Scribbly Broker

A publisher used for commands and queries based on the Mediator Design Pattern.

%% sequence displaying pipeline

sequenceDiagram
    Publish-->>Behavior: wraps handler with middleware
    Behavior-->>Handler: process notification
    Handler-->>Publisher: returns to caller

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Table of Contents

1. 🎁 Packages
2. 💪 Notifications
3. 🛒 Handlers
4. 🛁 Behaviors
5. 🛁 Pipelines
6. 🎉 Hosting

Example

Below is a brief snip of code to get you started before reading more.

1. Add a reference to the Scribbly.Broker.MicrosoftHosting package

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddScribblyBroker(options =>
{
    options.AsScoped = true;

    options.AddHandlersFromAssembly<Program>();

    options
        .AddBehavior<TracingBehavior>()
        .AddBehavior<ExceptionBehavior>();
});

2. Create some notifications INotification

public record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary) : INotification
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}

3. Create some queries INotification<TResult> (these accept data and return a result)

public record WeatherQuery(string Summary) : INotification<WeatherForecast>;

4. Create handlers INotificationHandler for the notifications

public sealed class WeatherForecastHandler(ILogger<WeatherForecastHandler> logger) : INotificationHandler<WeatherForecast> 
{
    /// <inheritdoc />
    public Task Handle(WeatherForecast notification, CancellationToken cancellationToken = default)
    {
        logger.LogInformation("Handled Weather: {Weather}", notification);
        return Task.CompletedTask;
    }
}

5. Create query handlers INotificationHandler for the messages that return results

public sealed class RandomQueryHandler: INotificationHandler<WeatherQuery, WeatherForecast>
{
    private static Random Random = new Random();
    
    /// <inheritdoc />
    public Task<WeatherForecast> Handle(WeatherQuery notification, CancellationToken cancellationToken = default)
    {
        return Task.FromResult(new WeatherForecast
        (
            DateOnly.FromDateTime(DateTime.Now.AddDays(Random.Next(1, 20))),
            Random.Next(12, 55),
            notification.Summary
        ));
    }
}

5. Publish and query

app.MapGet("/weather", async (IBrokerStream streamer, IBrokerPublisher publisher) =>
{
    var forecasts = new List<WeatherForecast>();

    foreach (var summary in summaries)
    {
        await foreach (var forecast in streamer.QueryStream<WeatherQuery, WeatherForecast>(new WeatherQuery(summary)))
        {
            forecasts.Add(forecast);

            await publisher.Publish(forecast);
        }
    }
    
    return forecasts;
});

🎁 Packages

Simply public interfaces and delegates used to interface with the framework.

The core framework executing and routing notificaitons to handlers.

A wraper leveraging the Microsoft DI container to resolve services and handlers.

An extension to allow asynconouse tracing and message tracking through the Broker framework

💪 Notifcations

🛒 Handlers

🛁 Behaviors

🛁 Pipelines

🎉 Hosting