Re: silent semantic changes in reiser4 (brief attempt to document the idea of what reiser4 wants to do with metafiles and why

["Dr. Giovanni A. Orlando" <gorlando@futuretg.com>]

Hans Reiser wrote:

> Alexander G. M. Smith wrote:
>
>> Hans Reiser wrote on Mon, 30 Aug 2004 23:43:13 -0700:
>>  
>>
>>> Alexander G. M. Smith wrote:
>>>   
>>>
>>>> Are you sneaking in file types there?  Just how does a file know which
>>>> plugins it supports?
>>>>     
>>>
>>> we have plugins with pluginids, is that what you mean by file type? 
>>> I think they are a bit different from file types.
>>>   
>>
>>
>>> From your white-paper: "Every file possesses a plugin id, and every
>>
>> directory possesses a plugin id.  This plugin id will identify a set
>> of methods."
>>
>> Functionally this is very close to a file type.
>>
> A file type is based on semantics of the contents, and a plugin id is 
> based on methods of the object.


Today I read this info on an article published by an excellent magazine, 
that will appears on October (we are Future Technologies :-) , you know)

Hans, like I comment to you time ago, we plan to implement the un-delete 
for ReiserFS 4, like an external plug-in in 2005.

Thanks,
Giovanni

>

>
>>  It classifies the
>> files into related groups, maybe not as finely as a MIME file type
>> which can distinguish between multiple varieties of text files.
>>
>> A file type would tell us that a file is a text file and can be opened
>> by certain applications (text/e-mail can be opened by e-mail reader,
>> text editor, etc) and have other properties (lists of standard
>> attributes, default icon).  A plugin ID says that the file can use text
>> related plugins (like a word count, or XML structure as a subdirectory).
>>
>> In both cases there is a global repository (I assume) that associates
>> the file type or plugin ID with a list of things about it.
>>
>> You could combine the two concepts, just have a file type ID that in the
>> global repository specifies what plugins it can use as well as the
>> userland properties (MIME string, etc) of that kind of file.  Or at 
>> least
>> make the type ID available to userland so it can be used there.
>>
>> Or is this binding irrelevant?  How often does the file type the user
>> sees not match the plugins desired for the file?  Or can a new subtype
>> be defined for just that file?  Which may mean that we need something
>> better than MIME strings for types (something which has inheritance).
>>
>> - Alex
>>
>>
>>  
>>
> I think that there may be some good use for a filename/metas/type 
> metafile.
>


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