Subscribe to EventStore catch-up subscription from the start with C# example

EventStore is an open-source database technology designed for storing, retrieving, and querying event data using a stream-based approach. In EventStore, a catch-up subscription is used to read events from a given point in a stream and catch up to the most recent events. When starting a catch-up subscription, you can specify the starting position using an event number or position. However, in some cases, you might want to start from the beginning or the very first event. Here’s how you can achieve that:

using EventStore.ClientAPI;
using System;

class Program
{
    static void Main(string[] args)
    {
        var connectionSettings = ConnectionSettings.Create()
            .SetDefaultUserCredentials(new UserCredentials("admin", "changeit"));

        var connection = EventStoreConnection.Create(connectionSettings, new Uri("tcp://localhost:1113"));

        connection.ConnectAsync().Wait();

        var streamName = "your-stream-name";
        var catchUpSubscriptionSettings = CatchUpSubscriptionSettings.Default;

        // Start from the beginning (event number 0)
        var startPosition = StreamPosition.Start;

        var subscription = connection.SubscribeToStreamFrom(
            streamName,
            startPosition,
            catchUpSubscriptionSettings,
            (subscription, resolvedEvent) =>
            {
                // Process the event
                Console.WriteLine($"Received event: {resolvedEvent.Event.EventType}");
            });

        Console.WriteLine("Catch-up subscription started. Press any key to stop...");
        Console.ReadKey();

        subscription.Stop();
        connection.Close();
    }
}

In this example, we are using the SubscribeToStreamFrom method to start a catch-up subscription from the very beginning of the specified stream. The Start constant is used as the starting position.

Make sure to replace placeholders like “your-stream-name” with the actual stream name you want to subscribe to.

Remember that EventStore supports various subscription modes, settings, and positions. Depending on your use case, you might need to adjust the subscription settings and event processing logic accordingly.