[Web Introduction] and [Web Service] Super detailed explanation

Main introduction to the Web

Web (World Wide Web) is a global wide area network , also known as the World Wide Web . It is a global, dynamically interactive, cross-platform distributed graphical information system based on hypertext and HTTP . It is a network service built on the Internet . It provides a graphical, easy-to-access and intuitive interface for viewers to find and browse information on the Internet. The documents and hyperlinks organize the information nodes on the Internet into an interactive system. Associative network structure .

Chinese name	Global Wide Area Network or World Wide Web	full name	World Wide Web
foreign name	Web	Manifestations	Hypertext, hypermedia, hypertext protocol
Alias	world wide web	Attributes	Distributed Graphical Information System

The Origin of the Web

In 1989, a group led by Tim Berners-Lee at CERN (European Institute for Particle Physics) submitted a new protocol for the Internet and a document system using the protocol. The group named this new system World Wide Web, and its The purpose is to enable scientists around the world to use the Internet to exchange their work documents.

The new system was designed to allow any user on the Internet to search for and retrieve documents from the databases of many document serving computers. By the end of 1990, the basic framework of this new system had been developed and implemented on a computer at CERN. In 1991, the system was transplanted to other computer platforms and officially released.

Features

Graphical

A very important reason why the Web is so popular is its ability to display colorful graphics and text simultaneously on one page. Before the Web, information on the Internet was only in text form . The Web can provide features that integrate graphics, audio, and video information.

Platform agnostic

No matter what the user's system platform is, you can access the WWW through the Internet. Browsing the WWW has no restrictions on the system platform. We can access WWW from Windows platform, UNIX platform, Mac intosh and other platforms. Access to the WWW is achieved through a software called a browser . Such as Mozilla's Firefox , Google 's Chrome , Microsoft's Internet Explorer , etc.

distributed

A large amount of graphics, audio and video information will occupy a considerable amount of disk space , and we cannot even predict how much information there will be. For the Web, it is not necessary to put all the information together. The information can be placed on different sites. You only need to indicate this site in the browser. Physically, information on a site is not necessarily logically integrated. From the user's perspective, the information is integrated.

Dynamic

Since the information of each Web site contains the information of the site itself, the information provider can frequently update the information on the site . Such as the development status of a certain agreement, the company's advertising, etc. Generally, all information sites try their best to ensure the timeliness of information . Therefore, the information on the Web site is dynamic and frequently updated, which is guaranteed by the information provider.

interactive

The interactivity of the Web is first reflected in its hyperlinks . The user's browsing order and the sites he visits are completely determined by him. In addition, dynamic information can be obtained from the server through FORM. Users can submit requests to the server by filling in the FORM, and the server can return corresponding information based on the user's request.

Web related concepts

Web page (Web page):
- A web page is a page in a website. Usually a web page is the basic element that constitutes a website and is a platform that hosts various website applications. In layman's terms, a website is made up of web pages.

Website (WebSite):
- A website refers to a collection of related web pages produced using tools such as HTML to display specific content according to certain rules. Simply put, a website is a communication tool, like a bulletin board, through which people can publish or collect information.
- A website is a collection of web pages that belong to the same

HTML (Hypertext Markup Language):
- "Hypertext" means that the page text can contain pictures, links, and even non-text elements such as music and programs.
- It is a specification and a standard. Hypertext Markup Language uses markup symbols to mark various parts of the web page to be displayed.
- The essence of a web page is a file generated by writing code in HTML language

Static pages:
- Refers to a Web page written in pure HTML language and presented with fixed content.
- All content presented by a static web page is written in the source file, and changing the content can only modify the source code.

dynamic webpages:
- In addition to HTML, Web pages written using corresponding dynamic program preambles
- The content presented in dynamic web pages is generally stored in a database, and the data is called through programming languages.

HTTP (Hypertext Transfer Protocol):
- A protocol for publishing and receiving HTML pages, defining request and response standards for Web clients and servers
- Works on TCP port 80 by default

HTTPS（HTTP over SSL）
- The SSL-based HTTP protocol uses the SSL protocol to protect HTTP transmission and make the HTTP protocol more secure.

Browser:
- An application that can receive and parse HTML language, enable HTML to be displayed graphically, and interact with Web servers

Web service component

To build a website, you generally need four components: Web service system, Web service software, Web development language, and database. This is just a relatively general division of the components of Web services. If you want to subdivide it, it can also be subdivided into operating system, storage (Web source files and databases), Web container, middleware, Web server language, and Web development framework. , Web applications, Web front-end frameworks, third-party content and other components. The content of this course does not focus on the construction and optimization of the Web, so it only explains the components according to the diagrams.

Web service system

As a network service, the Web must run and work based on an operating system. The Web service system here refers to the operating system on which the Web service runs.

Windows
As the most widely used computer operating system, Windows is undoubtedly a good operating system platform for running Web services. Both the desktop version of Windows and the server version of Windows have the ability to run Web services. However, for Web services in production environments, the server version of Windows is more likely to be used, such as Windows Server 2003, Windows Server 2008, and Windows Server 2012. wait
Windows has excellent graphical interface processing capabilities and has become the operating system of choice for many Web beginners.

Linux
The server-side operating system is undoubtedly dominated by Linux. Based on the advantages of open source, high efficiency, and security, Linux has become the preferred operating system for building Web services in production environments.
Common ones include CentOS, RatHat, and Ubuntu. Almost 99% of web services on the Internet run on Linux systems.

Web service software

Web service software refers to Web server, also called HTTP server, which is Web server software that responds to HTTP requests from browsers and sends out web page files. If you want to publish your website to the Internet so that users can access it, you need Web service software to build the website.

IIS（Internet Information Service）

IIS is Microsoft's own Internet server software in the Windows operating system. It provides server functions including Web, FTP, SMTP, etc. IIS can only run in Windows.
IIS comes with almost all versions of Windows. No separate download is required. It is operated with a full graphical interface. It inherits the operating style of Windows and is very simple and convenient to use.
IIS supports the publishing of static websites, as well as dynamic websites of ASP and http://ASP.NET . Using the corresponding middleware, it can also support the publishing of dynamic websites of PHP.
IIS has been criticized by the industry for its security. The famous file parsing vulnerability in IIS version 6.0 allows hackers to easily bypass website restrictions and upload WebShell to gain system permissions. The situation did not improve until IIS version 7.5.

Apache

Apache is the world's number one used web server software. It can run on almost all widely used computer platforms and is one of the most popular web server-side software due to its cross-platform and security features. It is fast, reliable and extensible through a simple API to compile interpreters such as Perl/Python into the server. At the same time, Apache, transliterated as Apache, is a tribe of North American Indians called the Apache tribe in the southwestern United States. It is also the name of a foundation, an armed helicopter, etc.
Although Apache can run perfectly on various operating systems, the vast majority of Apache still runs on Linux, and Apache has also become a built-in application of many Linux distributions.
Strictly speaking, Apache only supports publishing static websites, but it can support PHP, ASP, http://ASP.NET , and JSP through middleware , but Apache is still used by most to publish PHP websites.
Although Apache also has security vulnerabilities, due to its open source nature, vulnerability patching and version updates are very fast. Compared with IIS, Apache will be more secure.

Nginx

Nginx is a lightweight web server/reverse proxy server and email (IMAP/POP3) proxy server, and is released under a BSD-like protocol. Its characteristics are that it occupies less memory and has strong concurrency capabilities. In fact, nginx's concurrency capabilities do perform better among web servers of the same type. Users of nginx websites in mainland China include: Baidu, JD.com, Sina, NetEase, Tencent, Taobao, etc.
Nginx can only be installed on Linux systems, but there is also a ported version for Windows.
Nginx is the best alternative to Apache. Compared with Apache, Nginx consumes less resources and has better performance when handling high-concurrency services.
Nginx itself is just a reverse proxy software, which only supports HTML static pages and needs to use various middleware to support other dynamic pages.
Although Nginx is better than Apache in terms of performance, Nginx also has the disadvantages of fewer modules, more bugs, and poor stability.

Tomcat

Tomcat server is a free and open source Web application server. It is a lightweight application server and is commonly used in small and medium-sized systems and situations where there are not many concurrent access users. It is the first choice for developing and debugging JSP programs.
Tomcat can be used as a Web service software, and can also be used as a middleware for Apache to enable Apache to support JSP sites.
Tomcat can run on Windows and Linux

Weblogic

Weblogic is a middleware based on JAVAEE architecture. WebLogic is a Java application server used to develop, integrate, deploy and manage large-scale distributed Web applications, network applications and database applications.

web development language

Web development language refers to a language used to write dynamic web pages. Currently, almost all websites are written with dynamic web technology. Even if you find that the URL suffix is html when browsing many websites, it is still done through the background.

PHP (hypertext preprocessor)

PHP is a general-purpose open source scripting language. The syntax absorbs the characteristics of C language, Java and Perl, which is easy to learn and widely used. It is mainly suitable for the field of Web development. PHP's unique syntax is a mix of C, Java, Perl, and PHP's own syntax. It can execute dynamic web pages faster than CGI or Perl. Compared with other programming languages, dynamic pages made with PHP embed programs into HTML (an application under the Standard Universal Markup Language) document for execution, and the execution efficiency is much higher than CGI that completely generates HTML tags; PHP can also execute compiled code. Compilation can achieve encryption and optimize code running, making the code run faster.
PHP is currently the most widely used web development language

ASP (Dynamic Script Page)

It is a server-side scripting environment developed by Microsoft that can be used to create dynamic interactive web pages and build powerful web applications. When the server receives a request for an ASP file, it processes the server-side script code contained in the HTML page file that is used to build the HTML page that is sent to the browser. In addition to server-side script code, ASP files can also contain text, HTML (including associated client-side script), and COM component calls
ASP is simple and easy to maintain, making it the choice for small page applications. The ASP language is not object-oriented and is relatively difficult to develop. It is generally not used for large and medium-sized websites.

http://ASP.NET
- http://ASP.NET, also known as ASP+, is not just a simple upgrade of ASP, but a new generation scripting language launched by Microsoft. http://ASP.NET is a Web development platform based on the .NET Framework. It not only absorbs the greatest advantages of previous versions of ASP and adds many new features with reference to the development advantages of Java and VB languages, but also corrects the features of previous ASP versions. Run error.
- Generally found on websites of government agencies and state-owned enterprises

JSP (JAVA Server Page)
- JSP technology is somewhat similar to ASP technology. It inserts Java program segments (Scriptlet) and JSP tags (tags) into traditional web page HTML files to form a JSP file with the suffix .jsp. Web applications developed with JSP are cross-platform and can run under Linux as well as other operating systems.

CMS (content management system)
- CMS can be understood as a website template, which allows users to quickly generate customized personal or corporate sites based on unified website templates; CMS provides information display, information update, information deletion, information management and other functions required by common corporate websites, including Very detailed website style customization settings.
- CMS is written in various languages, the common ones are ASP, PHP, http://ASP.NET
- Common ones include Dongyi CMS, Dreamweaver CMS, PHPcms, etc.

database

Database (Database) is a warehouse of data, used to store and record data information. In the architecture of a dynamic website, the content displayed on the page is not written on the page, but stored in the database. The Web service calls the data in the database through dynamic language, generates a static page, and then passes it to the client browser. This avoids modifying the source files when the website content is updated. Just update the database.

MySQL

MySQL is a relational database management system developed by the Swedish MySQL AB company and is currently a product of Oracle. MySQL is one of the most popular relational database management systems. In terms of WEB applications, MySQL is the best RDBMS (Relational Database Management System) application software.
Currently the most widely used database system in Web architecture

SQL Server

SQL Server is a relational database management system (DBMS) developed and promoted by Microsoft. It was originally jointly developed by Microsoft, Sybase and Ashton-Tate, and launched the first OS/2 version in 1988. Microsoft SQL Server has been continuously updated in recent years. In 1996, Microsoft launched SQL Server 6.5 version; in 1998, SQL Server 7.0 version met users; SQL Server 2000 was launched by Microsoft in 2000, and the latest version was launched in 2017 SQL SERVER 2017.

Oracle

Oracle is a relational database management system from Oracle Corporation. It is a product that has always been in the leading position in the database field. It can be said that the Oracle database system is currently a popular relational database management system in the world. The system has good portability, easy use, and strong functions. It is suitable for various large, medium, small, and microcomputer environments. It is a database solution that is efficient, reliable and adapts to high throughput.

Access

Microsoft Office Access is a small relational database management system released by Microsoft. It combines the two features of MicrosoftJet Database Engine and graphical user interface, and is one of the programs in the Microsoft Office suite.

Database management tools

PhpMyAdmin: A MySQL database management tool based on PHP and built on the website host in a Web manner, allowing administrators to manage MySQL databases using a Web graphical interface.
Navicat: A set of fast, reliable and relatively cheap database management tools, designed to simplify database management and reduce system management costs. It is designed to meet the needs of database administrators, developers and small and medium-sized businesses.

Common architectures of web services

Web service architecture refers to the combination of development language + Web service software + database + operating system chosen to build Web services. Although strictly speaking, all components can be combined freely, but because certain types are often used together, With higher and higher compatibility, they gradually form a powerful web application platform.

LAMP

Linux + Apache + MySQL + PHP
Known as the golden combination of Web services, it is suitable for large-scale website architectures, has high stability, and is commonly used in corporate websites. The architecture used by most websites

LNMP

Linux + Nginx + MySQL + PHP
Use Nginx to replace Apache. Web sites with higher performance requirements can choose this architecture combination.

WAMP

Windows + Apache + MySQL + PHP
Run Apache on Windows operating system, suitable for small and medium-sized website architecture, easy to manage, common in education (universities, etc.), government institutions

other

IIS + ASP + Access: mostly used in schools, local governments and other sites
JSP + Tomcat + Oracle: mostly used in internal enterprise ERP systems and financial institution sites