registered with the Internet Assigned Number Authority (IANA) [5] or host
names registered for a specific domain. URIs are independent of the location
(a specific host) of the named object. For example:
mailto:[email protected]is a URI associated with e-mail. Note the mail URI does not specify any spe-
cific computer.
mailto:
The mailto:URI schema [6] designates an Internet mailing address of an
individual or service. It does not represent an actual Internet location, but
serves only to route Internet mail. For example:
mailto:[email protected]The mailto:URI appears frequently in web pages for providing e-mail
feedback. In addition, the values of certain Simple Mail Transfer Protocol
(SMTP) headers can be prepopulated by the URL. For example, clicking on the
URI that follows in a web browser will bring up a blank e-mail message
addressed To: [email protected] with the Subject:header
set to “Feedback”:
mailto:[email protected]?Subject=FeedbackA mailto: URI can appear in a SIP message as part of a list of Contact
headers.
URI schemas are associated with various protocols and services, such as:
FTP, HTTP, Mail, News, SIP, Telnet, and others.
In SIP, a Request-URI is defined in RFC 2543 as a type of URI used to indi-
cate the name of the destination for the SIP Request (INVITE, REGISTER,
SUBSCRIBE, and so on). As a SIP Request is forwarded by proxies, the
Request-URI can be changed as database lookups and feature invocations
change the final destination of the request.
The Universal Resource Locator (URL)
The Universal Resource Locator (URL) [7] describes the location of a resource
available on the Internet. Contrary to URI schemas, the schemas for URLs are
associated with specific hosts, protocols, and services. For example:
http://ws1.example.comis web server #1 for the domain example.com.
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