Do I understand correctly what protocols are?

Question

Computer networks

Hello! I have a question, but it's not really a question. I just don't have anyone to talk to. I have a little understanding of what networks and protocols are, but I'm not sure if I understand it correctly..
What are protocols anyway?? At me it is associated with a SQL server.
For example: MS SQL or MySQL server. Which accepts text over the network,
interprets it according to SQL rules, and, depending on the command, does some actions.
So .. As I understand the language and there is a protocol for the SQL server, is it like a set of rules that the interpreter follows?
The server also has an interpreter installed that knows many "languages" like http, ftp, smpt...
And when a text arrives at the server, it must first determine by what rules it should interpret the incoming text, which protocol is used is indicated in the first header, then the server interprets the incoming text according to the protocol rules.
Tell me, do I understand everything correctly?
Can you throw a couple of links if everything is correct, and what is the name of this very interpreter that accepts the text?

Answer 1

A protocol is some agreement regarding the format of the transmitted data. A set of rules by which a packet is formed on the transmitting side and parsed on the receiving side. The protocol defines the order, size, and purpose of the fields in a data packet. For example, in the UDP protocol, the location and size of the cells of the port number, checksum, data size in the packet, allowed packet size values, and so on are fixed.

Answer 2

In principle, the understanding is correct. Read more about the layered OSI model: https://ru.m.wikipedia.org/wiki/OSI_network_model
There is a general protocol for working with protocols at a low level - ASN.1: https://ru.m.wikipedia.org/wiki/ ASN.1 Use fiddler ( www.telerik.com/fiddler)
to view the http protocol . It shows the underside of HTTP(S). Well, each manufacturer provides the logic of work according to the protocol himself. The protocol only describes how the exchange should be carried out, but the protocol does not regulate how each side should implement it. Therefore, the implementation of the protocol remains on the conscience of the software or hardware manufacturer.

Answer 3

All right. Only you are talking about text protocols.
In general, a protocol is an agreement between two systems to interpret requests and communicate the results of executing requests (and their interpretation on the requester).
SQL is only half of the protocol. But there are more answers from SQL server.
This is also part of the protocol. That. SQL itself does not define the way to interact with the SQL server. But it helps to standardize the way queries are generated for it.
In the case of binary protocols, everything is the same, only the interaction of the system is organized in such a way that a person is not able to interpret (decrypt) the protocol without special means.
As a matter of fact for the machine it is not important, the text protocol, or not. For her, it's all binary sequences.
Text protocols are good for human debugging.
Binary for full utilization of the bandwidth of the physical channel.

Answer 4

As you said yourself, a protocol is a set of rules by which information is processed.
Separate names (http protocol, SMB protocol) describe a set of rules for processing data transmitted by a specific application (transmitting and receiving data over the network).