Async streams with IAsyncEnumerable in C Sharp (C#) - Mini Project: Build & Apply

Async streams with IAsyncEnumerable

📖 Scenario: You are building a simple program that simulates receiving messages one by one over time, like getting chat messages or sensor data.

🎯 Goal: Create an async stream using IAsyncEnumerable that yields messages with a delay, then consume and print each message asynchronously.

📋 What You'll Learn

Create an async method that returns IAsyncEnumerable<string> with 3 messages

Use await Task.Delay(1000) to simulate waiting between messages

Consume the async stream with await foreach to print each message

💡 Why This Matters

🌍 Real World

Async streams are useful when you receive data over time, like chat messages, sensor readings, or live logs.

💼 Career

Understanding async streams helps you write efficient, responsive applications that handle data without freezing the user interface.

1

Create async stream method

Create an async method called GetMessagesAsync that returns IAsyncEnumerable<string>. Inside it, use yield return to return these exact messages one by one: "Hello", "from", "async stream".

C Sharp (C#)

// Your code here

Need a hint?

Remember to mark the method as async and use IAsyncEnumerable<string> as the return type.

2

Add delay between messages

Inside the GetMessagesAsync method, add await Task.Delay(1000); before each yield return to wait 1 second between messages.

C Sharp (C#)

using System.Collections.Generic;
using System.Threading.Tasks;

async IAsyncEnumerable GetMessagesAsync()
{
    // Add delay before first message
    // Your code here
    yield return "Hello";
    // Add delay before second message
    // Your code here
    yield return "from";
    // Add delay before third message
    // Your code here
    yield return "async stream";
}

Need a hint?

Use await Task.Delay(1000); before each yield return to pause 1 second.

3

Consume async stream with await foreach

Create an async Main method. Inside it, use await foreach with variables message to iterate over GetMessagesAsync(). Inside the loop, print each message using Console.WriteLine(message);.

C Sharp (C#)

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

async IAsyncEnumerable GetMessagesAsync()
{
    await Task.Delay(1000);
    yield return "Hello";
    await Task.Delay(1000);
    yield return "from";
    await Task.Delay(1000);
    yield return "async stream";
}

// Your code here

Need a hint?

Use await foreach inside an async Main method to read messages.

4

Print all messages from async stream

Run the program to print all messages from GetMessagesAsync(). The output should show each message on its own line with a 1 second pause between them.

C Sharp (C#)

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

async IAsyncEnumerable GetMessagesAsync()
{
    await Task.Delay(1000);
    yield return "Hello";
    await Task.Delay(1000);
    yield return "from";
    await Task.Delay(1000);
    yield return "async stream";
}

class Program
{
    static async Task Main()
    {
        // Your code here
    }
}

Need a hint?

Run the program and watch the messages print one by one with delay.