[R] Problem accessing help files

[S Ellison]

Might this be a firewall-like issue and nothing to do with html or R?

If I understand the 2.10 help system, it operates by starting R as an
http server - effectively a web server, operating on the local machine
(127.0.0.1) with an unusual IP port (which doesn;t seem to be consistent
from one run to the next, perhaps because it's taking a randomly or
first available port in the high range). 
That established R as the default server for http requests made to the
machine with the particular port specified, yes?


The 'obvious' OS-related thing that could break this is a firewall
restriction on access to http on ports other than 80 and 8080, the
typical default ports. That could arise either because of incoming or
outgoing IP port resrtrictions; the firewall could either stop an
application asking for an odd port, or could stop R serving it.

It's unusual for a firewall to prevent access to th elocal host
(127.0.0.1) but it might be worth checking.

It could be fixed (or at least checked) by looking at the firewall
settings to see whether there were any port-specific restrictions (eg
'only allow http on ports 80 and 8080'  or equivalent).

Another possibility is to check the browser and OS http proxy options;
if they are set to point to a proxy _every time including local access
requests_ you'll presumably have similar problems.

Incidentally, i haven;t yet broached the idea of R acting as an http
server every time it calls help with our IT security folk; I'm rather
afraid of the possible consequence.  Call me paranoid if you like ...
but the depth of explanation they might require could be daunting.

Steve Ellison

>>> Duncan Murdoch <murdoch at stats.uwo.ca> 04/02/2010 00:45:21 >>>
On 03/02/2010 7:17 PM, Jonathan wrote:
> Duncan:
>    I suspect that you're right about the file association having been
the
> issue.  .html files were not associated with either browser. 
However, I
> fixed that by associating .html files with Firefox, but R still gave
me the
> same error!  If that was the problem, R didn't realize the
association had
> been changed.
> 
> I tried uninstalling R and reinstalling R, thinking maybe it takes a
> snapshot of associations once (at install), and keeps its own
internal table
> (even though that didn't sound all that intuitive).  No luck; R
still
> persisted in being unable to open help files.

R knows nothing about the associations.  They are handled by the
Windows 
shell functions.

And it's not .html files; Windows recognizes that the URL is a URL, and

sends it to whichever browser has registered itself to handle them.

So you might fix things by deleting and re-installing Firefox, telling

it to install itself as the default browser.  (Or tell IE to reinstall

itself as the default, if you really want to do that.)

You can also set up a shortcut to a URL ("New shortcut" from the
context 
menu on the desktop) and give it the URL that R tried.  This isn't a 
solution at all, since the URL only works for the current R session 
unless you set it to a fixed one with options(help.ports=12345), but it

might give some more insight into what's wrong.

Duncan Murdoch

> 
> Then I rebooted my machine.  I'm still getting the same error.
> Any other ideas?
> 
> Thanks,
> Jon
> 
> On Wed, Feb 3, 2010 at 5:57 PM, Duncan Murdoch <murdoch at stats.uwo.ca>
wrote:
> 
>> On 03/02/2010 5:14 PM, Jonathan wrote:
>>
>>> Rich:
>>>    Both IE and Firefox are unable to find the link you supplied. 
However,
>>> that's only because I've restarted my R session since I pasted the
error
>>> output (and it appears that each time I restart R, the URL is
slightly
>>> different).  This time, I get:
>>>
>>> ?sum
>>> starting httpd help server ... done
>>> Error in shell.exec(url) :
>>>  access to 'http://127.0.0.1:31836/library/base/html/sum.html'
denied
>>>  ---
>>> If I paste the new URL into either browser, I can read the entry
without
>>> issue.  This is what I've been doing to read help entries, but
it's
>>> tedious
>>> to copy and paste the URL into a browser every time I want to read
the
>>> entry
>>> for a particular function..
>>>
>>> Happy to hear any other ideas!
>>>
>>>
>> What happens if you paste that into the "Run" box on the start menu?
 It
>> looks to me as though the association between URLs and your browser
is
>> broken.
>>
>> Another likely problem is antivirus software.  If you can
temporarily turn
>> it off, see if that helps.
>>
>> Duncan Murdoch
>>
>

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