Channel Definition Format (CDF)

Date: March 10, 1997

Note:
This specification is a preliminary draft that will undergo changes in the future. Although the information is not final, we are providing the spec as a preview so that our partners may prepare for the final version.

Author:
Castedo Ellerman
Microsoft Corporation
castedoe@microsoft.com

Contents

• 1 Introduction
• 2 Element Definitions
  • 2.1 Common Elements of Channel and Item
  • 2.2 Channel Element
  • 2.3 Item Element
  • 2.4 UserSchedule Element
  • 2.5 Schedule Element
  • 2.6 Logo Element
  • 2.7 Tracking Element
  • 2.8 CategoryDef Element
• 3 Example
• 4 References

1 Introduction

The Channel Definition Format is an open specification that permits a web publisher to offer frequently updated collections of information, or channels, from any web server for automatic delivery to compatible receiver programs on PCs or other information appliances.

Automatic means that the user need only choose the channel once, and thereafter, scheduled deliveries of information to the client will occur without further user intervention.

Standard web server means that any web server that uses the HTTP 1.0 or later protocol can broadcast channels.

Compatible means any program that implements processing and retrieving content as specified by the Channel Definition Format described below.

When downloaded to a client, CDFs act as a local index to its channel's available content. For example, a receiver program can present the implicit hierarchy in a CDF within a channel selector.

2 Element Definitions

The Channel Definition Format is an application of the Extensible Markup Language (XML). Thus its definition consists of the various XML elements defined in this section. See the references section for information on XML work in progress.

The CDF contains the following major elements:

• Channel - defined a channel
• Item - defines a channel item, a unit of information which is available form a channel
• UserSchedule - reference to a client/user specified schedule
• Schedule - defines a particular schedule
• Logo - defines an image to represent a channel or channel item
• Tracking - defines user tracking parameters of a channel
• CategoyDef - defines a category, possibly as a child category of another category

For each one of these major elements there are a number of relevant minor elements. The following sections define the major elements along with the minor elements that are relevant to them. In each section, XML DTD declarations are provided for precise definition of elements and attributes. The collection of XML DTD declarations found in this specification can be arbitrarily extended to add new elements and attributes for new enhancements.

A number or minor elements are used by both the Channel element and the Item element. The following section defines these.

2.1 Common child elements of Channel and Item

The following elements provide basic information about both channels and channel items.

XML DTD

<!ELEMENT LastMod EMPTY>
<!ATTLIST LastMod VALUE CDATA #REQUIRED>
<!ELEMENT Title EMPTY>
<!ATTLIST Title VALUE CDATA #REQUIRED>
<!ELEMENT Abstract EMPTY>
<!ATTLIST Abstract VALUE CDATA #REQUIRED>
<!ELEMENT Author EMPTY>
<!ATTLIST Author VALUE CDATA #REQUIRED>
<!ELEMENT Publisher EMPTY>
<!ATTLIST Publisher VALUE CDATA #REQUIRED>
<!ELEMENT Copyright EMPTY>
<!ATTLIST Copyright VALUE CDATA #REQUIRED>
<!ELEMENT PublicationDate EMPTY>
<!ATTLIST PublicationDate VALUE CDATA #REQUIRED>
<!ELEMENT Keywords EMPTY>
<!ATTLIST Keywords VALUE CDATA #REQUIRED>
<!ELEMENT Category EMPTY>
<!ATTLIST Category VALUE CDATA #REQUIRED>
<!ELEMENT Rating EMPTY>
<!ATTLIST Rating PICS-Label CDATA #REQUIRED>

2.2 Channel Element

Defines a channel

XML DTD

<!ELEMENT Channel ( LastMod | Title | Abstract | Author | Publisher | Copyright | PublicationDate | Keywords | Category | Rating | Channel | Item | Schedule | IntroURI | Authorization | IsClonable | MinStorage | Tracking )* >

Attributes

<!ATTLIST Channel HREF CDATA #IMPLIED>
<!ATTLIST Channel IsClonable (YES | NO) "NO">

Elements shared between Channel elements and Item elements (see above):

LastMod, Title, Abstract, Author, Publisher, Copyright, PublicationDate, Logo, Keywords, Category, Ratings, Schedule

Child elements of the Channel element only:

XML DTD for minor elements

<!ELEMENT IntroURI EMPTY>
<!ATTLIST IntroURI VALUE CDATA #REQUIRED>
<!ELEMENT Authorization EMPTY>
<!ATTLIST Authorization VALUE CDATA #REQUIRED>
<!ELEMENT MinStorage EMPTY>
<!ATTLIST MinStorage VALUE CDATA "0">

2.3 Item Element

Defines an item of a channel, a unit of information for the user, usually corresponding to a web page.

XML DTD

<!ELEMENT Item ( LastMod, Title, Abstract, Author, Publisher, Copyright, PublicationDate, Keywords, Category, Rating, Schedule, Usage )* >

Attributes:

<!ATTLIST Item HREF CDATA #REQUIRED>
<!ATTLIST Item MIMEType CDATA #IMPLIED>
<!ATTLIST Item IsVisible (YES, NO) "YES">
<!ATTLIST Item Priority (HI, NORMAL, LOW) "NORMAL">
<!ATTLIST Item Precache (YES, NO, DEFAULT) "DEFAULT">

Elements shared between Channel elements and Item elements (see above):

LastMod, Title, Abstract, Author, Publisher, Copyright, PublicationDate, Logo, Keywords, Category, Ratings, Schedule

Child Element of the Item element only:

XML DTD for minor elements

<!ELEMENT Usage ANY>
<!ATTLIST Usage VALUE CDATA #REQUIRED>

2.4 UserSchedule Element

The UserSchedule element specifies a client side user defined schedule.

XML DTD

<!ELEMENT UserSchedule EMPTY>
<!ATTLIST UserSchedule VALUE (DAILY, WEEKLY, HOURLY) #REQUIRED>

2.5 Schedule Element

The Schedule element defines a bounded repeating interval of time.

XML DTD

<!ELEMENT Schedule ( StartDate?, EndDate?, IntervalTime?, EarliestTime?, LatestTime? ) >

Child Elements:

XML DTD for minor elements

<!ELEMENT StartDate EMPTY>
<!ATTLIST StartDate VALUE CDATA #REQUIRED>
<!ELEMENT EndDate EMPTY>
<!ATTLIST EndDate VALUE CDATA #REQUIRED>
<!ELEMENT IntervalTime EMPTY>
<!ATTLIST IntervalTime DAY CDATA "0">
<!ATTLIST IntervalTime HOUR CDATA "0">
<!ATTLIST IntervalTime MIN CDATA "0">
<!ATTLIST IntervalTime SEC CDATA "0">
<!ELEMENT EarliestTime EMPTY>
<!ATTLIST EarliestTime DAY CDATA "0">
<!ATTLIST EarliestTime HOUR CDATA "0">
<!ATTLIST EarliestTime MIN CDATA "0">
<!ATTLIST EarliestTime SEC CDATA "0">
<!ELEMENT LatestTime EMPTY>
<!ATTLIST LatestTime DAY CDATA "0">
<!ATTLIST LatestTime HOUR CDATA "0">
<!ATTLIST LatestTime MIN CDATA "0">
<!ATTLIST LatestTime SEC CDATA "0">

2.6 Logo Element

The Logo element defines an image that can be used to represent a channel or channel item.

XML DTD

<!ELEMENT Logo EMPTY>
<!ATTLIST Logo HREF CDATA #REQUIRED>
<!ATTLIST Logo TYPE (BIG WIDE SMALL REGULAR) "REGULAR">

2.7 Tracking Element

The Tracking element indicated how a channel can or should support user tracking.

XML DTD

<!ELEMENT Tracking (PostURL?)>
<!ELEMENT PostURL EMPTY>
<!ATTLIST PostURL HREF CDATA #REQUIRED>

2.8 CategoryDef Element

This profile provides a generic container for properties of a category. Item profiles (used by channel and article profiles) can reference to these category elements using the URI "#foo" when ID="foo" is a parameter in the Category tag.

XML DTD

<!ELEMENT Tracking (PostURL?)>
<!ELEMENT PostURL EMPTY>
<!ATTLIST PostURL HREF CDATA #REQUIRED>

4 Example

<!DOCTYPE Channel SYSTEM "http://www.w3c.org/Channel.dtd" >

<Channel HREF="http://www.foosports.com/foosports.cdf&
quot; IsClonable=YES
>

    <IntroUrl
VALUE="http://www.foosports.com/channel-setup.html" />
    <LastMod VALUE="1994.11.05T08:15-0500" />
    <Title VALUE="FooSports" />
    <Abstract VALUE="The latest in sports and atheletics from
FooSports" />
    <Author VALUE="FooSports" />

    <Schedule>
      <EndDate VALUE="1994.11.05T08:15-0500" />
      <IntervalTime DAY=1 />
      <EarliestTime HOUR=12 />
      <LatestTime HOUR=18 />
    </Schedule>

    <Logo HREF="http://www.foosports.com/images/logo.gif"
Type="REGULAR" />

    <Item HREF="http://www.foosports.com/articles/a1.ht
ml"
 >
       <LastMod VALUE="1994.11.05T08:15-0500" />

       <Title VALUE="How to get the most out of your mountain
bike" />
       <Abstract VALUE="20 tips on how to work your mountain-bike
to the bone and come out on top." />
       <Author VALUE="FooSports" />
    </Item>

    <Channel IsClonable=NO >
        <LastMod VALUE="1994.11.05T08:15-0500" />
        <Title VALUE="FooSports News" />
        <Abstract VALUE="Up-to-date daily sports news from
FooSports" />
        <Author VALUE="FooSports" />

        <Logo
HREF="http://www.foosports.com/images/newslogo.gif"
Type="REGULAR" />

        <Logo
HREF="http://www.foosports.com/images/newslogowide.gif"
Type="WIDE" />

        <Item
HREF="http://www.foosports.com/articles/news1.html" >
            <LastMod VALUE="1994.11.05T08:15-0500" />
            <Title VALUE="Michael Jordan does it again!"
/>
            <Abstract VALUE="Led by Michael Jordan in scoring, the
Chicago Bulls make it to the playoffs again!" />
            <Author VALUE="FooSports" />
        </Item>

        <Item
HREF="http://www.foosports.com/articles/news2.html" />
            <LastMod VALUE="1994.11.05T08:15-0500" />
            <Title VALUE="Islanders winning streak ends"
/>
            <Abstract VALUE="The New York islanders' 10-game
winning streak ended with a disappointing loss to the Rangers" />
            <Author VALUE="FooSports" />
        </Item>

    </Channel>

    <Item
HREF="http://www.foosports.com/animations/scrnsvr.html" />
       <Usage VALUE="ScreenSaver"></Usage>
    </Item>

    <Item
HREF="http://www.foosports.com/ticker.html" />
       <Title VALUE="FooSports News Ticker" />
       <Abstract VALUE="The latest sports headlines from
FooSports" />
       <Author VALUE="FooSports" />
       <LastMod VALUE="1994.11.05T08:15-0500"
/>

   <!-- This is an example of how Usage
can
be used for client enhancements -->
       <Usage VALUE="DesktopComponent">
         <Width VALUE=400 />
         <Height VALUE=80 />
       </Usage>

       <Schedule>
          <StartDate VALUE="1994.11.05T08:15-0500" />
          <EndDate VALUE="1994.11.05T08:15-0500" />
          <IntervalTime DAY=1 />
          <EarliestTime HOUR=12 />
          <LatestTime HOUR=18 />
       </Schedule>
    </Item>

</Channel>