Basic knowledge of http and www services, basic knowledge of www services

Basic knowledge of http and www services, basic knowledge of www services

I. http www Port:

The default port for the http www Service is 80.

Encrypted www Service, default http port: 443 (online banking, when you pay)

 

2. Basic Website access process:

Step 1: Enter www.baidu.com in the browser and press Enter. The system queries the local host file and DNS Cache Information to check whether the IP resolution record corresponding to the website exists. If yes, you can directly obtain the IP address and access the website. Generally, the DNS Cache does not have a resolution record during the first request.

 

Step 2: if the client does not have a DNS cache or the hosts does not have a corresponding domain name resolution record for www.baidu.com, the system will send a browser resolution request, if the local cache of the LNDS server has corresponding resolution records, the IP address is directly returned; if no, LDNS will continue to request other DNS servers.

 

Step 3: LDNS will "root began to request www.baidu.com domain name resolution, after a series of searches for various levels of DNS servers, will eventually find the wwwl.baidu.com domain name corresponding to the authorized DNS server, and this authorized DNS server, it is the server that an enterprise uses to manage domain name resolution when purchasing a domain name. This server has an IP address resolution record corresponding to www.baidu.com. If no record exists at this time, it indicates that the enterprise's O & M personnel did not resolve the domain name www.baidu.com.

 

Step 4: The authorized DNS server corresponding to www.baidu.com will send the final IP resolution record corresponding to www.baidu.com to LDNS

 

Step 5: LDNS sends the IP resolution record of www.baidu.com from the authorized DNS server to the client browser, and caches the resolution of the domain name and IP address locally in LDNS, so that records of the same resolution request can be returned more quickly next time.

 

Step 6: the client browser obtains the corresponding IP address of www.baidu.com. Next, the browser requests the web server corresponding to the IP address, and the web server receives and responds to the customer's request, return the content requested by the customer to the client browser

 

 

3. dynamic webpages, static webpages, and pseudo-static webpages

1) Static webpage

In the design of a webpage, a webpage in pure HTML format is usually called a "static webpage ". Early websites were generally made from static webpages. Compared with dynamic web pages, static Web pages refer to databases with no backend, without data and interactive networks.

Features: What you compile will show what you compile. Once the compilation is complete, there will be no changes. It is relatively difficult to maintain and update static Web pages. Each different web page must be updated independently. Generally, it is used for promotional websites with Fewer updates. Is the form of presentation by most small and medium-sized websites before 2001.

A.static web pages each page has a fixed URL, and the URL is generally suffixed in common forms such as .htm/. html/. shtml, and the address does not contain question marks.

B. once the webpage content is published to the website server, the content of each static webpage can be stored on the file system of the website server, regardless of whether there is any user access. That is to say, static web pages are files stored on servers. Each web page is an independent file.

C. Static web pages want to be stable, so they are easily indexed by search engines (advantages, seo)

D. Static Web pages are not supported by databases, and work is heavy in website production and maintenance. Therefore, it is difficult to rely entirely on static Web page production when the website information volume is large (disadvantage)

E. Poor interaction between static websites and huge functional limitations (disadvantages)

F. Web page programs are parsed on the user's browser side, such as the IE browser, so that the program resolution efficiency is higher. Because the server does not parse, more concurrent accesses can be accepted. When the client requests data from the server, the server returns the data directly (without any parsing). After the client obtains the data, it parses the data on the browser (advantage)

Important:

1. client browser-side parsing program, High Efficiency

2. html/shtml/jpg/wmv extension format

3. No database at the backend and no interaction with users

 

2) Dynamic Webpage

In contrast to a static webpage, the URL extension of the webpage is not a common form of suffix extension for static webpages such as .html,. htm, shtml, And. xml. It is suffixed in the form of. asp/. aspx/. php/. jsp/do/cgi/perl, and usually has a symbolic symbol in the dynamic Web site --"? & Etc.

Features:

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

B. websites using dynamic web technologies can implement more functions, such as user registration, user logon, online surveys, voting, user management, order management, and Weibo.

C. Most Dynamic Web pages are not webpage files that exist independently on the server. The server returns a complete page only when the user requests it.

D. "?" in a dynamic webpage There are some problems with indexing a search engine. Generally, it is impossible for a search engine to access all webpages from a website database, or for technical reasons, searching for a spider generally does not capture the "?"" Therefore, when using dynamic web pages for search engine promotion, some technical processing (pseudo static) is required to meet the requirements of search engines.

E. The program is parsed on the server. The server: php engine, java container

F. Because the program is parsed on the server, it will consume a lot of CPU and memory resources. Therefore, the efficiency is not as high as that of static Web pages.

Summary:

1. The program is parsed on the server, which consumes a lot of resources. Therefore, it is less efficient than static Web pages.

2. the URL suffix is asp/aspx/php/jsp/do/cgi/perl.

3. Architecture Optimization: low efficiency and low development, which may be converted to a static webpage to provide services

 

3) pseudo-static web pages (most important)

Disguise dynamic as static. Because the search engine cannot correctly read the dynamic webpage content with parameters, many pages with rich information on the webpage cannot be included by the search engine, the use of pseudo-static mainly aims to facilitate search engine indexing and improve user experience. Dynamic disguise as static does not improve the website's performance. On the contrary, it will reduce the website's performance. Today, many large websites use dynamic web pages to generate static Web pages, eliminating parameters in dynamic web pages, allowing search engines to include more content to optimize the effect of websites, generating static Web pages effectively solves the search engine indexing problem and improves the Website access performance.

Summary:

1. The dynamic web page is disguised as a static Web Page

2. Objective: To facilitate search engine indexing and improve user access and user experience

3. Because it is just a disguise, it is still dynamic, and the performance has not improved, but it has declined.

4. convert it to a real static interface as much as possible, unless the concurrency is not large, use rewrite to implement disguised State

 

 

Iv. web architecture optimization solution

 

Static programs are parsed on the client, which greatly reduces the pressure on the server, so the resolution efficiency is higher. In the actual high-concurrency website architecture, we can consider storing the data requested by users as static files on the hard disk or in the memory to reduce the pressure on dynamic servers, to improve user experience. For more information about the high-concurrency website architecture from dynamic to static, refer to Baidu

 

Examples of high-concurrency website architecture switching from dynamic to static:

 

1. Portal News Service (almost no changes are required once published)

 

Static conversion of news services is relatively simple. When news is published by editors, static files can be generated, and static content can be synchronized to all the server borrowing points throughout the country, which can then be accessed by users.

 

2. Video Service (once uploaded and released, almost no changes are required)

 

For youku video website, it takes about 1-2 hours for a user to upload a video, which requires review-transcoding-push.

 

 

V. IP, PV, and UV

 

1) IP-internet Protocol:

 

IP (independent IP), Internet protocol, refers to the number of independent IP addresses. The total number of visits from computers with different IP addresses to the network is an important indicator of website traffic analysis. The same IP address is calculated once from. The number of independent IP addresses is not standard, but only approximate data.

 

 

 

2) PV-Page View:

 

PV access volume: page view. Chinese translation refers to page browsing, that is, page views or clicks. Each refresh is calculated. The specific measurement of PV is to send a Request to the web server from the browser. After the web server receives the Request, it will send a webpage corresponding to the Request) send to the browser to generate a PV. Therefore, as long as the request is opened and sent to the browser, whether or not the page is fully opened (the download is complete), it should be recorded as one PV, but it should prevent users from refreshing PV, many websites place PV statistical programs at the bottom of the page. PV reflects the number of pages browsing a website, so every refresh is counted. That is to say, PV is proportional to the number of visitors, but PV is not the number of visitors to the page, but the number of pages accessed by the website.

 

 

 

3) UV-Unique Visitor:

 

UV (Independent Visitor): A computer client accessing the website is a visitor. The same client is calculated only once between and. UV Metric: 1. Website Server Resolution 2. Use cookie resolution