19. HTTP protocol and web base service

1. Web service:

Run in user space

Application Layer Protocol: http, HTTPS

Transport Layer Protocol: tcp, udp, SCTP

2, Transport Layer Port Division:

0-1023: Privileged port, Well known, is permanently assigned to the fixed app for Use.

1024-41951: also for the registered port, but the requirements are not particularly strict, assigned to the program to register for the use of an application; mysql:tcp3306

41952+: the client program randomly uses the port, the dynamic port, or the private port. Its scope is defined in//proc/sys/net/ipv4/ip_local_port_range;

3. A BSD SOCKET:IPC implementation that allows communication between processes located on different hosts (or the same host)

Socket API: encapsulates the system calls related to socket communication in the Kernel.

4. TCP FSM: finite state machine

Closed: off

Listen: Monitoring

Syn_sent:

Syn_recv

Establish

Fin_wait1: Breakup wait Stage 1

Close_wait

Fin_wait2

Last_wait

Time_wait

CLOSED

5. Socket Type:

Partition based on Transport layer protocol

SOCKET_STREAM:TCP sockets

SOCKET_DGRAM:UDP sockets

Socket_raw: Bare Socket

Based on the address format (socket Domain) used by the Socket:

Af_inet:address Family,ipv4

Af_inet6:address Family,ipv6

Af_unix: a different process on the same host, based on the use of the socket socket communication address, Unix_sock (not to the TCP downlevel encapsulation, but instead put the process in memory as a file for other processes to access Traffic)

6, the characteristics of the TCP protocol:

①, establishing connection: Three-time handshake

②, package data into segments, test and (crc32)

③, confirmation, retransmission, Timeout mechanism

④, sort: based on logical number control

⑤, Flow control: sliding window algorithm

⑥, congestion Control: slow start and congestion avoidance algorithms

7, http:hyper Text Transfer protocol: application layer protocol, is a text protocol, using tcp:80 port,

Html:hyper text Mark Language: Hypertext Markup language, which is a programming language.

Css:cascading style sheet: define page styles

js: javascript, Script Development language , client script (run on client), source hypertext file download to the client engine run, and Java is not related ;

8, Wen Service has two kinds of development technology:

Client Technology: JavaScript

Server-side technology: php, JSP (server-side scripting, running on the Server)

9. Http:

Text protocol, which means that the transfer of HTML to ASCII code transfer, the picture is binary storage, early can not be transmitted with HTTP.

Protocol Version:

Http/0.9: prototype version, less functionality and inadequate, rudimentary

Http/1.0: introduced the cache, mime, method

Mime:multipurpose Internet Mail extension: Multi-Purpose Internet Mail Extension protocol; It can transmit non-textual information and encode different format files

method:get, POST, HEAD, PUT, DELETE, TRACE, OPTIONS ... Wait a minute

Http/1.1: Enhanced Cache functionality

Http/2.0:

HTTP protocol Operating mode:

HTTP Request Message: HTTP requests

HTTP Response message: HTTP response

Note: an HTTP thing: an event consisting of an HTTP request and a corresponding HTTP Response.

Web Resource: The web Resource,web consists of (many) Resources.

Static resources: pictures, jpg, png, text, js, css, mp3,

Static resources do not require additional processing by the server, client requests, and the service sends resources directly

Dynamic Resources: The service side needs to be processed by the execution program, sent to the client is the result of the operation of the program, such as php, JSP

Note: there may be multiple resources on one page, and each resource requires a separate Request.

Identity mechanism for Web resources: url,uniform resource locator: a Uniform Resource locator that describes the location of a particular resource on a server.

URL format: scheme://server[:p Ort]/path/to/somesource

URL format example: http://www.sina.com.cn/index.html

Scheme: Specify protocol, http, ftp, etc.

Server[:p ort]: Www.sina.com.cn//default 80 port

File Path: index.html; can be omitted, default path (main Page)

10, a complete HTTP request processing process (server Side)

①, establishing, or processing a connection: accepting a request or rejecting a request

②: the process of receiving a request from a host request packet on a network for a specific resource, after three handshakes and four Disconnects.

③, processing request: to parse the request message, to obtain the resources requested by the client and the request method and other related information

④, Access Resources: Gets the requested resource in the request packet (typically to find resources on the hard disk, requires disk I/o)

⑤, Building Response Messages

⑥, Sending response messages

⑦, logging: used to analyze user wording

19. HTTP protocol and web base service