Network Working Group D. Royer
Internet-Draft INET-Consulting
Expires: January 27, 2006 July 26, 2005
iCalendar in XML Format (xCal)
draft-royer-calsch-xcal-00
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
The mailing list for discussion of this memo is
"ietf-calendar@imc.org". This is a rerelease of an expire draft with
updates and a much more simplivied approach. This approach uses an
exact 1 to 1 mapping between iCalendar and xml object.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Using XML For Representating iCalendar . . . . . . . . . . . . 4
2.1 XML Dependencies . . . . . . . . . . . . . . . . . . . . . 5
2.2 Working With Standard and XML iCalendar Representations . 5
2.2.1 Conversion . . . . . . . . . . . . . . . . . . . . . . 5
2.2.2 Mixed Use of Both Representations . . . . . . . . . . 5
2.3 Using Data Types . . . . . . . . . . . . . . . . . . . . . 6
2.4 Including Binary Content . . . . . . . . . . . . . . . . . 6
2.5 Including Multiple iCalendar Objects . . . . . . . . . . . 7
2.6 Mapping Property Parameters to XML . . . . . . . . . . . . 7
2.7 Mapping VCALENDAR object Properties to XML . . . . . . . . 8
2.8 Mapping All Component Properties to XML . . . . . . . . . 9
2.9 Namespace . . . . . . . . . . . . . . . . . . . . . . . . 12
2.10 Emailing the iCalendar XML Representation . . . . . . . . 13
2.11 iCalendar XML Representation and File Systems . . . . . . 14
3. Example Usage . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1 A well-formed and valid iCalendar XML document . . . . . . 15
3.2 Including binary content in attachments . . . . . . . . . 15
3.3 iCalendar XML document with multiple iCalendar objects . . 17
3.4 Using the iCalendar namespace . . . . . . . . . . . . . . 18
3.5 Publish meeting information . . . . . . . . . . . . . . . 19
3.6 Publish transparent annual event . . . . . . . . . . . . . 19
3.7 Meeting invitation . . . . . . . . . . . . . . . . . . . . 20
3.8 Assign a to-do . . . . . . . . . . . . . . . . . . . . . . 20
3.9 Publish busy time . . . . . . . . . . . . . . . . . . . . 21
3.10 Request busy time . . . . . . . . . . . . . . . . . . . . 22
3.11 Issue a CAP command . . . . . . . . . . . . . . . . . . . 22
4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
6. Security Considerations . . . . . . . . . . . . . . . . . . . 25
7. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . 26
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 26
Intellectual Property and Copyright Statements . . . . . . . . 27
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1. Introduction
The Extended Markup Language (XML) as defined in [XML] is gaining
widespread attention as a "web friendly" syntax for representing and
exchanging documents and data on the Internet. This interest
includes requests for and discussion of possible document type
definitions (DTD) and name-space for IETF standard formats such as
that defined by [RFC 2445]. This memo defines how XML can be used to
represent iCalendar objects and does not specify a DTD as iCalendar
can be extended.
NOTE: The [RFC 2445] is the definitive reference for the definition
of iCalendar semantics. This memo only provides an alternative, XML
representation for the standard syntax defined in [RFC 2445]. This
memo does not introduce any semantics not already defined by [RFC
2445].
An attempt has been made to leverage the standard features of the XML
syntax in order to represent the component iCalendar semantics. For
example, strong data typing is specified using the XML notation
declaration. The element type attributes are used to represent many
of the calendar properties that provide a "global attribute"
capability in an iCalendar object. Binary content in the ATTACH
component property may either be specified through an external entity
reference to a non-XML binary content or may be included in the XML
document's content information, after first being encoding using the
BASE64 scheme of [RFC 2146].
The publication of XML version 1.0 was followed by the publication of
a World-wide Web Consortium (W3C) recommendation on "Namespaces in
XML". A XML name-space is a collection of names, identified by a
URI. In anticipation of the broader use of XML namespaces. Within
this memo the term "xCal" will mean the XML namespace usage as
described in this memo.
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2. Using XML For Representating iCalendar
XML is a simplified version of the text markup syntax defined by ISO
8879, Standard Generalized Markup Language (SGML). XML was published
as a proposed recommendation [XML] by the World-wide Web Consortium
(W3C) on February 10, 1998.
In iCalendar names can be in upper case, lower case, or mixed case.
In xCal the predefined iCaledars names will be represented in lower
case only as XML element and attribute names are case sensitive..
Values to properties and parameters that are user specified may be in
upper, lower, or mixed case.
All iCalendar component names will be represented in xCal as XML
element names in lower case. The "BEGIN" iCalendar component will be
represented in xCal as: .
All iCalendar property names will be represented in xCal as XML
element names in lower case.
All iCalendar parameter names will be represented in xCal as XML
attribute names in lower case.
All iCalendar predefined names that are used as values will be
represented in xCal in lower case.
This example:
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
BEGIN:VEVENT
DTSTART;TZID=US/Pacific:19970714T170000Z
DTEND;TZID=US/Pacific:19970715T035959Z
SUMMARY:Bastille Day Party
END:VEVENT
END:VCALENDAR
Is represented in xCal as:
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2.0
-//hacksw/handcal//NONSGML v1.0//EN
19970714T170000Z
19970715T035959Z
Bastille Day Party
2.1 XML Dependencies
This memo specifies the XML representation for the standard iCalendar
format defined by [RFC 2445]. There are no XML dependencies other
than the [XML] and the [XMLNS] recommendations.
2.2 Working With Standard and XML iCalendar Representations
This memo defines an alternative, XML representation for the standard
iCalendar format defined in [RFC 2445]. This alternative
representation provides the same semantics as that defined in the
standard format. It is the goal of this memo to allow all [RFC 2445]
extensions and modifications to be translated into and from this XML
format.
2.2.1 Conversion
The standard format can be converted to and from this XML format
without loss of any calendaring information. When the XML
representation was defined, every attempt was made to use existing
component, property and parameter naming conventions. This greatly
facilitates transformations between the two representations.
2.2.2 Mixed Use of Both Representations
As previously indicated, conversion between the standard and XML
representations of iCalendar is a straightforward process. In
addition, mixed use of both representations is also possible using
MIME objects.
With the use of the MIME multipart content-types, compound MIME
entities containing a mix of the standard and XML representations can
be specified. This capability is useful in applications where both
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representations might be encountered. In addition, this capability
demonstrates the isomeric nature of the two representations. XML
applications conforming to this specification MUST be able to
properly parse and process a MIME multipart entity containing the
MIME type associated with this iCalendar XML document type.
Internet applications conforming to this memo MUST only send the
iCalendar XML document in a "multipart/alternative" MIME entity that
also contains an equivalent iCalendar object in the standard format
defined by [RFC2445]. This restriction will guarantee that the
iCalendar object can also be processed by Internet applications that
only support the standard iCalendar representation.
2.3 Using Data Types
Strong "data typing" is an integral design principle to the iCalendar
format. Strong data typing in iCalendar means that the format type
for each property value is well known. Within [RFC 2445], the data
type is called the "value type". The standard format defined by [RFC
2445] specifies a default value type for each calendar and component
property. In addition, many of the property definitions allow for
the specification of alternate value types. This XML representation
continues this design principle.
Explicit value/data typing in the XML representation is specified
with the "value" attribute on each element type. XML documents
conforming to this memo need only specify the "value" attribute on
element types when the value needs to override the default value/data
type defined in the iCalendar specifications. The formal public
identifier for standard value types all have the common string format
of:
2.4 Including Binary Content
Binary content can be included in an iCalendar object with the
"ATTACH" component property. In the standard iCalendar format this
content may either be specified through an external entity reference,
using a URI value type, or maybe specified within the iCalendar
object, after first BASE64 encoding the content.
The XML representation for iCalendar also supports including binary
content in an iCalendar object with the "attach" element type. It
also supports either an external reference to the non-XML binary
content or inclusion of the binary content after first encoding the
binary information using the BASE64 encoding of [RFC 2045].
http://host.com/bin/foo.exe
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MIICajCC
AdOgAwIBAgICBEUwDQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05l
dHNjYXBlIENvbW11bmljYXR5z...and so on...IENvcnBvc==
2.5 Including Multiple iCalendar Objects
The iCalendar format has the capability for including multiple,
individual iCalendar objects in a single data stream. The XML
representation can support this also. Individual iCalendar objects
are specified by the "vcalendar" element type. One or more
"vcalendar" element types are permitted within the parent element
type, called "iCalendar". For example:
2.0
2.0
>
2.6 Mapping Property Parameters to XML
The property parameters defined in the standard iCalendar format are
represented in the XML representation as an attribute on element
types. The following table specifies some of the attribute name
corresponding to each property parameter. This is true for all
iCalendar object parameters defined in any iCalendar specification.
The property and paramater names will be all lower case as shown
below in the example:
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+----------------+----------------+
| Property | Attribute |
| Parameter Name | Name |
+----------------+----------------+
| ALTREP | altrep |
| CN | cn |
| CUTYPE | cutype |
| DELEGATED-FROM | delegated-from |
| DELEGATED-TO | delegated-to |
| DIR | dir |
| FMTTYPE | fmttype |
| FBTYPE | fbtype |
| LANGUAGE | language |
| MEMBER | member |
| PARTSTAT | partstat |
| RANGE | range |
| RELATED | related |
| RELTYPE | reltype |
| ROLE | role |
| RSVP | rsvp |
| SENT-BY | sent-by |
| TZID | tzid |
| VALUE | value |
| ..... | ..... |
+----------------+----------------+
2.7 Mapping VCALENDAR object Properties to XML
Calendar properties defined in the standard iCalendar format provide
information about an iCalendar object, as a whole. The calendar
properties are represented in the XML representation as element types
as shown in this example:
+---------------+-----------+------------+
| Calendar | Tag | Example |
| Property Name | Name | Usage |
+---------------+-----------+------------+
| CALSCALE | calscale | |
| METHOD | method | |
| VERSION | version | |
| PRODID | prodid | |
| ... | ... | <...> |
+---------------+-----------+------------+
The semantics for these are as specified for the corresponding
calendar property in [RFC 2445].
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In addition to these attributes, the "iCalendar" element type can
also have the following attributes:
+-----------+-----------+---------+----------------------------+
| Attribute | Attribute | Default | Description |
| Name | Type | Value | |
+-----------+-----------+---------+----------------------------+
| xmlns | CDATA | FIXED | Used to specify the default|
| | | | iCalendar XML name space. |
| xmlns: + | CDATA | FIXED | Used to specify the |
| | | | |
+-----------+-----------+---------+----------------------------+
The semantics of the "xmlns" attribute, and any attribute with
"xmlns:" as a prefix, is as specified in [XMLNS]. It is used to
declare a namespace in XML. It can be used to declare the xCal XML
namespace in a XML document with a document type other than the
iCalendar XML document type. The iCalendar XML document type MUST
only use element types from the iCalendar namespace. To specify the
iCalendar namespace, the attribute value for the "xmlns" and any
attribute with the prefix "xmlns:" MUST be:
"http://www.ietf.org/rfc/rfcXXXX.txt"
NOTE: This attribute value will be replaced with the URL
"http://www.ietf.org/rfc/rfcxxxx.txt", where "xxxx" is the RFC
number, when this memo is published as a RFC.
For example:
2.8 Mapping All Component Properties to XML
Component properties in the standard iCalendar format provide
calendar information about the calendar component. The component
properties defined in the standard iCalendar format are represented
in the XML representation as element types. The following tables
specify the element types corresponding to each of the properties in
the specified property category in lower case. Example:
Descriptive Component Properties
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+----------------+-------------+--------------+
| Component | Element | Example |
| Property Name | Name | Usage |
+----------------+-------------+--------------+
| ATTACH | attach | |
| CATEGORIES | categories | |
| CLASS | class | |
| COMMENT | comment | |
| DESCRIPTION | description | |
| GEO | geo | |
| LOCATION | location | |
| PERCENT | percent | |
| PRIORITY | priority | |
| RESOURCES | resources | |
| STATUS | status | |
| SUMMARY | summary | |
+----------------+-------------+--------------+
Date and Time Component Properties
+----------------+------------+
| Component | Element |
| Property Name | Name |
+----------------+------------+
| COMPLETED | completed |
| DTEND | dtend |
| DUE | due |
| DTSTART | dtstart |
| DURATION | duration |
| FREEBUSY | freebusy |
| TRANSP | transp |
+----------------+------------+
Time Zone Component Properties
+----------------+-------------+
| Component | Element |
| Property Name | Name |
+----------------+-------------+
| TZID | tzid |
| TZNAME | tzname |
| TZOFFSETFROM | tzoffsetfrom|
| TZOFFSETTO | tzoffsetto |
| TZURL | tzurl |
+----------------+-------------+
Relationship Component Properties
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+----------------+---------------+
| Component | Element |
| Property Name | Name |
+----------------+---------------+
| ATTENDEE | attendee |
| CONTACT | contact |
| ORGANIZER | organizer |
| RECURRENCE-ID | recurrence-id |
| RELATED-TO | related-to |
| URL | url |
| UID | uid |
+----------------+---------------+
Recurrence Component Properties
+----------------+------------+
| Component | Element |
| Property Name | Name |
+----------------+------------+
| EXDATE | exdate |
| EXRULE | exrule |
| RDATE | rdate |
| RRULE | rrule |
+----------------+------------+
Alarm Component Properties
+----------------+------------+
| Component | Element |
| Property Name | Name |
+----------------+------------+
| ACTION | action |
| REPEAT | repeat |
| TRIGGER | trigger |
+----------------+------------+
Change Management Component Properties
+----------------+---------------+
| Component | Element |
| Property Name | Name |
+----------------+---------------+
| CREATED | created |
| DTSTAMP | dtstamp |
| LAST-MODIFIED | last-modified |
| SEQUENCE | sequence |
+----------------+---------------+
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Miscellaneous Component Properties
+----------------+----------------+
| Component | Element |
| Property Name | Name |
+----------------+----------------+
| REQUEST-STATUS | request-status |
+----------------+----------------+
...
...
The [RFC 2445] specification specifies that the equivalent component
properties to the "comment", "description", "location", "summary" and
"contact" element types can contain formatted content, such as is
specified by multiple lines of text. In such cases, the formatted
text should be specified in as CDATA Section content. The CDATA
section specifies arbitrary character data that is not meant to be
interpretted. It is not scanned for markup by the XML parser. The
CDATA Section in these element types MUST NOT contain markup or other
such alternate representation of the property value. The "altrep"
attribute is used to reference any such alternate representation for
the textual content of these element types.
2.9 Namespace
[XMLNS] defines "Namespaces in XML" to be a collection of names,
identified by a URI, which are used in XML documents as element types
and attribute names. The [XML] specification does not include a
definition for namespaces, but does set down some guidelines for
experimental naming of namespaces.
XML namespaces allow multiple markup vocabulary in a single document.
Considering the utility of the iCalendar properties in other
applications.
This memo defines the value that MUST be used in non-iCalendar XML
documents that reference element types or attribute lists from the
iCalendar namespace.
The following is an example of a well-formed but invalid "xdoc"
document type that includes elements and attribute lists from the
iCalendar namespace:
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2.10 Emailing the iCalendar XML Representation
It is expected that iCalendar XML documents will need to be sent over
SMTP/MIME email. The "text/xml" and "application/xml" content-types
have been registered for XML documents. However, use of these
content-type definitions present some problems for XML applications
such as calendaring and scheduling.
The "text/xml" and "application/xml" content-type definitions do not
provide for any header field parameters to identify the type of XML
document contained in the MIME entity. This means that a recipient
mail user agent must (MUA) open up each "text/xml" or "application/
xml" content in order to determine what object handler is needed to
process the information. To a MUA, all XML documents look like just
plain "text/xml" or "application/xml" content.
Additionally, it is accepted practice for a MUA to provide iconic
feedback to the user for individual content-types that are supported
by the MUA. For example, not only would feedback be provided for a
calendaring and scheduling content. Some further unique
identification would also be provided for each different scheduling
message; such as a meeting invitation, response to an invitation,
reschedule notice, cancellation notice, etc. In such cases,
acceptable performance by the MUA is dependent on the existence of
header field information, such as it provided in the definition of
the "text/calendar" content-type by [RFC 2445].
Internet application conforming to this memo MUST identify iCalendar
XML documents with the experimental content-type "application/
calendar+xml". The content-type header field SHOULD also contain a
"component" and "method" parameter to clearly identify a comma-
separated list of components and the singular method used in the
iCalendar XML document. For example, an iCalendar XML document
specifying a REQUEST for a VEVENT and VTODO would be specified with
the following content-type header field:
content-type:application/calendar+xml;method=REQUEST;component=VEVENT,VTODO
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The content-type can also include the "optinfo" parameter to specify
any other optional iCalendar information. The semantics of these
content-type parameters is as defined in [RFC 2445].
Internet applications conforming to this memo MUST only send the
iCalendar XML document in a "multipart/alternative" MIME entity that
also contains an equivalent iCalendar object in the standard format
defined by [RFC 2445]. This restrict will guarantee that the
iCalendar object can also be processed by internet applications that
only support the standard iCalendar format.
An XML application supporting the iCalendar XML document type MUST be
able to receive and properly process the "application/calendar+xml"
document contained within a "multipart" message content-type.
2.11 iCalendar XML Representation and File Systems
The iCalendar XML documents will be stored in file systems. The
accepted practice for file extensions for XML documents is the text
"XML". However, in order to uniquely identify iCalendar XML
documents for file association with applications that can directly
process this document type, it is RECOMMENDED that the file extension
be the text "XCS".
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3. Example Usage
The following sections provide various examples of iCalendar XML
documents.
3.1 A well-formed and valid iCalendar XML document
The following is a simple example of a iCalendar XML document. This
document is both a well-formed and valid XML document. The iCalendar
object specifies an appointment.
PUBLISH
2.0
-//HandGen//NONSGML vGen v1.0//EN
19981116T150000@cal10.host.com
19981116T145958Z
Project XYZ Review
Conference Room 23A
19981116T163000Z
19981116T190000Z
1998-ABC Corp-1234
Appointment,Work
3.2 Including binary content in attachments
The following is an example of a valid iCalendar XML document that
also includes an external reference to an attachment. The iCalendar
object specifies a meeting invitation with an attachment.
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REQUEST
2.0
-//HandGen//NONSGML vGen v1.0//EN
19981211T133000@cal1.host.com
19981211T132928Z
cap://host.com/jim
19981212T150000Z
19981212T160000Z
Department Meeting
Conference Room 23A
jim@host.com
MAILTO:joe@host.com
MAILTO:steve@host.com
http://host.com/pub/photos/holiday.jpg
The following is an example of a well-formed and valid iCalendar XML
document that includes an attachment as inline binary content. The
iCalendar object specifies a meeting invitation with an attachment.
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REQUEST
2.0
-//HandGen//NONSGML vGen v1.0//EN
19981211T133000@cal1.host.com
19981211T132928Z
MAILTO:jim@host.com
19981212T150000Z
19981212T160000Z
Department Meeting
Conference Room 23A
MAILTO:jim@host.com
MAILTO:joe@host.com
MAILTO:steve@host.com
MIICajCCAdOgAwIBAgI
CBEUwDQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXB
lIEjYXRpb25z...and so on...IENvcnBvc==
3.3 iCalendar XML document with multiple iCalendar objects
The following is an example of a well-formed and valid iCalendar XML
document that includes more than one iCalendar object.
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PUBLISH
2.0
-//HandGen//NONSGML vGen v1.0//EN
19981009T233000@cal1.host.com
19981009T232928Z
19981010T000000Z
19981010T235959Z
Register for conference
2
2.0
-//HandGen//NONSGML vGen v1.0//EN
PUBLISH
19981009T233010@cal1.host.com
19981009T233000Z
19981120T133000Z
19981122T183000Z
IT Conference
Downtowner Hotel
3.4 Using the iCalendar namespace
The following is an example of a snippet of a XML document that
includes elements from the iCalendar name-space.
19981123T133000Z
19981123T203000Z
1234567
999.99
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3.5 Publish meeting information
The following is a snippet of an iCalendar XML document that
publishes information about a meeting.
2.0
-//hacksw/handcal//NONSGML 1.0//EN
PUBLISH
19970901T130000Z-123401@host.com
19970901T130000Z
19970903T163000Z
19970903T190000Z
Annual Employee Review
PRIVATE
Business,Human Resources
3.6 Publish transparent annual event
The following is a snippet of an iCalendar XML document that
publishes information about an annually repeating event that is
transparent to busy time searches.
2.0
PUBLISH
19990101T125957Z-123403@host.com
19990101T130000Z
19991102
Our Blissful Anniversary
CONFIDENTIAL
TRANSPARENT
Anniversary,Personal,Special Occasion
FREQ=YEARLY
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3.7 Meeting invitation
The following is a snippet of an iCalendar XML document that
specifies an invitation for a meeting. The meeting occurs on the
first Monday of each year for five years.
REQUEST
2.0
-//hacksw/handcal//NONSGML 1.0//EN
19981220T130000Z-123403@host.com
19981220T130050Z
MAILTO:corprel@host.com
19990104T140000Z
19990104T220000Z
Annual Stockholders Meeting
One Corporate Drive, Wilmington, DL
MAILTO:mrbig@host.com
CAP:host.com/stockholders
Business,Meeting,Special Occasion
FREQ=YEARLY;COUNT=5;BYDAY=1MO
3.8 Assign a to-do
The following is a snippet of an iCalendar XML document for a to-do.
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REQUEST
2.0
-//hacksw/handcal//NONSGML 1.0//EN
19990104T133402@ical1.host.com
19990104T133410Z
19990104
19990129
MAILTO:dboss@host.com
Periodic Self Review
Complete your self review.
Contact me if you questions.
1
CONFIDENTIAL
CAP:dilbert@host.com
3.9 Publish busy time
The following is an iCalendar XML document that publishes busy time
information. The default value for the "method" attribute is
"PUBLISH" and does not need to be specified in this example.
2.0
-//hacksw/handcal//NONSGML 1.0//EN
19980313T133000@ical1.host.com
19990104T133010Z
CAP:host.com/jsmith
19980313T141711Z
19980410T141711Z
jsmith.ifb
19980314T233000Z/19980315T003000Z
19980316T153000Z/19980316T163000Z
19980318T030000Z/19980318T040000Z
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3.10 Request busy time
The following is a snippet of an iCalendar XML document that requests
a calendar user's busy time information.
REQUEST
2.0
-//hacksw/handcal//NONSGML 1.0//EN
19970901T083000@ical1.host.com
19970901T083000Z
MAILTO:jane_doe@host1.com
19971015T050000Z
19971016T050000Z
MAILTO:john_public@host2.com
3.11 Issue a CAP command
The following is a snippet of an iCalendar XML document that issues a
CAP command to delete a UID.
2.0
-//hacksw/handcal//NONSGML 1.0//EN
relcalid-22
DELETE
SELECT VEVENT FROM VAGENDA WHERE UID = 'abcd12345'
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4. Acknowledgments
The following have participated in the drafting and discussion of
this memo:
Greg FitzPatrick, Charles Goldfarb, Paul Hoffman, Lisa Lippert,
Thomas Rowe.
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5. IANA Considerations
TODO - registration if application/calendar+xml
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6. Security Considerations
CDATA Sections - - A XML iCalendar document may contain CDATA
sections to represent content for specific element types. The CDATA
section specifies arbitrary character data that is not meant to be
interpretted. It is not scanned by the XML parser for markup. While
this memo restricts that any CDATA section MUST NOT contain markup or
other such alternate representation for the property value, in
general, CDATA section from a non-conformant implementation can
contain content such as HTML markup. HTML text can be used to invoke
programs. Implementors should be aware that this may leave an
implementation open to malicious attack that might occur as a result
of executing the markup in the CDATA section.
PROCEDURAL ALARMS - - A XML iCalendar document can be created that
contains a "VEVENT" and "VTODO" calendar component with "VALARM"
calendar components. The "VALARM" calendar component can be of type
PROCEDURE and can have an attachment containing some sort of
executable program. Implementations that incorporate these types of
alarms are subject to any virus or malicious attack that might occur
as a result of executing the attachment.
ATTACHMENTS - - A XML iCalendar document can include references to
Uniform Resource Locators that can be programmed resources.
Implementers and users of this memo should be aware of the network
security implications of accepting and parsing such information.
In addition, the security considerations observed by implementations
of electronic mail systems should be followed for this memo.
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7. Bibliography
[FPI] F. Dawson, "iCalendar Formal Public Identifier", Internet
Draft,
http://www.internic.net/internet-drafts/draft-calsch-icalfpi-00.txt,
September 1998.
[ISO9070] "Information Technology_SGML Support Facilities_
Registration Procedures for Public Text Owner Identifiers", ISO/IEC
9070, Second Edition, International Organization for Standardization,
April 1991.
[RFC 2045] N. Freed, N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) - Part One: Format of Internet Message Bodies", RFC
2045, November 1996.
[RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, http://www.ietf.org/rfc/rfc2119.txt,
March 1997.
[RFC 2445] F. Dawson and D. Stenerson, "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)", RFC 2445,
http://www.ietf.org/rfc/rfc2445.txt, November 1998.
[XML] "Extensible Markup Language (XML)", Worldwide Web Consortium,
http://www.w3.org/TR/1998/REC-xml-19980210, February 1998.
[XML] "Extensible Markup Language (XML)", Worldwide Web Consortium,
http://www.w3.org/TR/1998/REC-xml-19980210, February 1998.
Author's Address
Doug Royer
INET-Consulting.com
267 Kentlands Blvd., #3041
Gaithersburg, MD 20878
US
Phone: (208)881-0380
Email: doug@royer.com
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