Time For Some Alphabet Soup

Whenever you variety an address into your web browser, or click on a relationship in a web page, you are making a subject matter for a in no doubt written material. Handled by the Hyper Text Transfer Protocol (HTTP), your request is dispatched ended the Internet to the server that holds the written document you privation. Assuming all goes well, the waiter will answer by sending the document, more often than not a web leaf consisting of essay and graphics.

Exactly what is HTTP? It is component part of the Internet Protocol (IP) suite, and is used by a "client," such as a web browser, to ensconce a relation next to the restaurant attendant that hosts a unusual website. The server monitors TCP dock 80 as it waits for next requests.

Connections on the Internet that let 2 computers to swap notes are created by the Transmission Control Protocol (TCP). TCP is panoplied to determine the requesting computer, and to in good order communicate notes to its finish.

Server To Web Browser - Behind The Scenes

Several TCP ports are on tap with standardised uses. For example, TCP Port 21 is typically undemonstrative for FTP (File Transfer Protocol) for uploading and downloading files. Port 80 is in general in use for HTTP.

If the dining-room attendant receives a substance string on TCP wharf 80 in the word of GET / HTTP/1.1 it will convey a feedback code, depending on whether the requested web page is acquirable or not. A true request will face suchlike this:

GET /faq.html HTTP/1.1


This is a behest for the page "faq" on the grownup piece of ground "mywebsite". The "host" essential be such that to recognize relating websites that are hosted on shared servers. If faq.html is available, the restaurant attendant will come back with thing like:

HTTP/1.1 200 OK

Date: Mon, 12 October 2005 22:38:34 GMT

Server: Apache/1.3.27 (Unix) (Red-Hat/Linux)

Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
... followed by the actual web folio.

How Data Gets Where It's Going

The eldest formation above, HTTP/1.1 200 OK, funds that the requested web page is accessible. Other codes may also be returned. For example, the code 404 channel the server cannot find the requested page.

When found, the web folio is sent via TCP as a series of accumulation packets, all beside a heading that specifies its end and its order in the notes beck. The miscellaneous packets can hold different paths to realize their finish.

Each is dispatched through with a router, which place different routers close by. If a association near the prototypal skilled worker is unavailable, the facts will be sent done other one. This allows the aggregation to accomplish its finish as fast as affirmable.

What Happens When It Gets There

When the web spectator receives the data, it sends rear an recognition. This insures that all the packets have been acceptable inside a persuaded event. If not, they will be re-transmitted by the restaurant attendant. TCP as well checks to be positive the assemblage is undamaged.

The facts is consequently reassembled in the letter-perfect order, acknowledgement to the series numeral of respectively background parcel.

And Presto! The web folio appears on your electronic computer screen, usually in a few seconds.



froeoir 發表在 痞客邦 PIXNET 留言(0) 人氣()