Boradcast Block for Rest Api

Use BroadcastBlock<T> when you want to perform multiple, independent actions on each piece of data that you have. For example, if you have a stream of images and you want to save each image to disk, display it in a UI, and upload it to a cloud server, a BroadcastBlock<T> could handle broadcasting each image to separate operations that handle those actions.

using System.Threading.Tasks.Dataflow;

namespace TplDataFlowDemo.DemoBlocks;

public class DemoBroadCastBlock
{
    private readonly BroadcastBlock<string> _broadcast;
    private readonly ActionBlock<string> _service1;
    private readonly ActionBlock<string> _service2;

    public DemoBroadCastBlock()
    {
        _broadcast = new BroadcastBlock<string>(message => message);
        _service1 = new ActionBlock<string>(ProcessService1);
        _service2 = new ActionBlock<string>(ProcessService2);

        _broadcast.LinkTo(_service1, new DataflowLinkOptions { PropagateCompletion = true });
        _broadcast.LinkTo(_service2, new DataflowLinkOptions { PropagateCompletion = true });
    }

    public async Task StartFlow(CancellationToken ct)
    {
        while (!ct.IsCancellationRequested)
        {
            // Simulate getting a new message, normally this could be from event or queue.
            var item = Guid.NewGuid().ToString();
            await _broadcast.SendAsync(item);
            // Simulate delay between each new item.
            await Task.Delay(1000);
        }
        _broadcast.Complete();
        await Task.WhenAll(_service1.Completion, _service2.Completion);
    }

    private async Task ProcessService1(string item)
    {
        // Simulate processing delay in Service 1.
        await Task.Delay(200);
        Console.WriteLine($"Service1: {item}");
    }

    private async Task ProcessService2(string item)
    {
        // Simulate processing delay in Service 2.
        await Task.Delay(300);
        Console.WriteLine($"Service2: {item}");
    }
}

// use in console like...

var broadCast = new DemoBroadCastBlock();
await broadCast.StartFlow(CancellationToken.None);

In this example, the BroadcastBlock is linked to two ActionBlock objects. When a number is posted to the BroadcastBlock, both ActionBlock objects receive the message and process it independently.

Files you can download:

Tpldataflowdemo