Load Balancers in C# and Azure

Understanding Load Balancers

When it feels like you’re balancing a dozen coffee cups in a busy café, each request an opportunity for
disaster, you’ll appreciate the work of a skilled barista—or, in the digital realm, a load balancer. In the
bustling world of server requests and network traffic, the load balancer is like a proficient maître d’ at a
high-end restaurant, ensuring every guest—here representing user requests—is attended to efficiently and
effectively. This scenario is critical in the context of .NET development and deployment on Azure, where managing
the flood of incoming traffic can be quite the challenge.

As any seasoned .NET developer knows, building a robust web solution involves not just creating effective code
but also ensuring it can handle the high-volume traffic it might garner. Now we aren’t just chess players
arranging the pieces; we’re strategists anticipating the movements. Here, a load balancer is not a luxury but a
necessity, adeptly directing traffic and requests to a cluster of servers to ensure no single server is
overwhelmed. Let’s explore the concept with the help of practical code samples.

Code Sample 1: Basic Round Robin Configuration

Imagine you’ve got a trio of servers ready to handle incoming connections for your .NET service. How do you
hand out the requests fairly? Here’s a simplistic round-robin approach in C#:

public class RoundRobinBalancer
private int _nextServerIndex;
private readonly object _lock = new object();
private readonly string[] _servers;

public RoundRobinBalancer(string[] servers)
_servers = servers;
_nextServerIndex = 0;

public string GetServer()
lock (_lock)
string assignedServer = _servers[_nextServerIndex];
_nextServerIndex = (_nextServerIndex + 1) % _servers.Length;
return assignedServer;

With this snippet, each server in the _servers array gets its turn to serve. Once the last server is
reached, we circle back to the beginning – a never-ending carousel for handling requests.

Code Sample 2: Implementing Health Checks

What happens if one of the servers spills its coffee? You don’t want to send requests to a server that can’t
handle them. Let’s add some health checks:

public class Server
public string Address { get; set; }
public bool IsOnline { get; set; }

public class HealthCheckBalancer
private int _nextServerIndex;
private readonly object _lock = new object();
private readonly Server[] _servers;

public HealthCheckBalancer(Server[] servers)
_servers = servers;
_nextServerIndex = 0;

public Server GetServer()
lock (_lock)
for (int i = 0; i < _servers.Length; i++)
int currentIndex = (_nextServerIndex + i) % _servers.Length;
if (_servers[currentIndex].IsOnline)
_nextServerIndex = (currentIndex + 1) % _servers.Length;
return _servers[currentIndex];
return null; // or throw exception, depending on your error handling logic

This more advanced structure considers the health status of each server, ensuring the patisserie stays afloat
even if one of the ovens stops working. If IsOnline is set to false, that server is temporarily
skipped over for traffic redirection—much like giving the barista a break if they’re spilling more coffee than
they’re serving.

Integrating such load-balancing strategies within a .NET application ensures no single machine bears the brunt
of the traffic. When deployed on a platform like Azure with its native load balancer services, developers can
enjoy an even more robust set of tools tailored for high availability and resilience.

Azure, known for its majestic blue skies of scalability, allows a C# application to almost sprout wings. Be it
Azure’s own load balancer for traffic management or Application Gateway for more sophisticated routing
decisions, the goal is the same: keep the application as responsive as a bee, buzzing from one request to
another without missing a beat.

By employing these principles and coding with vigilance for traffic surges, developers create not just working
software but digital maestros of user requests. The .NET ecosystem is rich with possibilities, and Azure’s
embracing infrastructure adds multiple layers of load management to keep the ballroom dance of network traffic
graceful and uninterrupted.

Ensuring Smooth Sailing: Exploring Load Balancing Algorithms in ASP.NET Core

Have you ever wondered what magic happens behind the scenes when you shop a Black Friday sale online without any
hiccups, despite millions of other shoppers doing the same? Let’s uncover that sorcery right here. It’s all about
load balancing—but not the kind of balance that involves standing on one foot. We’re talking about traffic
management for web applications, which is a critical aspect for any website that aspires to offer a seamless
user experience. Particularly, we are diving into the world of load balancing algorithms in ASP.NET Core, a
favorite among developers for creating robust web applications.

A Quick Refresher on Load Balancing

In essence, load balancing distributes incoming network traffic across a group of backend servers, also known as
a server farm or server pool. This process is essential in keeping applications running smoothly and
efficiently, preventing any one server from becoming a bottleneck. Think of it like a well-organized checkout at
a supermarket where each cashier’s workload is optimized to keep the lines moving quickly.

Diving Into ASP.NET Core’s Load Balancing Techniques

ASP.NET Core, with its cross-platform, high-performance framework, is a gem when it comes to supporting scalable
applications that can handle a heavy traffic load. When discussing load balancing within the context of ASP.NET
Core applications, we are typically talking about a few popular algorithms that have distinct ways of managing
traffic. Let’s look at a couple in detail.

1. Round Robin

Round Robin is the simplest form of load balancing and operates on a rotational basis. Imagine a circle of
servers, with each new request being sent to the next server in line. Once the last server is reached, it
circles back to the first. It’s fair, democratic, and ensures that no single server bears too much load.

public class RoundRobinLoadBalancer
private int _currentIndex = 0;
private readonly List<Server> _servers;

public RoundRobinLoadBalancer(List<Server> servers)
_servers = servers ?? throw new ArgumentNullException(nameof(servers));

public Server GetNextServer()
var server = _servers[_currentIndex];
_currentIndex = (_currentIndex + 1) % _servers.Count;
return server;


  • We have a _currentIndex variable that tracks the current server.
  • The _servers list holds our pool of server instances.
  • In GetNextServer we return the server at the current index and then increase the index for
    the next call. We use modulo (%) to loop back to the first index once we hit the end of
    the list.

2. Least Connections

The Least Connections algorithm, as the name implies, directs new requests to the server with the fewest active
connections. This is kind of like picking the shortest line at the checkout—not necessarily the next line, but
the one that will get you out fastest based on current load.

public class LeastConnectionsLoadBalancer
private readonly object _lock = new();
private readonly List<Server> _servers;

public LeastConnectionsLoadBalancer(List<Server> servers)
_servers = servers ?? throw new ArgumentNullException(nameof(servers));

public Server GetServerWithLeastConnections()
var server = _servers.OrderBy(s => s.ActiveConnections).FirstOrDefault();
return server;


  • We have a _servers list representing the servers in the pool.
  • The _lock ensures that the operation of picking a server and incrementing its connection
    count is atomic.
  • GetServerWithLeastConnections picks the server with the lowest ActiveConnections
    count, increments that count (since we’re about to send it a new connection), and then returns that

In practice, load balancing algorithms in ASP.NET Core are typically not implemented manually like this because
most production environments use specialized load balancing hardware or software (like a reverse proxy or a
cloud service). However, understanding these algorithms can help in making informed decisions regarding
handling web traffic.

Combining the Theory with Real-World Examples

In the real world, say we’re running a hot new social media startup that just went viral. Our servers are
getting hit like piñatas at a birthday party. By implementing a load balancing strategy with ASP.NET Core, we can
ensure that the user experience is smooth and responsive.

Imagine a user named Alex from New York, a user named Jamie from California, and another user named Sam from
Texas, all click on their favorite influencer’s new post. With round robin, each user’s request would be sent to
consecutive servers in the server pool. If we were using least connections, and Jamie’s and Sam’s requests occur
almost simultaneously but Alex’s server is slightly less busy, Alex’s comment will be posted first due to faster
server response.

Keeping the Human Connection

It’s been quite a journey exploring the technicalities of load balancing algorithms in ASP.NET Core. Remember,
while machines are the ones managing web traffic, it’s human ingenuity that designed these algorithms to make
everyone’s digital lives a bit smoother.

After delving deep into the algorithms, it’s important to look up from our screens and remember that there’s a
world out there full of human experiences waiting for us. Whether it’s imagining the thrill of managing your
website’s traffic during a viral moment, or experiencing the seamless work of load balancing firsthand by
casually browsing an online store during peak hours without a single delay—it’s all part of the beautiful dance
between technology and our daily lives.