Protocol Examples (Cambridge International A-Level Computer Science)

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
  • POP3, 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 server (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

POP3, IMAP & SMTP

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

SMTP

• SMTP is a push protocol: it is used for sending (uploading) emails
• 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

POP3

• POP3 is a pull protocol: it is used for receiving (downloading) emails from a mail server
• Once the email has been retrieved it is removed from the server

IMAP

• IMAP is also a pull protocol used for receiving (downloading) emails from a mail server
• Once the email has been retrieved, a copy is retained on the mail server

BitTorrent

• BitTorrent is a protocol for peer-to-peer file sharing over a network
• It allows files to be shared between thousands of users who are connected together over the internet
• Users share files directly with each other: the users' computers act as peers
• No web server or central device is used, and all users are of equal status
• This makes it efficient for sharing large files, as no single server has to supply the whole file to everyone
• While BitTorrent is a legal technology, it is sometimes used for sharing copyrighted content illegally, so ethical and legal use is important