Re: [PATCH] add FAQ section about "bad request" errors

Hello Stefan,

On Mon, May 23, 2016 at 8:34 PM, Stefan <luke1410_at_posteo.de> wrote:
> Hi Pavel,
>
> Thanks for the feedback.
> Can't say I disagree with your statement that emphasizing on one
> possible cause (and especially most likely not the most common one) for
> a 400-error is not the best way to go.
>
> But as far as I'm concerned this is not how the section is phrased. The
> first paragraph especially points to the server log as the first thing
> to check to trace down the actual problem. The following section then
> points to two known cases which can trigger the problem. I'd certainly
> support extending the list with any further known case, and IMO the list
> you provide is an absolutely reasonable extension to that list.

While I don't like the idea of adding an entry about this error to the
FAQ, I can think of this general advise for the users getting 400
'Bad request' errors:
The very first recommendation has to be to contact the system
administrator and trying the latest Subversion client. :) Further
recommendations should be to take a look at the logs and to check the
firewall, proxy and antivirus. Search the users@ mailing list or use
the web search. If nothing helped, search the bug tracker.

But in such case this is is not a Question - Answer FAQ format
anymore.

> Hence, if that's the main concern here, I'd certainly add the three
> mentioned causes to that section then.
>
> To me the FAQ section seems to be the most reasonable place to add these
> kind of known issues. IMO it's the location where someone who runs into
> the problem is likely to look for a solution (if he bothers searching
> for a solution at all, that is). Or would you suggest to put the
> information in some other place?

Merriam-Webster dictionary defines FAQ as
[[[
a document (as on a Web site) that provides answers to a list of
typical questions that users might ask regarding a particular subject
<check the FAQ>;
]]]

FAQ should contain answers to *typical questions* and here are some of
the good questions that are answered on SVN FAQ page:
* I've started svnserve, but it doesn't seem to be listening on port
  3690.
  https://subversion.apache.org/faq.html#svnserve-listen-host
* I cannot see the log entry for the file I just committed. Why?
  https://subversion.apache.org/faq.html#hidden-log
* Why does SVN log say "(no author)" for files committed or imported
  via Apache (ra_dav)?
  https://subversion.apache.org/faq.html#no-author
* How can I specify a Windows drive letter in a file: URL?
  https://subversion.apache.org/faq.html#windows-drive-letter
* How does Subversion handle binary files?
  https://subversion.apache.org/faq.html#binary-files

All of these questions are typical IMO; and there is a clear question
and it has a more or less clear answer. It's great to have these
questions answered on the FAQ.

But what about the entry about this 400 'Bad request' error? It does
not seem to be typical or frequent enough and it has too many possible
answers to provide a clear answer on how to solve the problem. You can
provide some basic guidance on how to narrow down the issue,
troubleshoot and identify the root cause. The steps for this are
pretty the same as for troubleshooting any other network related
problems.

> Regarding the concern about tweaking the LimitRequestFieldSize. I could
> certainly rephrase that section to emphasize that tweaking that value
> should be done with care considering the security impact. But given that
> you can run into an issue with the default limit here using SVN and it
> seems that at least for the 1.9 branch there is not going to be a final
> solution to completely prevent running into this situation, I really
> think this should be mentioned/written down somewhere so its on record
> and can be referenced for user support requests.

Aren't you putting the cart before the horse? Can we call these
SVN-4557 & SVN-4634 problems typical or frequent? I don't see that
many reports of these problems. Moreover, SVN-4557 is now solved and
I don't see any recommendation in SVN-4634 that the solution would be
to advise any config customizations.

> Regarding the layout: Right. Will correct the layout in the next version
> of the patch (assuming the usage of the line breaks rather than using
> proper paragraph sections is the concern here).
>
> What do you think? Would rephrasing/extending the section solve the
> concerns you have?

I think that the the entry about 400 'Bad request' errors should not
be on the FAQ. This is not a question that can be answered in clear
manner. The topic is much broader and does not fit FAQ format.

There may be other great places to publish troubleshooting guidance
about this error in general, but the official Subversion FAQ is not
one of them, IMO.

This is a great idea to provide provide basic troubleshooting advise
and tell about the cases when these problems can occur. But, again,
I don't think that the official Subversion FAQ is the right place for
this.

--
With best regards,
Pavel Lyalyakin
VisualSVN Team