Introduction to C# Streams

Welcome back! In this lesson, we will dive into Redis Streams — a powerful feature used for processing streams of data. This lesson will guide you through the basics and show you how Redis Streams can be essential for high-performance applications.

In this lesson, we'll learn about streams in Redis and how they can be used to handle continuous data flows. We'll learn how to create streams, add events to them, and read events from them.

Streams are a powerful data structure that allows you to process real-time data efficiently. Redis Streams are an append-only log structure that persists messages, allowing you to read historical data and replay missed events. Here are a few real-world scenarios where Redis Streams can be useful:

• Chat Applications: Redis Streams can be used to handle messages in real-time.
• Monitoring Systems: Streams can be used to process logs and events.
• User Activity Tracking: Streams can be used to track user actions in real-time.

Let's dive into the details!

Here's a quick preview:

• Use the StreamAdd method to add an event to a stream.
• Use the StreamRead method to read events from a stream.

Let's see how these commands work in practice.

using StackExchange.Redis;
using System;

class RedisStreamExample
{
    static void Main()
    {
        // Connect to Redis
        ConnectionMultiplexer redis = ConnectionMultiplexer.Connect("localhost");
        IDatabase db = redis.GetDatabase();

        // Add events to 'mystream'
        db.StreamAdd("mystream", new NameValueEntry[] { new NameValueEntry("event", "login"), new NameValueEntry("user", "Alice") });
        db.StreamAdd("mystream", new NameValueEntry[] { new NameValueEntry("event", "purchase"), new NameValueEntry("user", "Bob"), new NameValueEntry("amount", "100") });
        db.StreamAdd("mystream", new NameValueEntry[] { new NameValueEntry("event", "add_to_cart"), new NameValueEntry("user", "Alice"), new NameValueEntry("product", "laptop") });

        // Read messages from 'mystream'
        var messages = db.StreamRead("mystream", "0-0", count: 2);
        Console.WriteLine("Stream messages:");
        foreach (var message in messages)
        {
            Console.WriteLine($"ID: {message.Id}");
            foreach (var value in message.Values)
            {
                Console.WriteLine($"Key: {value.Name}, Value: {value.Value}");
            }
        }
    }
}

The above C# code snippet demonstrates how to add events to a Redis stream called mystream. Each event contains key-value pairs representing different actions performed by users.

This code reads the first two messages from mystream and prints them. Using StreamRead, you specify the stream name and the starting message ID to read from the beginning ("0-0"). For example, a message ID might look like 1633024800000-0, where 1633024800000 is the timestamp, and 0 is the sequence number. If multiple messages are added at the same timestamp, the sequence number will increment (e.g., 1633024800000-1, 1633024800000-2, etc.). The count parameter limits the number of messages read.