1)        WHAT IS THIS?

ANS: URL shortening is a technique on the World Wide Web in which a Uniform Resource Locator (URL) may be made substantially shorter in length and still direct to the required page. This is achieved by using an HTTP Redirect on a domain name that is short, which links to the web page that has a long URL.

For example:

The URL http://en.wikipedia.org/wiki/URL_ shortening can be shortened to http://bit.ly/urlwiki

This is very convenient for messaging technologies such as Twitter and Identi.ca, which severely limit the number of characters that may be used in a message. Short URLs allow otherwise long web addresses to be referred to in a tweet. In November 2009, the shortened links on one URL shortening service were accessed 2.1 billion times.

 

2)        WHY ARE WE GOING FOR THIS?

ANS: Some web developers on mainstream sites tend to pass descriptive attributes in the URL to represent data hierarchies, command structures, transaction paths or session information and this often results in a URL that contains a large number of characters, is awkward to reproduce and impossible to remember. Copying a URL that is hundreds of characters long can only really be successfully done by copy-and-paste. Trying to type one by hand will be time-consuming and may result in errors. Thus a short URL is more useful to write in an e-mail message or an internet forum post.

On Twitter and some instant-messaging services, there is a limit on the total number of characters that can be used in a message. Using a URL shortener, we can make it easier to include a URL within a short message. Some shortening services, such as tinyurl.com and bit.ly, can generate URLs that are human readable, although the resulting strings are longer than those generated by a length-optimized service. A QR Code (A QR code (abbreviated from Quick Response code) is a type of matrix barcode (or two-dimensional code) first designed for the automotive industry. More recently, the system has become popular outside of industry due to its fast readability and comparatively large storage capacity. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of any kind of data (e.g., binary, alphanumeric, or Kanji symbols) that stores a URL can be more readable by using a URL shortener to minimize the length of the URL it encodes.

   HOW TO REGISTER A SHORT URL?

ANS:  An increasing number of websites are registering their own short URLs to make sharing via Twitter and SMS easier. This can normally be done online, at the web pages of a URL shortening service. Short URLs often circumvent the intended use of top-level domains for indicating the country of origin; domain registration in many countries requires proof of physical presence within that country, although a redirected URL has no such guarantee.

 

WHAT ARE THE TECHNIQUES?

ANS:  In URL shortening, every long URL is associated with a unique key, which is the part after http://top-level domain name/.

For example http://tinyurl.com/m3q2xt has a key ofm3q2xt. Not all redirection is treated equally; the redirection instruction sent to a browser can contain in its header the HTTP status 301 (permanent redirect) or 302 (temporary redirect). In the field of search engine optimization it is believed that a permanent redirect will receive a higher ranking.

There are several techniques to implement a URL shortening. Keys can be generated in base 36, assuming 26 letters and 10 numbers. In this case, each character in the sequence will be 0, 1 to 9, a, b, c, ..., y, z. Alternatively, if uppercase and lowercase letters are differentiated, then each character can represent a single digit within a number of base 62 (26 + 26 + 10). In order to form the key, a hash function can be made, or a random number generated so that key sequence is not predictable. Or users may propose their own keys. For example,http://en.wikipedia.org/w/index.php?title=TinyURL&diff=283621022&oldid=283308287 can be shortened to http://bit.ly/tinyurlwiki.

Not all protocols are capable of being shortened, as of 2011, although protocols such as http, https, ftp, ftps, mailto, news, mms, rtmp, rtmpt, e2dk, pop, imap, nntp, news, ldap, gopher, dict and dns are being addressed by such services as URL Shortener. Typically, data: and java script: URLs are not supported for security reasons. Some URL shortening services support the forwarding of mailto URLs, as an alternative to address munging, to avoid unwanted harvest by web crawlers or bots. This may sometimes be done using short, CAPTCHA-protected URLs, but this is not common.

Tinyarro.wsurlrace.com, and qoiob.com use Unicode characters to achieve the shortest URLs possible, since more condensed URLs are possible with a given number of characters compared to those using a standard Latin alphabet.

 

WHAT ARE THE PROBLEMS WITH THIS?

ANS:

1)        The short services may stop working. So all the short URL’s under these services will be broken. This is called LINKROT.

2)      URL shortening sites are sometimes shut down by their hosting Internet service provider (ISP) because the links are being used for illicit purposes. This is called CLOSURE BY INTERNET SERVICE PROVIDER.

3)      Shortened internet links typically use foreign country domain names, and are therefore under the jurisdiction of that nation. Libya, for instance, exercised its control over the .ly domain in October 2010 to shut down vb.ly for violating Libyan pornography laws. Failure to predict such problems with URL shorteners and investment in URL shortening companies may reflect a lack of due diligence. This is called INTERNATIONAL LAW.

4)      Apart from this there are problems like security, blocking problems.

Thus, it has its own importance in today’s world. Try it friends… so that everyone can easily remember your blog or anything. :-).

Courtesy:wikipedia.com

Posted by

Ravi Teja (MGIT ECE 4th year)


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