The Several types of Websites

The different types of Web Sites - An important first step in planning a Web server is to determine what the company wants to accomplish with the server. The company must estimate how many visitors will be connecting to the Web site and what types of files stored on Web sites (graphics, multimedia, or text) will be delivered through the site.

Therefore, you should consider the different types of Web sites, To stand before the diversity of Internet services. And determine what is needed for our work.

The company must also assess its existing information technology staff. Some companies have a large staff with a depth of experience, while others have a small or relatively inexperienced staff.

Companies create Web sites for a wide variety of reasons and in a wide variety of forms. Each has a different purpose, requires different computer hardware and software, and requires different monetary and personnel resources. Decisions about server hardware and software should be driven by the volume and type of Web activities expected.

Different types of Web Sites include::

  • Development sites: Simple sites that companies use to evaluate different Web designs with little initial investment. A development site can reside on an existing PC running Web server software. Multiple testers access the site through their client computers on an existing LAN.
  • Intranets: Corporate networks that house internal memos, corporate policy handbooks, expense account worksheets, budgets, newsletters, and a variety of other corporate documents.
  • Extranets: Intranets that allow certain authorized parties outside the company (such as suppliers or strategic partners) to access certain parts of the information stored in the system.
  • Transaction-processing sites: Commerce sites such as business-to-business and business-to-consumer electronic commerce sites that must be available 24 hours a day, seven days a week. These sites must have spare server computers for handling high traffic volumes that occur periodically. In addition to requiring fast and reliable hardware, transaction-processing sites must run Web and commerce software that is efficient and easily upgraded when site traffic increases.
  • Content-delivery sites: Sites that deliver content such as news, histories, summaries, and other digital information. Visitors must be able to locate articles quickly with a fast and precise search engine. The content must be presented rapidly on the visitor’s screen. In general, these sites must be available 24 hours a day, seven days a week, just like transaction-processing sites. Hardware requirements for content sites are also similar to those of transaction-processing commerce sites.
Web Clients and Web Servers
When people use their Internet connections to become part of the Web, their computers become Web client computers on a worldwide client/server network. Client/server architectures are used in LANs, WANs, and the Web. 

In a client/server architecture, the client computers typically request services, such as printing, information retrieval, and database access, from the server, which processes the clients’ requests. The computers that perform the server function usually have more memory and larger, faster disk drives than the client computers they serve. 

The Internet connects many different types of computers running different types of operating system software.

Web Clients and Web Servers

Dynamic Content
The mix and type of Web pages a system is likely to deliver in response to client requests can affect Web server performance. A dynamic page is a Web page whose content is shaped by a program in response to user requests, whereas a static page is an unchanging page retrieved from disk.

A server delivering mostly static Web pages performs better than the same server delivering dynamic Web pages because static page delivery requires less computing power than dynamic page delivery. The largest performance differences between competing Web server products appear when servers deliver dynamic pages.

Dynamic content is non static information constructed in response to a Web client’s request. For example, if a Web client inquires about the status of an existing order by entering a unique customer number or order number into a form, the Web server searches the customer information (or sends a query to the back-end database in a higher tier) and generates a dynamic Web page based on the customer information it found (or that the database management software provided), thus fulfilling the client’s request. Assembled from back-end databases and internal data on the Web site, a dynamic page is a specific response to the requester’s query.

Server-Side Scripting.
The first Web sites to provide dynamic Web pages used an approach called server-side scripting. In server-side scripting (also called server-side includes or, more generally, server-side technologies), programs running on the Web server create the Web pages before sending them back to the requesting Web clients as parts of response messages.

Most server-side technologies are slow, so large Web sites used by online businesses today tend to use dynamic page-generation technologies.

Dynamic Page-Generation Technologies.
Microsoft developed a now widely used dynamic page-generation technology called Active Server Pages (ASP). Sun Micro systems developed a similar technology called Java Server Pages (JSP), and the open-source Apache Software Foundation sponsored a third alternative called PHP: Hypertext Preprocessor (PHP). Yet another alternative is available from Macromedia in its Cold Fusion product.

In these page-generation technologies, server-side scripts are mixed with HTML tagged text to create the dynamic Web page. For example, ASP allows Web programmers to use their choice of programming languages, such as VB Script, J script, or Perl. Java, a programming language created by Sun, can be used to produce dynamic pages. Such server-side programs are called Java servlets.

The Future of Dynamic Web Page Generation.
Many critics of dynamic page-creation technologies note that these approaches do not really solve the problem of dynamic Web page generation. They argue that these dynamic page creation approaches merely shift the task of creating dynamic pages from people who write HTML code to ASP (or JSP or PHP) programmers.

Several initiatives are under way that are directed at a more comprehensive solution to the dynamic Web page-creation problem. The Apache Cocoon Project is one of these initiatives. Apache Cocoon is a Web-development framework that allows programmers to query data that is in XML format and generate output in multiple formats, including HTML.

The HTML output option makes Cocoon a useful tool for generating dynamic Web pages. In this approach, the content is stored with XML tags that describe the semantics (meaning) of each content item. The information request is handled by a Java servlet that can read the XML file and select the requested content items using the XML tags in the content file.

Instead of creating a Web page, Cocoon can produce a response tailored to the request by applying a style sheet to the data. If a site visitor requests, for example, an Adobe Portable Document Format (PDF) file or a Wireless Markup Language (WML) file for display on a wireless handheld device, a Web site using Cocoon technology can generate the results in those file formats from its XML content files.

The Future of Dynamic Web Page Generation

Note that this model breaks the direct connection between logic and style. By separating the logic (the work of programmers) and style (the work of graphic artists) that is combined in the structure of HTML, Web designers believe that using the Cocoon model could make dynamic Web page design easier in the future.

Many industry experts believe that the Apache Cocoon Project and similar development efforts by Microsoft (the Microsoft.NET Framework) and Oracle will provide better ways to generate dynamic Web pages in the future.

Various Meanings of “Server”
All computers that are connected to the Internet and contain documents that their owners have made publicly available through their Internet connections are called Web servers. Unfortunately, the term “server” is used in many different ways by information systems professionals.

These multiple uses of the term can be confusing to people who do not have a strong background in computer technology. You are likely to encounter a number of different uses of the word “server.”

A server is any computer used to provide (or “serve”) files or make programs available to other computers connected to it through a network (such as a LAN or a WAN). The software that the server computer uses to make these files and programs available to the other computers is sometimes called server software. Sometimes this server software is included as part of the operating system that is running on the server computer.

Thus, some information systems professionals informally refer to the operating system software on a server computer as server software, a practice that adds considerable confusion to the use of the term “server.”

Similar terminology issues arise for server computers that perform e-mail processing and database management functions. Recall that the server computer that handles incoming and outgoing e-mail is usually called an e-mail server, and the software that manages e-mail activity on that server is frequently called e-mail server software.

The server computer on which database management software runs is often called a database server. Thus, the word “server” is used to describe several types of computer hardware and software, all of which might be found in a typical electronic commerce operation.

The only way to determine which server people are talking about when they use the term is from the context or by asking a clarifying question. If you hear a computer technician say, “The server is down today,” the problem might be in the hardware, the software, or a combination of the two!

Web Client/Server Communication.
When a person uses a Web browser to visit a Web site, the Web browser (also known as a Web client) requests files from the Web server at the company or organization that operates the Web site. Using the Internet as the transportation medium, the request is formatted by the browser using HTTP and sent to the server computer.

A moment later, when the server receives the request, it retrieves the file containing the Web page or other information that the client requested, formats it using HTTP, and sends it back to the client over the Internet.

When the requested information a file containing the text and markup tags of a Web page, in this instance arrives at the client computer, the Web browser software determines that the information is an HTML page. It displays the page on the client machine according to the directions defined in the page’s HTML code.

This process repeats as the client requests, the server responds, and the client displays the result. Sometimes, a single client request results in dozens or even hundreds of separate server responses to locate and deliver information.

AWeb page containing many graphics and other objects can be slow to appear in the client’s Web browser window because each page element (each graphic or multimedia file) requires a separate request and response.

Two-Tier Client/Server Architecture
The basic Web client/server model is a two-tier model because it has only one client and one server. All communication takes place on the Internet between the client and the server.

Of course, other computers are involved in forwarding packets of information across the Internet, but the messages are created and read only by the client and the server computers in a two-tier client/server architecture.  Shows how a Web client and a Web server communicate with each other in a two-tier client/server architecture.

Web Client/Server Communication


The message that a Web client sends to request a file or files from a Web server is called a request message. A typical request message from a client to a server consists of three major parts:
  •  Request line
  •  Optional request headers
  •  Optional entity body
When the server receives the request message, it executes the command included in the message (in this case, it sends a particular Web page file back to the client). The server does this by retrieving the Web page file from its disk (or another disk on a network to which it is connected) and then creating a properly formatted response message to send back to the client.

A server’s response consists of three parts that are identical in structure to a request message: a response header line, one or more response header fields, and an optional entity body. In the response, however, each part has a slightly different function than it does in the request.

The response header line indicates the HTTP version used by the server, the status of the response (whether the server found the file that the client wanted), and an explanation of the status information. Response header fields follow the response header line. A response header field returns information describing the server’s attributes. The entity body returns the HTML page requested by the client machine.

Three-Tier and N-Tier Client/Server Architectures
Although the two-tier client/server architecture works well for the delivery of Web pages, a Web site that delivers dynamic content and processes transactions must do more than respond to requests for Web pages.

A three-tier architecture extends the two-tier architecture to allow additional processing (for example, collecting the information from a database needed to generate a dynamic Web page) to occur before the Web server responds to the Web client’s request. Higher-order architectures that is, those that have more than three tiers are usually called n-tier architectures.

The third tier often includes databases and related software applications that supply information to the Web server. The Web server can then use the output of these software applications when responding to client requests, instead of just delivering a Web page.

Architectures that have four, five, or even more tiers include software applications (just as the three-tier systems), but they also include the databases and database management programs that work with the software  applications to generate information that the Web server can turn into Web pages, which it then sends to the requesting client.

Figure shows an overview of information flows in a three-tier architecture. Numbers on the flow arrows indicate the order in which the messages flow over the indicated paths.

Message flows in a three-tier client/server network


Source: Electronic Commerce\ Web Server Hardware and Software

Comments

  1. As a Dell employee I think your blog about several types of websites is really impressive. The decscription of various types of websites is very much useful, this information is so valuable. Thanks for sharing with us. Keep posting such nice information.

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  2. Thank you for this comment. I enjoyed reading your comment. Thanks

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