Understanding NGINX Architecture

To understand the architecture of NGINX, we first need to understand what NGINX actually is. NGINX is a highly efficient, event-driven, non-blocking, asynchronous, open-source web server that can be used as a reverse proxy, load balancer, HTTP cache, and even a mail proxy.

Main Components of NGINX Architecture

Worker Processes

A core component of the NGINX architecture is worker processes. These handle the requests sent to the server. The number of worker processes is defined in the configuration file (nginx.conf), typically equal to the number of CPU cores. For instance, in the following configuration, we have set a single worker process.

worker_processes 1;

Worker Connections

Worker connections are the connections that each worker process can handle. A connection can either be active or inactive. An active connection is one that's currently serving a resource, while an inactive connection is one that's idle or has completed its task. The maximum number of connections that each worker process can handle is also defined in the nginx.conf file within the events context.

events {
    worker_connections 1024;
}

In the above scenario, each worker process can open 1024 connections.

Event-Driven Architecture

NGINX adopts an event-driven architecture. This architecture is hardly blocked by I/O operations, and can offer high performance with limited resources. To understand this better, let's consider an example.

Imagine a Harry Potter movie marathon event. The server y(NGINX), in this scenario, is the event organizer who needs to address multiple requests, i.e. providing snacks, maintaining the movie schedule, handling queries etc., from participants (client). To do this efficiently, he employs "worker processes" (assistants) who independently handle these tasks. The number of attendees each assistant can cater to is the "worker connections". Instead of an assistant focusing on a single attendee until all tasks for them are completed, each assistant (worker process) uses a round-robin method to take a task from each attendee (request from client), do it as they can (non-blocking), and go to the next task (asynchronous). This way, the "event" - the movie marathon, runs smoothly and efficiently.

Configuration

NGINX configurations are defined in the ‘nginx.conf’ file. Directives are defined in this file, with some being context-specific. The three main contexts are events, HTTP, and mail. The following is an example of a simple NGINX configuration file.

worker_processes 1;

events {
    worker_connections 2000;
}

http {
    server {
        listen 80;

        location / {
            proxy_pass http://your_backend;
        }
    }
}

In the provided configuration, we've defined a single worker process with the capability of handling 2000 connections. The HTTP context is where we define the behavior of our server. We've defined a single server that listens on port 80 and proxies all requests to a backend server (http://your_backend).

Load Balancing

NGINX can perform load balancing to distribute network traffic to more than one server. It supports multiple load balancing methods including Round Robin, Least Connections and IP Hash. Using our movie scenario, let's imagine having multiple movie screening areas (servers). Our event organizer (NGINX) can distribute attendee groups (network traffic) to these areas (servers) equally (Round Robin), or to the area with the fewest attendees (Least Connections).

http {
    upstream backend {
        server backend1.example.com;
        server backend2.example.com;
        server backend3.example.com;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://backend;
        }
    }
}

In the above configuration, the upstream directive is used for defining the backend servers. Requests are then evenly distributed to them.

To conclude, NGINX is an impactful tool owing to its highly efficient, scalable and robust architecture that is driven by worker processes and worker connections running asynchronously. Whether used as a web server, a reverse proxy, or a load balancer, understanding its architectural design is undoubtedly beneficial. Remember to always configure NGINX appropriately to efficiently manage system resources, enhance performance, and ensure stability.