Computer science from A to Z

P is for Protocol

© INRIA Sophie Auvin - P comme Protocole

“Hello? - Hi, it's Michael. Can I come over? - Yes, sure. - See you soon. - Bye.” This may be a banal conversation, but it follows well established practices: a protocol.

In order to understand each other, computers too follow protocols.

When an e-mail relay transmits a message to another relay it follows a standardised procedure. The transmitter identifies itself, then transmits the sender's address, the recipient's address and the content of the message, and finally signals the end of the transmission. At each stage, the receiver responds “OK” or “Error” to guarantee the reliability of the communication.

Every application uses specially adapted protocols: HTTP for the web, HTTPS for secure transactions, WAP for connection of mobile phones to the Internet...

Wireless networks or contactless badge readers require special protocols: it is necessary to identify the interlocutor with whom you want to communicate, out of all those emitting signals at the same time in the surrounding area.

Thus, the art of conversation by computer is constantly being refined...

Did you know...?

© INRIA / Sophie Chauvin - Protocole

In an “ad hoc” network, computers communicate among themselves without going through a fixed infrastructure. Each participant plays the role of relay for the communications of the others. Complex protocols allow each data packet to find a step-by-step route to its recipient.

Keywords: Computer science from A to Z Science awareness

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