Fster is a virtual file system based on FUSE technology that allows users to access files according to associated metadata. It utilizes an XML configuration to define a hierarchy of files and folders, enabling dynamic organization and querying of media and other content. The system is designed to facilitate future developments such as a user-friendly editing interface and a plugin architecture for standard file formats.

1. FSter
Guglielmo’s Hyper File System
Lorenzo Bellini, Roberto Guido,
Marco Loregian, Michele Tameni
<name.surname>@itsme.it

2. What is FSter?
➔FSter is a virtual file system implementation, based
on Fuse technology and exploiting Tracker
metadata technology to allow access to files
according to the metadata they’re associated to
Itsme – Fster: Guglielmo's Hyper File System 2

3. Sample scenarios
➔Browsing the content of a drive, according to a user-
defined hierarchy based on metadata;
➔Associating metadata to files whenever operations are
performed on them;
➔Generating “virtual” files from metadata, e.g., a vCard
file dynamically built from metadata
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4. Requirements and
domain architecture
FSter uses libtracker-client to build
and execute sparql query on
tracker-store
Queries are built according to a
user-defined (XML) filesystem
hierarchy
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5. Configuration file
➔A configuration file defines what the user will see in
FSter directories
➔Configuration files must follow XML 1.0 standards
➔An XML schema of the configuration file is avalaible (Fster.xsd)
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6. Xml element: folder
➔Shows each RDF subject matching with defined
conditions as a folder and:
➔defines both inheritable and self conditions
➔Allows generating a folder name from metadata
➔allows nesting content object inside it
➔defines editing policies for the content
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7. Xml element: set_folder
➔Shows each RDF object used with a specific RDF
predicate as a folder and:
➔defines a RDF predicate to get the set of RDF objects used with it
➔defines inheritable conditions
➔allows nesting content objects inside it
➔defines the editing policies of the content
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8. Xml element: file
➔Shows each RDF subject matching with defined
conditions as a file and:
➔defines self conditions
➔Allows generating a file name from metadata
➔defines whether to expose the real file or a dump of file
metadata from the repository
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9. Examples: Fster media library (1)
➔Media grouped by images, audio and video
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10. Examples: Fster media library (2)
➔Building the SPARQL query for folder element
static GList* collect_children_from_storage (HierarchyNode *node, ItemHandler *parent)
{
(..)
more_statements = condition_policy_to_sparql (&(node->priv->self_policy), parent,
&values_offset);
statements = g_list_concat (statements, more_statements);
if (node->priv->child_policy.inherit == TRUE) {
parent_node = node->priv->node;
while (parent_node != NULL) {
more_statements = condition_policy_to_sparql (&(parent_node->priv-
>child_policy), parent, &values_offset);
statements = g_list_concat (statements, more_statements);
if (parent_node->priv->child_policy.inherit == TRUE)
parent_node = parent_node->priv->node;
else
break;
}
}
sparql = build_sparql_query (NULL, var, statements);
(..)
}
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11. Examples: Fster media library (3)
➔ <condition metadata="rdf:type" value="nfo:Audio" />
<name value="$self{nie:title}" />
SELECT ?item ?a WHERE { ?item nie:title ?a . ?item rdf:type
nfo:Audio }
➔ <condition metadata="rdf:type" value="nfo:Image" />
<name value="$self{nfo:fileName}" />
SELECT ?item ?a WHERE { ?item nfo:fileName ?a . ?item rdf:type
nfo:Image }
➔ <condition metadata="rdf:type" value="nfo:Video" />
<name value="$self{nfo:fileName}" />
SELECT ?item ?a WHERE { ?item nfo:fileName ?a . ?item rdf:type
nfo:Video }
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12. Examples: Fster music library (1)
➔Music grouped by artist, album or genre
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13. Examples: Fster music library (2)
➔Building the SPARQL query for folder_set element
static GList* collect_children_set (HierarchyNode *node, ItemHandler *parent)
{
(..)
statements = g_list_append (statements, g_strdup_printf ("?item %s ?a", node->priv-
>additional_option));
more_statements = condition_policy_to_sparql (&(node->priv->self_policy), parent,
&values_offset);
statements = g_list_concat (statements, more_statements);
if (node->priv->child_policy.inherit == TRUE) {
parent_node = node->priv->node;
while (parent_node != NULL) {
more_statements = condition_policy_to_sparql (&(parent_node->priv-
>child_policy), parent, &values_offset);
statements = g_list_concat (statements, more_statements);
if (parent_node->priv->child_policy.inherit == TRUE)
parent_node = parent_node->priv->node;
else
break;
}
}
sparql = build_sparql_query ("SELECT DISTINCT(?a)", 'a', statements);
(..)
}
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14. Examples: Fster music library (3)
➔ <folder>
<condition metadata="rdf:type" value=" nmm:MusicAlbum" />
SELECT ?item ?a WHERE { ?item nmm:albumTitle ?a . ?item
rdf:type nmm:MusicAlbum }
➔ <condition metadata="nmm:musicAlbum" value="$parent{/subject}" />
SELECT ?item ?a WHERE { ?item nie:title ?a . ?item
nmm:musicAlbum "urn:album:Ci%20Vuole%20Orecchio" }
➔ <set_folder metadata="nfo:genre">
SELECT DISTINCT(?a) WHERE { ?item nfo:genre ?a }
➔ <condition metadata="nfo:genre" value="$parent{nfo:genre}" />
SELECT ?item ?a WHERE { ?item nie:title ?a . ?item nfo:genre
"Folk" }
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15. Examples: Fster music library (4)
Itsme – Fster: Guglielmo's Hyper File System 15

16. Future development
➔SparQL in the <condition> tag
➔Plugin architecture allowing FSter to render
metadata exposing them in standard format
files (e.g., vcard, ...);
➔User-friendly configuration editing
interface
➔Creation of folders
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17. References
➔Code: http://gitorious.org/itsme/fster
➔Wiki: http://gitorious.org/itsme/pages/Fster
➔Mailing lists: http://lists.itsme.it/
➔Support: #itsme-dev on irc.freenode.net
Itsme – Fster: Guglielmo's Hyper File System 17

18. Thank you for your attention
www.itsme.it
Lorenzo Bellini, Roberto Guido,
Marco Loregian, Michele Tameni
<name.surname>@itsme.it