Network Working Group T. Hare
Internet-Draft Individual
Expires: November 17, 2005 May 16, 2005
Guideline for use of XML with iCalendar elements
draft-hare-xcalendar-03
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on November 17, 2005.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This memo defines a guideline for using XML to represent calendaring
information that corresponds to the iCalendar, Internet Calendaring
and Scheduling Core Object Specification defined by [RFC 2445] and
the protocols defined by [RFC2446], [RFC2447] and [CAP]. This memo
applies to all [RFC 2445] extensions and modifications.
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].
Hare Expires November 17, 2005 [Page 1]
Internet-Draft iCalendar XML Guideline May 2005
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Using XML For Representing iCalendar . . . . . . . . . . . . . 5
3. XML and XSL Dependencies . . . . . . . . . . . . . . . . . . . 6
4. Working With Standard and XML iCalendar Representations . . . 7
5. Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6. Mixed Use of Both Representations . . . . . . . . . . . . . . 9
7. Using Data Types . . . . . . . . . . . . . . . . . . . . . . . 10
8. Namespaces . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9. Emailing documents with iCalendar XML Representation . . . . . 13
10. iCalendar XML Representation and File Systems . . . . . . . 14
11. Example Usage . . . . . . . . . . . . . . . . . . . . . . . 15
11.1 Example DTD . . . . . . . . . . . . . . . . . . . . . . . 15
11.2 An example XSL transformation . . . . . . . . . . . . . . 28
11.3 A well-formed and valid iCalendar XML document . . . . . . 34
11.4 Including binary content in attachments . . . . . . . . . 34
11.5 Including binary content inline . . . . . . . . . . . . . 35
11.6 iCalendar XML document with multiple iCalendar objects . . 36
11.7 Using the iCalendar namespace . . . . . . . . . . . . . . 37
11.8 Publish meeting information . . . . . . . . . . . . . . . 38
11.9 Publish transparent annual event . . . . . . . . . . . . . 38
11.10 Meeting invitation . . . . . . . . . . . . . . . . . . . 39
11.11 Assign a to-do . . . . . . . . . . . . . . . . . . . . . 39
11.12 Publish busy time . . . . . . . . . . . . . . . . . . . 40
11.13 Request busy time . . . . . . . . . . . . . . . . . . . 41
11.14 Issue a CAP command . . . . . . . . . . . . . . . . . . 41
11.15 A well-formed and valid XML document which can be
transformed into iCalendar . . . . . . . . . . . . . . . 41
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 44
13. Security Considerations . . . . . . . . . . . . . . . . . . 45
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 45
A. Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . 46
Intellectual Property and Copyright Statements . . . . . . . . 48
Hare Expires November 17, 2005 [Page 2]
Internet-Draft iCalendar XML Guideline May 2005
1. Introduction
The Extended Markup Language (XML) as defined in [XML] has gained
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-spaces for IETF standard formats such as
that defined by [RFC 2445], [RCF 2446], and [RFC 2447].
This memo defines how XML can be used to represent iCalendar
objects,and how iCalendar namespaces can be used with other XML
documents. An example DTD is provided although use of a DTD is not
required.
This memo does not try to enforce any specific one-to-one mapping
between XML objects and iCalendar objects, but instead attempts to
document the method whereby XML developers can provide
interoperability with iCalendar.
NOTE: The [RFC 2445] is the definitive reference for the definition
of iCalendar semantics. This memo only provides a guideline for
representing such semantics in XML. This memo does not introduce any
new semantics for items already defined by [RFC 2445]. [RFC 2446],
[RFC 2447], and [CAP] are the references for protocols for the
exchange of iCalendar objects. This memo does not introduce any new
protocols or functions beyond those in the respective documents.
An attempt has been made to guide the developer in use of XML to
represent iCalendar semantics, allowing XML-based applications to
make use of the iCalendar [RFC2445] and related protocols [RFC2446],
[RFC2447], and [CAP] semantics and to provide interoperability
between XML-based applications and iCalendar-compliant applications.
The publication of XML version 1.0 was followed by publication of two
World-wide Web Consortium (W3C) recommendations relevant to this
memo. The first was a recommendation on "Namespaces in XML" and the
other was a recommendation on "Extensible Stylesheet Language" and
"Extensible Stylesheet Language Transformation" (XSL and XSLT). An
XML name-space is a collection of names, identified by a URI. An XSL
transformation(XSLT)is a document in the Extensible Stylesheet
Language (XSL) which provides a method for transforming an XML
document into some other form. In anticipation of the use of XML
namespaces, this memo includes the definition of URIs to be used to
identify the namespaces for iCalendar [RFC 2445], iTIP [RFC 2446],
iMIP [RFC 2447] and CAP elements. XML applications that conform to
this memo and also use namespaces MAY include other non-iCalendar
namespaces.
Hare Expires November 17, 2005 [Page 3]
Internet-Draft iCalendar XML Guideline May 2005
Documents MAY include a Document Type Definition (DTD), an XML
schema, or may reference external versions of either. This memo
allows documents containing iCalendar XML objects to be constructed
with either. DTDs and Schemas are outside the scope of this memo. A
document containing a DTD or schema MAY include definitions for
calendar elements. Any document conforming to this memo MUST provide
an XSL transformation which will render those calendar elements
into standard iCalendar/iTIP/iMIP/CAP (as appropriate) elements.
Hare Expires November 17, 2005 [Page 4]
Internet-Draft iCalendar XML Guideline May 2005
2. Using XML For Representing 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.
Hare Expires November 17, 2005 [Page 5]
Internet-Draft iCalendar XML Guideline May 2005
3. XML and XSL Dependencies
This memo specifies the XML representation for the standard iCalendar
elements defined by [RFC 2445], [RFC 2446], [RFC2447], and [CAP].
There are no XML dependencies other than the [XML] and the [XMLNS]
recommendations.
This memo requires that conforming documents include a reference to
an [XSL] stylesheet for transforming the document into standard
iCalendar format. How the transformation is done is left to the
implementor. Providing an XSL transform into iCalendar objects does
not preclude providing other transforms.
Hare Expires November 17, 2005 [Page 6]
Internet-Draft iCalendar XML Guideline May 2005
4. Working With Standard and XML iCalendar Representations
This memo provides a guideline for using alternative, XML
representations for the standard iCalendar elements defined in [RFC
2445]. These alternative representations SHOULD provide 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.
Hare Expires November 17, 2005 [Page 7]
Internet-Draft iCalendar XML Guideline May 2005
5. Conversion
This memo requires any compliant document to be transformable into
standard iCalendar information. It is recognized that such
conversion MAY be asymmetric, since compliant documents MAY include
information which is not representable in iCalendar and which would
be lost during any "round trip" conversions. This does not preclude
implementation of "round-trippable" transformations, but they are not
required.
To formalize and standardize the interchange of iCalendar information
through XML, each conforming document MUST include reference to an
XSL stylesheet which can transform the document into a standard
iCalendar [RFC 2445] document of MIME content-type "text/calendar".
Hare Expires November 17, 2005 [Page 8]
Internet-Draft iCalendar XML Guideline May 2005
6. Mixed Use of Both Representations
As previously indicated, conversion between the XML and standard
representations of iCalendar is a straightforward process using XSL
transformations. In addition, mixed use of both representations is
also possible using MIME objects.
While MIME multipart content-types can be used to provide a mix of
both the standard and XML representations, this is NOT required.
Instead, each document MUST include a reference to an XSL stylesheet
which can transform the XML representation into standard iCalendar
(and possibly, iTIP, iMIP, or CAP) syntax.
With the use of the MIME multipart content-types, compound MIME
entities containing a mix of the standard and XML representations can
be specified. Internet applications conforming to this memo MAY send
both the standard and XML representation of the iCalendar objects, to
provide compatibility with Internet applications which cannot process
the required XSL transformation.
Hare Expires November 17, 2005 [Page 9]
Internet-Draft iCalendar XML Guideline May 2005
7. 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. The required XSL
transformation in this memo MUST create iCalendar elements with
proper types. Consult iCalendar [RFC 2445] for documentation of
value types.
Hare Expires November 17, 2005 [Page 10]
Internet-Draft iCalendar XML Guideline May 2005
8. Namespaces
[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.
Documents and applications conforming to this memo MAY use multiple
namespaces with the iCalendar, iTIP, iMIP, and CAP namespaces.
Multiple namespaces MUST be used for the different iCalendar and
protocol elements. This requirement is intended to provide clarity
in the document, by discriminating calendar object elements
from protocol elements.
The document at the namespace URI does not contain any defintions but
serves as a unique identifier to allow specification of different
namespaces. Applications complying with this memo MUST use the
following URIs for namespace elements:
iCalendar: http://www.ietf.org/rfc/rfc2445.txt
iTIP: http://www.ietf.org/rfc/rfc2446.txt
iMIP: http://www.ietf.org/rfc/rfc2447.txt
CAP: http://www.ietf.org/internet-drafts/
draft-ietf-calsch-cap-13.txt
NOTE: the URI for CAP will be replaced with the RFCxxxx reference
when CAP is completed.
The following is an example of a well-formed but invalid "xdoc"
document type that includes elements and attribute lists from the
iCalendar and iTIP namespaces.
Hare Expires November 17, 2005 [Page 11]
Internet-Draft iCalendar XML Guideline May 2005
<?xml version="1.0" encoding="UTF-8"?>
<xdoc>
<iCal:vcalendar iTIP:method="publish"
xmlns:iCal="http://www.ietf.org/rfc/RFC2445.txt"
xmlns:iTIP="http://www.ietf.org/rfc/RFC2446.txt">
<iCal:vevent>
<!--- VEVENT elements go here -->
</iCal:vevent>
<!-- Remainder of the XML document, each element from the -->
<!-- iCalendar namespace with the "iCal:" prefix. -->
</xdoc>
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.
iCalendar provides for "experimental" elements. These elements are
represented in iCalendar with element names beginning with "X-". Any
experimental element in a document which conforms to this memo MUST
be represented by a namespace different than those used for
iCalendar, iTIP, iMIP, or CAP. This requirement is intended to
simplify implementation of extensions and experimental items.
Hare Expires November 17, 2005 [Page 12]
Internet-Draft iCalendar XML Guideline May 2005
9. Emailing documents with 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.
All documents conforming to this memo SHOULD be sent as content-type
"text/xml" or "application/xml". When iCalendar elements may be
mixed with others, it is not practical for an MUA to determine,
without opening the document, if iCalendar XML elements exist within
the document.
If a part of a MIME multi-part message contains only XML-represented
iCalendar objects, and it is wished to provide the ability for an
application to determine content based upon the MIME headers, the
content-types "text/xml+calendar" or "application/xml+calendar" MAY
be used.
Internet applications conforming to this memo MUST include in any
iCalendar XML document that is sent, the XSL stylesheet reference to
be used to provide transformation from the XML representation to the
standard representation. This restriction guarantees that a standard
iCalendar object can be produced from the iCalendar XML document.
Internet applications conforming to this memo MAY 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], to provide compatibility with applications
which cannot process XML or XSL transformations.
An XML application comforming to the guidelines in this memo MUST be
able to receive and properly process the "application/xml" document
contained within a "multipart" message content-type, and MUST be
capable of performing the XSL transformation of the iCalendar
elements of the document into a standard iCalendar document.
Hare Expires November 17, 2005 [Page 13]
Internet-Draft iCalendar XML Guideline May 2005
10. 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, IF a document contains only XML representations of
iCalendar data, then for file association with applications that can
directly process this document type, it is RECOMMENDED that the file
extension be the text "xcs".
Hare Expires November 17, 2005 [Page 14]
Internet-Draft iCalendar XML Guideline May 2005
11. Example Usage
The following sections provide various examples of documents using
iCalendar elements in XML.
11.1 Example DTD
The following is a DTD which can be used to represent iCalendar [RFC
2445] objects. While this DTD represents the iCalendar objects as
currently defined, this document does not imply that this is the only
way to represent them, nor that this is the best DTD to do so. This
is provided as an example, only.
<?xml version="1.0" encoding="UTF-8"?>
<!-- ******************* -->
<!-- Entity declarations -->
<!-- ******************* -->
<!ENTITY % attr.altrep "
altrep ENTITY #IMPLIED
">
<!ENTITY % attr.cn "
cn CDATA ''
">
<!ENTITY % attr.cutype "
cutype NMTOKEN 'INDIVIDUAL'
">
<!-- Valid name tokens are "INDIVIDUAL", "GROUP", "RESOURCE" -->
<!-- "ROOM", "UNKNOWN", a non-standard "X-" name or another -->
<!-- IANA registered name. -->
<!ENTITY % attr.delegated-from "
delegated-from CDATA #IMPLIED
">
<!-- delegated-from value is a calendar user address -->
<!ENTITY % attr.delegated-to "
delegated-to CDATA #IMPLIED
">
<!-- delegated-to value is one or more calendar user addresses -->
<!ENTITY % attr.dir "
dir ENTITY #IMPLIED
">
<!-- dir value is a URI to a directory entry -->
Hare Expires November 17, 2005 [Page 15]
Internet-Draft iCalendar XML Guideline May 2005
<!ENTITY % attr.fmttype "
fmttype CDATA #REQUIRED
">
<!-- fmttype value is any IANA registered content type -->
<!ENTITY % attr.fbtype "
fbtype NMTOKEN 'BUSY'
">
<!-- Valid token values are "FREE", "BUSY", "BUSY-UNAVAILABLE", -->
<!-- "BUSY-TENTATIVE", a non-standard "X-" name or another -->
<!-- IANA registered name. -->
<!ENTITY % attr.language "
language CDATA #IMPLIED
">
<!-- language value is a valid RFC 1766 language string -->
<!ENTITY % attr.member "
member CDATA #IMPLIED
">
<!-- member value is one or more calendar user addresses -->
<!ENTITY % attr.partstat "
partstat NMTOKEN 'NEEDS-ACTION'
">
<!-- Valid token value for VEVENT: "NEEDS-ACTION", "ACCEPTED", -->
<!-- "DECLINED", "TENTATIVE", "DELEGATED", a non-standard "X- -->
<!-- name or another IANA registered name. -->
<!-- Valid token value for VTODO: "NEEDS-ACTION", "ACCEPTED", -->
<!-- "DECLINED", "TENTATIVE", "DELEGATED", "COMPLETED", -->
<!-- "IN-PROGRESS, a non-standard "X- name or another IANA -->
<!-- registered name. -->
<!-- Valid token value for VJOURNAL: "NEEDS-ACTION", "ACCEPTED", -->
<!-- "DECLINED", a non-standard "X- name or another IANA -->
<!-- registered name. -->
<!ENTITY % attr.range "
range NMTOKEN 'THISONLY'
">
<!-- Valid token values are "THISONLY" or "THISANDPRIOR" or -->
<!-- "THISANDFUTURE" -->
<!ENTITY % attr.related "
related NMTOKEN 'START'
">
<!-- Valid token values are "START" or "END" -->
Hare Expires November 17, 2005 [Page 16]
Internet-Draft iCalendar XML Guideline May 2005
<!ENTITY % attr.reltype "
reltype NMTOKEN 'PARENT'
">
<!-- Valid token values are "PARENT", "CHILD", SIBLING", -->
<!-- a non-standard "X-" name or any IANA registered name. -->
<!ENTITY % attr.role "
role NMTOKEN 'REQ-PARTICIPANT'
">
<!-- Valid token values are "CHAIR", "REQ-PARTICIPANT", -->
<!-- "OPT-PARTICIPANT", "NON-PARTICIPANT", a non-standard "X-" -->
<!-- name or any IANA registered name. -->
<!ENTITY % attr.rsvp "
rsvp NMTOKEN 'FALSE'
">
<!-- Valid token values are "TRUE" or "FALSE", -->
<!ENTITY % attr.sent-by "
sent-by CDATA #IMPLIED
">
<!-- sent-by value is a calendar user address -->
<!ENTITY % attr.tzid "
tzid CDATA #IMPLIED
">
<!-- tzid value is a time zone identifier -->
<!ENTITY % cal.comp "
vevent | vtodo | vjournal | vfreebusy | vtimezone
">
<!ENTITY % vevent.opt1 "
class | created | description | dtstamp | dtstart | geo |
last-modified | location | organizer | priority | recurrence-id |
sequence | status | summary | transp | uid | url |
(dtend | duration)
">
<!-- These properties may only appear once in a VEVENT -->
<!ENTITY % vevent.optm "
attach | attendee | categories | comment | contact |
exdate | exrule | rdate | related-to | resources | request-status |
rrule
">
<!-- These properties may appear one or more times in a VEVENT -->
<!ENTITY % vtodo.opt1 "
Hare Expires November 17, 2005 [Page 17]
Internet-Draft iCalendar XML Guideline May 2005
class | completed | created | description | dtstamp | dtstart |
geo | last-modified | location | organizer | percent | priority |
recurrence-id | sequence | status | summary | uid | url |
(due | duration)
">
<!-- These properties may only appear once in a VTODO -->
<!ENTITY % vtodo.optm "
attach | attendee | categories | comment | contact |
exdate | exrule | request-status | related-to | resources |
rdate | rrule
">
<!-- These properties may appear one or more times in a VTODO -->
<!ENTITY % vjournal.opt1 "
class | created | description | dtstart | dtstamp | last-modified |
organizer | recurrence-id | sequence | status | summary | uid | url
">
<!-- These properties may only appear once in a VJOURNAL -->
<!ENTITY % vjournal.optm "
attach | attendee | categories | comment | contact |
exdate | exrule | related-to | rdate | rrule | request-status
">
<!-- These properties may appear one or more times in a VJOURNAL -->
<!ENTITY % vfreebusy.opt1 "
contact | dtstamp | dtstart | dtend | duration |
organizer | uid | url
">
<!-- These properties may only appear once in a VFREEBUSY -->
<!ENTITY % vfreebusy.optm "
attendee | comment | freebusy | request-status
">
<!-- These properties may appear one or more times in a -->
<!-- VFREEBUSY -->
<!ENTITY % vtimezone.man "
tzid
">
<!-- These properties must appear in a VTIMEZONE -->
<!ENTITY % vtimezone.opt1 "
last-modified | tzurl
">
<!-- These properties may only appear once in a VTIMEZONE -->
Hare Expires November 17, 2005 [Page 18]
Internet-Draft iCalendar XML Guideline May 2005
<!ENTITY % vtimezone.mann "
(standard | daylight), (standard | daylight)*
">
<!-- These properties must appear in a VTIMEZONE and may -->
<!-- appear multiple times -->
<!ENTITY % standard.man "
dtstart | tzoffsetto | tzoffsetfrom
">
<!-- These properties must appear in a STANDARD, but only once -->
<!ENTITY % standard.optm "
comment | rdate | rrule | tzname
">
<!-- These properties may appear one or more times in a STANDARD -->
<!ENTITY % daylight.man "
dtstart | tzoffsetto | tzoffsetfrom
">
<!-- These properties must appear in a DAYLIGHT, but only once -->
<!ENTITY % daylight.optm "
comment | rdate | rrule | tzname
">
<!-- These properties may appear one or more times in a DAYLIGHT -->
<!ENTITY % audio.man "
action, trigger
">
<!-- These properties must appear in an audio VALARM. -->
<!ENTITY % audio.optx "
duration | repeat
">
<!-- These properties may appear once in an audio VALARM. If one -->
<!-- appears, then both must appear. -->
<!ENTITY % audio.opt1 "
attach
">
<!-- These properties may appear once in an audio VALARM. -->
<!ENTITY % valarm.audio "
(%audio.man;), (%audio.optx;)*, (%audio.opt1;)
">
<!ENTITY % display.man "
Hare Expires November 17, 2005 [Page 19]
Internet-Draft iCalendar XML Guideline May 2005
action, description, trigger
">
<!-- These properties must appear in a display VALARM. -->
<!ENTITY % display.optx "
duration | repeat
">
<!-- These properties may appear once in a display VALARM. If -->
<!-- one appears, then both must appear. -->
<!ENTITY % valarm.display "
(%display.man;), (%display.optx;)*
">
<!ENTITY % email.man "
action, description, summary, trigger
">
<!-- These properties must appear in an email VALARM. -->
<!ENTITY % email.optx "
duration | repeat
">
<!-- These properties may appear once in an email VALARM. If one -->
<!-- appears, then both must appear. -->
<!ENTITY % email.optm "
attach
">
<!-- These properties may appear one or more times in an email -->
<!-- VALARM. -->
<!ENTITY % email.mann "
attendee
">
<!-- These properties must appear in an email VALARM. The may -->
<!-- appear more than once. -->
<!ENTITY % valarm.email "
(%email.man;), (%email.optx;)*, (%email.optm;)*,
(%email.mann;)*
">
<!ENTITY % procedure.man "
action, attach, trigger
">
<!-- These properties must appear in an audio VALARM. -->
<!ENTITY % procedure.optx "
Hare Expires November 17, 2005 [Page 20]
Internet-Draft iCalendar XML Guideline May 2005
duration | repeat
">
<!-- These properties may appear once in an procedure VALARM. -->
<!-- If one appears, then both must appear. -->
<!ENTITY % procedure.opt1 "
description
">
<!-- These properties may appear once in a procedure VALARM -->
<!ENTITY % valarm.procedure "
(%procedure.man;), (%procedure.optx;)*, (%procedure.opt1;)?
">
<!-- ******************************************** -->
<!-- iCalendar value type notation declarations -->
<!-- ******************************************** -->
<!-- NOTE: The "XCAL" text in the following NOTATION values
will be replaced with the text "RFC xxxx", where "xxxx" is the RFC
number, when this memo is published as a RFC. -->
<!NOTATION BINARY PUBLIC "-//IETF//NOTATION XCAL/Value Type/Binary//EN">
<!NOTATION BOOLEAN PUBLIC "-//IETF//NOTATION XCAL/Value Type/Boolean//EN">
<!NOTATION CALADR PUBLIC "-//IETF//NOTATION XCAL/Value Type/Calendar
User Address//EN">
<!NOTATION DATE PUBLIC "-//IETF//NOTATION XCAL/Value Type/Date//EN">
<!NOTATION DATE-TIME PUBLIC "-//IETF//NOTATION XCAL/Value
Type/Date-Time//EN">
<!NOTATION DURATION PUBLIC "-//IETF//NOTATION XCAL/Value
Type/Duration//EN">
<!NOTATION FLOAT PUBLIC "-//IETF//NOTATION XCAL/Value Type/Float//EN">
<!NOTATION INTEGER PUBLIC "-//IETF//NOTATION XCAL/Value Type/Integer//EN">
<!NOTATION PERIOD PUBLIC "-//IETF//NOTATION XCAL/Value
Type/Period of Time//EN">
<!NOTATION RECUR PUBLIC "-//IETF//NOTATION XCAL/Value
Type/Recurrence Rule//EN">
<!NOTATION TEXT PUBLIC "-//IETF//NOTATION XCAL/Value Type/Text//EN">
Hare Expires November 17, 2005 [Page 21]
Internet-Draft iCalendar XML Guideline May 2005
<!NOTATION TIME PUBLIC "-//IETF//NOTATION XCAL/Value Type/Time//EN">
<!NOTATION URI PUBLIC "-//IETF//NOTATION XCAL/Value Type/URI//EN">
<!NOTATION UTC-OFFSET PUBLIC "-//IETF//NOTATION XCAL/Value
Type/UTC-Offset//EN">
<!NOTATION X-NAME PUBLIC "-//IETF//NOTATION XCAL/Value Type/X-Name//EN">
<!-- ************************************************* -->
<!-- iCalendar property element/attribute declarations -->
<!-- ************************************************* -->
<!ELEMENT br EMPTY>
<!-- Signifies a new line in the TEXT value content information -->
<!-- Description component properties element type declarations -->
<!ELEMENT attach (extref | b64bin)>
<!-- extref holds a reference to an external entity that -->
<!-- has the attachment. b64bin holds the inline BASE64 encoded -->
<!-- binary data for the attachment as defined in RFC 2045. -->
<!ELEMENT extref EMPTY>
<!ATTLIST extref
uri ENTITY #REQUIRED>
<!ELEMENT b64bin (#PCDATA)>
<!ATTLIST b64bin
%attr.fmttype;
value NOTATION (BINARY) #IMPLIED>
<!ELEMENT categories (item)*>
<!ELEMENT item (#PCDATA)>
<!ATTLIST item
%attr.language;
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT class (#PCDATA)>
<!ATTLIST class
%attr.language;
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT comment (#PCDATA)*>
<!ATTLIST comment
%attr.language;
%attr.altrep;
Hare Expires November 17, 2005 [Page 22]
Internet-Draft iCalendar XML Guideline May 2005
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT description (#PCDATA)*>
<!ATTLIST description
%attr.language;
%attr.altrep;
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT geo (lat, lon)>
<!ELEMENT lat (#PCDATA)>
<!ATTLIST lat value NOTATION (FLOAT) #IMPLIED>
<!-- A decimal degree float number to 6 decimal places -->
<!ELEMENT lon (#PCDATA)>
<!ATTLIST lon value NOTATION (FLOAT) #IMPLIED>
<!-- A decimal degree float number to 6 decimal places -->
<!ELEMENT location (#PCDATA)>
<!ATTLIST location
%attr.language;
%attr.altrep;
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT percent (#PCDATA)>
<!ATTLIST percent
value NOTATION (INTEGER) #IMPLIED>
<!ELEMENT priority (#PCDATA)>
<!ATTLIST priority
value NOTATION (INTEGER) #IMPLIED>
<!ELEMENT resources (#PCDATA)>
<!ATTLIST resources
%attr.language;
%attr.altrep;
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT status (#PCDATA)>
<!ATTLIST status
%attr.language;
%attr.altrep;
value NOTATION (TEXT) #IMPLIED>
<!-- Text value must match the valid values for the particular -->
<!-- calendar component. -->
<!ELEMENT summary (#PCDATA)>
<!ATTLIST summary
Hare Expires November 17, 2005 [Page 23]
Internet-Draft iCalendar XML Guideline May 2005
%attr.language;
%attr.altrep;
value NOTATION (TEXT) #IMPLIED >
<!-- Data and time component property element type declarations -->
<!ELEMENT dtstart (#PCDATA)>
<!ATTLIST dtstart
%attr.tzid;
value NOTATION (DATE-TIME | DATE) "DATE-TIME">
<!ELEMENT dtend (#PCDATA)>
<!ATTLIST dtend
%attr.tzid;
value NOTATION (DATE-TIME | DATE) "DATE-TIME">
<!ELEMENT due (#PCDATA)>
<!ATTLIST due
%attr.tzid;
value NOTATION (DATE-TIME | DATE) "DATE-TIME">
<!ELEMENT completed (#PCDATA)>
<!ATTLIST completed
value NOTATION (DATE-TIME) #IMPLIED>
<!ELEMENT duration (#PCDATA)>
<!ATTLIST duration
value NOTATION (DURATION) #IMPLIED>
<!ELEMENT freebusy (#PCDATA)>
<!ATTLIST freebusy
%attr.fbtype;
value NOTATION (PERIOD) #IMPLIED>
<!ELEMENT transp (#PCDATA)>
<!ATTLIST transp
value NOTATION (TEXT) #IMPLIED>
<!-- Text value must be one of the valid enumerations. -->
<!-- Time zone component property element type declarations -->
<!ELEMENT tzid (#PCDATA)>
<!ATTLIST tzid
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT tzname (#PCDATA)>
<!ATTLIST tzname
%attr.language;
Hare Expires November 17, 2005 [Page 24]
Internet-Draft iCalendar XML Guideline May 2005
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT tzoffsetfrom (#PCDATA)>
<!ATTLIST tzoffsetfrom
value NOTATION (UTC-OFFSET) #IMPLIED>
<!ELEMENT tzoffsetto (#PCDATA)>
<!ATTLIST tzoffsetto
value NOTATION (UTC-OFFSET) #IMPLIED>
<!ELEMENT tzurl EMPTY>
<!ATTLIST tzurl
uri ENTITY #REQUIRED>
<!-- Relationship component property element type declarations -->
<!ELEMENT attendee (#PCDATA)>
<!ATTLIST attendee
%attr.language;
%attr.cn;
%attr.role;
%attr.partstat;
%attr.rsvp;
%attr.cutype;
%attr.member;
%attr.delegated-to;
%attr.delegated-from;
%attr.sent-by;
%attr.dir;
value NOTATION (CALADR) #IMPLIED>
<!ELEMENT contact (#PCDATA)*>
<!ATTLIST contact
%attr.language;
%attr.altrep;
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT organizer (#PCDATA)>
<!ATTLIST organizer
%attr.language;
%attr.cn;
%attr.sent-by;
%attr.dir;
value NOTATION (CALADR) #IMPLIED>
<!ELEMENT recurrence-id (#PCDATA)>
<!ATTLIST recurrence-id
%attr.tzid;
Hare Expires November 17, 2005 [Page 25]
Internet-Draft iCalendar XML Guideline May 2005
%attr.range;
value NOTATION (DATE-TIME | DATE) "DATE-TIME">
<!ELEMENT related-to (#PCDATA)>
<!ATTLIST related-to
%attr.reltype;
value NOTATION (TEXT) #IMPLIED>
<!ELEMENT url EMPTY>
<!ATTLIST url
uri ENTITY #REQUIRED>
<!ELEMENT uid (#PCDATA)>
<!ATTLIST uid
value NOTATION (TEXT) #IMPLIED>
<!-- Recurrence component property element type declarations -->
<!ELEMENT exdate (#PCDATA)>
<!ATTLIST exdate
%attr.tzid;
value NOTATION (DATE-TIME | DATE) "DATE-TIME">
<!ELEMENT exrule (#PCDATA)>
<!ATTLIST exrule
value NOTATION (RECUR) #IMPLIED>
<!ELEMENT rdate (#PCDATA)>
<!ATTLIST rdate
%attr.tzid;
value NOTATION (DATE-TIME | DATE) "DATE-TIME">
<!ELEMENT rrule (#PCDATA)>
<!ATTLIST rrule
value NOTATION (RECUR) #IMPLIED>
<!-- Alarm component property element type declarations -->
<!ELEMENT action (#PCDATA)>
<!ATTLIST action
value NOTATION (TEXT) #IMPLIED>
<!-- Text value must be a valid enumeration -->
<!ELEMENT repeat (#PCDATA)>
<!ATTLIST repeat
value NOTATION (INTEGER) #IMPLIED>
<!ELEMENT trigger (#PCDATA)>
Hare Expires November 17, 2005 [Page 26]
Internet-Draft iCalendar XML Guideline May 2005
<!ATTLIST trigger
%attr.related-to;
value NOTATION (DURATION | DATE-TIME) "DURATION">
<!-- Change management component property element type -->
<!-- declarations -->
<!ELEMENT created (#PCDATA)>
<!ATTLIST created
value NOTATION (DATE-TIME) #IMPLIED>
<!ELEMENT dtstamp (#PCDATA)>
<!ATTLIST dtstamp
value NOTATION (DATE-TIME) #IMPLIED>
<!ELEMENT last-modified (#PCDATA)>
<!ATTLIST last-modified
value NOTATION (DATE-TIME) #IMPLIED>
<!ELEMENT sequence (#PCDATA)>
<!ATTLIST sequence
value NOTATION (INTEGER) #IMPLIED>
<!-- Miscellaneous component property element type declarations -->
<!ELEMENT request-status (#PCDATA)>
<!ATTLIST request-status
%attr.language;
value NOTATION (TEXT) #IMPLIED>
<!-- iCalendar object element type declarations -->
<!ELEMENT iCalendar (vcalendar+)>
<!ELEMENT vcalendar (%cal.comp;)*>
<!ATTLIST vcalendar
%attr.language;
xmlns CDATA #FIXED 'http://www.ietf.org/internet-drafts/draft-
hare-xcalendar-01.txt'
calscale CDATA "GREGORIAN"
method CDATA "PUBLISH"
version CDATA #REQUIRED
prodid CDATA #IMPLIED>
<!-- version - Must be "2.0" if document conforms to this spec. -->
<!-- calscale - Calendar scale. Default is GREGORIAN. -->
<!-- method - C&S method. Default is iTIP PUBLISH. -->
<!-- prodid - ISO 9070 FPI for product that generated iCalendar. -->
Hare Expires November 17, 2005 [Page 27]
Internet-Draft iCalendar XML Guideline May 2005
<!-- "vevent" element type declaration -->
<!ELEMENT vevent ((%vevent.opt1;)*, (%vevent.optm;)*, valarm*)>
<!-- "vtodo" element type declaration -->
<!ELEMENT vtodo ((%vtodo.opt1;)*, (%vtodo.optm;)*, valarm*)>
<!-- "vjournal" element type declaration -->
<!ELEMENT vjournal ((%vjournal.opt1;)*, (%vjournal.optm;)*)>
<!-- "vfreebusy" element type declaration -->
<!ELEMENT vfreebusy ((%vfreebusy.opt1;)*, (%vfreebusy.optm;)*)>
<!-- "vtimezone" element type declaration -->
<!ELEMENT vtimezone (%vtimezone.man;, (%vtimezone.opt1;)*,
(%vtimezone.mann;)*)>
<!ELEMENT standard (((%standard.man;)*), (%standard.optm;)*)>
<!ELEMENT daylight (((%daylight.man;)*), (%daylight.optm;)*)>
<!ELEMENT valarm ((%valarm.audio;) | (%valarm.display;) |
(%valarm.email;) | (%valarm.procedure;))>
11.2 An example XSL transformation
The following is an example of an XSL transformation which can
convert an xCalendar document into an iCalendar [RFC 2445] text
object. Again, this is an example and not presented as the only or
best way to accomplish the transformation.
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ical="http://www.ietf.org/rfc/rfc2445.txt"
xmlns:itip="http://www.ietf.org/rfc/rfc2446.txt"
xmlns="http://www.ietf.org/rfc/rcf2445.txt">
<!-- ======================================================================== -->
<!-- xcal2ics.xsl XSL transformation of xCalendar documents to iCalendar file -->
<!-- Tim Hare, April 2004 -->
<!-- Tim Hare, August 2004 - updated to wrap at 75 chars -->
<!-- Tim Hare, November 2004 - removed unused template, cleanup -->
<!-- Tim Hare, May 2005 - added function to quote some characters -->
<!-- This transformation may be freely used, attribution is appreciated -->
<!-- Concepts and inspiration due to rdf2ical from Masahide Kanzaki -->
<!-- who should also receive attribution -->
Hare Expires November 17, 2005 [Page 28]
Internet-Draft iCalendar XML Guideline May 2005
<!-- ======================================================================== -->
<!-- define output format for iCalendar for use in result-document instr. -->
<xsl:output method="text" media-type="text/calendar" />
<xsl:template match="icalendar|iCalendar|ical:icalendar|ical:iCalendar">
<xsl:apply-templates select="vcalendar|ical:vcalendar" />
</xsl:template>
<xsl:template match="vcalendar|ical:vcalendar">
<xsl:call-template name="emit_text">
<!-- parameter "line" is entire result of here to end of with-param -->
<xsl:with-param name="line">
<xsl:text>BEGIN:VCALENDAR</xsl:text>
</xsl:with-param>
</xsl:call-template>
<xsl:if test="not(@method) and
not(@Method) and
not(@ical:method) and
not(@ical:Method)">
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:text>METHOD:PUBLISH</xsl:text>
</xsl:with-param>
</xsl:call-template>
</xsl:if>
<xsl:for-each select="@*">
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="local-name()" />
</xsl:call-template>
<xsl:text>:</xsl:text>
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="current()" />
</xsl:call-template>
</xsl:with-param>
</xsl:call-template>
</xsl:for-each>
<xsl:apply-templates select="./*" />
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:text>END:VCALENDAR</xsl:text>
</xsl:with-param>
</xsl:call-template>
</xsl:template>
<xsl:template name="eachcomponent" match="vevent|vtodo|vjournal|valarm|ical:vevent|ical:vtodo|ical:vjournal|ical:valarm">
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:text>BEGIN:</xsl:text>
<xsl:call-template name="stringcap">
Hare Expires November 17, 2005 [Page 29]
Internet-Draft iCalendar XML Guideline May 2005
<xsl:with-param name="s" select="local-name()" />
</xsl:call-template>
</xsl:with-param>
</xsl:call-template>
<xsl:for-each select="./*" >
<xsl:call-template name="eachproperty" />
</xsl:for-each>
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:text>END:</xsl:text>
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="local-name()" />
</xsl:call-template>
</xsl:with-param>
</xsl:call-template>
</xsl:template>
<xsl:template name="eachproperty">
<xsl:if test="local-name() != 'categories' and
local-name() != 'CATEGORIES' and
local-name() != 'geo' and
local-name() != 'GEO' and
local-name() != 'resources' and
local-name() != 'RESOURCES'">
<!-- this block outputs a property with all of its parameters -->
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="local-name()" />
</xsl:call-template>
<xsl:for-each select="@*">
<xsl:call-template name="eachparam">
<xsl:with-param name="p" select="local-name()" />
</xsl:call-template>
</xsl:for-each>
<xsl:text>:</xsl:text>
<!-- call replace-text to quote newline, semicolon, colon, reverse solidus, and comma -->
<xsl:call-template name="quote-some">
<xsl:with-param name="text"><xsl:value-of select="." /></xsl:with-param>
</xsl:call-template>
</xsl:with-param>
</xsl:call-template>
<!-- end of regular properties ouput block -->
</xsl:if>
<xsl:if test="local-name() = 'categories' or
local-name() = 'CATEGORIES' or
local-name() = 'resources' or
local-name() = 'RESOURCES'">
<!-- this block outputs a Categories or Resources property -->
Hare Expires November 17, 2005 [Page 30]
Internet-Draft iCalendar XML Guideline May 2005
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="local-name()" />
</xsl:call-template>
<xsl:for-each select="@*">
<xsl:call-template name="eachparam">
<xsl:with-param name="p" select="local-name()" />
</xsl:call-template>
</xsl:for-each>
<xsl:text>:</xsl:text>
<xsl:for-each select="./item|./ITEM">
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="current()" />
</xsl:call-template>
<xsl:if test="position() != last()">
<xsl:text>,</xsl:text>
</xsl:if>
</xsl:for-each>
</xsl:with-param>
</xsl:call-template>
<!-- end of Categories or Resources property output block -->
</xsl:if>
<xsl:if test="local-name() = 'geo' or
local-name() = 'GEO'">
<!-- this block outputs a Geo property -->
<xsl:call-template name="emit_text">
<xsl:with-param name="line">
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="local-name()" />
</xsl:call-template>
<xsl:text>:</xsl:text>
<xsl:value-of select="lat" />
<xsl:text>;</xsl:text>
<xsl:value-of select="lon" />
</xsl:with-param>
</xsl:call-template>
<!-- end of Geo property output block -->
</xsl:if>
</xsl:template>
<xsl:template name="eachparam">
<xsl:param name="p" />
<xsl:text>;</xsl:text>
<xsl:call-template name="stringcap">
<xsl:with-param name="s" select="string($p)"/>
</xsl:call-template>
<xsl:text>=</xsl:text>
<xsl:value-of select="." />
Hare Expires November 17, 2005 [Page 31]
Internet-Draft iCalendar XML Guideline May 2005
</xsl:template>
<!-- Capitalize and output a string -->
<xsl:template name="stringcap">
<xsl:param name="s"/>
<xsl:value-of select="translate($s,'abcdefghijklmnopqrstuvwxyz','ABCDEFGHIJKLMNOPQRSTUVWXYZ')"/>
</xsl:template>
<!-- Emit text, 75 character max per line, recursively -->
<xsl:template name="emit_text">
<xsl:param name="limit" select="number(75)"/> <!-- default limit is 75 " -->
<xsl:param name="line"/>
<xsl:value-of select="substring(normalize-space($line),1,$limit)" />
<!-- Output the newline string -->
<xsl:text> </xsl:text>
<xsl:if test="string-length($line) > $limit">
<xsl:text> </xsl:text>
<xsl:call-template name="emit_text">
<xsl:with-param name="limit" select="($limit - 1)" /> <!-- use 74 allow for space -->
<xsl:with-param name="line" select="substring($line,($limit + 1))" />
</xsl:call-template>
</xsl:if>
</xsl:template>
<!-- ACK: ASPN replace-string function used to model this
http://aspn.activestate.com/ASPN/Cookbook/XSLT/Recipe/65426
via Dan Connolly, W3C
all characters to be quoted are in this template rather than doing multiple calls to the template
in the hopes that this will improve performance.
-->
<xsl:template name="quote-some">
<!-- rfc2445#sec4.3.11 says to quote DQUOTE, newline, semicolon, colon,
reverse solidus, comma -->
<xsl:param name="text">
<xsl:choose>
<xsl:when test="contains($text,'"')">
<xsl:variable name="before" select="substring-before($text,'"')
<xsl:variable name="before" select="substring-after($text,'"')/>
<xsl:value-of select="$before"/>
<xsl:value-of select="\"" />
<xsl:call-template name="quote-some">
<xsl:with-param name="text" select="&after" />
</xsl:call-template>
</xsl:when>
<xsl:when test="contains($text,'
')">
<xsl:variable name="before" select="substring-before($text,'
')
<xsl:variable name="before" select="substring-after($text,'
')/>
<xsl:value-of select="$before"/>
<xsl:value-of select="\n" />
<xsl:call-template name="quote-some">
Hare Expires November 17, 2005 [Page 32]
Internet-Draft iCalendar XML Guideline May 2005
<xsl:with-param name="text" select="&after" />
</xsl:call-template>
</xsl:when>
<xsl:when test="contains($text,';')">
<xsl:variable name="before" select="substring-before($text,';')/>
<xsl:variable name="before" select="substring-after($text,';')/>
<xsl:value-of select="$before"/>
<xsl:value-of select="\;" />
<xsl:call-template name="quote-some">
<xsl:with-param name="text" select="&after" />
</xsl:call-template>
</xsl:when>
<xsl:when test="contains($text,':')">
<xsl:variable name="before" select="substring-before($text,':')/>
<xsl:variable name="before" select="substring-after($text,':')/>
<xsl:value-of select="$before"/>
<xsl:value-of select="\:" />
<xsl:call-template name="quote-some">
<xsl:with-param name="text" select="&after" />
</xsl:call-template>
</xsl:when>
<xsl:when test="contains($text,'\')">
<xsl:variable name="before" select="substring-before($text,'\')/>
<xsl:variable name="before" select="substring-after($text,'\')/>
<xsl:value-of select="$before"/>
<xsl:value-of select="\\" />
<xsl:call-template name="quote-some">
<xsl:with-param name="text" select="&after" />
</xsl:call-template>
</xsl:when>
<xsl:when test="contains($text,',')">
<xsl:variable name="before" select="substring-before($text,',')/>
<xsl:variable name="before" select="substring-after($text,',')/>
<xsl:value-of select="$before"/>
<xsl:value-of select="\," />
<xsl:call-template name="quote-some">
<xsl:with-param name="text" select="&after" />
</xsl:call-template>
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="$text"/>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>
Hare Expires November 17, 2005 [Page 33]
Internet-Draft iCalendar XML Guideline May 2005
11.3 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. It also
contains the required reference to the XSL transformation. The
iCalendar object specifies an appointment.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
"http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt">
<?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>
<iCalendar>
<vcalendar method="PUBLISH"
version="2.0"
prodid="-//HandGen//NONSGML vGen v1.0//EN">
<vevent>
<uid>19981116T150000@cal10.host.com</uid>
<dtstamp>19981116T145958Z</dtstamp>
<summary>Project XYZ Review</summary>
<location>Conference Room 23A</location>
<dtstart>19981116T163000Z</dtstart>
<dtend>19981116T190000Z</dtend>
<categories>
<item>Appointment</item>
</categories>
</vevent>
</vcalendar>
</iCalendar>
11.4 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.
Hare Expires November 17, 2005 [Page 34]
Internet-Draft iCalendar XML Guideline May 2005
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
"http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt"
<?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>
<iCalendar>
<vcalendar>
<method>REQUEST</method>
<version>2.0</version>
<prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
<vevent>
<uid>19981211T133000@cal1.host.com</uid>
<dtstamp>19981211T132928Z</dtstamp>
<organizer>cap://host.com/jim</organizer>
<dtstart>19981212T150000Z</dtstart>
<dtend>19981212T160000Z</dtend>
<summary>Department Meeting</summary>
<location>Conference Room 23A</location>
<attendee role="CHAIR">jim@host.com</attendee>
<attendee role="REQ-PART"
rsvp="TRUE">MAILTO:joe@host.com</attendee>
<attendee role="REQ-PART"
rsvp="TRUE">MAILTO:steve@host.com</attendee>
<attach>http://host.com/pub/photos/holiday.jpg</attach>
</vevent>
</vcalendar>
</iCalendar>
11.5 Including binary content inline
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.
Hare Expires November 17, 2005 [Page 35]
Internet-Draft iCalendar XML Guideline May 2005
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
"http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt">
<?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>
<iCalendar>
<vcalendar>
<method>REQUEST</method>
<version>2.0</version>
<prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
<vevent>
<uid>19981211T133000@cal1.host.com</uid>
<dtstamp>19981211T132928Z</dtstamp>
<organizer>MAILTO:jim@host.com</organizer>
<dtstart>19981212T150000Z</dtstart>
<dtend>19981212T160000Z</dtend>
<summary>Department Meeting</summary>
<location>Conference Room 23A</location>
<attendee role="CHAIR">MAILTO:jim@host.com</attendee>
<attendee role="REQ-PART"
rsvp="TRUE">MAILTO:joe@host.com</attendee>
<attendee role="REQ-PART"
rsvp="TRUE">MAILTO:steve@host.com</attendee>
<attach fmttype="IMAGE/JPEG">MIICajCCAdOgAwIBAgI
CBEUwDQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXB
lIEjYXRpb25z...and so on...IENvcnBvc==</attach>
</vevent>
</vcalendar>
</iCalendar>
11.6 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.
Hare Expires November 17, 2005 [Page 36]
Internet-Draft iCalendar XML Guideline May 2005
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE iCalendar PUBLIC "-//IETF//DTD XCAL/iCalendar XML//EN"
"http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt">
<?xml-stylesheet href="xcal2ics.xsl" type="text/xsl" output="text" ?>
<iCalendar annotation="IT Conference Prep">
<vcalendar>
<method>PUBLISH</method>
<version>2.0</version>
<prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
<vtodo>
<uid>19981009T233000@cal1.host.com</uid>
<dtstamp>19981009T232928Z</dtstamp>
<dtstart>19981010T000000Z</dtstart>
<due>19981010T235959Z</due>
<summary>Register for conference</summary>
<priority>2</priority>
</vtodo>
</vcalendar>
<vcalendar>
<version>2.0</version>
<prodid>-//HandGen//NONSGML vGen v1.0//EN</prodid>
<method>PUBLISH</method>
<vevent>
<uid>19981009T233010@cal1.host.com</uid>
<dtstamp>19981009T233000Z</dtstamp>
<dtstart>19981120T133000Z</dtstart>
<dtend>19981122T183000Z</dtend>
<summary>IT Conference</summary>
<location>Downtowner Hotel</location>
</vevent>
</vcalendar>
</iCalendar>
11.7 Using the iCalendar namespace
The following is an example of a snippet of a XML document that
includes elements from the iCalendar name-space.
<x xmlns:xcal="http://www.ietf.org/internet-drafts/
draft-hare-xcalendar-01.txt"
xmlns:pdi="http://pdi.org/schema">
<xcal:dtstart>19981123T133000Z</xcal:dtstart>
<xcal:dtend>19981123T203000Z</xcal:dtend>
<pdi:idnum>1234567</pdi:idnum>
<pdi:usage>999.99</pdi:usage>
</x>
Hare Expires November 17, 2005 [Page 37]
Internet-Draft iCalendar XML Guideline May 2005
11.8 Publish meeting information
The following is a snippet of an iCalendar XML document that
publishes information about a meeting.
<iCalendar>
<vcalendar>
<version>2.0</version>
<prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
<method>PUBLISH</method>
<vevent>
<uid>19970901T130000Z-123401@host.com</uid>
<dtstamp>19970901T130000Z</dtstamp>
<dtstart>19970903T163000Z</dtstart>
<dtend>19970903T190000Z</dtend>
<summary>Annual Employee Review</summary>
<class>PRIVATE</class>
<categories>Business,Human Resources</categories>
</vevent>
</vcalendar>
</iCalendar>
11.9 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.
<iCalendar>
<vcalendar>
<version>2.0</version>
<prodid-//hacksw/handcal//NONSGML 1.0//EN</prodid>
<method>PUBLISH</publish>
<vevent>
<uid>19990101T125957Z-123403@host.com</uid>
<dtstamp>19990101T130000Z</dtstamp>
<dtstart value="DATE">19991102</dtstart>
<summary>Our Blissful Anniversary</summary>
<class>CONFIDENTIAL</class>
<transp>TRANSPARENT</transp>
<categories>Anniversary,Personal,Special Occasion</categories>
<rrule>FREQ=YEARLY</rrule>
</vevent>
</vcalendar>
</iCalendar>
Hare Expires November 17, 2005 [Page 38]
Internet-Draft iCalendar XML Guideline May 2005
11.10 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.
<iCalendar>
<vcalendar>
<method>REQUEST</method>
<version>2.0</version>
<prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
<vevent>
<uid>19981220T130000Z-123403@host.com</uid>
<dtstamp>19981220T130050Z</dtstamp>
<organizer>MAILTO:corprel@host.com</organizer>
<dtstart>19990104T140000Z</dtstart>
<dtend>19990104T220000Z</dtend>
<summary>Annual Stockholders Meeting</summary>
<location>One Corporate Drive, Wilmington, DL</location>
<attendee role="CHAIR">MAILTO:mrbig@host.com</attendee>
<attendee cutype="GROUP"
rsvp="TRUE">CAP:host.com/stockholders</attendee>
<categories>Business,Meeting,Special Occasion</categories>
<rrule>FREQ=YEARLY;COUNT=5;BYDAY=1MO</rrule>
</vevent>
</vcalendar>
</iCalendar>
11.11 Assign a to-do
The following is a snippet of an iCalendar XML document for a to-do.
Hare Expires November 17, 2005 [Page 39]
Internet-Draft iCalendar XML Guideline May 2005
<iCalendar>
<vcalendar>
<method>REQUEST</method>
<version>2.0</version>
<prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
<vtodo>
<uid>19990104T133402@ical1.host.com</uid>
<dtstamp>19990104T133410Z</dtstamp>
<dtstart value="DATE">19990104</dtstart>
<due value="DATE">19990129</due>
<organizer>MAILTO:dboss@host.com</organizer>
<summary>Periodic Self Review</summary>
<description>Complete your self review.
Contact me if you questions.</description>
<priority>1</priority>
<class>CONFIDENTIAL</class>
<attendee>CAP:dilbert@host.com</attendee>
</vtodo>
</vcalendar>
</iCalendar>
11.12 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.
<iCalendar>
<vcalendar>
<version>2.0</version>
<prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
<vfreebusy>
<uid>19980313T133000@ical1.host.com</uid>
<dtstamp>19990104T133010Z</dtstamp>
<organizer>CAP:host.com/jsmith</organizer>
<dtstart>19980313T141711Z</dtstart>
<dtend>19980410T141711Z</dtend>
<url>jsmith.ifb</url>
<freebusy>19980314T233000Z/19980315T003000Z</freebusy>
<freebusy>19980316T153000Z/19980316T163000Z</freebusy>
<freebusy>19980318T030000Z/19980318T040000Z</freebusy>
</vfreebusy>
</vcalendar>
</iCalendar>
Hare Expires November 17, 2005 [Page 40]
Internet-Draft iCalendar XML Guideline May 2005
11.13 Request busy time
The following is a snippet of an iCalendar XML document that requests
a calendar user's busy time information.
<iCalendar>
<vcalendar>
<method>REQUEST</method>
<version>2.0</version>
<prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
<vfreebusy>
<uid>19970901T083000@ical1.host.com</uid>
<dtstamp>19970901T083000Z</dtstamp>
<organizer>MAILTO:jane_doe@host1.com</organizer>
<dtstart>19971015T050000Z</dtstart>
<dtend>19971016T050000Z</dtend>
<attendee>MAILTO:john_public@host2.com</attendee>
</vfreebusy>
</vcalendar>
</iCalendar>
11.14 Issue a CAP command
The following is a snippet of an iCalendar XML document that issues a
CAP command to delete a UID.
<iCalendar xmlns="http://www.ietf.org/internet-drafts/draft-hare-xcalendar-01.txt"
xmlns:CAP="="http://www.ietf.org/internet-drafts/draft-ietf-calsch-cap-13.txt">
<vcalendar>
<version>2.0</version>
<prodid>-//hacksw/handcal//NONSGML 1.0//EN</prodid>
<target>relcalid-22</target>
<CAP:cmd id="random but unique per CUA">DELETE</CAP:cmd>
<CAP:vquery>
<CAP:query>SELECT VEVENT FROM VAGENDA WHERE UID = 'abcd12345'</CAP:query>
</CAP:vquery>
</vcalendar>
</iCalendar>
11.15 A well-formed and valid XML document which can be transformed
into iCalendar
The following is a simple example document which contains some date
and time elements . This document is both a well-formed and valid
XML document. It contains a DTD and references a stylesheet which
transforms the schedule elements into iCalendar. The time used is a
Hare Expires November 17, 2005 [Page 41]
Internet-Draft iCalendar XML Guideline May 2005
"floating" time, without timezone information, to simplify the
example.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE tour [
<!ELEMENT tourdata (performer,tourname,gig+)>
<!ELEMENT performer (#PCDATA)>
<!ELEMENT tourname (#PCDATA)>
<!ELEMENT gig (venue,date,time)>
<!ELEMENT venue (#PCDATA)>
<!ELEMENT date (#PCDATA)>
<!ELEMENT time (#PCDATA)]>
<?xml-stylesheet type="text/xsl" href="tour2ical.xsl" output="text">
<tour>
<performer>Frank Dylan</performer>
<tourname>Rolling Blunder Revue</tourname>
<gig>
<venue>East Sandusky, Ohio Civic Auditorium</venue>
<date>01/03/1997</date>
<time>21:00:00</time>
</gig>
<gig>
<venue>Sandlot, NM Lost Highway Cafe</venue>
<date>08/09/1997</date>
<time>12:00:00</time>
</gig>
</tour>
The required stylesheet to transform the document into an iCalendar
object (tour2ical.xsl) . Note that some of the transformations,
notably date and time, would need more work to provide the robustness
usually needed for applications; the simple method here is used as an
example only.
Hare Expires November 17, 2005 [Page 42]
Internet-Draft iCalendar XML Guideline May 2005
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" media-type="text/calendar" />
<xsl:template match="tour">
BEGIN:VCALENDAR
METHOD:PUBLISH
<xsl:for-each select="./gig">
BEGIN:VEVENT
<!-- since no datestamps in original -->
<!-- use same date & time -->
DTSTAMP:<xsl:call-template name="getdate" />
DTSTART:<xsl:call-template name="getdate" />
SUMMARY:<xsl:value-of select="../tourname" />
DESCRIPTION:<xsl:value-of select="../performer" />
<xsl:text> </xsl:text>
<xsl:value-of select="./venue" />
</xsl:for-each>
</xsl:template>
<xsl:template name="getdate">
<xsl:value-of select="substring(date,7,4)" />
<xsl:value-of select="substring(date,1,2)" />
<xsl:value-of select="substring(date,4,2)" />
<xsl:text>T</xsl:text>
<xsl:value-of select="substring(time,1,2)" />
<xsl:value-of select="substring(time,4,2)" />
<xsl:value-of select="substring(time,7,2)" />
</xsl:template>
</xsl:stylesheet>
Hare Expires November 17, 2005 [Page 43]
Internet-Draft iCalendar XML Guideline May 2005
12. Acknowledgments
This document is based on previous work by Frank Dawson, Eric R.
Plamondon, Doug Royer, and Surendra K. Reddy, whose previous XML-
iCalendar work provided the basis for this document. Their previous
xCalendar work also acknowledged the contributions of Greg
FitzPatrick, Charles Goldfarb, Paul Hoffman, Lisa Dusseault and
Thomas Rowe. The rdf2ical.xsl transformation created by Masahide
Kanzaki provided inspiration and concepts for the XSL transformation
in this document. The primary author of this version of the document
(T. Hare), however, assumes responsibility for all content,
omissions, and especially errors.
Hare Expires November 17, 2005 [Page 44]
Internet-Draft iCalendar XML Guideline May 2005
13. 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
interpreted. 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, since the XML objects in this memo may be exchanged via
many possible mechanisms, the security considerations observed by
implementations of those mechanisms should be followed for this memo.
Author's Address
Tim Hare
An individual
3048 Bell Grove Dr.
Tallahassee, FL 32308
US
Phone: (850)414-4209
Email: TimHare@comcast.net
Hare Expires November 17, 2005 [Page 45]
Internet-Draft iCalendar XML Guideline May 2005
Appendix A. 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.
[RFC 2446] F. Dawson, R. Hopson, S. Mansour, S. Silverberg
"iCalendar Transport- independent Interoperability Protocol", RFC
2446, http://www.ietf.org/rfc/rfc2446.txt, November 1998
[RFC 2447] F. Dawson, S. Mansour, S. Silverberg "iCalendar Message-
based Interoperability Protocol", RFC 2447,
http://www.ietf.org/rfc/rfc2447.txt, November 1998
[CAP] G. Babics, P. Hill, S. Mansour, D. Royer "Calendar Access
Protocol", Internet-Draft,
http://www.ietf.org/internet-drafts/draft-ietf-calsch-cap-13.txt,
January 2004
[Previous xCalendar work] F. Dawson, S. Reddy, D. Royer, E. Plamondon
"iCalendar DTD Document (xCal)", Internet-Draft,
http://www.ietf.org/internet-drafts/draft-ietf-many-xcal-03.txt, July
2002
[XML] "Extensible Markup Language (XML)", Worldwide Web Consortium,
http://www.w3.org/TR/REC-xml, October 2000.
[XSL] "Extensible Stylesheet Language (XSL)", Worldwide Web
Consortium, http://www.w3.org/TR/xsl, October 2001.
Hare Expires November 17, 2005 [Page 46]
Internet-Draft iCalendar XML Guideline May 2005
[XSLT] "Extensible Stylesheet Language Transformations (XSLT)",
Worldwide Web Consortium, http://www.w3.org/TR/xslt, November 1999.
Hare Expires November 17, 2005 [Page 47]
Internet-Draft iCalendar XML Guideline May 2005
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Hare Expires November 17, 2005 [Page 48]