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Accessing WWW/Internet documents from LP/CLP

• The HTTP, FTP, etc. protocols are ASCII protocols which can be added relatively easily to any system (provided it has a socket interface or equivalent).
• Applications: search tools, content analyzers, reading html templates, etc. Also access to remote modules via WWW:
  :- use_module('http://www.xx.y/prolog/p.pl')
• E.g., PiLLoW protocol support:
  • fetch_url((URL), Request,Response) -
  • Some (Request) options:
    • head: only interested in the header.
    • timeout(Time): specifies number of seconds for timeout (fails).
    • if_modified_since(Date)
    • authorization(Scheme,Param)
  • Some possible elements of (Response):
    • content((Content)): document as a list of characters.
    • status((Type),(Code),(Phrase)).
    • last_modified((Date)).
    • expires((Date)).
    • location((URL)) (document has moved).
  • url_info((URL), Info): parses a URL.
• Example:
  ?:- url_info('http://www.xx/foo.html',UI), fetch_url(UI,[],R),
  member(content(C),R), html2terms(R,Terms).