1. Enumerating and Describing Web Resources
Channel Definition Format (CDF)
Meta Content Framework (MCF)
Venkata Krishna Potta
and
Ketan Reddy Peddabachi
Instructor:
Dr. Michael Nelson
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2. Presentation Overview
Motivation
CDF
Understanding CDF Files
Example Implementations
CDF channel creation
MCF
Understanding MCF
Building blocks
Predefined Properties and Categories
Conclusion
References
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3. CS 791/891 "Web Syndication Formats"
Motivation
There has always been the need for a standard way of representing or making data machine-usable.
To achieve this, a number of techniques have been proposed in the past like MCF(1996), CDF(1997).
MCF and CDF had succeeded in making metadata share a common data model and vocabulary.
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4. CDF (Channel Definition Format) –An intro
The Channel Definition Format (CDF) is a file format that provides a logical grouping of the information found on the internet. The CDF file defines “Channels” which enumerate a group of related Web sites.
Was first introduced by Microsoft in the year 1997
Microsoft has removed CDF support from Internet Explorer 7.
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5. Understanding CDF Files
Standard text files
Content indexing, independent of content format
Hence a CDF-based channel can include any kind of Web content or applications built on HTML, JavaScript, Java, or ActiveX technology.
Scheduled Web Crawlers
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6. Example Implementations
Microsoft Active Channel technology (supported by Microsoft Internet Explorer 4.0 or later )
Smart offline Favorites (supported by Internet Explorer 5 or later )
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7. Major CDF file elements
CHANNEL/Sub channel: element to define the channel itself
ITEM: defines a channel item, a unit of information which is available form a channel
UserSchedule - reference to a client/user specified schedule
TITLE, ABSTRACT: elements can be used to describe the contents of each item or channel element
LOGO: defines an image to represent a channel or channel item
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CDF channel creation
2 Step Process:
Writing a CDF file with a list of URLs pointing to existing content
Linking to this CDF file to make it discoverable.
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9. CS 791/891 "Web Syndication Formats"
Creating the CDF File
Start and end the CDF file with the CHANNEL element
<CHANNEL
HREF=“
LASTMOD=" T22:12"
PRECACHE="YES"
LEVEL="1"> .
</CHANNEL>
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10. Creating the CDF File [Contd.]
Nest TITLE and ABSTRACT elements within the CHANNEL element.
<TITLE>Title of your Channel</TITLE>
<ABSTRACT>Synopsis of your channel's contents.</ABSTRACT>
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11. Creating the CDF File [Contd.]
Create an update SCHEDULE.
<SCHEDULE>
<INTERVALTIME DAY="14"/>
</SCHEDULE>
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12. Creating the CDF File [Contd.]
Add optional LOGO images.
<LOGO HREF=" STYLE="IMAGE-WIDE"/>
<LOGO HREF=" STYLE="IMAGE"/>
<LOGO HREF=" STYLE="ICON"/>
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13. Creating the CDF File [Contd.]
Specify individual pages with the ITEM element, if desired.
<ITEM HREF=" LASTMOD=" T22:12"
PRECACHE="YES"
LEVEL="1">
<TITLE>Sports Today</TITLE>
<ABSTRACT>Synopsis of Sports Today content.</ABSTRACT>
<LOGO HREF=" STYLE=“image"/>
<LOGO HREF=" STYLE=“icon"/>
</ITEM>
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14. Creating the CDF File [Contd.]
Save the text file with a .cdf extension.
A sample CDF file
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15. CS 791/891 "Web Syndication Formats"
Linking the CDF file
Linking your Web page to the CDF file depends on whether you are creating
a Channel or
an Offline Favorite.
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16. Smart offline Favorites (IE 6.0)
Favourites->Add to Favourites
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17. Setting the Level element
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18. Scheduling the updates
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19. CS 791/891 "Web Syndication Formats"
Why CDF?
What's in it for Developers?
CDF files give Web authors another way to organize their sites
Personalized, password-protected content, log page hits, Active Channel screen savers etc can all be delivered to the user’s desktops.
What's in it for Users?
Offline browsing saves connection charges, navigation and download time
users can elect to have updated information automatically delivered directly to their desktop
Users can choose to monitor specific CDF files and only download the pages pointed to by that file.
Sites are now more personalized and intuitive
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20. Meta Content Framework (MCF)
Definition:
“The Meta Content Framework (MCF) is a tool to provide information about information.” Reference
“Meta Content Framework was a specification of a format for structuring metadata information about web sites and other data.” Reference
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Understanding MCF
The conceptual building blocks
Objects
Categories
Properties
How these are stored?
The Directed Linked Graph - mathematical model.
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MCF Building blocks
Objects
They represent things in the real-world.
Ex. Web pages, companies, people etc.
Properties
They give information about objects.
Ex. Web page has properties like size, URL, author etc.
Categories
It specifies an objects’ property / property type.
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23. Property vs property type:
Example for property type is sizeInBytes, can be applied to any web page.
If applied to a single object, it becomes property.
Ex. For web page at has sizeInBytes property whose value is 5,676.
We can relate this to the ‘object’ and ‘instance’ concepts in OOP.
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24. CS 791/891 "Web Syndication Formats"
Property types
They are also objects.
They can have properties.
Ex. sizeOfPage is property type, which can have properties like
It can only be applied to web pages.
Its value is a number.
The number specifies bytes.
We can create our own property types.
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25. CS 791/891 "Web Syndication Formats"
Category
The value of the property type for an object species the category.
Ex. Property type typeOf for an object can be applied in many ways.
An object representing a person can be typeOfDoctor and typeOfGolfer.
“Doctor” is an MCF object whose typeOf is Category.
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26. Storing Objects and Properties
We need syntax to store Objects, properties and
categories so that humans can create them and
computers can exchange and use them.
To represent MCF we use XML.
In XML
an Object is represented by an element.
Properties are represented by elements contained inside of object element.
the type of element is the Category of the object.
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27. CS 791/891 "Web Syndication Formats"
Example 1
Example showing the Object, its properties in XML.
<WebPage>  <size>5676</size>  <url>
</WebPage>
Object
Properties
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Example 2
Example showing an object whose property value is another object, mapped using a pointer.
The IDs for the objects should be unique.
<WebPage id=" ">  <size>5676</size>  <url>
</WebPage>
 <homePage unit=" "/>
</Person>
Cross Referencing
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29. Domain and Range Properties
For a software that reads our MCF block, may not understand the author and homePage properties. To explain this we may use Domain and Range properties.
These are similar to the ones in the Set Theory.
They tell any computer program that knows MCF that the author property maps Web pages to people, and that homePage maps people to Web pages.
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30. CS 791/891 "Web Syndication Formats"
Example
<WebPage id=" ">  <size>5676</size>  <url>
</WebPage>
 <homePage unit=" "/>
</Person>
<PropertyType id="author">  <domain unit="WebPage"/>  <range unit="Person"/>
</PropertyType>
<PropertyType id="homePage">  <domain unit="Person"/>  <range unit="WebPage"/>
<PropertyType id="size">  <domain unit="WebPage"/>  <range unit="Integer"/>
<PropertyType id=" ">  <domain unit="Person"/>  <range unit="String"/>
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31. The Directed Linked Graph (DLG) Formalism
Objects are represented by nodes.
Properties by arcs.
Labels on arcs represent Property types.
Reference
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32. Predefined property types and categories in MCF
typeOf: Used to link objects to categories.
<Person id="Bill Clinton">  <typeOf unit="American"/>  <typeOf unit="Jogger"/>  <typeOf unit="Politician"/>
</PropertyType>
Data Types:
Java data types like Integer, Float, Boolean and Char.
Domain and Range
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33. Category Type : superType
superType: Expresses a relationship between two Categories.
<Category id="WebPage">  <description>Used as the typeOf any Web  page</description>
</Category>
<Category id="NetscapePage">  <superType unit="WebPage"/>  <description>Used as the typeOf any page at hom e.netscape.com</description>
 </Category >
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34. Property type : superPropertyType
PropertyType and superPropertyType: superProperties are generalizations of other properties.
<PropertyType id="parent">  <domain unit="Person"/>  <range unit="Person"/>
</PropertyType>
<PropertyType id="father">  <superPropertyType unit="parent"/>
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35. Property type: FunctionalPropertyType
FunctionalPropertyType: An object can have any number of typeOf properties. In some cases, though, you want only one property of a given type to apply to an object.
<FunctionalPropertyType id="department-Number">  <!-- a department can only have one number -->  <domain unit="Department"/>  <range unit="Integer"/>
</PropertyType>
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36. Category Type: mutuallyDisjoint
mutuallyDisjoint: Whereas an object can have many Categories (via typeOf properties), some Categories are incompatible with each other.
<Category id="Float">  <mutuallyDisjoint unit="Char"/>
</Category>
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37. CS 791/891 "Web Syndication Formats"
Property Type: parent
parent: Parent is a very general Property type commonly observed between objects.
<Chapter id="c1">  <keyword>wildlife</keyword>
</Chapter>
<Section id="s1.1">  <keyword>mammals</keyword>  <parent unit="c1"/>
</Section>
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38. Property type: inherits
Inheritance: A single property applies to a great number of objects.
<WebPage id="w0001">   <url>   <typeOf>TextualityPage</typeOf>
</WebPage>
<WebPage id="w0002">   <url>   <typeOf>TextualityPage</typeOf>
<Category id="TextualityPage">  <superType unit="WebPage"/>  <inherits propertytype="AuthorOrg" unit="TextualityInc"/>  <inherits propertytype="SiteMap" unit="TextualitySiteMap"/>  <inherits propertytype="CopyrightNotice"> Copyright &copy;   Textuality Services, Inc. All rights reserved.</inherits>
</Category>
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39. CS 791/891 "Web Syndication Formats"
Property types
Compound Properties: Ex. Address.
<Company id="Textuality">  <name>Textuality Services, Inc.</name>  <address>321 - 3495 Cambie Street Vancouver B.C. Canada  </address>  <streetAddress>321 - 3495 Cambie Street </streetAddress>  <City>Vancouver </City>  <Region>B.C. </Region>  <Country>Canada </Country>  <Telephone> </Telephone>
</Company>
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40. Property types and categories [Contd.]
Inverting Properties: In the normal MCF in XML we group a bunch of properties with an object. Some times we inverse this using the INVERSE attribute.
<PropertyType id="parent">  <domain unit="Person"/>  <range unit="Person"/>  <superPropertyType unit="father" inverse ="true"/>  <superPropertyType unit="mother" invers e="true"/>
</PropertyType>
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41. CS 791/891 "Web Syndication Formats"
Conclusion
MCF and CDF have not been widely accepted. Their use is very limited.
But they have succeeded in laying the foundation for other techniques to represent metadata in a standard machine usable formats.
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42. CS 791/891 "Web Syndication Formats"
References
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