metafs

[Nagy Zoltan <kirk@xxxxxxxx>]

Hello all,

sorry for the large posting - and for my intermediate english.

the past few months i tried to figure out a better way to organize data,
because in extereme conditions automatic/dynamic (re)organiziation would
be very good to have - i recently found this paper, which i found very 
similar
to this: http://bryanmills.net:8086/uploads/metafs/bmills-final.pdf

i imagined a two sided approach to came up with an acceptable solution
* object tagging:
   it is obvious that people can give very precise information to a given
   object, in this example i would take some papers
       [obj1]    -    filename:    'something1.pdf'
                   type = "paper"
                   filetype = "application/pdf"
                   title = {Title1},
                   author = {Author1},
                   year = {2005},
       [obj2]    -    filename:    'xasd1.XXXpdf'
                   type = "paper"
                   filetype = "pdf"
                   title = {Title2},
                   author = {Author2},
                   year = {2005}
       [obj3]    -    filename:    'qqq.pdf'
                   type = "paper"
                   filetype = "pdf"
                   title = {Title3},
                   author = {Author3},
                   /** year = {2005} no set **/
       [obj4]    -    filename:    'asd.png'
                   type = "image/png"
                   filetype = "png"
                   title = {Title2},
                   author = {Author2},
                   year = {2005}

   all this data is accessible thru extended attributes

* layout rules
   the user must give some guidance - about in what way he want's to see
   those files in this example i will choose the following rules:
       x_node0    =    _root_
       x_node1    =    {parent:x_node0}
                   {entry:"paper",
                       require:{type = "paper"},
                           unassigned:{collect,"unassigned"}
                                                       }
       x_node2    =    {parent:x_node1}    {entry:"by_year"}
       x_node3    =    {parent:x_node2}    {entry:#year,
                       type:collection,
                           unassigned:{collect,"year-not-set"}
       x_node4    =    {parent:x_node3}    {entry:#author|'_'|#title,
                       unassigned:{cascade}    }
   
   i hope that this understandable

the desired layout would be for those files:
   
   /
   /paper
   /paper/by_year
   /paper/by_year/2005
   /paper/by_year/2005/Author1_Title1.pdf    -->    [obj1]
   /paper/by_year/2005/Author2_Title2.pdf    -->    [obj2]
   /paper/by_year/year-not-set/qqq.pdf    -->    [obj3]
   /unassigned/asd.png                    -->    [obj4]

and if someone adds some new rules
       x_node5    =    {parent:x_node2}    {entry:"by_author",
                       type:collection,
                           unassigned:{collect,"unknown-author"}
       x_node6    =    {parent:x_node5}    {entry:#title|'_'|#year    }
then the following nodes should appear
   /paper/by_author
   /paper/by_author/Author1/Title1_2003    --> [obj1]
   [...]

the biggest power of this, that it is possible for an object to show up
at many places dynamically.
i think that this can be implemented as an 'overlay' (userland)filesystem,
with some lightweight database help

i know that algorithm for this kind of dynamic layout comes at a
very high price - it is/and will be a problem, it will be a big challange
to minimize it's impact on the overall performance - but for now, i think
about a relativly 'slow' changing object set.

what's the biggest problem with this?
how could it be
   - more adaptive to user's needs
   - faster at runtime
   - i welcome tips for implementing it - the right way
   - ..or why should i forget it :)

cheers,
kirk

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