Libraries

RDF Parser - multiple RDF syntaxes
RDF Databases - triple stores
Algae - generalized RDF query

RDF Databases

RdfDB - in memory triple store
ObjectDB - persistent triple store over SQL
SqlDB - interface to SQL DB with arbitrary structure
FingerDB - cute toy to query over finger protocol

RdfDB

defined by an interface (API)
scratch space for graph manipulations
typed node with specific interfaces (for instance, String has an encoding)
elementary search capabilities
statementsMatching [p s o]
advanced search capabilities
processQuerySet (array of constraints)

ObjectDB

persistent SQL graph store
space efficient for scalability
each string and URL appears only once (atomic)
statements use external keys (integers) for (p s o)
some rewrite functionality (AKA rules)
implements statementsMatching for users of that interface
implements processQuerySet for optimized algae queries

Algae

generalized RDF statement queries

describes a graph with variables in some node positions

s-expression syntax

query ::	"(ask '(" contstraints+ ") :collect '(" variable+ "))"
contstraint ::	urlvar ' ' urlvar ' ' urlvarstr
urlvar ::	URL \| variable
urlvarstr ::	URL \| variable \| string
variable ::	'?' name
string ::	'"' text '"'

(ask '(

      (http://...#type ?annot http://...#Annotation)

      (http://...#Author ?annot "Joe")

      (http://...#Annotates ?annot ?doc)

    ):collect '(?doc))

inspired by algernon - principal difference:
- algae is not access-limited - algernon assumes triples are accessed by subject only

Algae Query Data Structure

algae parser produces a data structure to represent the graph query
all triples-store queries langauges represent a graph
other query formats can produce the same structure and leverage off the database query support

for example, there is support ILRT strawman (prolog inspired query format)

{http://...#type} (FRIEND , http://...#Friend)
{http://...#Address} (FRIEND , ADDRESS)
{http://...#Street} (ADDRESS , STREET)

Algae is SQL-like

combinatorial solution set
yields every combination that matches query:

Friend
id	name
586	Dick
14	Jane
703	Spot

Address
id	street
586	218 12th Street West
14	6219 6th Avenue
586	123 Elmstraas

SELECT Friend.name,Address.street

FROM Friend,Address

WHERE Friend.id=Address.id

query results
name	street
Dick	218 12th Street West
Jane	6219 6th Avenue
Dick	123 Elmstraas

Algae Query on Repeated Property

predicate	subject	object

rdf:type	myFriends:Dick	Rolodex:Friend
Rolodex:Address	myFriends:Dick	[anoymous node 23]
Rolodex:Street	[anoymous node 23]	218 12th Street West
Rolodex:Address	myFriends:Dick	[anoymous node 614]
Rolodex:Street	[anoymous node 614]	123 Elmstraas
rdf:type	myFriends:Jane	Rolodex:Friend
Rolodex:Address	myFriends:Jane	[anoymous node 218]
Rolodex:Street	[anoymous node 218]	6219 6th Avenue
rdf:type	myFriends:Spot	Rolodex:Friend

(ask '((rdf:type ?friend Rolodex:Friend)
       (Rolodex:Address ?friend ?addrNode)
       (Rolodex:Street ?addrNode ?street)
       ) :collect '(?friend ?street))

query results
?friend	?street
myFriends:Dick	218 12th Street West
myFriends:Dick	123 Elmstraas
myFriends:Jane	6219 6th Avenue

Database Support for Algae

database support comes from implementing statementsMatching
Algae calls the database's statementsMatching for each constraint of the algae query
Algae's interpretAlgae uses results from statementsMatching to constrain calls for subsequent calls
ObjectDB (the SQL-backed DB) implements interpretAlgae to move the join off the the SQL server
other databases may support statementsMatching, like a finger-backed RDF datasource
statementsMatching(finger:lastReadMail myFriend:spot NULL) would return the statement asserting the last time Spot read his mail.

SqlDB

combined with object_maker to apply RDF structure to any SQL database.
moves all data into the semantic web
all your database belong to us*)
SqlDB implements only triplesMatching right now

* silly popular culture reference

SqlDB Example: ACLs Query to W3C Site

algae(namespace '(a http://localhost/SqlDB#) 
    attach '("W3C::Rdf::SqlDB" ("properties:/usr/local/perl/modules/Conf/chacl.prop" "name:a::W3Cacls")) 

    ask '(a::W3Cacls
     (a::uris.uri ?uri0 http://www.w3.org/Member/Overview.html)
     (a::uris.acl ?uri0 ?t1)
     (a::acls.acl ?acl0 ?t1)
     (a::ids.value ?id0 "eric")
     (a::idInclusions.id ?idInc0 ?id0)
     (a::acls.id ?acl0 ?t0)
     (a::idInclusions.groupId ?idInc0 ?t0)
    )
    collect '(?t0) 
   ) -> 
("100")
("102")

Cost

010505  7:39:24             71 Query       SELECT id FROM uris WHERE uri="http://www.w3.org/Member/Overview.html"
                     71 Query       SELECT acl FROM uris WHERE uris.id=1
                     71 Query       SELECT access FROM acls WHERE acl="6"
                     71 Query       SELECT id FROM ids WHERE value="eric"
                     71 Query       SELECT id FROM ids WHERE value="eric"
                     71 Query       SELECT groupId FROM idInclusions WHERE idInclusions.id=2112
                     71 Query       SELECT groupId FROM idInclusions WHERE idInclusions.id=2112
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3122
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
                     71 Query       SELECT id FROM acls WHERE acls.access=3955
010505  7:39:25             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=100
010505  7:39:30             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=102
010505  7:39:31             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=103
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=104
010505  7:39:32             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=105
010505  7:39:38             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=106
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=115
010505  7:39:44             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=117
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=120
010505  7:39:45             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=2112
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=7756
010505  7:39:46             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=9546
010505  7:39:47             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=100
010505  7:39:52             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=102
010505  7:39:53             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=103
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=104
010505  7:39:54             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=105
010505  7:40:00             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=106
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=115
010505  7:40:06             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=117
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=120
010505  7:40:07             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=2112
010505  7:40:08             71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=7756
                     71 Query       SELECT 1 FROM idInclusions WHERE idInclusions.groupId=9546

ProcessQuerySet: Algae Query

algae(namespace '(a http://localhost/SqlDB#) 
    attach '("W3C::Rdf::SqlDB" ("properties:/usr/local/perl/modules/Conf/chacl.prop" "name:a::W3Cacls")) 

    ask '(a::W3Cacls
     (a::uris.uri ?uri0 http://www.w3.org/Member/Overview.html)
     (a::uris.acl ?uri0 ?t1)
     (a::acls.acl ?acl0 ?t1)
     (a::ids.value ?id0 "eric")
     (a::idInclusions.id ?idInc0 ?id0)
     (a::acls.id ?acl0 ?t0)
     (a::idInclusions.groupId ?idInc0 ?t0)
    )
    collect '(?t0) 
   )

ProcessQuerySet: SQL Query

SELECT idInc0.groupId FROM
    uris as uri0,acls as acl0,ids as id0,idInclusions as idInc0 WHERE
    uri0.uri='http://www.w3.org/Member/Overview.html' AND
    acl0.acl=uri0.acl AND
    id0.value='eric' AND
    idInc0.id=id0.id AND
    idInc0.groupId=acl0.id

+---------+
| groupId |
+---------+
|     100 |
|     102 |
+---------+

Contacts

discuss this and other library-related stuff on www-rdf-perllib@w3.org

These slides will be available at http://www.w3.org/2001/Talks/0505-perl-RDF-lib/