TagFS — Tag Semantics for Hierarchical File Systems Bonus Track: Introducing SemFS 2006 2006 Web3.0 2006 Stephan Bloehdorn Institute AIFB, University of Karlsruhe, Germany Olaf Görlitz ISWeb, University of Koblenz-Landau, Germany Simon Schenk ISWeb, University of Koblenz-Landau, Germany Max Völkel Forschungszentrum Informatik, Karlsruhe, Germany talk Max Völkel Forschungszentrum Informatik, Karlsruhe, Germany

Motivation „ Every user [...] indicated that their attempts to establish elaborate filing schemas for archived information failed because they proved to require more time and effort than the information was worth.“ Barreau and Nardi, 1995 Contributions Mapping file system semantics to tagging semantics Architecture for a semantic file system

„ Every user [...] indicated that their attempts to establish elaborate filing schemas for archived information failed because they proved to require more time and effort than the information was worth.“ Barreau and Nardi, 1995

Contributions

Mapping file system semantics to tagging semantics

Architecture for a semantic file system

Hierarchical file systems have some problems Single locaction property E.g. where to put a song produced by two artists? Each file may be only in one folder There are links/shortcuts, but where to put the „primary“ file? Browsing to maximum specifity E.g. 5 clicks for /My Music/Fatboy Slim/2006/danceable/favourite even if there are only 5 Fatboy Slim songs altogether The more you organise, the more you have to browse Missing orthogonality E.g. /2003/Fatboy Slim/favourite or /favourite/Fatboy Slim/2003 ? Many dimensions, only one access path No query refinement FS lists only directories explicitly placed there, no help

Single locaction property

E.g. where to put a song produced by two artists?

Each file may be only in one folder

There are links/shortcuts, but where to put the „primary“ file?

Browsing to maximum specifity

E.g. 5 clicks for /My Music/Fatboy Slim/2006/danceable/favourite even if there are only 5 Fatboy Slim songs altogether

The more you organise, the more you have to browse

Missing orthogonality

E.g. /2003/Fatboy Slim/favourite or /favourite/Fatboy Slim/2003 ?

Many dimensions, only one access path

No query refinement

FS lists only directories explicitly placed there, no help

Tagging Simple idea: Instead of putting resources in folders (nested containers), put tags (labels) on resources Tagging user interfaces User sees a resource, can type in tags (simple, single keywords, separated by space or comma) User can click on a tag, UI lists all resources with that tag assigned Conjunctive queries: e.g. fatboyslim+favourite Examples: del.icou.us, flickr, 100 more Who has used a tagging system? new Web2.0

Simple idea:

Instead of putting resources in folders (nested containers), put tags (labels) on resources

Tagging user interfaces

User sees a resource, can type in tags (simple, single keywords, separated by space or comma)

User can click on a tag, UI lists all resources with that tag assigned

Conjunctive queries: e.g. fatboyslim+favourite

Examples: del.icou.us, flickr, 100 more

Who has used a tagging system?

Example: del.icio.us Tagging Browsing Queries

Comparison File system: partition of the adress space Tagging: overlapping sets a b a+b+c a+c b+c a+b c a b c /a /a/b /a/c /a /a/b /a/b/c /a/c /a/c/b /c /c/b /c/b/a /c/a /c/a/b /b /b/a /b/a/c /b/c /b/c/a

File system: partition of the adress space

Tagging: overlapping sets

Mapping file system semantics to tagging semantics Query and Browse – the easy parts Query Use path as query, e.g. /a/b/c = query for a + b + c Browsing / a Contained files: all resources tagged with a (  if not to many) Contained folders: All tags b , for which the conjunctive query a+b is not empty Any tag is a good starting point! Note: Virtual directory views are computed at runtime

Query

Use path as query, e.g. /a/b/c = query for a + b + c

Browsing / a

Contained files: all resources tagged with a (  if not to many)

Contained folders: All tags b , for which the conjunctive query a+b is not empty

Any tag is a good starting point!

Note: Virtual directory views are computed at runtime

Mapping file system semantics to tagging semantics Tagging – the hard part Changing existing tagging Copy file from a to b = tag file with b also Move file from a to b = remove tag a , add tag b Delete file from a = remove tag a Rename a to b = for all files tagged with a : remove a , add b Add files to TagFS Add file to folder a = add file to TagFS; tag file with a  File identity determined by hash or filename  Allows updating a file, if content is changed externally Delete files from TagFS  Move file to deleteMe = delete file Create tag a = create folder a  This folder would not be shown, because it‘s empty

Changing existing tagging

Copy file from a to b = tag file with b also

Move file from a to b = remove tag a , add tag b

Delete file from a = remove tag a

Rename a to b = for all files tagged with a : remove a , add b

Add files to TagFS

Add file to folder a = add file to TagFS; tag file with a

 File identity determined by hash or filename  Allows updating a file, if content is changed externally

Delete files from TagFS

 Move file to deleteMe = delete file

Create tag a = create folder a

 This folder would not be shown, because it‘s empty

Tagging in the file system Many locaction property Each file may carry as many tags as desired Browsing until result is small enough Each folder contains all files tagged with the folder name Orthogonality of information dimensions Path interpreted as a conjunctive query, e.g. Lisa Ekdahl/2006 is the same as 2006/Lisa Ekdahl Not all reviewers agreed on this  Query refinement Each folder lists useful query refinements as sub-folers Providing all standard filesystem operations  compatibility with existing applications

Many locaction property

Each file may carry as many tags as desired

Browsing until result is small enough

Each folder contains all files tagged with the folder name

Orthogonality of information dimensions

Path interpreted as a conjunctive query, e.g. Lisa Ekdahl/2006 is the same as 2006/Lisa Ekdahl

Not all reviewers agreed on this 

Query refinement

Each folder lists useful query refinements as sub-folers

Providing all standard filesystem operations

 compatibility with existing applications

Introducing SemFS Implementing TagFS with SemFS Web2.0 Web3.0 Semantic Desktop RDF keywords Bonus Track

Implementing TagFS with SemFS

What is a file system?

What is a file system? Organising files … An address given as path expression := Letter “ : “ ( “ “ name)* File System dir! response files folders name metadata metadata

What is a file system? … managing binary data File System metadata data 1011 write 1011 read 1011

What is a file system? … managing binary data File System rename metadata data

What is a file system? … managing binary data File System Add file or delete file metadata data

What is a file system? Organising files and managing binary data View( path )  Metadata-Table Contained files, Contained directories, Metadata: getName, getDate, … Binary content irrelevant Update Metadata: setName, setDate, add file, delete file, move file Binary+Metadata: read file, write file, trunc file

View( path )  Metadata-Table

Contained files,

Contained directories,

Metadata: getName, getDate, …

Binary content irrelevant

Update

Metadata: setName, setDate, add file, delete file, move file

Binary+Metadata: read file, write file, trunc file

What is a virtual file system? Organising files and managing binary data op Virtual File System Looks and behaves like a file system… … but is no file system. It‘s implemen-ted differently. metadata data X Flickr CMS File System metadata data

What is a semantic file system? Organising files and managing binary data. op Semantic File System Flexible implementation. Unified metadata  unified search metadata data X Flickr CMS File System

Architecture of SemFS: Filters Input: Frontend gets path SemFS maintains a list of filters , Formal: Filter(graph, path)  (filtered graph, shorter path) Each filter is asked sequencially to process a path A filter consumes some parts of a path, and returns a filtered metadata graph Filter can delegate to a particular filter or delegate back to filter chain Output: Finally the filtered metadata graph is transformed to a directory view

Input: Frontend gets path

SemFS maintains a list of filters ,

Formal: Filter(graph, path)  (filtered graph, shorter path)

Each filter is asked sequencially to process a path

A filter consumes some parts of a path, and returns a filtered metadata graph

Filter can delegate to a particular filter or delegate back to filter chain

Output: Finally the filtered metadata graph is transformed to a directory view

Architecture of SemFS: Example for Filters Filter-List: [Favourite, Artist , Main] Main-Filter processes “My Music“ and returns filtered graph, containing all music-resources. Delegates to Artist-Filter. Artist-Filter processes “Fatboy Slim“ and returns all resource, that have e.g. the dc:creator „Fatboy Slim“. Delegates to filter chain. Favourites-Filter processes “favourite“ and returns all resources accesses more than n times in the last x days Main Artist Favourite My MusicFatboy Slimfavourite Fatboy Slimfavourite favourite

Filter-List: [Favourite, Artist , Main]

Main-Filter processes “My Music“ and returns filtered graph, containing all music-resources. Delegates to Artist-Filter.

Artist-Filter processes “Fatboy Slim“ and returns all resource, that have e.g. the dc:creator „Fatboy Slim“. Delegates to filter chain.

Favourites-Filter processes “favourite“ and returns all resources accesses more than n times in the last x days

Architecture of SemFS: Example for Filters Filter-List: [Favourite, Artist , Main] Main-Filter processes “My Music“ and returns filtered graph, containing all music-resources. Delegates to Artist-Filter. Artist-Filter processes “Fatboy Slim“ and returns all resource, that have the rdfs:label „Fatboy Slim“. Delegates to filter chain. Favourites-Filter processes “favourite“ and returns all resources accesses more than n times in the last x days Main Artist Favourite My MusicFatboy Slimfavourite Fatboy Slimfavourite favourite View( path )  Metadata-Table Contained files, Contained directories, Metadata: getName, getDate, …

Filter-List: [Favourite, Artist , Main]

Main-Filter processes “My Music“ and returns filtered graph, containing all music-resources. Delegates to Artist-Filter.

Artist-Filter processes “Fatboy Slim“ and returns all resource, that have the rdfs:label „Fatboy Slim“. Delegates to filter chain.

Favourites-Filter processes “favourite“ and returns all resources accesses more than n times in the last x days

View( path )  Metadata-Table

Contained files,

Contained directories,

Metadata: getName, getDate, …

Architecture of SemFS: Class-Handlers Different content-types have different meta-data and different ways to read/write E.g. local bookmarks, remote bookmarks, images, mp3 files, … Idea: access each class of content types via a Class-Handler Metadata: getName, getDate, … Can be cached in metadata graph Updates Metadata: setName, setDate, add file, delete file, move file Binary+Metadata: read file, write file, trunc file Other metadata operations, e.g. setGenre in ID3-tags

Different content-types have different meta-data and different ways to read/write

E.g. local bookmarks, remote bookmarks, images, mp3 files, …

Idea: access each class of content types via a Class-Handler

Metadata: getName, getDate, …

Can be cached in metadata graph

Updates

Metadata: setName, setDate, add file, delete file, move file

Binary+Metadata: read file, write file, trunc file

Other metadata operations, e.g. setGenre in ID3-tags

Architecture of SemFS: Summary: Metadata Graph, Filters, Class-Handlers Metadata graph (RDF) Holds all metadata acts as a unifying cache, when content has ist own metadata Filters Create the view, organise resources (not limited to files) Class Handlers Handle different content types and manages binary data

Metadata graph (RDF)

Holds all metadata

acts as a unifying cache, when content has ist own metadata

Filters

Create the view, organise resources (not limited to files)

Class Handlers

Handle different content types and manages binary data

Using SemFS: A tagging file system (TagFS) One Filter: Tag-Filter Consumes a single path segment a Contained files: Returns all resources tagged with a Contained folders: All tags b , for which the conjunctive query a+b is not empty One Class Handler Delegates classic metadata queries to underlying file store Binary content resides in a folder of a classic file system Tag-queries handled by metadata graph New problems  No two files may have the same name (when rendered) Rename at insertion or display time

One Filter: Tag-Filter

Consumes a single path segment a

Contained files: Returns all resources tagged with a

Contained folders: All tags b , for which the conjunctive query a+b is not empty

One Class Handler

Delegates classic metadata queries to underlying file store

Binary content resides in a folder of a classic file system

Tag-queries handled by metadata graph

New problems

 No two files may have the same name (when rendered)

Rename at insertion or display time

Conclusions TagFS Many locaction property Browsing only until result is small enough, no further Orthogonality of information dimensions Query refinement Compatible with existing applications SemFS An efficient way to implement virtual file systems with pluggable semantics Allows rapid and solid prototype creation Interoperability with Semantic Desktop applications Download Prototype at http://isweb.uni-koblenz.de/Research (Linux only, WebDAV/Windows in progress) Thank you. Questions?

TagFS

Many locaction property

Browsing only until result is small enough, no further

Orthogonality of information dimensions

Query refinement

Compatible with existing applications

SemFS

An efficient way to implement virtual file systems with pluggable semantics

Allows rapid and solid prototype creation

Interoperability with Semantic Desktop applications

BACKUP

Contact Information Max Völkel (author, presenter) Forschungszentrum Informatik, Karlsruhe, Germany http://www.fzi.de Stephan Bloehdorn (author) Institute AIFB, University of Karlsruhe, Germany http://aifb.uni-karlsruhe.de / Olaf Görlitz (author) and Simon Schenk (author) ISWeb, University of Koblenz-Landau, Germany http://isweb.uni-koblenz.de /

Max Völkel (author, presenter)

Forschungszentrum Informatik, Karlsruhe, Germany

http://www.fzi.de

Stephan Bloehdorn (author)

Institute AIFB, University of Karlsruhe, Germany

http://aifb.uni-karlsruhe.de /

Olaf Görlitz (author) and Simon Schenk (author)

ISWeb, University of Koblenz-Landau, Germany

http://isweb.uni-koblenz.de /

Architecture

Tagging Ontology