pan>:schedule_workers(+Dict)

Called if there is no immediately free worker to handle the incomming request. The request is forwarded to the thread __http_scheduler as the hook is called in time critical code.

3.10 Custom Error Pages

It is possible to create arbitrary error pages for responses generated when a http_reply term is thrown. Currently this is only supported for status 403 (authentication required). To do this, instead of throwing http_reply(authorise(Term)) throw http_reply(authorise(Term), [], Key), where Key is an arbitrary term relating to the page you want to generate. You must then also define a clause of the multifile predicate http:status_page_hook/3:

http:status_page_hook(+TermOrCode, +Context, -CustomHTML)

TermOrCode is either the first argument of the http_reply exception or the HTTP status code, i.e., the hook is called twice. New code should using the Term. Context is the third argument of the http_reply exception which was thrown, and CustomHTML is a list of HTML tokens. A page equivalent to the default page for 401 is generated by the example below.

:- multifile http:status_page_hook/3.

http:status_page_hook(authorise(Term), _Context, HTML) :-
    phrase(page([ title('401 Authorization Required')
                ],
                [ h1('Authorization Required'),
                  p(['This server could not verify that you ',
                     'are authorized to access the document ',
                     'requested.  Either you supplied the wrong ',