Protocol
An agreed set of rules for how messages are formed and exchanged.
Glossary
Handshake
A brief exchange in which two parts agree how they will communicate before getting to work.
In one line
A brief exchange in which two parts agree how they will communicate before getting to work.
Also callednegotiation
A handshake is an opening conversation. Before two parts begin exchanging data in earnest, they confirm who they are and settle on the terms of their cooperation. It is a short ritual that prevents a great deal of confusion later.
When a component first appears, a driver and the hardware perform a handshake of sorts, establishing a shared understanding that everything afterwards depends on. They agree on the pace, the format, and the rules they will both follow.
The handshake is also where each side learns what the other is capable of. They can settle on the best arrangement both can manage, rather than guessing or assuming, which lets them cooperate at the highest level they share.
If a handshake fails, it is far better to discover the mismatch at the very start than midway through important work. A failed handshake is an early, honest warning that two parts cannot yet cooperate, giving the system a chance to respond before any real harm is done.
In practice
In practice, a handshake is like two people meeting and quickly agreeing which language to speak before the real conversation begins. That brief opening saves endless misunderstanding afterward. Two parts of a computer settle their terms the same way before they start exchanging data.
