RIF: Bringing Order to Chaos

Sandro Hawke (sandro@w3.org), W3C / MIT
RuleML 2009, 5 November 2009
http://www.w3.org/2009/Talks/1105-ruleml/

An Emergent Order

It's a diverse world

Many rules technologies
Many data sources
Many kinds of applications

Can't control chaos

Can't control people
Value in creativity

Interlingua

Translators

Linear (~one per language)

Overview

General outline:

RIF as interlingua for rules (now)
RIF and the Semantic Web
- Data integration, via RIF mapping rules (soon)
- Micro Applications (vision)

My angle:

Linked Data (live RDF)
Inference (formal semantics, eg OWL)
Web Standards
Open Source Web Hacker

Plus Discussion

Rule Interchange: Mission

Produce:

a core rule language
plus extensions

... which together allow rules to be:

translated between rule languages
and thus transferred between rule systems.

The Working Group will have to balance the needs of a diverse community

including Business Rules
and Semantic Web users

... specifying extensions for which it can:

articulate a consensus design and
which are sufficiently motivated by use cases.

RIF History

RuleML initiative, TimBL's cwm/n3 (Fall 2000)

W3C Submissions (2004-2005): SWRL, SWRL-FOL, SWSL, WRL

Workshop (April 2005), ~80 people

F2F1 (December 2005) ~50 people

Use Cases and Requirements (2006)

F2F5, RIF Core WD1 (2007 Q1) ~ 20 people

Production Rules, Builtins, etc (2008)

F2F13, RIF Last Call (July 2009) ~ 15 people

Candidate Recommendation (October 2009)

Community

Business rules vendors
- ILOG [now IBM] (chair), Fair Isaac, Oracle, TIBCO, JBoss...
Commercial Research
- IBM (chair), HP, ...
Non-Commercial Research
- NRC, Bolzano, DERI, MITRE, REWERSE, ...
... others
- Betfair, OMG

Rule Language Features

Rule Language Features - BLD

scattered names of rule language features, with one set grouped as BLD

Rule Language Features - PRD

scattered names of rule language features, with one set grouped as PRD

Rule Language Features - Core

scattered names of rule language features, grouped into PRD, BLD, Core

Result

Dialects (Core + Extensions)

Builtins

Works with RDF, OWL

Standard access to XML data: in development

Test Suite

Extensible

RIF Core

Datalog

if p(...) and q(...) then r(...)

Datatypes, Builtins

xsd numeric
xsd strings, with regular expressions
xsd dates, times, durations
lists

Aligned with RDF (as superset)

Frames for triples
IRI constants

RIF Basic Logic Dialect (BLD)

Same Datatypes, Builtins

Adds functions terms (Positive Horn Logic)

if p(...,f(?x, 3), ..) ... then r(..., g(?y), ...)

Adds open lists (like Prolog)

May add equality in conclusion (open issue)

RIF Production Rule Dialect (PRD)

Operational Semantics (not Model Theoretic)

Adds: Retract, Modify, Execute (Print)

Adds: New

Adds: ineg (true if fact is not in current KB)

Machine-Friendly XML

<!DOCTYPE Document [
  <!ENTITY ppl  "http://example.com/people#">
  <!ENTITY cpt  "http://example.com/concepts#">
  <!ENTITY dc   "http://purl.org/dc/terms/">
  <!ENTITY rif  "http://www.w3.org/2007/rif#">
  <!ENTITY func "http://www.w3.org/2007/rif-builtin-function#">
  <!ENTITY pred "http://www.w3.org/2007/rif-builtin-predicate#">
  <!ENTITY xs   "http://www.w3.org/2001/XMLSchema#">
]>

<Document 
    xmlns="http://www.w3.org/2007/rif#"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:xs="http://www.w3.org/2001/XMLSchema#">
  <payload>
   <Group>
    <id>
      <Const type="&rif;iri">http://sample.org</Const>
    </id>
    <meta>
      <Frame>
        <object>
          <Const type="&rif;local">pd</Const>
        </object>
        <slot ordered="yes">
          <Const type="&rif;iri">&dc;publisher</Const>
          <Const type="&rif;iri">http://www.w3.org/</Const>
        </slot>
        <slot ordered="yes">
          <Const type="&rif;iri">&dc;date</Const>
          <Const type="&xs;date">2008-04-04</Const>
        </slot>
      </Frame>
    </meta>
    <sentence>
     <Forall>
       <declare><Var>item</Var></declare>
       <declare><Var>deliverydate</Var></declare>
       <declare><Var>scheduledate</Var></declare>
       <declare><Var>diffduration</Var></declare>
       <declare><Var>diffdays</Var></declare>
       <formula>
         <Implies>
           <if>
             <And>
               <formula>
                 <Atom>
                   <op><Const type="&rif;iri">&cpt;perishable</Const></op>
                   <args ordered="yes"><Var>item</Var></args>
                 </Atom>
               </formula>
               <formula>
                 <Atom>
                   <op><Const type="&rif;iri">&cpt;delivered</Const></op>
                   <args ordered="yes">
                     <Var>item</Var>
                     <Var>deliverydate</Var>
                     <Const type="&rif;iri">&ppl;John</Const>
                   </args>
                 </Atom>
               </formula>
               <formula>
                 <Atom>
                   <op><Const type="&rif;iri">&cpt;scheduled</Const></op>
                   <args ordered="yes">
                     <Var>item</Var>
                     <Var>scheduledate</Var>
                   </args>
                 </Atom>
               </formula>
               <formula>
                 <Equal>
                   <left><Var>diffduration</Var></left>
                   <right>
                     <External>
                       <content>
                         <Expr>
                           <op><Const type="&rif;iri">&func;subtract-dateTimes</Const></op>
                           <args ordered="yes">
                             <Var>deliverydate</Var>
                             <Var>scheduledate</Var>
                           </args>
                         </Expr>
                       </content>
                     </External>
                   </right>
                 </Equal>
               </formula>
               <formula>
                 <Equal>
                   <left><Var>diffdays</Var></left>
                   <right>
                     <External>
                       <content>
                         <Expr>
                           <op><Const type="&rif;iri">&func;days-from-duration</Const></op>
                           <args ordered="yes">
                             <Var>diffduration</Var>
                           </args>
                         </Expr>
                       </content>
                     </External>
                   </right>
                 </Equal>
               </formula>
               <formula>
                 <External>
                   <content>
                     <Atom>
                       <op><Const type="&rif;iri">&pred;numeric-greater-than</Const></op>
                       <args ordered="yes">
                         <Var>diffdays</Var>
                         <Const type="&xs;integer">10</Const>
                       </args>
                     </Atom>
                   </content>
                 </External>
               </formula>
             </And>
           </if>
           <then>
             <Atom>
               <op><Const type="&rif;iri">&cpt;reject</Const></op>
               <args ordered="yes">
                 <Const type="&rif;iri">&ppl;John</Const>
                 <Var>item</Var>
               </args>
             </Atom>
           </then>
         </Implies>
       </formula>
     </Forall>
    </sentence>
    <sentence>
     <Forall>
       <declare><Var>item</Var></declare>
       <formula>
         <Implies>
           <if>
             <Atom>
               <op><Const type="&rif;iri">&cpt;unsolicited</Const></op>
               <args ordered="yes"><Var>item</Var></args>
             </Atom>
           </if>
           <then>
             <Atom>
               <op><Const type="&rif;iri">&cpt;reject</Const></op>
               <args ordered="yes">
                 <Const type="&rif;iri">&ppl;Fred</Const>
                 <Var>item</Var>
               </args>
             </Atom>
           </then>
         </Implies>
       </formula>
     </Forall>
    </sentence>
   </Group>
  </payload>
 </Document>

Presentation Syntaxes

One used in BLD spec, another used in PRD spec

Document(
  Prefix(ppl  <http://example.com/people#>)
  Prefix(cpt  <http://example.com/concepts#>)
  Prefix(dc   <http://purl.org/dc/terms/>)
  Prefix(rif  <http://www.w3.org/2007/rif#>)
  Prefix(func <http://www.w3.org/2007/rif-builtin-function#>)
  Prefix(pred <http://www.w3.org/2007/rif-builtin-predicate#>)
  Prefix(xs   <http://www.w3.org/2001/XMLSchema#>)
  
  (* "http://sample.org"^^rif:iri _:pd[dc:publisher -> "http://www.w3.org/"^^rif:iri
                                      dc:date -> "2008-04-04"^^xs:date] *)
  Group
  (
    Forall ?item ?deliverydate ?scheduledate ?diffduration ?diffdays (
        cpt:reject(ppl:John ?item) :-
            And(cpt:perishable(?item)
                cpt:delivered(?item ?deliverydate ppl:John)
                cpt:scheduled(?item ?scheduledate)
                ?diffduration = External(func:subtract-dateTimes(?deliverydate ?scheduledate))
                ?diffdays = External(func:days-from-duration(?diffduration))
                External(pred:numeric-greater-than(?diffdays 10)))
    )
 
    Forall ?item (
        cpt:reject(ppl:Fred ?item) :- cpt:unsolicited(?item)
    )
  )
)

Room for something better.

RDF and OWL

Okay to use RIF rules on RDF

Okay to use with OWL (in all its variants)

Okay to implement OWL 2 RL with RIF Core

XML

Draft (won't be a standard soon)

Access to XML / XML-like data from rules

What if my feature is missing?

Double-check the specs

Check mailing list, Wiki

public-rif-dev@w3.org

Check the Framework for Logic Dialects

Use as a menu of features
Already has negations, aggregates, etc
Can't all be used together
Implementation may be difficult

Okay to define your own dialects

Extensions: Interoperability

What should non-implementing systems do?

If non-implementers should...	Your extension should...
ignore it	use annotations (metadata)
stop	extend the syntax
rewrite	[not yet supported]

Extending the Syntax

Add XML Elements, in your own namespace

Non-implementing systems will reject document

Document it, share on public-rif-dev@w3.org

Possible Fallback Mechanism

Ideally, non-implementing systems could look up extension

Syntactic sugar -> perfect rewrites

Other rewrites have some "impact"

Proposed as XTAN, but not adopted in RIF

RIF Status

RIF implementations

Test Suite

http://www.w3.org/2005/rules/wiki/Category:Test_Case
http://www.w3.org/2005/rules/test/
Currently: 51 Approved, 37 Proposed

It's time!

The Future:

Implementations
New Extensions, Dialects
New Uses and Markets for Rules

Part 2: RIF in the Semantic Web

You already believe in rule interchange

Relation to the Web?

Decentralization

Massive Scale

(My main use case for RIF)

Simple Semantic Web Scenario

Alice publishes an RDF web page:

She wants to say...	Her RDF (in Turtle)
I'm selling a 1st Generation Apple iPod Nano.	@prefix sales: <http://example.org/sales> @prefix apple: <http://apple.example.com/products> @prefix : <> :Alice sales:offering :item22. :item22 rdf:type apple:iPodNanoGen1.

Charlie queries for:

?who sales:offering ?item.   
?item rdf:type apple:iPodNanoGen1.

... and he see Alice's listing!

Add a Little Inference

But really Charlie queries for:

?who sales:offering ?item.   
?item rdf:type apple:iPod.

If he wants to see Alice's listing, he must:

Look up IRI terms, and
Does OWL inference

And Apple must:

Apple's Content	Which means...
apple:iPodNanoGen1 rdfs:subClassOf apple:iPodNano. apple:iPodNano rdfs:subClassOf apple:iPod.	Every Gen1 Nano is a Nano, every Nano is an iPod
apply:iPodNanoGen1 rdfs:subClassOf [ rdf:type owl:Restriction; owl:onProperty apple:memorySizeMeg; owl:hasValue "1024"; ]	Every Gen1 Nano has 1024M memory

Apple's Content

Which means...

apple:iPodNanoGen1 rdfs:subClassOf apple:iPodNano.
apple:iPodNano rdfs:subClassOf apple:iPod.

Every Gen1 Nano is a Nano, every Nano is an iPod

apply:iPodNanoGen1 rdfs:subClassOf [
    rdf:type owl:Restriction;
    owl:onProperty apple:memorySizeMeg;
    owl:hasValue "1024";
]

Every Gen1 Nano has 1024M memory

Rules?

Implement "RL" subset of OWL

More expressive than OWL (eg builtins)

Especially vocabulary mapping

Frank's selling his Zune, using non-Apple vocabulary
Robert provides iPod - Zune mapping rules

Many Kinds of Data

Some data currently in some computer:

From producer: product information
From seller: product and service offerings
Customer support (instructions, upgrades, ...)
Social network (who you trust, who interests you)
Personal information shared with friends
Public records (financial, legal, political, ...)

Data Source (cont'd)

Science (medical, environmental, economic, ...)
News, Blogs, Public photos, videos
Event listings (performances, meetings)
Review, opinions, product experiences, preferences
Personal location, location history
Financial transactions

Wild Scenario

A Shopping Scenario

You're in a store, considering buying an item
You use your phone to scan the item, and now it can figure out
- Its price at other stores, nearby
- Its price for delivery, and how how long you'd have to wait
- Maybe: where it was made, and under what conditions
- Is it's producer a good corporate citizen?
- Does its producer agree with your political views (uh oh)
- How many houses does its CEO own?
- Did your spouse/housemate just buy some? Or something like it?

More...

- How your friends feel about this product
- How Consumer Reports (or some such service) reviewed it
- Product liability suits
- Endorsements
- Maybe: Payment for Endorsements
- For electronics: compatibility information
- For mechanical items: How repairable is it? MTTF, MTTR
- For food: nutritional information, health benefits and risks
- Demographics of this brand, these products

Data Publication

Those are all things some computer knows about

It's a question of permissions

And the cost of data integration

Knowledge is Power (Information has Value)

The Future of Applications

Apps using data from unknown sources

IT Dashboard

http://it.usaspending.gov/

A lot of apps are just queries

And the rest just add update?

Model-View-Controller revisited

MVC takes over...

Model = Data + Rules
View = XML transform (rules?)
Controller = Data authoring

All shared on Web

Application = pick one of each

Micro Applications

Data modeling the world
Independent views on that data
Various ways of expressing ourselves

Models * Views * Controllers = Ocean of Apps

Micro App is a bookmark, an ad hoc collection of these

Order among the chaos of applications

(Someday.)

Conclusion

RIF is ready to try out. Pick your dialect.

http://www.w3.org/TR/rif-overview

Extend it as necessary

Send "subscribe" (in subject) to public-rif-dev-request@w3.org

Rules are key to open data integration

The future is:

Chaotic Web of Data
... made orderly by Rules