Midas: Microsoft/Pointcast Channel Definition Format

(Prev Next) Part of UserLand's MIDAS Website. 3/29/97.

Microsoft/Pointcast Channel Definition Format

Channel Definition Format (CDF)

Date: 3/8/97

Authors:
Castedo Ellerman, Microsoft, castedoe@microsoft.com
Jason Douglas, PointCast, jdouglas@pointcast.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 CategoyDef Element

3 Example

4 References

1 Introduction

The Channel Definition Format is a standard, 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 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 minor elements that a relevant to a major 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.

Elements Description Type # allowed Default

LastMod Last modified date for this web page ISO 8601:1988 Date 0 or 1

Title Title String 0 or 1

Abstract Short description summarizing the article (200 characters or less recommended) String (between start and end tags) 0 or 1

Author Author String Any

Publisher Publisher String Any

Copyright Copyright String 0 or 1

PublicationDate Publication Date String 0 or 1

Logo Visual Logo for channel Logo element Any

Keywords Comma delimited keywords that match this channel String Any

Category A category to which this web page belongs in. The string value is a URI to a CategoryDef element. Category element Any

Ratings Rating of the channel by one or more ratings services. (String found in PICS label meta tag.) String Any

Schedule Schedule for keeping channel up to date Schedule element 0 or 1

UserSchedule Reference to a client/user specified schedule UserSchedule element 0 or 1

XML DTD

<!ELEMENT LastMod EMPTY>
<!ATTLIST LastMod VALUE CDATA #REQUIRED>
<!ELEMENT Title EMPTY>
<!ATTLIST Title VALUE CDATA #REQUIRED>
<!ELEMENT Abstract ANY>
<!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

Attribute Description Type # allowed Default

HREF URI for the next updated version of this channel URI No

IsClonable Can channel be copied or moved within the channel changer hierarchy Boolean No

<!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:

Elements Description Type # allowed Default

Channel One or more subchannels of this channel Channel element or link Any

Item One or more article profiles, each providing information on a unit of content, usually a web page. Item Profile Any

IntroURI URI to introductory web page for channel. Can provide general and setup information URI 0 or 1

Authorization Certification of executable content downloadable by this channel ("Authenticode for channels") URI 0 or 1

MinStorage Minimum storage size required, in kilobytes Number 0 or 1 0

Tracking Profile providing information on how channel should perform user tracking Tracking Profile 0 or 1

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:

Attribute Description Type # allowed Default

HREF URI of article contents URI Exactly One N/A

MIMEType MIME Type of article contents String 0 or 1

IsVisible This item should be visible to the user. Boolean 0 or 1 "YES"

Priority Priority of this item
("HI", "NORMAL", "LOW") String 0 or 1 "NORMAL"

Precache Publisher recommended download behavior.
"YES" = do retrieve contents into cache
"NO" = do not retrieve contents into cache
"DEFAULT" = what ever user has as default String 0 or 1 "DEFAULT"

<!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:

Element Description Type # allowed Default

Usage Start tag should have VALUE=usage where usage indicates how this item should be used. Children elements can specify more parameters. Any profile 0 or 1

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.

Attribute Description Type # allowed Default

UserSchedule ID/name for predefined/client defined schedule String 0 or 1

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:

Child Element Description Type # allowed Default

Start This is the day upon which the schedule will start to apply. ISO 8601:1988 Date 0 or 1 Start immediately

End This is the day upon which the schedule expires and no longer applies. ISO 8601:1988 Date 0 or 1 Never end

IntervalTime The interval of time that the schedule should repeat over IntervalTime element 0 or 1 Only perform once (infinity)

EarliestTime Earliest time during the schedule interval that the schedule applies to. EarliestTime element 0 or 1 At the beginning of the interval

LatestTime Latest time during the schedule interval that the schedule applied to. If it is not equal to EarliestTime, then the time is randomly chosen in range. LatestTime element 0 or 1 At the beginning of the interval

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.

Attribute Name Description Type # allowed Default

HREF (Required) URL to the image for the logo URI Exactly One N/A

Type String indicating what context image should be used.
("BIG", "WIDE", "SMALL", "REGULAR") String Any "REGULAR"

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.

Child Element Description Type # allowed Default

PostURL The URL to post tracking results to URL Exactly One N/A

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.

Child Element Description Type # allowed

CategoryName Name of category String Exactly One

Description Textual description of category String 0 or 1

CategoryDef Sub-categories Category element Any

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" IsClonable=YES >

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


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


    <Channel IsClonable=NO >
        <LastMod VALUE="1994.11.05T08:15-0500" />
        <Title VALUE="FooSports News" />
        <Abstract>Up-to-date daily sports news from
FooSports</Abstract>
        <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> Led by Michael Jordan in scoring, the 
                                 Chicago Bulls make it to the playoffs
again!
            <Abstract/>
            <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>
                The New York islanders' 10-game winning streak
                      ended with a disappointing loss to the Rangers
            <Abstract/>
            <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>The latest sports headlines from
FooSports</Abstract>
       <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>
5 References

The XML W3C Working Draft is at http://www.w3.org/pub /WWW/TR/WD-xml-961114.html

[RFC-1738] Berners-Lee, T., Masinter, L., and M. McCahill, Editors, "Uniform Resource Locators (URL)", RFC 1738, CERN, Xerox Corporation, University of Minnesota, December 1994.

[RFC-2045] Freed, N., and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, Innosoft, First Virtual Holdings, November 1996.

[RFC-2048] Freed, N., Klensin, J., and J. Postel, "Multipurpose Internet Mail Extensions (MIME) Part Four: MIME Registration Procedures", RFC 2048, Innosoft, MCI, ISI, November 1996.

Elements	Description	Type	# allowed	Default
LastMod	Last modified date for this web page	ISO 8601:1988 Date	0 or 1
Title	Title	String	0 or 1
Abstract	Short description summarizing the article (200 characters or less recommended)	String (between start and end tags)	0 or 1
Author	Author	String	Any
Publisher	Publisher	String	Any
Copyright	Copyright	String	0 or 1
PublicationDate	Publication Date	String	0 or 1
Logo	Visual Logo for channel	Logo element	Any
Keywords	Comma delimited keywords that match this channel	String	Any
Category	A category to which this web page belongs in. The string value is a URI to a CategoryDef element.	Category element	Any
Ratings	Rating of the channel by one or more ratings services. (String found in PICS label meta tag.)	String	Any
Schedule	Schedule for keeping channel up to date	Schedule element	0 or 1
UserSchedule	Reference to a client/user specified schedule	UserSchedule element	0 or 1

Attribute	Description	Type	# allowed	Default
HREF	URI for the next updated version of this channel	URI	No
IsClonable	Can channel be copied or moved within the channel changer hierarchy	Boolean	No

Element	Description	Type	# allowed	Default
Usage	Start tag should have VALUE=usage where usage indicates how this item should be used. Children elements can specify more parameters.	Any profile	0 or 1

Child Element	Description	Type	# allowed	Default
Start	This is the day upon which the schedule will start to apply.	ISO 8601:1988 Date	0 or 1	Start immediately
End	This is the day upon which the schedule expires and no longer applies.	ISO 8601:1988 Date	0 or 1	Never end
IntervalTime	The interval of time that the schedule should repeat over	IntervalTime element	0 or 1	Only perform once (infinity)
EarliestTime	Earliest time during the schedule interval that the schedule applies to.	EarliestTime element	0 or 1	At the beginning of the interval
LatestTime	Latest time during the schedule interval that the schedule applied to. If it is not equal to EarliestTime, then the time is randomly chosen in range.	LatestTime element	0 or 1	At the beginning of the interval

Attribute Name	Description	Type	# allowed	Default
HREF (Required)	URL to the image for the logo	URI	Exactly One	N/A
Type	String indicating what context image should be used. ("BIG", "WIDE", "SMALL", "REGULAR")	String	Any	"REGULAR"

(Prev Next) Part of UserLand's MIDAS Website. 3/29/97.

Microsoft/Pointcast Channel Definition Format

Channel Definition Format (CDF)

Contents

1 Introduction

2 Element Definitions

2.1 Common child elements of Channel and Item

XML DTD

2.2 Channel Element

XML DTD

Attributes

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

Child elements of the Channel element only:

XML DTD for minor elements

2.3 Item Element

XML DTD

Attributes:

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

Child Element of the Item element only:

XML DTD for minor elements

2.4 UserSchedule Element

XML DTD

2.5 Schedule Element

XML DTD

Child Elements:

XML DTD for minor elements

2.6 Logo Element

XML DTD

2.7 Tracking Element

XML DTD

2.8 CategoryDef Element

XML DTD

4 Example

5 References

This page was last built with Frontier on a Macintosh on Sat, Mar 29, 1997 at 4:37:47 PM. Thanks for checking it out! Dave