In Detail : What Is URI, URL , URN


    URI stands for Uniform Resource Identifier. A URI is the most general. A URI is parsed for basic syntax without regard to the scheme, if any, that it specifies, and it need not refer to a particular server. URL and URN are subcategories of URI.

The string form of URI has the syntax

The components inside square brackets [..] are optional. The URIs are of two types
1. An absolute URI - specifies a scheme.
2. A relative URI - which doesn't specify a scheme.

URIs are classified according to whether they are opaque or hierarchical.

Opaque URI :
     An opaque URI is an absolute URI whose scheme-specific part doesn't begin with a slash character ('/'). Some examples are

Hierarchical URI :
    A hierarchical URI is either absolute URI whose scheme-specific part begins with a slash('/') character, or a relative URI, that doesn't specify a scheme.

Some examples are :


    URL stands for Uniform Resource Locator . A URL is the traditional name for a network address consisting of a scheme (like "http") and an address (site name) and resource or path name.A URL includes a host name, scheme, and other components. The URL string is parsed according to rules for its scheme. The scheme can be "http","https","ftp". When you construct a URL, an Input Stream is created automatically. Every URL is a URI, but not every URI is URL. examples are


    URN stands for Uniform Resource Name. URN is subcategory of URI. URNs name resources but don't explain how to locate them, typical examples of URNs, you have seen include