Network Working Group C. Daboo
Internet-Draft Apple, Inc.
Intended status: Standards Track M. Douglass
Expires: December 6, 2009 RPI
S. Lees
Microsoft
June 4, 2009
iCalendar XML Representation
draft-daboo-et-al-icalendar-in-xml-00
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Abstract
This specification defines a format for representing iCalendar data
in XML.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Converting from iCalendar to XML . . . . . . . . . . . . . . . 4
3.1. Pre-processing . . . . . . . . . . . . . . . . . . . . . . 4
3.2. iCalendar stream (2445bis section 3.4) . . . . . . . . . . 4
3.3. Components (2445bis section 3.6) . . . . . . . . . . . . . 6
3.4. Properties (2445bis section 3.5) . . . . . . . . . . . . . 6
3.4.1. Special Cases for Properties . . . . . . . . . . . . . 8
3.4.1.1. Multi-valued Properties . . . . . . . . . . . . . 8
3.4.1.2. GEO Property . . . . . . . . . . . . . . . . . . . 9
3.4.1.3. REQUEST-STATUS Property . . . . . . . . . . . . . 9
3.5. Parameters (2445bis section 3.4) . . . . . . . . . . . . . 9
3.5.1. VALUE parameter . . . . . . . . . . . . . . . . . . . 10
3.6. Values (2445bis section 3.3) . . . . . . . . . . . . . . . 11
3.6.1. Binary (2445bis section 4.3.1) . . . . . . . . . . . . 11
3.6.2. Boolean (2445bis section 4.3.2) . . . . . . . . . . . 11
3.6.3. Calendar User Address (2445bis section 4.3.3) . . . . 11
3.6.4. Date (2445bis section 4.3.4) . . . . . . . . . . . . . 11
3.6.5. Date-Time (2445bis section 4.3.5) . . . . . . . . . . 12
3.6.6. Duration (2445bis section 4.3.6) . . . . . . . . . . . 12
3.6.7. Float (2445bis section 4.3.7) . . . . . . . . . . . . 12
3.6.8. Integer (2445bis section 4.3.8) . . . . . . . . . . . 12
3.6.9. Period of Time (2445bis section 4.3.9) . . . . . . . . 13
3.6.10. Recurrence Rule (2445bis section 4.3.10) . . . . . . . 13
3.6.11. Text (2445bis section 4.3.11) . . . . . . . . . . . . 13
3.6.12. Time (2445bis section 4.3.12) . . . . . . . . . . . . 13
3.6.13. URI (2445bis section 4.3.13) . . . . . . . . . . . . . 13
3.6.14. UTC Offset (2445bis section 4.3.14) . . . . . . . . . 13
3.7. Extensions . . . . . . . . . . . . . . . . . . . . . . . . 14
4. Converting from XML into iCalendar . . . . . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6.1. Namespace Registration . . . . . . . . . . . . . . . . . . 14
6.2. Media Type . . . . . . . . . . . . . . . . . . . . . . . . 15
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
8. Normative References . . . . . . . . . . . . . . . . . . . . . 16
Appendix A. Relax NG Schema . . . . . . . . . . . . . . . . . . . 16
Appendix B. XML Stylesheet for conversion to iCalendar . . . . . 40
Appendix C. Example . . . . . . . . . . . . . . . . . . . . . . . 40
C.1. iCalendar Data . . . . . . . . . . . . . . . . . . . . . . 40
C.2. XML Data . . . . . . . . . . . . . . . . . . . . . . . . . 41
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1. Introduction
The iCalendar data format [I-D.ietf-calsify-rfc2445bis] is a widely
deployed interchange format for calendaring and scheduling data.
While many applications and services consume and generate calendar
data, iCalendar is a specialized format that requires its own parser/
generator. In contrast, XML-based formats are widely used for
interoperability between applications, and the many tools that
generate, parse, and manipulate XML make it easier to work with than
iCalendar.
The purpose of this specification is to define an XML format that
allows iCalendar data to be converted to XML, and then back to
iCalendar, without losing any semantic meaning in the data. Anyone
creating XML calendar data according to this specification will know
that their data can be converted to a valid iCalendar representation
as well.
Several key design decisions have been made:
Round-tripping: i.e., converting an iCalendar instance to XML and
back will give the same result as the starting point.
Make the conversion process as simple as possible.
Make it easy to work with the XML without needing to re-parse it.
It is worth explaining the rationale behind this decision. One
result is that this specification breaks up date/time values from
iCalendar into separate year, month, day, hour, minute, and second
elements. By separating the values into different elements, it
becomes much easier to transform or query over the resulting XML.
For instance, given a set of xCal elements representing events, it
is easy to find the events that start at a particular time or in a
particular year, month, or day. Given a date / time value in the
xCal format described here, it would be easy to transform it to
HTML while removing unneeded sub-elements; no additional parsing
is needed.
Preserve the semantics of the iCalendar data. This decision is
important: the semantics of iCalendar is preserved in the XML so a
full understanding of iCalendar is required in order to actually
use the data, whether it be in the iCalendar or XML formats.
2. Conventions Used in This Document
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 [RFC2119].
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When XML element types in the namespace
"urn:ietf:params:xml:ns:icalendar" are referenced in this document
outside of the context of an XML fragment, the string "ICAL:" will be
prefixed to the element types.
Some examples in this document contain "partial" XML documents used
for illustrative purposes. In these examples, three periods "..."
are used to indicate a portion of the document that has been removed
for compactness.
3. Converting from iCalendar to XML
This section describes how iCalendar data is converted to XML using a
simple, predictable mapping between the iCalendar data model and XML
elements.
3.1. Pre-processing
iCalendar data uses a line folding mechanism to limit lines of data
to a maximum line length (typically 72 characters) to ensure maximum
likelihood of preserving data integrity as it is transported via
various means (e.g., email) - see Section 3.1 of
[I-D.ietf-calsify-rfc2445bis].
Prior to converting iCalendar data into XML all folded lines MUST be
unfolded.
iCalendar data uses an "escape" character sequence for text values
and parameter values. When such text elements are converted into XML
the escaping MUST be removed.
iCalendar uses a base64 encoding for binary data. The base64
encoding MUST remain when converted to XML.
3.2. iCalendar stream (2445bis section 3.4)
iCalendar has a well defined object model for its data that makes
mapping to XML a simple process of following a set of rules for
mapping the various object model types into XML elements.
At the top-level of the iCalendar object model is an "iCalendar
stream". This object encompasses multiple "iCalendar objects". In
XML, the entire stream is contained in the root ICAL:icalendar XML
element.
Example:
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...
An iCalendar stream can contain one or more iCalendar objects. Each
iCalendar object, delimited by BEGIN:VCALENDAR and END:VCALENDAR, is
enclosed by the ICAL:vcalendar XML element.
Example:
...
iCalendar objects are comprised of a set of "components",
"properties", "parameters" and "values". A "component" can contain
other "components" or "properties". A "property" has a value and
optionally a set of "parameters".
In XML, "components" are contained within an ICAL:components XML
element. With that element, another ICAL:components element could
appear (representing components nested within components) or the
ICAL:properties XML element could appear. ICAL:properties is used to
encapsulate iCalendar properties.
Each iCalendar property will be mapped to its own XML element as
described below. Within each of these elements there is an optional
ICAL:parameters XML element used to encapsulate any iCalendar
parameters. Additionally there will be one or more XML elements
representing the value of the iCalendar property.
Example:
...
...
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+------------------+----------------+------------------+
| Item | XML element | XML Definition |
+------------------+----------------+------------------+
| iCalendar Stream | ICAL:icalendar | Appendix A # 3.4 |
| VCALENDAR | ICAL:vcalendar | Appendix A # 3.6 |
+------------------+----------------+------------------+
3.3. Components (2445bis section 3.6)
Each calendar component in the VCALENDAR object, delimited by BEGIN
and END, will be converted to an enclosing XML element with the same
name, but in lowercase:
+-----------+----------------+--------------------+
| Component | XML element | XML Definition |
+-----------+----------------+--------------------+
| VEVENT | ICAL:vevent | Appendix A # 3.6.1 |
| VTODO | ICAL:vtodo | Appendix A # 3.6.2 |
| VJOURNAL | ICAL:vjournal | Appendix A # 3.6.3 |
| VFREEBUSY | ICAL:vfreebusy | Appendix A # 3.6.4 |
| VTIMEZONE | ICAL:vtimezone | Appendix A # 3.6.5 |
| STANDARD | ICAL:standard | Appendix A # 3.6.5 |
| DAYLIGHT | ICAL:daylight | Appendix A # 3.6.5 |
| VALARM | ICAL:valarm | Appendix A # 3.6.6 |
+-----------+----------------+--------------------+
3.4. Properties (2445bis section 3.5)
iCalendar properties , whether they apply to the VCALENDAR object or
to the components, are handled in a consistent way.
iCalendar properties are enclosed in the XML element ICAL:properties.
Each invidivual iCalendar property is represented in XML by an
element of the same name as the iCalendar property, but in lowercase.
For example, the CALSCALE property is represented in XML by the ICAL:
calscale element.
Example:
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...
...
...
...
Each property can contain an ICAL:parameters XML element
encapsulating any iCalendar parameters associated with the iCalendar
property.
Each property will contain one or more "value" XML elements as
described below representing the value of the iCalendar property.
+------------------+-----------------------+-----------------------+
| Property | XML element | XML Definition |
+------------------+-----------------------+-----------------------+
| CALSCALE | ICAL:calscale | Appendix A # 3.7.1 |
| METHOD | ICAL:method | Appendix A # 3.7.2 |
| PRODID | ICAL:prodid | Appendix A # 3.7.3 |
| VERSION | ICAL:version | Appendix A # 3.7.4 |
| ATTACH | ICAL:attach | Appendix A # 3.8.1.1 |
| CATEGORIES | ICAL:categories | Appendix A # 3.8.1.2 |
| CLASS | ICAL:class | Appendix A # 3.8.1.3 |
| COMMENT | ICAL:comment | Appendix A # 3.8.1.4 |
| DESCRIPTION | ICAL:description | Appendix A # 3.8.1.5 |
| GEO | ICAL:geo | Appendix A # 3.8.1.6 |
| LOCATION | ICAL:location | Appendix A # 3.8.1.7 |
| PERCENT-COMPLETE | ICAL:percent-complete | Appendix A # 3.8.1.8 |
| PRIORITY | ICAL:priority | Appendix A # 3.8.1.9 |
| RESOURCES | ICAL:resources | Appendix A # 3.8.1.10 |
| STATUS | ICAL:status | Appendix A # 3.8.1.11 |
| SUMMARY | ICAL:summary | Appendix A # 3.8.1.12 |
| COMPLETED | ICAL:completed | Appendix A # 3.8.2.1 |
| DTEND | ICAL:dtend | Appendix A # 3.8.2.2 |
| DUE | ICAL:due | Appendix A # 3.8.2.3 |
| DTSTART | ICAL:dtstart | Appendix A # 3.8.2.4 |
| DURATION | ICAL:duration | Appendix A # 3.8.2.5 |
| FREEBUSY | ICAL:freebusy | Appendix A # 3.8.2.6 |
| TRANSP | ICAL:transp | Appendix A # 3.8.2.7 |
| TZID | ICAL:tzid | Appendix A # 3.8.3.1 |
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| TZNAME | ICAL:tzname | Appendix A # 3.8.3.2 |
| TZOFFSETFROM | ICAL:tzoffsetfrom | Appendix A # 3.8.3.3 |
| TZOFFSETTO | ICAL:tzoffsetto | Appendix A # 3.8.3.4 |
| TZURL | ICAL:tzurl | Appendix A # 3.8.3.5 |
| ATTENDEE | ICAL:attendee | Appendix A # 3.8.4.1 |
| CONTACT | ICAL:contact | Appendix A # 3.8.4.2 |
| ORGANIZER | ICAL:organizer | Appendix A # 3.8.4.3 |
| RECURRENCE-ID | ICAL:recurrence-id | Appendix A # 3.8.4.4 |
| RELATED-TO | ICAL:related-to | Appendix A # 3.8.4.5 |
| URL | ICAL:url | Appendix A # 3.8.4.6 |
| UID | ICAL:uid | Appendix A # 3.8.4.7 |
| EXDATE | ICAL:exdate | Appendix A # 3.8.5.1 |
| RDATE | ICAL:rdate | Appendix A # 3.8.5.2 |
| RRULE | ICAL:rrule | Appendix A # 3.8.5.3 |
| ACTION | ICAL:action | Appendix A # 3.8.6.1 |
| REPEAT | ICAL:repeat | Appendix A # 3.8.6.2 |
| TRIGGER | ICAL:trigger | Appendix A # 3.8.6.3 |
| CREATED | ICAL:created | Appendix A # 3.8.7.1 |
| DTSTAMP | ICAL:dtstamp | Appendix A # 3.8.7.2 |
| LAST-MODIFIED | ICAL:last-modified | Appendix A # 3.8.7.3 |
| SEQUENCE | ICAL:sequence | Appendix A # 3.8.7.4 |
| REQUEST-STATUS | ICAL:request-status | Appendix A # 3.8.8.3 |
+------------------+-----------------------+-----------------------+
3.4.1. Special Cases for Properties
Some properties in iCalendar can contain "structured" value data.
This includes lists of "standard" value types, as well as values with
specific "fields". In XML, these "structured" values are represented
as separate XML elements in various ways for ease of processing using
standard XML tools.
3.4.1.1. Multi-valued Properties
The following iCalendar properties can have values that consist of a
list of "standard" iCalendar values separated by a specific
delimiter. In XML these properties are represented by an XML element
that contains multiple "value" elements (Section 3.6).
+------------+-----------------+-----------------------+
| Property | XML element | XML Definition |
+------------+-----------------+-----------------------+
| CATEGORIES | ICAL:categories | Appendix A # 3.8.1.2 |
| RESOURCES | ICAL:resources | Appendix A # 3.8.1.10 |
| FREEBUSY | ICAL:freebusy | Appendix A # 3.8.2.6 |
| EXDATE | ICAL:exdate | Appendix A # 3.8.5.1 |
| RDATE | ICAL:rdate | Appendix A # 3.8.5.2 |
+------------+-----------------+-----------------------+
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3.4.1.2. GEO Property
In iCalendar, the GEO property value is defined as a semi-colon
separated list of two FLOAT values, the first representing latitude
and the second longitude.
In XML, the value for the ICAL:geo element is represented by an ICAL:
value element containing an ICAL:latitude element and an ICAL:
longitude element, each of which contain text values representing the
FLOAT values. See Appendix A # 3.8.1.6.
3.4.1.3. REQUEST-STATUS Property
In Icalendar, the REQUEST-STATUS property value is defined as a semi-
colon separated list of two or three TEXT values. The first
represents a code, the second a description, and the third (optional)
additional data.
In XML, the value for the ICAL:request-status element is represented
by an ICAL:value element containing an ICAL:code element, and iCAL:
description element, and optionally and ICAL:data element, each of
which contain the corresponding TEXT values. See Appendix A #
3.8.8.3.
3.5. Parameters (2445bis section 3.4)
iCalendar parameters are enclosed in the XML element ICAL:parameters
which optionally occurs once in each property XML element.
Each invidivual iCalendar parameter is represented in XML by an
element of the same name as the iCalendar parameter, but in
lowercase. For example, the PARTSTAT parameter is represented in XML
by the ICAL:partstat element.
Example:
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...
...
NEEDS-ACTION
...
Each parameter contains either text, or one or more child XML
elements representing iCalendar value types.
+----------------+---------------------+---------------------+
| Parameter | XML element | XML Definition |
+----------------+---------------------+---------------------+
| ALTREP | ICAL:altrep | Appendix A # 3.2.1 |
| CN | ICAL:cn | Appendix A # 3.2.2 |
| CUTYPE | ICAL:cutype | Appendix A # 3.2.3 |
| DELEGATED-FROM | ICAL:delegated-from | Appendix A # 3.2.4 |
| DELEGATED-TO | ICAL:delegated-to | Appendix A # 3.2.5 |
| DIR | ICAL:dir | Appendix A # 3.2.6 |
| ENCODING | ICAL:encoding | Appendix A # 3.2.7 |
| FMTTYPE | ICAL:fmttype | Appendix A # 3.2.8 |
| FBTYPE | ICAL:fbtype | Appendix A # 3.2.9 |
| LANGUAGE | ICAL:language | Appendix A # 3.2.10 |
| MEMBER | ICAL:member | Appendix A # 3.2.11 |
| PARTSTAT | ICAL:partstat | Appendix A # 3.2.12 |
| RANGE | ICAL:range | Appendix A # 3.2.13 |
| RELATED | ICAL:related | Appendix A # 3.2.14 |
| RELTYPE | ICAL:reltype | Appendix A # 3.2.15 |
| ROLE | ICAL:role | Appendix A # 3.2.16 |
| RSVP | ICAL:rsvp | Appendix A # 3.2.17 |
| SENT-BY | ICAL:sent-by | Appendix A # 3.2.18 |
| TZID | ICAL:tzid | Appendix A # 3.2.19 |
+----------------+---------------------+---------------------+
3.5.1. VALUE parameter
iCalendar defines a VALUE parameter (Section 3.2.20 of
[I-D.ietf-calsify-rfc2445bis]. This parameter is not mapped to an
XML element. Instead, the value type is handled by having different
XML elements for each value, and these appear inside of ICAL:property
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elements. Thus, when converting from iCalendar to XML, any VALUE
parameters are skipped. When converting from XML into iCalendar, the
appropriate VALUE parameter MUST be included in the iCalendar
property if the value type is not the default value type for that
property.
3.6. Values (2445bis section 3.3)
iCalendar value types are mapped into XML elements with a matching
name in all lowercase. In some cases, iCalendar defines "structured"
values and these are mapped into separate child elements in each
value element, as described by the simple DTD definitions below.
Some properties allow for multiple values and these are represented
by separate matching value XML elements.
3.6.1. Binary (2445bis section 4.3.1)
Description: iCalendar BINARY property values are represented by the
ICAL:binary XML element. The content of the element is base64
encoded data. Whitespace MAY be inserted into the data at any
point to "wrap" the data to reasonable line lengths. When
converting back to iCalendar the whitespace MUST first be removed.
XML Definition: Appendix A # 3.3.1
3.6.2. Boolean (2445bis section 4.3.2)
Description: iCalendar BOOLEAN property values are represented by
the ICAL:boolean XML element. The content of the element is text
containing either of "TRUE" or "FALSE".
XML Definition: Appendix A # 3.3.2
3.6.3. Calendar User Address (2445bis section 4.3.3)
Description: iCalendar CAL-ADDRESS property values are represented
by the ICAL:cal-address XML element. The content of the element
is a URI.
XML Definition: Appendix A # 3.3.3
3.6.4. Date (2445bis section 4.3.4)
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Description: iCalendar DATE property values are represented by the
ICAL:date XML element. The content of the element is three child
elements representing the year, month and day values in the date.
XML Definition: Appendix A # 3.3.4
3.6.5. Date-Time (2445bis section 4.3.5)
Description: iCalendar DATE-TIME property values are represented by
the ICAL:date-time XML element. The content of the element is six
child elements representing the year, month, day, hour, minute and
second values in the date-time. In addition, an XML attribute is
used to indicate whether the date-time value represents a UTC
based date-time (represented by a trailing "Z" in the iCalendar
value).
XML Definition: Appendix A # 3.3.5
3.6.6. Duration (2445bis section 4.3.6)
Description: iCalendar DURATION property values are represented by
the ICAL:duration XML element. The content of the element is
various child elements representing the possible combinations of
week, day, hour, minute and second values. In addition, an XML
attribute is used to indicate whether the duration value
represents a positive or negative offset.
XML Definition: Appendix A # 3.3.6
3.6.7. Float (2445bis section 4.3.7)
Description: iCalendar FLOAT property values are represented by the
ICAL:float XML element. The content of the element is a text
representation of a floating point number.
XML Definition: Appendix A # 3.3.7
3.6.8. Integer (2445bis section 4.3.8)
Description: iCalendar INTEGER property values are represented by
the ICAL:integer XML element. The content of the element is a
text representation of an integer number.
XML Definition: Appendix A # 3.3.8
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3.6.9. Period of Time (2445bis section 4.3.9)
Description: iCalendar PERIOD property values are represented by the
ICAL:period XML element. The content of the element is two child
elements representing the start date-time and end date-time or
positive duration.
XML Definition: Appendix A # 3.3.9
3.6.10. Recurrence Rule (2445bis section 4.3.10)
Description: iCalendar RECUR property values are represented by the
ICAL:recur XML element. The content of the element is child
elements representing the various components of a recurrence rule.
XML Definition: Appendix A # 3.3.10
3.6.11. Text (2445bis section 4.3.11)
Description: iCalendar TEXT property values are represented by the
ICAL:text XML element. The content of the element is simple text.
XML Definition: Appendix A # 3.3.11
3.6.12. Time (2445bis section 4.3.12)
Description: iCalendar TIME property values are represented by the
ICAL:time XML element. The content of the element is three child
elements representing the hour, minute and second values in the
time. In addition, an XML attribute is used to indicate whether
the time value represents a UTC based time (represented by a
trailing "Z" in the iCalendar value).
XML Definition: Appendix A # 3.3.12
3.6.13. URI (2445bis section 4.3.13)
Description: iCalendar URI property values are represented by the
ICAL:uri XML element. The content of the element is a URI.
XML Definition: Appendix A # 3.3.13
3.6.14. UTC Offset (2445bis section 4.3.14)
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Description: iCalendar UTC-OFFSET property values are represented by
the ICAL:utc-offset XML element. The content of the element is
two or three child elements representing the hour, minute and
(optional) second values in the UTC offset. In addition, an XML
attribute is used to indicate whether the offset value represents
a positive or negative offset.
XML Definition: Appendix A # 3.3.14
3.7. Extensions
iCalendar extension properties and parameters (ones with an "X-"
prefix in their name) are handled in the same way as other properties
and parameters: the property or parameter is represented by an XML
element with the same name, but in lowercase. e.g., the "X-FOO"
property in iCalendar turns into the ICAL:x-foo element in XML.
4. Converting from XML into iCalendar
When converting from XML back to iCalendar, any elements in the XML
that are not in the "urn:ietf:params:xml:ns:icalendar" namespace MUST
be ignored.
When converting component, property and parameter values, the names
SHOULD be converted to uppercase. Although iCalendar names are case
insensitive, common practice is to keep them all uppercase following
the actual definitions in [I-D.ietf-calsify-rfc2445bis].
Backslash escaping and line folding MUST be applied to the resulting
iCalendar data as required by [I-D.ietf-calsify-rfc2445bis].
5. Security Considerations
This extension does not introduce any new security concerns than
those already described in iCalendar.
6. IANA Considerations
This document uses one new URN to identify a new XML namespace, and
one new media type. The URN conforms to a registry mechanism
described in [RFC3688].
6.1. Namespace Registration
Registration request for the iCalendar namespace:
URI: urn:ietf:params:xml:ns:icalendar
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Registrant Contact: See the "Authors' Addresses" section of this
document.
XML: None. Namespace URIs do not represent an XML specification.
6.2. Media Type
This section defines the MIME media type for use with iCalendar in
XML data.
To: ietf-types@iana.org
Subject: Registration of media type application/xml+calendar
Type name: application
Subtype name: xml+calendar
Required parameters: none
Optional parameters: charset, method, component and optinfo as
defined for the text/calendar media type
Encoding considerations: iCalendar data is typically UTF-8 and thus
the XML representation will follow that. As a result, for 7-bit
transports, data in UTF-8 MUST be encoded in quoted-printable or
base64.
Security considerations: See Section 5.
Interoperability considerations: This media type provides an
alternative syntax to iCalendar data based on XML.
Published specification: This specification.
Applications which use this media type: Applications that currently
make use of the text/calendar media type can use this as an
alternative.
Additional information:
Magic number(s): None
File extension(s): XML data should use "xml" as the file
extension.
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Macintosh file type code(s): None specified.
Person & email address to contact for further information: See the
"Author's Address" section of this document.
Intended usage: COMMON
Restrictions on usage: There are no restrictions on where this media
type can be used.
Author: See the "Author's Address" section of this document.
Change controller: IETF
7. Acknowledgments
This specification originated from the work of the XML technical
committee of the Calendaring and Scheduling Consortium.
8. Normative References
[I-D.ietf-calsify-rfc2445bis] Desruisseaux, B., "Internet
Calendaring and Scheduling Core Object
Specification (iCalendar)",
draft-ietf-calsify-rfc2445bis-10 (work
in progress), April 2009.
[RFC2119] Bradner, S., "Key words for use in
RFCs to Indicate Requirement Levels",
BCP 14, RFC 2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry",
BCP 81, RFC 3688, January 2004.
Appendix A. Relax NG Schema
Below is a Relax NG schema for iCalendar in XML. This schema uses
the compact notation of Relax NG. The numeric section numbers given
in the comments refer to section in [I-D.ietf-calsify-rfc2445bis].
The ordering of elements follows the section ordering of
[I-D.ietf-calsify-rfc2445bis].
The Relax NG compact notation "?" operator is used to indicate an
unordered list of items. However, that operator, as defined, allows
"mixing" each element that it operates on at any depth within the
other elements, rather than just allowing "mixing" of siblings only.
As a result, the schema provided allows certain constructs that are
not allowed in iCalendar. Given that there is no sibling-only
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unordered list operator in RelaxNG, this is the best representation
that can be given.
# Relax NG Schema for iCalendar in XML
default namespace = "urn:ietf:params:xml:ns:icalendar"
# 3.2 Property Parameters
# 3.2.1 Alternate Text Representation
altrepparam = element altrep { value-uri }
# 3.2.2 Common Name
cnparam = element cn { text }
# 3.2.3 Calendar User Type
cutypeparam = element cutype {
"INDIVIDUAL" |
"GROUP" |
"RESOURCE" |
"ROOM" |
"UNKNOWN"
}
# 3.2.4 Delegators
delfromparam = element delegated-from { value-cal-address+ }
# 3.2.5 Delegatees
deltoparam = element delegated-to { value-cal-address+ }
# 3.2.6 Directory Entry Reference
dirparam = element dir { value-uri }
# 3.2.7 Inline Encoding
encodingparam = element encoding {
"8BIT" |
"BASE64"
}
# 3.2.8 Format Type
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fmttypeparam = element fmttype { text }
# 3.2.9 Free/Busy Time Type
fbtypeparam = element fbtype {
"FREE" |
"BUSY" |
"BUSY-UNAVAILABLE" |
"BUSY-TENTATIVE"
}
# 3.2.10 Language
languageparam = element language { text }
# 3.2.11 Group or List Membership
memberparam = element member { value-cal-address+ }
# 3.2.12 Participation Status
partstatparam = element partstat {
type-partstat-event |
type-partstat-todo |
type-partstat-jour
}
type-partstat-event = (
"NEEDS-ACTION" |
"ACCEPTED" |
"DECLINED" |
"TENTATIVE" |
"DELEGATED"
)
type-partstat-todo = (
"NEEDS-ACTION" |
"ACCEPTED" |
"DECLINED" |
"TENTATIVE" |
"DELEGATED" |
"COMPLETED" |
"IN-PROCESS"
)
type-partstat-jour = (
"NEEDS-ACTION" |
"ACCEPTED" |
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"DECLINED"
)
# 3.2.13 Recurrence Identifier Range
rangeparam = element range {
"THISANDFUTURE"
}
# 3.2.14 Alarm Trigger Relationship
trigrelparam = element related {
"START" |
"END"
}
# 3.2.15 Relationship Type
reltypeparam = element reltype {
"PARENT" |
"CHILD" |
"SIBLING"
}
# 3.2.16 Participation Role
roleparam = element role {
"CHAIR" |
"REQ-PARTICIPANT" |
"OPT-PARTICIPANT" |
"NON-PARTICIPANT"
}
# 3.2.17 RSVP Expectation
rsvpparam = element rsvp {
"TRUE" |
"FALSE"
}
# 3.2.18 Sent By
sentbyparam = element sent-by { value-cal-address }
# 3.2.19 Time Zone Identifier
tzidparam = element tzid { text }
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# 3.3 Property Value Data Types
# 3.3.1 BINARY
value-binary = element binary { text }
# 3.3.2 BOOLEAN
value-boolean = element boolean {
("TRUE" | "FALSE")
}
# 3.3.3 CAL-ADDRESS
value-cal-address = element cal-address { text }
# 3.3.4 DATE
value-date = element date {
element year { text },
element month { text },
element day { text }
}
# 3.3.5 DATE-TIME
value-date-time = element date-time {
attribute utc { "yes" | "no" },
element year { text },
element month { text },
element day { text },
element hour { text },
element minute { text },
element second { text }
}
# 3.3.6 DURATION
value-duration = element duration {
attribute sign { "+" | "-" },
(
(
element day { text },
element hour { text }?,
element minute { text }?,
element second { text }?
) |
(
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element hour { text },
element minute { text }?,
element second { text }?
) |
(
element minute { text },
element second { text }?
) |
(
element second { text }
) |
element week { text }
)
}
# 3.3.7 FLOAT
value-float = element float { text }
# 3.3.8 INTEGER
value-integer = element integer { text }
# 3.3.9 PERIOD
value-period = element period {
value-date-time,
(
value-date-time |
value-duration
)
}
# 3.3.10 RECUR
value-recur = element recur {
type-freq,
(type-until | type-count)?,
element interval { text }?,
element bysecond { text }*,
element byminute { text }*,
element byhour { text }*,
type-byday*,
type-bymonthday*,
type-byyearday*,
type-byweekno*,
element bymonth { text }*,
type-bysetpos*,
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element wkst { type-weekday }?
}
type-freq = element freq {
"SECONDLY" |
"MINUTELY" |
"HOURLY" |
"DAILY" |
"WEEKLY" |
"MONTHLY" |
"YEARLY"
}
type-until = element until {
type-date |
type-date-time
}
type-count = element count { text }
type-weekday = (
"SU" |
"MO" |
"TU" |
"WE" |
"TH" |
"FR" |
"SA"
)
type-byday = element byday {
element ordwk {
text
}?,
element weekday { type-weekday }
}
type-bymonthday = element bymonthday {
text
}
type-byyearday = element byyearday {
text
}
type-byweekno = element byweekno {
text
}
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type-bysetpos = element bysetpos {
text
}
# 3.3.11 TEXT
value-text = element text { text }
# 3.3.12 TIME
value-time = element time {
attribute utc { "yes" | "no" },
element hour { text },
element minute { text },
element second { text }
}
# 3.3.13 URI
value-uri = element uri { text }
# 3.3.14 UTC-OFFSET
value-utc-offset = element utc-offset {
attribute sign { "+" | "-" },
element hour { text },
element minute { text },
element second { text }?
}
# 3.4 iCalendar Stream
start = element icalendar { vcalendar+ }
# 3.6 Calendar Components
vcalendar = element vcalendar {
type-calprops,
type-component
}
type-calprops = element properties {
property-prodid &
property-version &
property-calscale? &
property-method?
}
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type-component = element components {
(
component-vevent |
component-vtodo |
component-vjournal |
component-vfreebusy |
component-vtimezone
)*
}
# 3.6.1 Event Component
component-vevent = element vevent {
type-eventprop,
element components {
component-valarm+
}?
}
type-eventprop = element properties {
property-dtstamp &
property-dtstart &
property-uid &
property-class? &
property-created? &
property-description? &
property-geo? &
property-last-mod? &
property-location? &
property-organizer? &
property-priority? &
property-seq? &
property-status-event? &
property-summary? &
property-transp? &
property-url? &
property-recurid? &
property-rrule? &
(property-dtend | property-duration)? &
property-attach* &
property-attendee* &
property-categories* &
property-comment* &
property-contact* &
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property-exdate* &
property-rstatus* &
property-related* &
property-resources* &
property-rdate*
}
# 3.6.2 To-do Component
component-vtodo = element vtodo {
type-todoprop,
element components {
component-valarm+
}?
}
type-todoprop = element properties {
property-dtstamp &
property-uid &
property-class? &
property-completed? &
property-created? &
property-description? &
property-geo? &
property-last-mod? &
property-location? &
property-organizer? &
property-percent? &
property-priority? &
property-recurid? &
property-seq? &
property-status-todo? &
property-summary? &
property-url? &
property-rrule? &
(
(property-dtstart?, property-dtend? ) |
(property-dtstart, property-duration)?
) &
property-attach* &
property-attendee* &
property-categories* &
property-comment* &
property-contact* &
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property-exdate* &
property-rstatus* &
property-related* &
property-resources* &
property-rdate*
}
# 3.6.3 Journal Component
component-vjournal = element vjournal {
type-jourprop
}
type-jourprop = element properties {
property-dtstamp &
property-uid &
property-class? &
property-created? &
property-dtstart? &
property-last-mod? &
property-organizer? &
property-recurid? &
property-seq? &
property-status-jour? &
property-summary? &
property-url? &
property-rrule? &
property-attach* &
property-attendee* &
property-categories* &
property-comment* &
property-contact* &
property-description? &
property-exdate* &
property-related* &
property-rdate* &
property-rstatus*
}
# 3.6.4 Free/Busy Component
component-vfreebusy = element vfreebusy {
type-fbprop
}
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type-fbprop = element properties {
property-dtstamp &
property-uid &
property-contact? &
property-dtstart? &
property-dtend? &
property-duration? &
property-organizer? &
property-url? &
property-attendee* &
property-comment* &
property-freebusy* &
property-rstatus*
}
# 3.6.5 Time Zone Component
component-vtimezone = element vtimezone {
element properties {
property-tzid &
property-last-mod? &
property-tzuurl?
},
element components {
(component-standard | component-daylight) &
component-standard* &
component-daylight*
}
}
component-standard = element standard {
type-tzprop
}
component-daylight = element daylight {
type-tzprop
}
type-tzprop = element properties {
property-dtstart &
property-tzoffsetto &
property-tzoffsetfrom &
property-rrule? &
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property-comment* &
property-rdate* &
property-tzname*
}
# 3.6.6 Alarm Component
component-valarm = element valarm {
audioprop | dispprop | emailprop
}
type-audioprop = element properties {
property-action &
property-trigger &
(property-duration, property-repeat)? &
property-attach?
}
type-dispprop = element properties {
property-action &
property-description &
property-trigger &
property-summary &
property-attendee+ &
(property-duration, property-repeat)? &
property-attach*
}
type-emailprop = element properties {
property-action &
property-description &
property-trigger &
(property-duration, property-repeat)?
}
# 3.7 Calendar Properties
# 3.7.1 Calendar Scale
property-calscale = element calscale {
element parameters { empty }?,
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element text { "GREGORIAN" }
}
# 3.7.2 Method
property-method = element method {
element parameters { empty }?,
value-text
}
# 3.7.3 Product Identifier
property-prodid = element prodid {
element parameters { empty }?,
value-text
}
# 3.7.4 Version
property-version = element version {
element parameters { empty }?,
value-text
}
# 3.8 Component Properties
# 3.8.1 Descriptive Component Properties
# 3.8.1.1 Attachment
property-attach = element attach {
element parameters {
fmttypeparam? &
encodingparam?
}?,
value-uri | value-binary
}
# 3.8.1.2 Categories
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property-categories = element categories {
element parameters {
languageparam? &
}?,
value-text+
}
# 3.8.1.3 Classification
property-class = element class {
element parameters { empty }?,
element text {
"PUBLIC" |
"PRIVATE" |
"CONFIDENTIAL"
}
}
# 3.8.1.4 Comment
property-comment = element comment {
element parameters {
altrepparam? &
languageparam?
}?,
value-text
}
# 3.8.1.5 Description
property-description = element description {
element parameters {
altrepparam? &
languageparam?
}?,
value-text
}
# 3.8.1.6 Geographic Position
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property-geo = element geo {
element parameters { empty }?,
element value {
element latitude { text },
element longitude { text }
}
}
# 3.8.1.7 Location
property-location = element location {
element parameters {
altrepparam? &
languageparam?
}?,
value-text
}
# 3.8.1.8 Percent Complete
property-percent = element percent-complete {
element parameters { empty }?,
value-integer
}
# 3.8.1.9 Priority
property-priority = element priority {
element parameters { empty }?,
value-integer
}
# 3.8.1.10 Resources
property-resources = element resources {
element parameters {
altrepparam? &
languageparam?
}?,
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value-text+
}
# 3.8.1.11 Status
property-status-event = element status {
element parameters { empty }?,
element text {
"TENTATIVE" |
"CONFIRMED" |
"CANCELLED"
}
}
property-status-todo = element status {
element parameters { empty }?,
element text {
"NEEDS-ACTION" |
"COMPLETED" |
"IN-PROCESS" |
"CANCELLED"
}
}
property-status-jour = element status {
element parameters { empty }?,
element text {
"DRAFT" |
"FINAL" |
"CANCELLED"
}
}
# 3.8.1.12 Summary
property-summary = element summary {
element parameters {
altrepparam? &
languageparam?
}?,
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value-text
}
# 3.8.2 Date and Time Component Properties
# 3.8.2.1 Date/Time Completed
property-completed = element completed {
element parameters { empty }?,
value-date-time
}
# 3.8.2.2 Date/Time End
property-dtend = element dtend {
element parameters {
tzidparam?
}?,
value-date-time |
value-date
}
# 3.8.2.3 Date/Time Due
property-due = element due {
element parameters {
tzidparam?
}?,
value-date-time |
value-date
}
# 3.8.2.4 Date/Time Start
property-dtstart = element dtstart {
element parameters {
tzidparam?
}?,
value-date-time |
value-date
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}
# 3.8.2.5 Duration
property-duration = element duration {
element parameters { empty }?,
value-duration
}
# 3.8.2.6 Free/Busy Time
property-freebusy = element freebusy {
element parameters {
fbtypeparam?
}?,
value-period+
}
# 3.8.2.7 Time Transparency
property-transp = element transp {
element parameters { empty }?,
element text {
"OPAQUE" |
"TRANSPARENT"
}
}
# 3.8.3 Time Zone Component Properties
# 3.8.3.1 Time Zone Identifier
property-tzid = element tzid {
element parameters { empty }?,
value-text
}
# 3.8.3.2 Time Zone Name
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property-tzname = element tzname {
element parameters {
languageparam?
}?,
value-text
}
# 3.8.3.3 Time Zone Offset From
property-tzoffsetfrom = element tzoffsetfrom {
element parameters { empty }?,
value-utc-offset
}
# 3.8.3.4 Time Zone Offset To
property-tzoffsetto = element tzoffsetto {
element parameters { empty }?,
value-utc-offset
}
# 3.8.3.5 Time Zone URL
property-tzurl = element tzurl {
element parameters { empty }?,
value-uri
}
# 3.8.4 Relationship Component Properties
# 3.8.4.1 Attendee
property-attendee = element attendee {
element parameters {
cutypeparam? &
memberparam? &
roleparam? &
partstatparam? &
rsvpparam? &
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deltoparam? &
delfromparam? &
sentbyparam? &
cnparam? &
dirparam? &
languageparam?
}?,
value-cal-address
}
# 3.8.4.2 Contact
property-contact = element contact {
element parameters {
altrepparam? &
languageparam?
}?,
value-text
}
# 3.8.4.3 Organizer
property-organizer = element organizer {
element parameters {
cnparam? &
dirparam? &
sentbyparam? &
languageparam?
}?,
value-cal-address
}
# 3.8.4.4 Recurrence ID
property-recurid = element recurrence-id {
element parameters {
tzidparam? &
rangeparam?
}?,
value-date-time |
value-date
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}
# 3.8.4.5 Related-To
property-related = element related-to {
element parameters {
reltypeparam?
}?,
value-text
}
# 3.8.4.6 Uniform Resource Locator
property-url = element url {
element parameters { empty }?,
value-uri
}
# 3.8.4.7 Unique Identifier
property-uid = element uid {
element parameters { empty }?,
value-text
}
# 3.8.5 Recurrence Component Properties
# 3.8.5.1 Exception Date/Times
property-exdate = element exdate {
element parameters {
tzidparam?
}?,
value-date-time+ |
value-date+
}
# 3.8.5.2 Recurrence Date/Times
property-rdate = element rdate {
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element parameters {
tzidparam?
}?,
value-date-time+ |
value-date+ |
value-period+
}
# 3.8.5.3 Recurrence Rule
property-rrule = element rrule {
element parameters { empty }?,
value-recur
}
# 3.8.6 Alarm Component Properties
# 3.8.6.1 Action
property-action = element action {
element parameters { empty }?,
element text {
"AUDIO" |
"DISPLAY" |
"EMAIL"
}
}
# 3.8.6.2 Repeat Count
property-repeat = element repeat {
element parameters { empty }?,
value-integer
}
# 3.8.6.3 Trigger
property-repeat = element repeat {
(
element parameters {
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trigrelparam?
}?,
value-duration
) |
(
element parameters { empty }?,
value-date-time
)
}
# 3.8.7 Change Management Component Properties
# 3.8.7.1 Date/Time Created
property-created = element created {
element parameters { empty }?,
value-date-time
}
# 3.8.7.2 Date/Time Stamp
property-dtstamp = element dtstamp {
element parameters { empty }?,
value-date-time
}
# 3.8.7.3 Last Modified
property-last-mod = element last-modified {
element parameters { empty }?,
value-date-time
}
# 3.8.7.4 Sequence Number
property-seq = element sequence {
element parameters { empty }?,
value-integer
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}
# 3.8.8 Miscellaneous Component Properties
# 3.8.8.3 Request Status
property-rstatus = element request-status {
element parameters {
languageparam?
}?,
element value {
element code { text },
element description { text },
element data { text }?
}
}
Appendix B. XML Stylesheet for conversion to iCalendar
TO DO
Appendix C. Example
Below is some example iCalendar data and its representation in XML as
defined by this specification.
C.1. iCalendar Data
BEGIN:VCALENDAR
CALSCALE:GREGORIAN
PRODID:-//Example Inc.//Example Calendar//EN
VERSION:2.0
BEGIN:VEVENT
DTSTAMP:20080205T191224Z
DTSTART:20081006
SUMMARY:Planning meeting
UID:4088E990AD89CB3DBB484909
END:VEVENT
END:VCALENDAR
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C.2. XML Data
GREGORIAN
-//Example Inc.//Example Calendar//EN
2.0
200825
191224
2008106
Planning meeting
4088E990AD89CB3DBB484909
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Authors' Addresses
Cyrus Daboo
Apple Inc.
1 Infinite Loop
Cupertino, CA 95014
USA
EMail: cyrus@daboo.name
URI: http://www.apple.com/
Mike Douglass
Rensselaer Polytechnic Institute
110 8th Street
Troy, NY 12180
USA
EMail: douglm@rpi.edu
URI: http://www.rpi.edu/
Steven Lees
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
USA
EMail: Steven.Lees@microsoft.com
URI: http://www.microsoft.com/
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