The key elements of the network protocol are: 1. Grammar, that is, the structure or format of data and control information; 2. Semantics, that is, what kind of control information needs to be sent, what action to complete and what kind of response to make; 3. Timing also means "rules", that is, detailed descriptions of the order in which events are implemented.
Key elements of network protocols:
1. Grammar, that is, the structure or format of data and control information;
2. Semantics, that is, what control information needs to be sent, what actions to complete and what responses to make;
3. Timing, that is, the detailed description of the event implementation sequence.
Key elements of network protocols:
The three elements of network protocols are syntax, semantics and rules (timing), among which the protocol in the local area network is the most important.
HTTP protocol introduction
HTTP is an object-oriented protocol belonging to the application layer. Due to its simple and fast method, it is suitable for distributed hypermedia information systems. It was proposed in 1990 and has been continuously improved and expanded after several years of use and development. The sixth version of HTTP/1.0 is currently used in the WWW. The standardization work of HTTP/1.1 is in progress, and the HTTP-NG (Next Generation of HTTP) proposal has been put forward.
The main features of the HTTP protocol can be summarized as follows:
1. Support client/server mode.
2. Simple and fast: When the client requests services from the server, it only needs to transmit the request method and path. Commonly used request methods are GET, HEAD, and POST. Each method specifies a different type of contact between the client and the server.
Because the HTTP protocol is simple, the program size of the HTTP server is small, so the communication speed is very fast.
3. Flexible: HTTP allows the transmission of any type of data object. The type being transferred is marked by Content-Type.
4. No connection: The meaning of no connection is to limit each connection to only process one request. After the server processes the client's request and receives the client's response, it disconnects. This method saves transmission time.
5. Stateless: The HTTP protocol is a stateless protocol. Stateless means that the protocol has no memory ability for transaction processing. The lack of status means that if subsequent processing requires the previous information, it must be retransmitted, which may result in an increase in the amount of data transferred per connection. On the other hand, the server responds faster when it does not need previous information.
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