From: Robert Klemme <shortcutter@...>
Date: 2008-08-01T18:49:11+09:00
Subject: Re: libxml: is it possible not to use doctype declaration?

2008/7/30 Phill Davies <binary011010@verizon.net>:
> ruud grosmann wrote:
>>
>> hi Phill,
>>
>> I've tried it right away. I ended up with the following:
>>
>> XML::Parser.default_load_external_dtd = false
>> XML::Parser.default_validity_checking = false
>> XML::Parser.default_substitute_entities = false
>>
>>        parser = XML::Parser.file( file)
>>        #parser.default_substitute_entities = false
>>        #parser.default_load_external_dtd = false
>>        #parser.default_validity_checking = false
>>        doc = parser.parse
>>        node = doc.find( xpath).first
>>
>> But the script still tries to resolve the entity. The doctype
>> definition is a slightly changed real one. The message I get with the
>> above code is:
>>
>> Operation in progress./tmp/ut21.uit:3: I/O warning : failed to load
>> external entity "http://ruud.grosmann.nl/op/dtd/publicatie.dtd"
>> e publicaties 1.0//NL" "http://ruud.grosmann.nl/op/dtd/publicatie.dtd"
>>
>> You were right that the methods are not instance methods, although I
>> am not sure how to conclude that from the documentation.
>>
>> Did I something wrong in the script?
>>
>> regards, Ruud
>>
>> On 30/07/2008, Phill Davies <binary011010@verizon.net> wrote:
>>
>>>
>>> Whoops, those were supposed to be class variables. What you really want
>>> to do (I think) is more like:
>>>
>>> LibXML::XML::Parser.default_load_external_dtd = false
>>> LibXML::XML::Parser.default_validity_checking = false
>>>
>>> And then:
>>> parser = LibXML::XML::Parser.file(<file>)
>>> doc = parser.parse
>>>
>>> That seems to work with your example.
>>>
>>> Phill Davies wrote:
>>>
>>>>
>>>> To start, the rdoc documentation can be found at
>>>> http://libxml.rubyforge.org/rdoc/index.html. Now I don't know this for
>>>> sure, but
>>>>
>>>> <!DOCTYPE test PUBLIC "-//FARAWAY//DTD-verweg//NL"
>>>> "http://some.site.nl/dtd/test.dtd">
>>>>
>>>> doesn't look like a real doctype definition, so if you can pull it out
>>>> of your xml (by hand, not programmatically) before trying to parse it,
>>>> I'd say that would be a good idea. That being said, there are two
>>>> attributes of the XML::Parser class that look like they may be of
>>>> interest: default_load_external_dtd and default_validity_checking. Try
>>>> setting both of those to false, unless you have a real dtd to validate
>>>> against and the example above was fake. Of course, since this is using
>>>> XML::Parser instead of XML::Document I think you would need to do
>>>> e.g.: parser = XML::Parser.file(<file>)
>>>> parser.default_load_external_dtd = false
>>>> parser.default_validity_checking = false
>>>> doc = parser.parse
>>>>
>>>> ... and then go from there.
>>>> Phill D.
>>>>
>>>> Phlip wrote:
>>>>
>>>>>
>>>>> ruud grosmann wrote:
>>>>>
>>>>>
>>>>>>
>>>>>> Is using libxml the right thing to do to, or are there smarter
>>>>>> alternatives?
>>>>>>
>>>>>
>>>>> Libxml-ruby is the most complete & accurate parser of the big three
>>>>> (REXML, Libxml-ruby, and Hpricot), and its documentation can be very
>>>>> challenging. How much of the original C Libxml documentation have you
>>>>> been able to read?
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
> Hey Ruud,
>   Nope, I can't see that you're doing anything wrong. I guess all I can say
> is if can send the actual XML so I can give it a try with it (because when I
> use your original example it seems to work fine as long as I set those class
> variables). Also, the error message you sent was broken up, if you could
> please try to send that again it would probably help. Here's what I'm using:
> <?xml version="1.0" encoding="utf-8"?>
> <!DOCTYPE test PUBLIC "-//FARAWAY//DTD-verweg//NL"
> "http://some.site.nl/dtd/test.dtd">
> <test>
> <p>this is a test</p>
> </test>
>
> And here's the error I get when I don't set those class variables:
>
> test.xml:2:
> I/O
> warning :
> failed to load HTTP resource
> TYPE test PUBLIC "-//FARAWAY//DTD-verweg//NL"
> "http://some.site.nl/dtd/test.dtd"

Hm, Java XML parsers I know have a special callback that you can set
that will deal with resolving external entities.  I could not find
anything similar in libxml documentation but maybe I just looked in
the wrong places.  With that you could load the file just once (or
even fetch it from some internal memory or file system).  Also, I find
it a bit strange that those flags are global - this can introduce
weird bugs when using an application which parses XML concurrently and
needs different flags for each process...

Kind regards

robert

-- 
use.inject do |as, often| as.you_can - without end