Protocol Examples (Cambridge (CIE) A Level Computer Science): Revision Note

Standard protocols

• A protocol is a set of rules that govern communication on a network

• There are protocols for different purposes, such as:

  • HTTP & HTTPS

  • FTP

  • POP, IMAP & SMTP

  • BitTorrent

HTTP & HTTPS

• Hypertext Transfer Protocol (HTTP) allows communication between clients and servers for website viewing

• HTTP allows clients to receive data from the sever (fetching a webpage) and send data to the server (submitting a form, uploading a file)

• HTTPS works in the same way as HTTP but with an added layer of security

• All data sent and received using HTTPS is encrypted

• HTTPS is used to protect sensitive information such as passwords, financial information and personal data

FTP

• File Transfer Protocol (FTP) allows sending and receiving files between computers

• Uploading and downloading files to/from a web server is often completed using FTP

• FTP offers greater efficiency and support for bulk transfers and large files such as resuming interrupted transfers

• FTP clients are software applications that use the FTP protocol to make the process easier for users

POP, IMAP & SMTP

• A family of protocols that handle sending and receiving of email across the internet (WAN)

SMTP

• Simple Mail Transfer Protocol (SMTP) is a protocol that allows communication between an email sender and the email server, and between different email servers using the internet

• In the diagram above, SMTP is used to transfer the senders email to their email providers server and SMTP is used to transfer the email to the recipients email server

POP

• Post Office Protocol (POP) is a protocol for downloading emails to a device from an email server

• Once the email has been retrieved it is removed from the server

IMAP

• Internet Message Access Protocol (IMAP) is a protocol for downloading emails to a device from an email server

• Once the email has been retrieved, a copy is retained on the mail server

Advantages & disadvantages of POP/IMAP

BitTorrent

• BitTorrent is a peer-to-peer (P2P) file-sharing protocol used to distribute large amounts of data efficiently across the internet

• Instead of downloading a file from a single central server, BitTorrent allows users to download pieces of the file from multiple users (peers) who already have parts of it

• This makes file sharing:

  • Faster, as downloads come from many sources at once

  • More efficient, as it reduces the load on any single server

• BitTorrent is often used for:

  • Sharing large files, such as software, videos, or games

  • Decentralised distribution, which avoids the need for central hosting

• While BitTorrent is a legal technology, it is sometimes used for sharing copyrighted content illegally, so ethical and legal use is important