Fluent Configuration Builder

Overview

RCommon uses a fluent builder pattern to configure framework services during application startup. The entry point is the AddRCommon() extension method on IServiceCollection, which returns an IRCommonBuilder instance. You then chain With* methods on that builder to activate features such as GUID generation, system time, and common factories.

This approach keeps all RCommon configuration in one place, makes dependencies explicit, and prevents double-registration of the same service.

Installation

NuGet Package

dotnet add package RCommon.Core

Configuration

Call AddRCommon() inside Program.cs (or Startup.ConfigureServices for older host models) and chain the features you need:

using RCommon;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddRCommon()
    .WithSequentialGuidGenerator(options =>
    {
        options.DefaultSequentialGuidType = SequentialGuidType.SequentialAtEnd;
    })
    .WithDateTimeSystem(options =>
    {
        options.Kind = DateTimeKind.Utc;
    });

AddRCommon() registers core infrastructure immediately (caching options, event bus, event router). Each subsequent With* call registers the corresponding service into IServiceCollection and returns the same builder so calls can be chained.

What AddRCommon registers automatically

Calling AddRCommon() with no additional configuration registers:

• CachingOptions (caching disabled by default)
• EventSubscriptionManager (singleton)
• IEventBus backed by InMemoryEventBus (singleton)
• IEventRouter backed by InMemoryTransactionalEventRouter (scoped)

Usage

Basic setup — minimal configuration

builder.Services.AddRCommon();

This is sufficient when you only need the built-in event infrastructure and do not require GUID generation or system time abstractions.

Full configuration chain

builder.Services.AddRCommon()
    .WithSimpleGuidGenerator()
    .WithDateTimeSystem(options => options.Kind = DateTimeKind.Utc)
    .WithCommonFactory<IMyService, MyService>();

Creating a custom builder extension

If you are writing an RCommon add-on package you can extend IRCommonBuilder with your own With* method. Follow the same pattern used by the built-in methods:

using Microsoft.Extensions.DependencyInjection;
using RCommon;

public static class MyFeatureBuilderExtensions
{
    public static IRCommonBuilder WithMyFeature(
        this IRCommonBuilder builder,
        Action<MyFeatureOptions> configure)
    {
        builder.Services.Configure<MyFeatureOptions>(configure);
        builder.Services.AddTransient<IMyFeature, MyFeature>();
        return builder;
    }
}

Consumers then call it like any other built-in method:

builder.Services.AddRCommon()
    .WithMyFeature(options => { options.Timeout = TimeSpan.FromSeconds(30); });

API Summary

IServiceCollection extension

Method	Description
AddRCommon()	Creates an RCommonBuilder, registers core services, and returns IRCommonBuilder.

IRCommonBuilder interface

Member	Description
Services	The underlying IServiceCollection. Useful inside extension methods to register additional services.
WithSequentialGuidGenerator(Action<SequentialGuidGeneratorOptions>)	Registers SequentialGuidGenerator as IGuidGenerator.
WithSimpleGuidGenerator()	Registers SimpleGuidGenerator as IGuidGenerator.
WithDateTimeSystem(Action<SystemTimeOptions>)	Registers SystemTime as ISystemTime.
WithCommonFactory<TService, TImplementation>()	Registers a service/implementation pair together with an ICommonFactory<TService>.
Configure()	Finalizes configuration and returns the IServiceCollection. Called internally by AddRCommon().

Guard against double registration

The builder tracks whether a GUID generator or date/time system has already been configured. Calling the same With* method twice throws an RCommonBuilderException, preventing accidental duplicate registrations.