Configure<ChronicleAspNetCoreOptions>(options =>
{
    options.EventStore = "my-event-store";
    options.EventStoreNamespaceResolverType = typeof(CustomNamespaceResolver);
});

builder.Services.Configure<ChronicleAspNetCoreOptions>(options =>
{
    options.EventStore = "my-event-store";
    options.EventStoreNamespaceResolver = new CustomNamespaceResolver(someConfiguration);
});

Configuration priority

1. Instance configuration (EventStoreNamespaceResolver) when set to a non-default instance
2. Type configuration (EventStoreNamespaceResolverType) when provided
3. Default HTTP header resolver

Example: Web app setup

using Cratis.Chronicle;
using Cratis.Chronicle.EventSequences;

var builder = WebApplication.CreateBuilder(args);

builder.AddCratisChronicle(options =>
{
    options.EventStore = "production-store";
    options.WithHttpHeaderNamespaceResolver("x-tenant-id");
});

var app = builder.Build();
app.MapPost("/api/cart/{cartId}/items", async (string cartId, IEventLog eventLog) =>
{
    var itemAdded = new ItemAddedToCart(ProductId: "product-123", Quantity: 1);
    await eventLog.Append(cartId, itemAdded);
    return Results.Ok();
});
app.Run();

record ItemAddedToCart(string ProductId, int Quantity);

For non-web contexts, see DotNET client usage.