Page 185 - Computer_Science_F5

Computer Science Application layer in daily uses
(a) Web browsing: Web browsers use HTTP/HTTPS to access web pages, retrieve
data, and display content to users. Figure 3.38 shows a user can enter the Internet
through the World Wide Web and request information from the server.
Client
FOR ONLINE READING ONLY

Desktop Server
HTTP request
Database
HTML response
PC Internet
Web server

Laptop
Figure 3.28: Web browsing in Application layer (To redraw)

(b) Email Services: Email clients use SMTP, IMAP, and POP3 to send, receive, and
organise emails.
(c) File Sharing: Services like Google Drive and Dropbox use FTP/SFTP protocols
for file transfers between clients and servers. This is file sharing as shown in
Figure 2.29.

Normal text

Encryption

Decryption

Client Normal text
Server

Figure 3.29: File sharing in Application layer
(d) Remote access: Protocols like SSH (Secure Shell) provide secure remote access
to servers and devices over a network.

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for Advanced Secondary Schools

Computer Science Form 5.indd 176 23/07/2024 12:33