Some basic notes for Web services

1. MIME (Multipurpose Internet Mail Extension, Multipurpose Internet Mail Extension)

It is the source of the ability of SMTP to transfer non-text format files, introduce him to HTTP, then HTTP can also transfer the picture sound and other non-text format files, so he is also HTTP can transfer non-text format file source.

Non-textual data is re-encoded into text before it is transmitted, and the receiver can revert it back to its original format in the opposite way and open it with the appropriate program.

2.flash,applet (in Java),

Flash also becomes a language. You can have dynamic Web pages.

3. Dynamic Web pages

The server-side stored document is not HTML format, but is a script developed by the programming language. pass the browser parameter to the script, execute it on the server, and generate an HTML document after the run is completed, which is generated temporarily and sends the resulting document to browser.

4.php

. PHP is not a plain text file, it is a Web server that is a Web server that runs according to a protocol. php files generate HTML files and send them to browser.

5. Caching

Http1.0 introduced the concept of caching. In short, it is used to store previously browsed information, such as forward and backward reading the page is very fast, in fact, is read from the cache. Cache a lot of content directly in the local. Refresh, whether or not the local cache will be re-read. So don't do nothing to refresh, that will increase your traffic. Of course, if you visit a website that is not visible, you have to clean it up.

6. The process of accessing the Web

Resolves the URL to IP (via DNS server), which is equivalent to entering IP in browser. This will continue to send requests to the Web server. The server listens on a port.

7. HTTP Message +tcp Headers +IP packet header. Here's an HTTP message.

The HTTP message is divided into: Request message, Response message.

The request message includes methods, host hosts, version, connection, head, body, and so on;

Response messages include version, status State code (1**, 2** success, 3** redirection, 4** client error message 404 indicates that a nonexistent file was requested, 5** server-side error message), Reason-phrase (interpreted), headers , Entity-body.

8. An original ecological Web server does not parse dynamic Web pages, parsing is resolved by a specific process after parsing to the Web server again sent out.

9. Long Connection

Each time you get a resource, you have to shake the handshake four times and then download it again three times. A long connection is not immediately disconnected after acquiring a resource, but it is not good for a server with a large number of accesses because other processes are not waiting.

(idle) time-out disconnects. Only how many objects are allowed at most.

The impact of long connections on the server is very large.

10. Multithreading to single-threaded model servers

When a lot of processes are requested, a single thread is a service. Multithreading is the process by which a service process produces the same processes that serve a process, and other requests are handled like this, which is a multithreaded server.

11. A process that processes n requests for a server

Each request has its own state and can even tell the process that I have obtained my own resource object.

12. Multi-process + server for each process can process multiple requests

The above 10, 11, 12 are talking about the server processing model.

13. How to obtain a resource HTTP method

, POST, PUT, DELETE, TRACE, OPTIONS, CONNECTION

14.Client, Server

Client:ie, Firefox, Chrome, Opera, Safari

Server:apache (httpd), IIS, Nginx, lighttpd, THTTPD, etc.

Application servers (which can handle static and dynamic requests within the server): IIS, Tomcat (Apache, open Source, JSP), Websphere (ibm,jsp), Weblogic (Oracle), JBoss (RedHat )

15.Apache (a patchy server before a nickname, later called Apache)

16. Virtual Hosting

It has only one physical host. Virtual Host method: IP-based virtual host, Port-based virtual host, domain-based virtual host.