Client-server architecture in Rest API - Step-by-Step Execution

Concept Flow - Client-server architecture

Client sends request

↓

Server receives request

↓

Server processes request

↓

Server sends response

↓

Client receives response

↓

Client uses data

The client sends a request to the server, the server processes it and sends back a response, which the client then uses.

Execution Sample

Rest API

GET /api/data HTTP/1.1
Host: example.com

--- Server processes request ---
HTTP/1.1 200 OK
Content-Type: application/json

{"message": "Hello, client!"}

This shows a client sending a GET request and the server responding with a JSON message.

Execution Table

Step	Action	Details	Result
1	Client sends request	GET /api/data to server	Request sent over network
2	Server receives request	Server listens on port	Request accepted
3	Server processes request	Reads GET /api/data	Prepares JSON response
4	Server sends response	HTTP 200 OK with JSON	Response sent over network
5	Client receives response	Reads HTTP status and body	Data available to client
6	Client uses data	Parses JSON message	Displays or uses message
7	End	No more actions	Communication complete

💡 Communication ends after client receives and uses server response

Variable Tracker

Variable	Start	After Step 1	After Step 3	After Step 5	Final
request	None	GET /api/data	GET /api/data	GET /api/data	None (processed)
response	None	None	{"message": "Hello, client!"}	{"message": "Hello, client!"}	Used by client
client_data	None	None	None	{"message": "Hello, client!"}	Displayed or used

Key Moments - 3 Insights

Why does the client wait after sending the request?

The client waits because it needs the server's response to continue. See execution_table step 5 where the client receives the response.

What happens if the server does not send a response?

The client will keep waiting or timeout. The flow stops before step 5 in the execution_table, so no data is available to the client.

Is the server always running to receive requests?

Yes, the server listens continuously for requests as shown in step 2 of the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the server doing at step 3?

A Processing the request

B Receiving the request

C Sending the response

D Client parsing data

💡 Hint

Check the 'Action' and 'Details' columns at step 3 in the execution_table.

At which step does the client receive the server's response?

A Step 2

B Step 5

C Step 4

D Step 6

💡 Hint

Look for 'Client receives response' in the 'Action' column of the execution_table.

If the server sends a different JSON message, which variable in variable_tracker changes?

A request

B client_data

C response

D None

💡 Hint

The 'response' variable holds the server's message as shown in variable_tracker.

Concept Snapshot

Client-server architecture:
- Client sends request to server
- Server listens and processes request
- Server sends response back
- Client receives and uses response
- Communication happens over network
- Server runs continuously to serve clients

Full Transcript

Client-server architecture works by the client sending a request to the server. The server listens for requests and when it receives one, it processes it. Then the server sends back a response. The client waits for this response and uses the data it receives. This communication happens over a network. The server is always running to handle incoming requests. This flow ensures that clients can get data or services from servers anytime they ask.