differences between http, urn, url

[Former Member]

Hi,

When it comes to namespace it can start with either of http, urn url. without sending any links ( I have gone thorugh previous threads) could you please tell me in real time scenario when we will go for http and when we will go for urn & url ??

Any help in this regard is highly appreciated

Regards

Kumar

[Former Member]

Hi Srinivasa,

<b>HTTP: </b> Short for HyperText Transfer Protocol, the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page.

For more details about HTTP please check below link:

<a href="http://www.webopedia.com/TERM/H/HTTP.html">http://www.webopedia.com/TERM/H/HTTP.html</a>

<b>URN</b> : A URN (Uniform Resource Name) is an Internet resource with a name that, unlike a URL, has persistent significance - that is, the owner of the URN can expect that someone else (or a program) will always be able to find the resource. A frequent problem in using the Web is that Web content is sometimes moved to a new site or a new page on the same site. Since links are made using Uniform Resource Locators (URLs), they no longer work when content is moved.

A URN looks something like a URL. For example, here's a hypothetical URN:

urn:def://alpha_peter

where "def://" might indicate an agency or an accessible directory of all dictionaries, glossaries, and encyclopedias on the Internet and "blue laser" was the name of a term. The result of using the agency could be the "best definition," the "longest definition," or even all definitions that the agency could find of "blue laser."

A comparable URL would need to specify one specific location for a definition such as:

http://www.abcex.com/alpha.htm

For more about URN please check below link:

<a href="http://searchwebservices.techtarget.com/sDefinition/0,,sid26_gci214164,00.html">http://searchwebservices.techtarget.com/sDefinition/0,,sid26_gci214164,00.html</a>

<b>URL</b> : Abbreviation of Uniform Resource Locator, the global address of documents and other resources on the World Wide Web.

The first part of the address indicates what protocol to use, and the second part specifies the IP address or the domain name where the resource is located.

For example, the two URLs below point to two different files at the domain rampeter.com. The first specifies an executable file that should be fetched using the FTP protocol; the second specifies a Web page that should be fetched using the HTTP protocol:

For more details about URL please see:

<a href="http://www.webopedia.com/TERM/U/URL.html">http://www.webopedia.com/TERM/U/URL.html</a>

Regards,

Subhasha Ranjan

[Former Member]

Hi Srinivas rao,

A Name space should be globally unique identifier usually expressed as either a

URI:uniform Resource indicator,URL,(but not necessarily point to web resouce)

or URN(uniform resource name,like a URI but without a protocol assignment).

Hope my answer will help you.

Please let me know if you have any questions?

Thanks and Regards,

Chandu.

[henrique_pinto]

The namespace could be any string that uniquely defines the scope of those determined fields of the XML file. Usually, you use a URI to define that unique string, and since URLs are the most common URIs, people tend to use plain http URLs as the namespace (it doesn't need to be a valid url). But using "urn:test" for example isn't wrong.

From the specification:

URI

URI = Uniform Resource Identifier

There are two types of URIs: URLs and URNs

URL

URL = Uniform Resource Locator

<protocol>:// <host> [:<port>] [<path> [? <query>]]

URN

URN = Uniform Resource Name.

URNs define XML schemas.

urn:<namespace>:<string>

Regards,

Henrique.