Web server vs application server in Nginx - Visual Side-by-Side Comparison

Process Flow - Web server vs application server

Client sends HTTP request

↓

Web Server receives request

↓

Static content

↓

Serve file

↓

Application Server processes

↓

Response sent back to Web Server

↓

Web Server sends response to Client

The client sends a request to the web server. The web server serves static files directly or forwards dynamic requests to the application server, which processes them and returns a response.

Execution Sample

Nginx

server {
  listen 80;
  location / {
    root /var/www/html;
    index index.html;
  }
  location /app/ {
    proxy_pass http://localhost:8080;
  }
}

Nginx configuration serving static files from /var/www/html and forwarding /app/ requests to an application server on port 8080.

Process Table

Step	Request URL	Web Server Action	Application Server Action	Response Sent
1	/index.html	Serve static file /var/www/html/index.html	N/A	Static HTML content
2	/app/data	Forward request to app server at localhost:8080	Process dynamic request, generate JSON	JSON response
3	/about.html	Serve static file /var/www/html/about.html	N/A	Static HTML content
4	/app/login	Forward request to app server at localhost:8080	Process login, generate session token	Session token response
5	/favicon.ico	Serve static file /var/www/html/favicon.ico	N/A	Icon file content

💡 All requests handled either by serving static files or forwarding to application server for dynamic content.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5
Request URL	N/A	/index.html	/app/data	/about.html	/app/login	/favicon.ico
Web Server Action	N/A	Serve static file	Forward to app server	Serve static file	Forward to app server	Serve static file
Application Server Action	N/A	N/A	Process dynamic request	N/A	Process login	N/A
Response Sent	N/A	Static HTML	JSON response	Static HTML	Session token	Icon file

Key Moments - 3 Insights

Why does the web server forward some requests to the application server?

Because those requests need dynamic processing which the web server alone cannot do, as shown in execution_table rows 2 and 4.

Can the web server serve dynamic content by itself?

No, the web server serves static files directly but forwards dynamic requests to the application server, as seen in the execution_table where only static URLs are served directly.

What happens if a request is for a static file?

The web server serves the file directly without involving the application server, as shown in execution_table rows 1, 3, and 5.

Visual Quiz - 3 Questions

Look at the execution table, what action does the web server take for the request '/app/data'?

A Serve static file

B Forward request to application server

C Return 404 error

D Cache the response

💡 Hint

Check the 'Web Server Action' column for step 2 in the execution_table.

At which step does the application server generate a session token?

A Step 4

B Step 3

C Step 1

D Step 5

💡 Hint

Look at the 'Application Server Action' column for step 4 in the execution_table.

If the web server did not forward '/app/login' requests, what would happen?

A Static login page would be served

B Application server would still process the request

C Request would fail or return an error

D Request would be cached

💡 Hint

Refer to the concept_flow and execution_table showing forwarding is needed for dynamic content.

Concept Snapshot

Web server handles HTTP requests.
Serves static files directly.
Forwards dynamic requests to application server.
Application server processes logic and returns response.
Nginx example: static content served from root, dynamic proxied to app server.

Full Transcript

When a client sends a request, the web server first checks if it is for static content like HTML or images. If yes, it serves the file directly. If the request is for dynamic content, such as data or login, the web server forwards it to the application server. The application server processes the request, runs any needed code, and sends back a response. The web server then sends this response to the client. This separation helps handle static and dynamic content efficiently.