Application Protocols
Computer Science: OCR GCSE, topic 1.3.24
Web Protocols
Any network application needs to have a set of protocols so that it can structure data for transmission.
Hypertext transfer protocol
- Hypertext transfer protocol (HTTP) defines how data should be exchanged between web browsers (clients) and web servers.
- HTTP relies on the idea of requests and responses.
- HTTP is mainly used to access websites from servers.
HTTP secure
- Hypertext transfer protocol secure (HTTPS) is a secure version of HTTP.
- HTTPS uses secure socket layer (SSL) to encrypt the data that is sent between the client and the server.
File transfer protocol
- File transfer protocol (FTP) defines how binary and text data can be requested from a server and transmitted back to the client.
- FTP is used to download or transfer files over a network.
E-mail Protocols
E-mail clients are also network applications which need a set of protocols.
Post Office Protocol
- The Post Office Protocol (POP) is a common e-mail protocol which defines how emails can be retrieved from a mail server.
- Inboxes are not kept in sync:
- Once a user has downloaded their mail from the server, the server deletes their copy.
- Only a local copy remains.
Internet Message Access Protocol
- Internet Message Access Protocol (IMAP) is another protocol for retrieving e-mails from a mail server.
- IMAP allows e-mails to be kept in sync:
- Actions on your local machine are synced with the server.
- Inboxes remain consistent across multiple devices.
- IMAP is becoming more popular than POP because of the ability to sync multiple devices.
Simple Mail Transfer Protocol
- Simple Mail Transfer Protocol (SMTP) defines how e-mail messages are sent from an e-mail client to a mail server.
- Almost all e-mails are sent using SMTP.
Test yourself on Application Protocols
What is FTP commonly used for?
Which of the following are protocols used to receive email?
Why would Internet Message Access Protocol (IMAP) and Post Office Protocol (POP) not be used together in an email client?
What is the main issue with Post Office Protocol compared to Internet Message Access Protocol?