I would be satisfied when a returned 404 error code will be handled within a reasonable (configurable) time delay. As for redirection, there I would not mind if it is not included.
Restrictions like that are not a problem for me, because this is for building a pdf that accesses many internet located files. The check on existence is therefore especially meant for spotting missing or misnamed files.

Hans van der Meer

On 16 May 2018, at 12:41, Henri Menke <henrimenke@gmail.com> wrote:

On 05/16/2018 09:31 PM, Hans van der Meer wrote:
I tried to determine the existence of a file on the internet. See the
following macro call:

        % Test if file exists.
        \edef\theurl{\linkprotocol://\urlbase\xmlatt{#1}{link}\thesuffix}
        \doiffileelse
        {\theurl}
        {\verbose{HVDM-PEV-TEST}{file exists: \theurl}}
        {\verbose{HVDM-PEV-TEST}{file does not exist: \theurl}}

It seems that \doiffileelse always results in true except for local
files where nonexistence is correctly handled.

For example the following url definitely does not exist but nevertheless
\doiffileelse reports its existence:
HVDM-PEV-TEST   > file exists:
http://hansvandermeer.myqnapcloud.com/archive/denhaag/hga-dtb-1869-6040.pdf

Is it possible that the \doiffile macros are extended for files on the
internet or a correponding set \doifurl is developed?

I'm not speaking for the devs here, but I don't think that this is going
to be included.  It would require that all webpages send proper 404
codes and timeout after reasonable delay.  Also how would you handle
redirects?  Should the ConTeXt run be stalled because checking for a
files existence on the web is caught in a redirect loop?


Hans van der Meer



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