Reorganizing examples of relative references resolution in A.3 of OPC

Sat Jun 14 03:32:56 CEST 2014

The space character is treated very similarly to "[".  That
is, CreatePartUri escapes the space character.  But
Create reports an error when verbatim space appears,
and converts escaped space back to verbatim space.

Regards,
Makoto

2014-06-14 10:27 GMT+09:00 MURATA Makoto <eb2m-mrt at asahi-net.or.jp>:

> Dear colleagues,
>
> I am still wondering if the itemized list in A.3 of OPC
> is needed.  How is the itemized list implemented in
> src\Base\System\IO\Packaging\PackUriHelper.cs ?
>
> First, given a string x,
>
>   PackUriHelper.CreatePartUri(new Uri(x, UriKind.Relative))
>
> performs Steps 1, 2, 3, 4, 5, 6 and 9 but does not support
> Steps 7 or 8.  In particular, percent encoded backslashes
> are converted to verbatim slashes by Steps 4 and 5.
> Multiple consecutive forward slashes (the target of Step
> 7) does not cause an error, but a trailing forward slash
> (the target of Step 8) causes an argument error.
>
> Second,
>
>   PackUriHelper.Create(baseUri,new Uri(x, UriKind.Relative))
>
> reports an error when x contains what is touched by Steps
> 1, 2, 3, 4, 5, 6, 8, and 9, where baseUri is a valid URI
> of the http scheme.  Meanwhile,
>
>   PackUriHelper.Create(baseUri,part)
>
> exhibits interesting results, where part is the output of
> the CreatePartUri method (the first code snipet).  Step 1
> done by CreatePartUri is *undone* by the Create method.
> That is, %5B and %5D are converted back to "[" and "]".
>
> Here are my opinions.
>
> - Is the behaviour of "[" and "]" (escaping by
>   CreatePartUri and unescaping by Create) intentional?
>
> - One could argue that the support of Steps 1, 2, 3, 4, 5,
>   6 and 9 in CreatePartUri is merely for recovering from
>   errors and that these steps are NOT for handling correct
>   part names.  This is because PackUriHelper.Create
>   cannot handle part names containing "errors" such as
>   backslashes.
>
> Regards,
> Makoto
>
>
> 2014-06-09 11:52 GMT+09:00 MURATA Makoto <eb2m-mrt at asahi-net.or.jp>:
>
> I made two mistakes.
>>
>> First, web requests based the pack scheme are supported.
>> But this support is done by
>>
>>   System.IO.Packaging.PackWebRequest
>>
>> rather than
>>
>>   System.Net.WebRequest
>>
>> Second, PackUriHelper can generate URIs of the pack
>> scheme.  For example,
>>
>>   let baseUri = new Uri("http://www.example.com", UriKind.Absolute)
>>   let part = new Uri ("/foo", UriKind.Relative)
>>   let packUri = PackUriHelper.Create(baseUri, part)
>>
>>   System.Console.WriteLine("generated uri: {0}", packUri);;
>>
>> returns
>>
>>   generated uri: pack://http:,,www.example.com,/foo
>>
>> Regards,
>> Makoto
>>
>>
>>
>> Second,
>>
>>
>> 2014-06-08 15:35 GMT+09:00 MURATA Makoto <eb2m-mrt at asahi-net.or.jp>:
>>
>> Folks,
>>>
>>> I did some more experiments.  My conclusion is
>>> that .Net (with the possible exception of Web
>>> Presentation Foundation) does not support the
>>> pack scheme.
>>>
>>> I thought that System.Uri of .Net can handle
>>> the pack scheme.  But my experiment suggest
>>> otherwise.  For example,
>>>
>>>  new Uri(@"pack://http%3a,,www.site.com,windows,p1.xps/",
>>> UriKind.Absolute)
>>>
>>> raises a UriFormatException.  I tried all examples shown
>>> in 29500-2, but none of them parsed correctly.
>>>
>>> I also tried
>>>
>>>   WebRequest.Create (@"pack://http%3a,,www.site.com,windows,p1.xps/");;
>>>
>>> But I got an UriFormatException, again.
>>>
>>> PackUriHelper supports the creation of part names,
>>> which begin with "/".  But they do not appear to support
>>> the creation of park URIs.
>>>
>>> Regards,
>>> Makoto
>>>
>>>
>>>
>>> 2014-06-07 15:27 GMT+09:00 MURATA Makoto <eb2m-mrt at asahi-net.or.jp>:
>>>
>>> Folks
>>>>
>>>> I did an experiment using F# of Visual Studio 2010 and
>>>> .Net framework 4.
>>>>
>>>> For each bullet in the itemized list in A.3., I created an
>>>> example string.  Then, I executed
>>>>
>>>>   PackUriHelper.CreatePartUri(new Uri(x, UriKind.Relative))
>>>>
>>>> for each example string.  The source program and the
>>>> output is available at:
>>>>
>>>> https://www.assembla.com/spaces/IS29500/wiki/OPC_Annex_A3_Testing
>>>>
>>>>
>>>> It is not easy to interpret the result of this experiment.
>>>> One could argue that each input string is a part name.
>>>> One could also argue that each input string is merely
>>>> an erroneous input and that the resulting string is a
>>>> part name.  One could also argue that each string is
>>>> a Unicode string that can be converted to a part name.
>>>> We can discuss in Prague.
>>>>
>>>> Regards,
>>>> Makoto
>>>>
>>>>
>>>> 2014-06-05 15:27 GMT+09:00 MURATA Makoto <eb2m-mrt at asahi-net.or.jp>:
>>>>
>>>>
>>>>> Folks,
>>>>>
>>>>> I am not thiking about how examples (A.3) of resolution
>>>>> of relative references in Annex A should be improved.
>>>>>
>>>>> A.3 has caused a lot of confusions, since it does not distinguish two
>>>>> cases: relatvies references beginning with "/" and those not beginning
>>>>> with it.  The right approach is to clearly use resolution of relative
>>>>> references as specified in RFC 3986 and demonstrate examples.  In
>>>>> particular, we should show what the remove_dot_segments and merge
>>>>> procedures in RFC 3986 do as part of this resolution.
>>>>>
>>>>> A related problem is the absense of base URIs in A.3.  Obviously,
>>>>> base URIs play key reoles in the resolution of relative
>>>>> references.  Why are they not mentioned?  As a result, all examples
>>>>> in A.3 appear to begin with "/".  There are no examplses that
>>>>> do not begin with "/".
>>>>>
>>>>> I am trying to reogranize examples thoroughly now.  I will
>>>>> report back in a few days.
>>>>>
>>>>> Regards,
>>>>> Makoto
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> Praying for the victims of the Japan Tohoku earthquake
>>>>
>>>> Makoto
>>>>
>>>
>>>
>>>
>>> --
>>>
>>> Praying for the victims of the Japan Tohoku earthquake
>>>
>>> Makoto
>>>
>>
>>
>>
>> --
>>
>> Praying for the victims of the Japan Tohoku earthquake
>>
>> Makoto
>>
>
>
>
> --
>
> Praying for the victims of the Japan Tohoku earthquake
>
> Makoto
>

-- 

Praying for the victims of the Japan Tohoku earthquake

Makoto
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