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by 王文良 2018-03-14 09:56:44, 回應(0), 人氣(168)

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HTML5 and CSS3 Fundamentals

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A system of top-level Domain Names was created ... .edu for educational institutions, .mil for Military, .gov for Government, .net for Network related resources, .org for Non-profit organizations, .com for Commercial organizations, etc. Later, other countries and a plethora of top-level domains were added and others for commercial and other interests.

The web browser will query databases of domain names and their associated IP Addresses and will translate the requests automatically for the user without his or her knowledge. Typically, each Internet Service Provider has a Domain Name System server that can be queried for resolving Domain Names into IP Addresses. The databases that contain this Domain Name information stay synchronized around the globe, although sometimes the synchronization process can take minutes or hours to complete.

The Purpose for Standards Groups

At every step of the way, one or more organizations were formed to help identify standards for these technologies comprised of experts and luminaries who were pushing these technologies forward. They would meet both virtually and in person to define and discuss the merits of adding new features to a given standard and would encourage organizations who were creating hardware and software to follow these standards so that products from different vendors could work together seamlessly. Perhaps one of the most influential and important standards body you will hear about is the W3C, or rather, the World Wide Web Consortium. They were one of the groups responsible for the latest version of HTML, version 5. Another is the WHATWG, or rather, the Web Hypertext Application Technology Working Group, which is comprised of a subset of the W3C and several additional experts and organizations that have a vested interest in the vitality of the World Wide Web. The background of HTML5, the previous versions of HTML, as well as the standards organizations involved is fascinating because you get a peek into both the process and the politics of these organizations.

Recap of the World Wide Web Technical Overview

From a purely technical perspective, you should now understand a few things:

  1. First of all, hopefully you now have an answer to the question everyone first starting out asks: "why the heck did they make URLs so convoluted? Wouldn't it be easier to just type in 'microsoft' instead of 'http://www.microsoft.com'?" There's an evolution of technologies, and furthermore, it was never intended for use by the masses. At some point commercialized and individual access to the internet dwarfed the intended use, however the technologies created 30 years ago are still in play.
  2. Second, hopefully you will begin see the purpose of things like http:// ... in which you are saying you want to access a specific channel of traffic, HTTP, or rather, World Wide Web traffic, as opposed to FTP (File Transfer Protocol) for working with large files, SMTP (Simple Mail Transfer Protocol) for sending email, and so on.
  3. Third, hopefully you see the purpose of .com, .edu, .net and so on ... at least, you understand the original purpose, and you understand how those domain names are translated into the actual IP Addresses that are utilized by routers to move traffic around the internet to it's intended destination.
  4. Fourth, hopefully you can see that the specifics of HTML - and all other standards - are decided on by a body of individuals who understand what is needed and propose and debate the merits of adding or removing parts of a given specification. You should also see the purpose for these standards - so that organizations creating hardware and software to support the World Wide Web can achieve a high degree of interoperability.
  5. Fifth, hopefully you can see the role that each component plays in the exchange of documents and other resources ... the web browser is responsible for interacting with the end user who requests a document by typing in a web address or clicks on a hyperlink. It also packages up that request and begins the process of requesting the document from it's host, the computer called the web server. The message is packaged using the HTTP protocol, which you can think of as an electronic envelope geared towards stateless request / response style transmissions between two computers. Routers are special devices that know how to interpret the address encoded in electronic envelopes, or rather, the HTTP messages, and route them closer to their ultimate destination. A web server is merely a computer at a given web address that is listening for HTTP requests, and if the address is valid, returns the requested document or resource using the same HTTP message addressing as a response.
參考網站: http://mjwtech.co.uk/
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