Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
A Five Minute Intro to XML
Roger L. Costello
The MITRE Corporation
1
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
2
You have data …
How should you structure it?
Here's some data about a Canon camera:
Canon-Sure-Shot-Z155
37-155mm zoom
4.8-11.7
$318 USD
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
The XML approach is to "wrap"
each data item in start/end tags
<Camera>
<name>Canon-Sure-Shot-Z155</name>
<f-stop>4.8-11.7</f-stop>
<focal-length>37-155mm zoom</focal-length>
<cost>$318 USD</cost>
</Camera>
Canon.xml
3
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
4
XML Terminology
<name>Canon-Sure-Shot-Z155</name>
Start tag
End tag
Data
Element
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
What's the date?
<date>05-10-99</date>
The XML tags are generally very
useful in describing properties of
the data. However, in this case more
is needed. That is, more data about
the data (metadata) is needed.
5
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
XML Attributes
<date format="dd-mm-yy">05-10-99</date>
attribute
Things to note:
1. Attributes are "bundled" in with the start tag.
2. Attributes take this form:
attribute-name="attribute-value"
6
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Common Design Pattern:
IDentify classes
Instead of this:
<Camera>
<name>Canon-Sure-Shot-Z155</name>
<f-stop>4.8-11.7</f-stop>
<focal-length>37-155mm zoom</focal-length>
<cost>$318 USD</cost>
</Camera>
Design like this:
<Camera ID="Canon-Sure-Shot-Z155">
<f-stop>4.8-11.7</f-stop>
<focal-length>37-155mm zoom</focal-length>
<cost>$318 USD</cost>
</Camera>
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Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
The General Design Pattern
<Class ID="instance">
<property1>data value</property1>
<property2>data value</property2>
...
<property-n>data value</property-n>
</Class>
Things to note:
1. Names of Classes by convention begin with uppercase.
2. Names of properties by convention begin with lowercase.
8
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Example
<CameraStore ID="Hunts-Camera-Store">
<location>Malden, MA</location>
<inventory>
<Camera ID="Canon-Sure-Shot-Z155">
<f-stop>4.8-11.7</f-stop>
<focal-length>37-155mm zoom</focal-length>
<cost>$318 USD</cost>
</Camera>
<Camera ID="Olympus-mju-II">
<f-stop>2.8</f-stop>
<focal-length>35mm</focal-length>
<cost>$178 USD</cost>
</Camera>
...
</inventory>
</CameraStore>
Hunts.xml
9
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
10
With OWL you can define the Camera Class
(which is used in the XML document)
"Qualify"
the element
(Class) to indicate
that it is provided
by OWL
<owl:Class rdf:ID="Camera">
</owl:Class>
"Qualify"
Elements
and attributes
provided by
OWL
the attribute
(ID) to indicate
that it is provided
by RDF
Elements
and attributes
provided by
RDF
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Why use XML?
• It is a universally accepted standard way of
structuring data (syntax).
• It is a W3C recommendation (W3C = World Wide
Web Consortium)
• The marketplace supports it with a lot of
free/inexpensive tools.
• The alternative to using XML is to define your
own proprietary data syntax, and then build your
own proprietary tools to support the proprietary
syntax (Not a very appealing idea).
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Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
A Quick Introduction to
OWL Web Ontology Language
Roger L. Costello
David B. Jacobs
The MITRE Corporation
(The creation of this tutorial was sponsored by DARPA)
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Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
13
What is OWL?
Answer: OWL is a set of XML elements and attributes,
with standardized meaning, that are used to
define terms and their relationships.
OWL extends RDF Schema:
Class
equivalentProperty
sameIndividualAs
...
subClassOf
resource
ID
...
OWL
OWL elements and attributes
(i.e., OWL Vocabulary)
RDF Schema
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Example of using OWL to define
two terms and their relationship
Example: Define the terms "Camera" and "SLR".
State that SLRs are a type of Camera.
Here's how these two terms (classes) and their
relationship is defined using the OWL vocabulary:
<owl:Class rdf:ID="Camera"/>
<owl:Class rdf:ID="SLR">
<rdfs:subClassOf rdf:resource="#Camera"/>
</owl:Class>
14
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Quick Intro Contents
• In this quick intro we present an example to
demonstrate one of the utilities of OWL:
– The example shows how OWL can be used to
bridge terminology differences and thus
enhance interoperability.
15
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Example: Bridging the
Terminology Gap using OWL
• A key problem in achieving interoperability
is to be able to recognize that two pieces of
data are talking about the same thing, even
though different terminology is being used.
• The following slides presents an example to
show how OWL may be used to bridge the
"terminology gap".
16
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Interested in
Purchasing a Camera
• Scenario:
– I am interested in purchasing a camera with a
75-300mm zoom lens size, that has an aperture
of 4.5-5.6, and a shutter speed that ranges from
1/500 sec. to 1.0 sec.
– I launch my personal "Web Bot" which crawls
the Web looking for Web sites that can fulfill
my request.
– Assume that there exists an OWL Camera
Ontology, which the Web Bot can "consult"
upon its travels across the Web.
17
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Is this document relevant?
The Web Bot
finds this
document at a
Web site:
Is it relevant?
(Note: SLR = Single Lens
Reflex)
<PhotographyStore rdf:ID="Hunts"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<store-location>Malden, MA</store-location>
<phone>617-555-1234</phone>
<catalog rdf:parseType="Collection">
<SLR rdf:ID="Olympus-OM-10"
xmlns="http://www.camera.org#">
<lens>
<Lens>
<focal-length>75-300mm zoom</focal-length>
<f-stop>4.5-5.6</f-stop>
</Lens>
</lens>
<body>
<Body>
<shutter-speed rdf:parseType="Resource">
<min>0.002</min>
<max>1.0</max>
<units>seconds</units>
</shutter-speed>
</Body>
</body>
<cost rdf:parseType="Resource">
<rdf:value>325</rdf:value>
<currency>USD</currency>
</cost>
</SLR>
</catalog>
</PhotographyStore>
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Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
19
A Match?
<PhotographyStore rdf:ID="Hunts"
xmlns:rdf="&rdf;#">
<store-location>Malden, MA</store-location>
<phone>617-555-1234</phone>
<catalog rdf:parseType="Collection">
<SLR rdf:ID="Olympus-OM-10"
xmlns="http://www.camera.org#">
<lens>
<Lens>
<focal-length>75-300mm zoom</focal-length>
<f-stop>4.5-5.6</f-stop>
</Lens>
</lens>
<body>
<Body>
<shutter-speed rdf:parseType="Resource">
<min>0.002</min>
<max>1.0</max>
<units>seconds</units>
</shutter-speed>
</Body>
</body>
<cost rdf:parseType="Resource">
<rdf:value>325</rdf:value>
<currency>USD</currency>
</cost>
</SLR>
</catalog>
</PhotographyStore>
Match?
I am interested in purchasing a camera with a
75-300mm zoom lens size, that has an aperture of
4.5-5.6, and a shutter speed that ranges from
1/500 sec. to 1.0 sec.
To determine if there is a match, these questions must be answered:
1. What's the relationship between "SLR" and "Camera"?
2. What's the relationship between "focal-length" and "size"?
3. What's the relationship between "f-stop" and "aperture"?
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
20
Relationship between
SLR and Camera?
The Web Bot "consults" the OWL Camera Ontology. This
OWL statement tells the Web Bot that a SLR is a type of Camera:
<owl:Class rdf:ID="SLR">
<rdfs:subClassOf rdf:resource="#Camera"/>
</owl:Class>
<PhotographyStore
rdf:ID="Hunts"
<SLR>
…
</SLR>
</PhotographyStore>
Hunts.xml
Web
Bot
"Relationship between
Camera and SLR?" <owl:Class rdf:ID="SLR">
<rdfs:subClassOf rdf:resource="#Camera"/>
</owl:Class>
"SLR is a type of
Camera."
Camera.owl
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Relationship between
focal-length and lens size?
This OWL statement tells the Web Bot that
focal-length is equivalent to lens size:
<owl:DatatypeProperty rdf:ID="focal-length">
<owl:equivalentProperty rdf:resource="#size"/>
<rdfs:domain rdf:resource="#Lens"/>
<rdfs:range rdf:resource="&xsd;#string"/>
</owl:DatatypeProperty>
"focal-length is synonymous with (lens) size.
focal-length is to be used within a Lens.
focal-length has a value that is a string."
21
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Relationship between
f-stop and aperture?
This OWL statement tells the Web Bot that f-stop
is equivalent to aperture:
<owl:DatatypeProperty rdf:ID="f-stop">
<owl:equivalentProperty rdf:resource="#aperture"/>
<rdfs:domain rdf:resource="#Lens"/>
<rdfs:range rdf:resource="&xsd;#string"/>
</owl:DatatypeProperty>
The Web Bot now recognizes that the XML document it found at the Web site
- is talking about Cameras, and it
- does show the lens size, and it
- does show the aperture for the camera, and
- the values for lens size, aperture, and shutter speed are met.
Thus, the Web Bot recognizes that the XML document is a match!
22
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
23
Semantic Definitions Separate
from Application!
<SLR rdf:ID="Olympus-OM-10"
xmlns="http://www.camera.org#">
<lens>
<Lens>
<focal-length>75-300mm zoom</focal-length>
<f-stop>4.5-5.6</f-stop>
</Lens>
</lens>
<body>
<Body>
<shutter-speed rdf:parseType="Resource">
<min>0.002</min>
<max>1.0</max>
<units>seconds</units>
</shutter-speed>
</Body>
</body>
<cost rdf:parseType="Resource">
<rdf:value>325</rdf:value>
<currency>USD</currency>
</cost>
</SLR>
Hunts.xml
"Relationship between
Camera and SLR?"
Semantic Definitions
<owl:Class rdf:ID="SLR">
<rdfs:subClassOf rdf:resource="#Camera"/>
</owl:Class>
"SLR is a type of
Camera."
Web Bot
(application)
"Relationship between
aperture and f-stop?"
"f-stop is synonymous
with aperture."
"Relationship between
size and focal-length?"
"focal-length is
synonymous with
size."
<owl:DatatypeProperty rdf:ID="focal-length">
<owl:equivalentProperty rdf:resource="#size"/>
<rdfs:domain rdf:resource="#Lens"/>
<rdfs:range rdf:resource="&xsd;#string"/>
</owl:DatatypeProperty>
<owl:DatatypeProperty rdf:ID="f-stop">
<owl:equivalentProperty rdf:resource="#aperture"/>
<rdfs:domain rdf:resource="#Lens"/>
<rdfs:range rdf:resource="&xsd;#string"/>
</owl:DatatypeProperty>
Camera.owl
See the article "Why use OWL?" for a discussion of why it is good practice to separate the semantic definitions
from the application.
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Summary: Interoperability
despite terminology differences!
• The example demonstrated how a Web Bot
application was able to dynamically process an
XML document from a Web site, despite the fact
that the XML document used terminology
different than was used to express the request.
This interoperability was achieved by using the
OWL Camera Ontology!
• This example also demonstrated the architectural
design principle of cleanly separating the
application code (e.g., Web Bot) from the semantic
definitions (e.g., Camera.owl).
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Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
25
Demo of interoperability in a
heterogeneous data environment
Hunts.xml
Camera
Application
What do you know
about SLR?
SLR is a type of
Camera.
Camera.owl
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Demo - searching for Camera,
lens size, aperture info
• The Camera Application is searching for
documents that meet this desire:
– I am interested in purchasing a Camera with a 75300mm zoom lens size, that has an aperture of 4.5-5.6,
and a shutter speed that ranges from 1/500 sec. to 1.0
sec.
• The Camera Application understands the terms
(i.e., elements) Camera, lens size, and aperture.
• If a document uses terms that it does not
understand, then the Camera application
"consults" the Camera Ontology.
26
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
27
Hunts.xml - uses unfamiliar
terminology
?
<PhotographyStore>
<catalog rdf:parseType="Collection">
<SLR rdf:ID="Olympus-OM-10"
xmlns="http://www.xfront.com/owl/ontologies/camera/#">
<lens>
<Lens>
<focal-length>75-300mm zoom</focal-length>
<f-stop>4.5-5.6</f-stop>
</Lens>
</lens>
<body>
<Body>
<shutter-speed rdf:parseType="Resource">
<min>0.002</min>
<max>1.0</max>
<units>seconds</units>
</shutter-speed>
</Body>
</body>
</SLR>
</catalog>
</PhotographyStore>
Need to
consult the
Camera
Ontology!
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
28
QuikPhoto.xml - uses familiar
terminology
<Camera>
<lens>
<Lens>
<size>75-300mm zoom</size>
<aperture>4.5-5.6</aperture>
</Lens>
</lens>
<body>
<Body>
<shutter-speed rdf:parseType="Resource">
<min>0.002</min>
<max>1.0</max>
<units>seconds</units>
</shutter-speed>
</Body>
</body>
</Camera>
No need to
consult the
Camera
Ontology.
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
29
Lesson Learned
• The Camera Application is able to process
documents that uses unfamiliar terminology.
Interoperates!
Community A
uses terms SLR,
f-stop, focal-length
Community B
uses terms Camera,
aperture, lens size
OWL Camera Ontology
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Who's Using Ontologies?
• Real estate investment agencies are using
Ontologies to exchange data with regulatory
agencies (Data Consortium - Real Estate Data
Standards).
• Reuter's Health is using Ontologies to describe the
content of articles and sort them into various news
feeds (using SNOMED Ontology).
• Electric utilities describe their networks using
Ontologies for exchange purposes (CIM/XML).
• SUN has a large knowledge management initiative
called swoRDfish that uses Ontologies.
30
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Related Articles
"Why use OWL?" by Roger L. Costello
http://www.xfront.com/owl/motivation/sld001.htm
"Why use OWL?" by Adam Pease
http://www.xfront.com/why-use-owl.html
"Using OWL to Avoid Syntactic Rigor Mortis" by Roger L. Costello
http://www.xfront.com/avoiding-syntactic-rigor-mortis.html
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Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
The OWL Camera Ontology
is Online!
Here is the URL to a pictorial view of the Camera Ontology:
http://www.xfront.com/owl/ontologies/camera/sld001.htm
Here is the URL to the camera.owl document:
http://www.xfront.com/owl/ontologies/camera/camera.owl
Here are the URLs to 7 physical expressions (instance documents):
http://www.xfront.com/owl/ontologies/camera/Query1.xml
http://www.xfront.com/owl/ontologies/camera/Hunts.xml
http://www.xfront.com/owl/ontologies/camera/Query2.xml
http://www.xfront.com/owl/ontologies/camera/Hunts2.xml
http://www.xfront.com/owl/ontologies/camera/RJs.xml
http://www.xfront.com/owl/ontologies/camera/OlympusOutletStore.xml
http://www.xfront.com/owl/ontologies/camera/OlympusCorp.xml
32
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
The Robber and the Speeder
Roger L. Costello
David B. Jacobs
The MITRE Corporation
(The creation of this tutorial was sponsored by DARPA)
33
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
34
An OWL Ontology can be used to answer
questions that are implicit in your data
4
How many
guns/people
are registered
in a gun
<GunLicense>
license?
<registeredGun>
Can this gun
be registered
in other gun
licenses?
3
1
How many guns can have this serial number?
<Gun>
<serial>ABCD</serial>
2
</Gun>
</registeredGun>
How many people can have
this driver's license number?
<holder>
<Person>
<driversLicenseNumber>ZXYZXY</driversLicenseNumber>
</Person>
</holder>
</GunLicense>
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
35
The OWL Gun License Ontology
answers the questions!
A gun license 4
registers one
gun to one
person.
<GunLicense>
1
Only one gun can have this serial number.
<registeredGun>
A gun can be
<Gun>
registered in
<serial>ABCD</serial>
only one gun
2
</Gun>
license.
</registeredGun>
Only one person can have this
3
driver's license number.
<holder>
<Person>
<driversLicenseNumber>ZXYZXY</driversLicenseNumber>
</Person>
</holder>
</GunLicense>
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
The Robber and the Speeder
• On the next few slides is an example that
shows how an OWL Ontology provides the
necessary information to link a robber and a
speeder.
• Thanks to Ian Davis for this example!
36
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Robber drops gun while fleeing!
First of all a robbery takes place. The robber drops his gun while
fleeing. This report is filed by the investigating officers:
<RobberyEvent>
<date>...</date>
<description>...</description>
<evidence>
<Gun>
<serial>ABCD</serial>
</Gun>
</evidence>
<robber>
<Person /> <!-- an unknown person -->
</robber>
</RobberyEvent>
37
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Speeder stopped
Subsequently a car is pulled over for speeding. The traffic officer
files this report electronically while issuing a ticket:
<SpeedingOffence>
<date>...</date>
<description>...</description>
<speeder>
<Person>
<name>Fred Blogs</name>
<driversLicenseNumber>ZXYZXY</driversLicenseNumber>
</Person>
</speeder>
</SpeedingOffence>
38
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
The speeder owns a gun with the
same serial number as the robbery gun!
At police headquarters (HQ), a computer analyzes each report
as it is filed. The computer uses the driver's license information
to look up any other records it has about Fred Blogs (the speeder)
and discovers this gun license:
<GunLicense>
<registeredGun>
<Gun>
<serial>ABCD</serial>
</Gun>
</registeredGun>
<holder>
<Person>
<driversLicenseNumber>ZXYZXY</driversLicenseNumber>
</Person>
</holder>
</GunLicense>
39
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Case Solved?
• Not yet! These questions must be answered before the
speeder can be arrested as the robbery suspect:
1
– Can multiple guns have the same serial number?
• If so, then just because Fred Blogs owns a gun with the same serial number as
the robbery gun does not mean it was his gun that was used in the robbery.
2
– Can multiple people have the same driver's license number?
• If so, then the gun license information may be for someone else.
3
– Can a gun be registered in multiple gun licenses?
• If so, then the other gun licenses may show the holder of the gun to be
someone other than Fred Blogs.
4
– Can a gun license have multiple holders of a registered gun?
• If so, then there may be another gun license document (not available at the
police HQ) which shows the same registered gun but with a different holder.
• The OWL Gun License Ontology provides the information
needed to answer these questions!
40
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
41
Can multiple guns have
the same serial number?
This OWL statement tells the computer at police HQ that each gun
is uniquely identified by its serial number:
<owl:InverseFunctionalProperty rdf:ID="serial">
<rdfs:domain rdf:resource="Gun"/>
<rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</owl:InverseFunctionalProperty>
1
Only one gun can have this serial number.
<Gun>
<serial>ABCD</serial>
</Gun>
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
42
Can multiple people have
the same driver's license number?
The following OWL statement tells the computer that a driver's
license number is unique to a Person:
<owl:InverseFunctionalProperty rdf:ID="driversLicenseNumber">
<rdfs:domain rdf:resource="Person"/>
<rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</owl:InverseFunctionalProperty>
2
Only one person can have this
driver's license number.
<Person>
<driversLicenseNumber>ZXYZXY</driversLicenseNumber>
</Person>
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
43
Can a gun be registered in
multiple gun licenses?
The next OWL statement tells the computer that the registeredGun
property uniquely identifies a GunLicense, i.e., each gun is associated
with only a single GunLicense:
<owl:InverseFunctionalProperty rdf:ID="registeredGun">
<rdfs:domain rdf:resource="GunLicense"/>
<rdfs:range rdf:resource="Gun"/>
</owl:InverseFunctionalProperty>
A gun can be
registered in
only one gun
license.
3
<GunLicense>
<registeredGun>
<Gun>
<serial>ABCD</serial>
</Gun>
</registeredGun>
...
</GunLicense>
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
44
Can a gun license have
multiple holders of a registered gun?
The police computer uses the following OWL statement to determine that the gun on the
license is the same gun used in the robbery. This final statement seals the speeder's fate.
It tells the computer that each GunLicense applies to only one gun and one person. So,
there is no doubt that the speeder is the person who owns the gun:
<owl:Class rdf:ID="GunLicense">
<owl:intersectionOf rdf:parseType="Collection">
<owl:Restriction>
<owl:onProperty rdf:resource="#registeredGun"/>
<owl:cardinality>1</owl:cardinality>
</owl:Restriction>
<owl:Restriction>
<owl:onProperty rdf:resource="#holder"/>
<owl:cardinality>1</owl:cardinality>
</owl:Restriction>
</owl:intersectionOf>
</owl:Class>
A gun license 4
registers one
gun to one
person.
<GunLicense>
<registeredGun>
...
<holder>
...
</GunLicense>
Roger L. Costello, David B. Jacobs. © 2003 The MITRE Corporation.
Summary
• An OWL Ontology provides additional
information about your data.
– Example: The Gun License Ontology provided
the data needed for the police computer to link
the Robber and the Speeder!
• OWL is intended to be used when
processing Web documents. Thus, OWL
enables an ad-hoc exploitation of Web
documents, i.e., the Semantic Web!
45