Network Working Group R. Fielding Request for Comments: 2616 ...

with a scheme name followed by a colon. For definitive information onURL syntax and semantics, see "Uniform Resource Identifiers (URI):Generic Syntax and Semantics," RFC 2396 [42] (which replaces RFCs1738 [4] and RFC 1808 [11]). This specification adopts thedefinitions of "URI-reference", "absoluteURI", "relativeURI", "port","host","abs_path", "rel_path", and "authority" from thatspecification.The HTTP protocol does not place any a priori limit on the length ofa URI. Servers MUST be able to handle the URI of any resource theyserve, and SHOULD be able to handle URIs of unbounded length if theyprovide GET-based forms that could generate such URIs. A serverSHOULD return 414 (Request-URI Too Long) status if a URI is longerthan the server can handle (see section 10.4.15).Note: Servers ought to be cautious about depending on URI lengthsabove 255 bytes, because some older client or proxyimplementations might not properly support these lengths.3.2.2 http URLThe "http" scheme is used to locate network resources via the HTTPprotocol. This section defines the scheme-specific syntax andsemantics for http URLs.http_URL = "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]]If the port is empty or not given, port 80 is assumed. The semanticsare that the identified resource is located at the server listeningfor TCP connections on that port of that host, and the Request-URIfor the resource is abs_path (section 5.1.2). The use of IP addressesin URLs SHOULD be avoided whenever possible (see RFC 1900 [24]). Ifthe abs_path is not present in the URL, it MUST be given as "/" whenused as a Request-URI for a resource (section 5.1.2). If a proxyreceives a host name which is not a fully qualified domain name, itMAY add its domain to the host name it received. If a proxy receivesa fully qualified domain name, the proxy MUST NOT change the hostname.Fielding, et al. Standards Track [Page 19]RFC 2616 HTTP/1.1 June 1999