HTTP and WWW service basics

A. http www port:

the default port for the http protocol www service is:

encrypted www service,http default port:443(NET silver, when paying)

Two User access to the basic process of the site:

The first step: The client user enters the www.baidu.com website URL from the browser , returns, the system queries the local host file and the DNS cache information, Find out if there is a URL corresponding to the IP resolution record. If there is a direct fetch to the IP address and then visit the website,theDNS cache is not parsed for the first time when the request is generally on.

Step Two: If the client does not haveDnsCache orhoststhere's no correspondingwww.baidu.comwebsite URL of the domain name resolution record, then, the system will be the browser's resolution request, to the client local settingsDNSServer Address resolution (thisDNSto beLDNS, i.e.Local DNS), ifLndsThe server's local cache has a corresponding parse record, and it returns directly to theIPaddress; if not,LDNSwill be responsible for continuing to request otherDNSserver.

Step Three:LDNSwill be fromDNSSystem of ".the root start requestwww.baidu.comDomain name resolution, through a series of search all levelsDNSserver, you will eventually find thewwwl.baidu.comAuthorization for Domain name correspondenceDNSserver, and this authorizationDNSserver is the server that the enterprise uses to manage domain name resolution when purchasing a domain name. This server haswww.baidu.comcorresponding to theIPparse the record, if not at this time, it means that the enterprise operation and maintenance personnel did not givewww.baidu.comdomain name to do parsing.

Fourth step:www.baidu.com domain name corresponding to the authorized DNS server will www.baidu.com The corresponding final IP parsing records sent to LDNS

Fifth Step: LDNS received from the authorized DNS server about www.baidu.com corresponding IP resolution Records sent to the client browser, and cache the domain name and IP corresponding parsing locally in LDNS so that the next time the same parse request is returned faster

The sixth step: The client browser obtains the corresponding IP address of the www.baidu.com , then the browser will request to obtain the IP address corresponding to the Web Server, Web The server receives the customer's request and responds to processing, returning the customer's requested content to the client browser

Three Dynamic pages, static pages, pseudo-static pages

1) static Web page

in the design of the Web page, pure HTML -formatted web pages are often referred to as "static pages." The early sites were usually made from static Web pages. Static Web pages, as opposed to dynamic Web pages, refers to a database without a background, without data and an interactive network.

Features: What you make up, it shows what, once written, there will be no change. the maintenance and update of static Web pages is relatively troublesome , each page needs to be updated separately, generally used to update less publicity-based sites. Is the form of most of the small and medium-sized websites that were early 2001 years ago.

A. static pages Each page has a fixed URL, and the Web page URL is usually suffixed with . htm/.html/.shtml and other common forms. And the address does not contain a question mark

B. Once the content of the Web page is posted on the Web server, the content of each static webpage can be saved on the Web server file system, regardless of whether or not there are user access, that is, the static Web page is a real file stored on the server, each page is a separate file.

C. static Web page want to stability, therefore, easy to be indexed by search engines (advantages,seo)

D. Static Web pages do not support the database, in the site production and maintenance of large workload, so when the site information is very large when the full reliance on static Web page production method is more difficult (disadvantage)

E. Static web sites are less interactive and have significant functional limitations (drawbacks)

F. Web programs in the user browser-side resolution, such as IE Browser, so that the program resolution is more efficient, because the server does not parse, so can accept more concurrent access. When the client requests data from the server, the server returns the data directly (without any parsing), and when the client gets the data, the browser-side parsing is displayed (the advantage)

Focus:

1. Client browser-side resolver, high efficiency

2. extension format html/shtml/jpg/wmv format

3. Backend has no database, no interaction with user

2) Dynamic Web page

relative to a static web page, that is, the Web page The suffix of the URL is not a common suffix extension form for static web pages such as . Html/.htm/shtml/.xml . Instead, they are suffixed with . Asp/.aspx/.php/.jsp/do/cgi/perl , and usually have iconic symbols in dynamic web URLs - -"?& wait

Characteristics:

A. Dynamic Web pages generally based on database technology, can greatly reduce the workload of site maintenance

B. Web sites with Dynamic Web technologies can achieve more features such as user registration, user login, online surveys, polls, user management, order management, Twitter, etc.

C. Dynamic Web pages are mostly not web pages that exist on the server alone, and the server returns a full page only when the user requests it.

D. in the Dynamic Web page, "? "There are some problems in search engine collection, search engine generally can not access all the pages from a database of a website, or for technical reasons, search spiders generally do not catch the url"? "After the content, so the use of Dynamic Web site in search engine promotion needs to do a certain technical processing (pseudo-static) to adapt to the search engine to grasp the requirements

E. program on theserver, server: PHP engine,java container

F. because the program is parsed on the server side, it consumes a lot of CPU and memory resources and so on, so efficiency is inferior to static web page

Summarize:

1. The program is parsed on the server side, so it consumes a lot of resources. Therefore, efficiency is inferior to static web pages

2.URL suffix is generally Asp/aspx/php/jsp/do/cgi/perl

3. Architecture optimization: Poor efficiency, low development, can be converted to a static Web services

3) pseudo-static web page (most important)

disguise the dynamic as static. Because the search engine cannot read the dynamic webpage content with the parameter correctly, cause a lot of pages with rich information can not be included in the search engine, the main purpose of pseudo-static is convenient for the search engine to ingest and enhance the user experience. Dynamic masquerading as static does not improve the performance of the site, but instead degrades the performance of the site. Now many large-scale web site will use Dynamic Web pages to generate static web technology, to eliminate Dynamic Web page parameters, so that search engines to include more content, to optimize the effect of the site, to generate static Web pages do a good job of solving the problem of search engine, and can improve the site's access performance.

Summarize:

1. Dynamic Web page masquerading as static web page

2. Purpose: Facilitate the search engine to ingest, enhance user access and user experience

3. Performance is not improved because it is just a disguise, actually dynamic, but it drops

4. as much as possible into a true static interface, unless the concurrency is not very large, using rewrite to realize the camouflage state

Four Web Architecture Optimization Scenarios

because the static program in the client parsing, greatly reduces the pressure of the server, so the resolution is more efficient. In the actual high-concurrency Web site architecture, we can consider the data that the user requested is parsed and stored as a static file on the hard disk or in memory to reduce the pressure on the dynamic server, thereby improving the user experience. For high concurrency site architecture from dynamic to static content can refer to Baidu

examples of high concurrent site architectures from dynamic to static:

1. Portal News Service (once the release is complete, almost no changes required)

For news business static conversion is relatively simple, by the editor to publish news, you can generate static files, and then synchronize the static content to all the servers in the country, and then provide access to the user

2. Video service (once upload is complete, almost no changes)

Youku video site, users upload video, need to undergo a review - transcoding process, probably need 1-2 hours, audit - transcoding - push.

Five IP,PV,UV

1) ip-internet Protocol:

IP ( standalone IP), or Internet protocol, refers to the number of independent IPs. The total number of computers accessing the network from different IP addresses is an important index of website traffic analysis. xx:00-24:The same IP address is calculated once in the XX. the number of independent IPs is not standard, just approximate data.

2) pv-page View:

PVnumber of visits: that isPage View, the Chinese translation is the page view, that is, page views or clicks, the user each refresh is calculated once. PVa specific measure is to send a network from the browserWebrequests from the server (Request), after the network server receives the request, a Web page that corresponds to the request (page) to the browser, resulting in aPV. So as long as it is open this request sent to the browser, whether this page is completely open (download completed), then all should be recorded as1aPV, but prevents users from swipingPV, many websites putPVThe statistical program is placed at the bottom of the page. PVreflects the number of pages viewed on a site, so each refresh is counted once. MeansPVproportional to the number of visitors, butPVis not the number of visitors to the page, but the number of pages visited by the site.

3) Uv-unique Visitor:

UV(Independent visitor): A computer client visiting a website is a guest. xx:00-24: The same client is counted only once in the XX. UV metric:1. Site Server Resolution 2. use cookies to distinguish

HTTP and WWW service basics