SWI-Prolog -- http:open

Documentation
- Reference manual
- Packages
  - SWI-Prolog HTTP support
    - The HTTP client libraries
      - library(http/http_open): HTTP client library
        
        http_open/3
        
        map_method/2
        
        disable_encoding_filter/1
        
        http_set_authorization/2
        
        open_hook/6
        
        keep_alive/4
        
        http_close_keep_alive/1
        
        open_options/2
        
        write_cookies/3
        
        update_cookies/3

[nondet,multifile]http:open_options(+Parts, -Options)

This hook is used by the HTTP client library to define default options based on the the broken-down request-URL. The following example redirects all trafic, except for localhost over a proxy:

:- multifile
    http:open_options/2.

http:open_options(Parts, Options) :-
    option(host(Host), Parts),
    Host \== localhost,
    Options = [proxy('proxy.local', 3128)].

This hook may return multiple solutions. The returned options are combined using merge_options/3 where earlier solutions overrule later solutions.