JSON data formats for vCard and iCalendar P. Kewisch Internet-Draft Mozilla Intended status: Standards Track C. Daboo Expires: August 22, 2014 Apple, Inc. M. Douglass RPI February 18, 2014 jCal: The JSON format for iCalendar draft-ietf-jcardcal-jcal-09 Abstract This specification defines "jCal", a JSON format for iCalendar data. The iCalendar data format is a text format for capturing and exchanging information normally stored within a calendaring and scheduling application, for example tasks and events. JSON is a lightweight, text-based, language-independent data interchange format commonly used in internet applications. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on August 22, 2014. Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect Kewisch, et al. Expires August 22, 2014 [Page 1] Internet-Draft jCal February 2014 to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 4 3. Converting from iCalendar to jCal . . . . . . . . . . . . . . 4 3.1. Pre-processing . . . . . . . . . . . . . . . . . . . . . 4 3.2. iCalendar Stream and Objects (RFC5545 section 3.4) . . . 5 3.3. Components (RFC5545 section 3.6) . . . . . . . . . . . . 6 3.4. Properties (RFC5545 section 3.7 and 3.8) . . . . . . . . 6 3.4.1. Special Cases for Properties . . . . . . . . . . . . 7 3.4.1.1. GEO Property (RFC5545 Section 3.8.1.6) . . . . . 8 3.4.1.2. REQUEST-STATUS Property (RFC5545 Section 3.8.8.3) 8 3.5. Parameters (RFC5545 section 3.2) . . . . . . . . . . . . 9 3.5.1. VALUE parameter . . . . . . . . . . . . . . . . . . . 10 3.5.2. Multi-value Parameters . . . . . . . . . . . . . . . 11 3.6. Values (RFC5545 section 3.3) . . . . . . . . . . . . . . 11 3.6.1. Binary (RFC5545 section 3.3.1) . . . . . . . . . . . 12 3.6.2. Boolean (RFC5545 section 3.3.2) . . . . . . . . . . 12 3.6.3. Calendar User Address (RFC5545 section 3.3.3) . . . . 12 3.6.4. Date (RFC5545 section 3.3.4) . . . . . . . . . . . . 12 3.6.5. Date-Time (RFC5545 section 3.3.5) . . . . . . . . . . 13 3.6.6. Duration (RFC5545 section 3.3.6) . . . . . . . . . . 13 3.6.7. Float (RFC5545 section 3.3.7) . . . . . . . . . . . . 14 3.6.8. Integer (RFC5545 section 3.3.8) . . . . . . . . . . . 14 3.6.9. Period of Time (RFC5545 section 3.3.9) . . . . . . . 14 3.6.10. Recurrence Rule (RFC5545 section 3.3.10) . . . . . . 15 3.6.11. Text (RFC5545 section 3.3.11) . . . . . . . . . . . . 16 3.6.12. Time (RFC5545 section 3.3.12) . . . . . . . . . . . . 16 3.6.13. URI (RFC5545 section 3.3.13) . . . . . . . . . . . . 17 3.6.14. UTC Offset (RFC5545 section 3.3.14) . . . . . . . . . 17 3.7. Extensions . . . . . . . . . . . . . . . . . . . . . . . 17 4. Converting from jCal into iCalendar . . . . . . . . . . . . . 18 5. Handling Unrecognized Properties or Parameters . . . . . . . 18 5.1. Converting iCalendar into jCal . . . . . . . . . . . . . 19 5.2. Converting jCal into iCalendar . . . . . . . . . . . . . 19 5.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 19 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 7.1. UNKNOWN iCalendar Value Data Type . . . . . . . . . . . . 22 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 9.1. Normative References . . . . . . . . . . . . . . . . . . 23 9.2. Informative References . . . . . . . . . . . . . . . . . 24 Kewisch, et al. Expires August 22, 2014 [Page 2] Internet-Draft jCal February 2014 Appendix A. Implementation Status (to be removed prior to publication as an RFC, as well as the reference to RFC6982) . . . . . . . . . . . . . . . . . . . . . . 24 Appendix B. ABNF Schema . . . . . . . . . . . . . . . . . . . . 25 Appendix C. Examples . . . . . . . . . . . . . . . . . . . . . . 27 C.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . . . 27 C.1.1. iCalendar Data . . . . . . . . . . . . . . . . . . . 27 C.1.2. jCal Data . . . . . . . . . . . . . . . . . . . . . . 27 C.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . . . 28 C.2.1. iCalendar Data . . . . . . . . . . . . . . . . . . . 28 C.2.2. jCal Data . . . . . . . . . . . . . . . . . . . . . . 29 Appendix D. Change History (to be removed prior to publication as an RFC) . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 1. Introduction The iCalendar data format [RFC5545] 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, JSON-based formats as defined in [RFC4627] are the native format for JavaScript widgets and libraries and it is appropriate to have a standard form of calendar data that is easier to work with than iCalendar. The purpose of this specification is to define "jCal", a JSON format for iCalendar data. jCal is defined as a straightforward mapping into JSON from iCalendar, so that iCalendar data can be converted to JSON, and then back to iCalendar, without losing any semantic meaning in the data. Anyone creating jCal calendar data according to this specification will know that their data can be converted to a valid iCalendar representation as well. The key design considerations are essentially the same as those for [RFC6321], that is: Round-tripping (converting an iCalendar instance to jCal and back) will give the same semantic result as the starting point. For example, all components, properties and property parameters are guaranteed to be preserved. Ordering of elements and case of property and parameter names will not necessarily be preserved. Kewisch, et al. Expires August 22, 2014 [Page 3] Internet-Draft jCal February 2014 The iCalendar data semantics are to be preserved, allowing a simple consumer to easily browse the data in jCal. A full understanding of iCalendar is still required in order to modify and/or fully comprehend the calendar data. Extensions to the underlying iCalendar specification must not lead to requiring an update to jCal. 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]. The underlying format used for jCal is JSON. Consequently, the terms "object" and "array" as well as the four primitive types (strings, numbers, booleans, and null) are to be interpreted as described in Section 1 of [RFC4627]. Some examples in this document contain "partial" JSON 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 jCal This section describes how iCalendar data is converted to jCal using a simple mapping between the iCalendar data model and JSON elements. In [RFC5545], iCalendar objects are comprised of a set of "components", "properties", "parameters" and "values". The top level of iCalendar data typically contains a stream of iCalendar objects, each of which can be considered a "component". A "component" can contain other "components" or "properties". A "property" has a "value" and a set of zero or more "parameters". Each of these entities have a representation in jCal, defined in the following sections. The representation of a iCalendar object in JSON will be named "jCal object" throughout this document. 3.1. Pre-processing iCalendar uses a line folding mechanism to limit lines of data to a maximum line length (typically 75 octets) to ensure maximum likelihood of preserving data integrity as it is transported via various means (e.g., email) - see Section 3.1 of [RFC5545]. Kewisch, et al. Expires August 22, 2014 [Page 4] Internet-Draft jCal February 2014 iCalendar data uses an "escape" character sequence for text values and property parameter values. See Section 3.1 and 3.3 of [RFC5545] as well as [RFC6868]. When converting from iCalendar to jCal, first iCalendar lines MUST be unfolded. Afterwards, any iCalendar escaping MUST be unescaped. Finally JSON escaping (e.g., for control characters) MUST be applied. The reverse order applies when converting from jCal to iCalendar. First, JSON escaping MUST be unescaped. Afterwards, iCalendar escaping MUST be applied. Finally, long lines SHOULD be folded as described in [RFC5545]. iCalendar uses a base64 encoding for binary data. However, it does not restrict the encoding from being applied to non-binary value types. So the following rules are applied when processing a property with the "ENCODING" property parameter set to "BASE64": o If the property value type is "BINARY", the base64 encoding MUST be preserved. o If the value type is not "BINARY", the "ENCODING" property parameter MUST be removed, and the value MUST be base64 decoded. When base64 encoding and decoding is used, it MUST conform to Section 4 of [RFC4648], which is the base64 method used in [RFC5545]. One key difference in the formatting of values used in iCalendar and jCal is that in jCal the specification uses date/time values aligned with the extended format of [ISO.8601.2004], which is more commonly used in internet applications that make use of the JSON format. The sections of this document describing the various date and time formats contain more information on the use of the complete representation, reduced accuracy or truncated representation. 3.2. iCalendar Stream and Objects (RFC5545 section 3.4) At the top level of the iCalendar object model is an "iCalendar stream". This stream encompasses multiple "iCalendar objects". As the typical use case is transporting a single iCalendar object, there is no defined equivalent to an "iCalendar stream" in jCal. To transport multiple jCal objects in a stream, a simple JSON array can be used. Example: Kewisch, et al. Expires August 22, 2014 [Page 5] Internet-Draft jCal February 2014 ["vcalendar", [ /* Add jCal properties in place of this comment */ ], [ /* Add jCal components in place of this comment */ ] ] 3.3. Components (RFC5545 section 3.6) Each iCalendar component, delimited by "BEGIN" and "END", will be converted to a fixed length array with three fields that have a specific structure: 1. A string with the name of the iCalendar component, but in lowercase. 2. An array of jCal properties as described in Section 3.4. 3. An array of jCal components, representing the sub-components of the component in question. This mapping applies to the top level iCalendar objects, as well as individual sub-components in the same way. The iCalendar to jCal component mapping is valid for both current iCalendar components and any new iCalendar components added in the future. Conversion is to be done in the same way. While the grouping of properties and sub-components does not retain the original order specified in the iCalendar data, the semantics of a component are preserved. Example: ["vevent", [ /* Add jCal properties in place of this comment */ ], [ /* Add jCal components in place of this comment */ ] ] 3.4. Properties (RFC5545 section 3.7 and 3.8) iCalendar properties, whether they apply to the "VCALENDAR" object or to a component, are handled in a consistent way in the jCal format. Each individual iCalendar property is represented in jCal by an array with three fixed elements, followed by one or more additional elements, depending on if the property is a multi-value property as described in Section 3.1.2 of [RFC5545]. Kewisch, et al. Expires August 22, 2014 [Page 6] Internet-Draft jCal February 2014 The array consists of the following fixed elements: 1. The name of the property, as a lowercase string. The iCalendar format specifies that property names are case-insensitive, and recommends that they be rendered in uppercase. In jCal, they MUST be in lowercase. 2. An object containing the parameters as described in Section 3.5. If the property has no parameters, an empty object is used to represent that. 3. The type identifier string of the value, in lowercase. Due to special casing of certain properties as described in Section 3.4.1, it is important that parsers check both the type identifier and the value data type and do not rely on assumptions based on the property name. The remaining elements of the array are used for one or more values of the property. For single-value properties, the array has exactly four elements; for multi-valued properties, as described in [RFC5545] Section 3.1.2, each value is another element, and there can be any number of additional elements. In the following example, the "categories" property is multi-valued and has two values, while the summary property is single-valued: Example: ["vevent", [ ["summary", {}, "text", "Meeting with Fred"], ["categories", {}, "text", "Meetings", "Work"] ... ], [ /* sub-components */ ] ] 3.4.1. Special Cases for Properties This section describes some properties that have special handling when converting to jCal. Kewisch, et al. Expires August 22, 2014 [Page 7] Internet-Draft jCal February 2014 3.4.1.1. GEO Property (RFC5545 Section 3.8.1.6) 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 jCal, the value for the "geo" property value is represented as an array of two values. The first value of the property represents the latitude, the second value represents the longitude. When converting from jCal to iCalendar, the two values MUST be converted using a semi-colon as the separator character. Example ["vevent", [ ["geo", {}, "float", [ 37.386013, -122.082932 ] ] ... ], ... ] 3.4.1.2. REQUEST-STATUS Property (RFC5545 Section 3.8.8.3) 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 any additional data. In jCal, the value for the "request-status" property value is represented as an array with two or three values. The first array element corresponds to the code, the second element corresponds to the description and the third element corresponds to the additional data. Each value is represented using a string value. If there is no additional data in the iCalendar value, the last element of the array SHOULD NOT be present. When converting from jCal to iCalendar, the two or three values MUST be converted using a semi-colon as the separator character. iCalendar Example: Kewisch, et al. Expires August 22, 2014 [Page 8] Internet-Draft jCal February 2014 BEGIN:VEVENT ... REQUEST-STATUS:2.0;Success REQUEST-STATUS:3.7;Invalid calendar user;ATTENDEE: mailto:jsmith@example.com ... END:VEVENT jCal Example: ["vevent": [ ["request-status", {}, "text", ["2.0", "Success"] ], ["request-status", {}, "text", [ "3.7", "Invalid calendar user", "ATTENDEE:mailto:jsmith@example.org" ] ], ... ], ... ] 3.5. Parameters (RFC5545 section 3.2) Property parameters are represented as a JSON object where each key- value pair represents the iCalendar parameter name and its value. The name of the parameter MUST be in lowercase, the original case of the parameter value MUST be preserved. For example, the "PARTSTAT" property parameter is represented in jCal by the "partstat" key. Any new iCalendar parameters added in the future will be converted in the same way. Example: Kewisch, et al. Expires August 22, 2014 [Page 9] Internet-Draft jCal February 2014 ["vevent": [ ["attendee", { "partstat": "ACCEPTED", "rsvp": "TRUE", "role": "REQ-PARTICIPANT" }, "cal-address", "mailto:jsmith@example.org" ], ["summary", {}, "text", "Meeting"], ... ], ... ] 3.5.1. VALUE parameter iCalendar defines a "VALUE" property parameter (Section 3.2.20 of [RFC5545]). This property parameter MUST NOT be added to the parameters object. Instead, the value type is signaled through the type identifier in the third element of the array describing the property. When converting a property from iCalendar to jCal, the value type is determined as follows: 1. If the property has a "VALUE" parameter, that parameter's value is used as the value type. 2. If the property has no "VALUE" parameter but has a default value type, the default value type is used. 3. If the property has no "VALUE" parameter and has no default value type, "unknown" is used. Converting from jCal into iCalendar is done as follows: 1. If the property's value type is "unknown", no "VALUE" parameter is included. 2. If the property's value type is the default type for that property, no "VALUE" parameter is included. 3. Otherwise, a "VALUE" parameter is included, and the value type is used as the parameter value. See Section 5 for information on handling unknown value types. Kewisch, et al. Expires August 22, 2014 [Page 10] Internet-Draft jCal February 2014 3.5.2. Multi-value Parameters In [RFC5545], some parameters allow using a COMMA-separated list of values. To ease processing in jCal, the value to such parameters MUST be represented in an array containing the separated values. The array elements MUST be string values. Single-value parameters can be represented either using a single string value or an array with one string element. A jCal parser MUST be able to understand both value data types. An example for a such parameter is the iCalendar "DELEGATED-FROM" and "DELEGATED-TO" parameter, more such parameters may be added in extensions. The iCalendar specification requires encapsulation between DQUOTE characters if a parameter value contains a colon, a semicolon or a comma. These extra DQUOTE characters do not belong to the actual parameter value, and hence are not included when the parameter is converted to jCal. Example 1: ["attendee", { "delegated-to": ["mailto:jdoe@example.org", "mailto:jqpublic@example.org"] }, "cal-address", "mailto:jsmith@example.org" ] Example 2: ["attendee", { "delegated-to": "mailto:jdoe@example.org" }, "cal-address", "mailto:jsmith@example.org" ] 3.6. Values (RFC5545 section 3.3) The following subsections specify how iCalendar property value data types, which are defined in the subsections of [RFC5545] Section 3.3, are represented in jCal. Kewisch, et al. Expires August 22, 2014 [Page 11] Internet-Draft jCal February 2014 3.6.1. Binary (RFC5545 section 3.3.1) Description: iCalendar "BINARY" property values are represented by a property with type identifier "binary". The value element is a JSON string with base64 encoded data, conforming to Section 4 of [RFC4648], which is the base64 method used in [RFC5545]. Example: ["attach", {}, "binary", "SGVsbG8gV29ybGQh"] 3.6.2. Boolean (RFC5545 section 3.3.2) Description: iCalendar "BOOLEAN" property values are represented by a property with the type identifier "boolean". The value is a JSON boolean value. Example: ["x-non-smoking", {}, "boolean", true] 3.6.3. Calendar User Address (RFC5545 section 3.3.3) Description: iCalendar "CAL-ADDRESS" property values are represented by a property with the type identifier "cal-address". The value is a JSON string with the URI as described in [RFC3986]. Example: ["attendee", {}, "cal-address", "mailto:kewisch@example.com"] 3.6.4. Date (RFC5545 section 3.3.4) Description: iCalendar "DATE" property values are represented by a property with the type identifier "date". The value elements are JSON strings with the same date value specified by [RFC5545], but represented using the extended format of the complete representation specified in [ISO.8601.2004], Section 4.1.2.2. Other variations, for example representation with reduced accuracy, MUST NOT be used. ABNF Schema: date = year "-" month "-" day ;YYYY-MM-DD Kewisch, et al. Expires August 22, 2014 [Page 12] Internet-Draft jCal February 2014 Example: ["dtstart", {}, "date", "2011-05-17"] 3.6.5. Date-Time (RFC5545 section 3.3.5) Description: iCalendar "DATE-TIME" property values are represented by a property with the type identifier "date-time". The value elements are JSON strings with the same date value specified by [RFC5545], but represented using the extended format of the complete representation specified in [ISO.8601.2004], Section 4.3.2. Other variations, for example representation with reduced accuracy, MUST NOT be used. The same restrictions with respect to leap seconds and timezone offsets as specified in [RFC5545] Section 3.3.5 apply. ABNF Schema: date-complete = year "-" month "-" day ;YYYY-MM-DD time-complete = hour ":" minute ":" second [zone] ; HH:MM:SS datetime = date-complete "T" time-complete Examples: ["dtstart", {}, "date-time", "2012-10-17T12:00:00"], ["dtstamp", {}, "date-time", "2012-10-17T12:00:00Z"], ["dtend", { "tzid": "Europe/Berlin" }, "date-time", "2011-10-17T13:00:00" ] 3.6.6. Duration (RFC5545 section 3.3.6) Description: iCalendar "DURATION" property values are represented by a property with the type identifier "duration". The value elements are JSON strings with the same duration value specified by [RFC5545]. Example: ["duration", {}, "duration", "P1D"] Kewisch, et al. Expires August 22, 2014 [Page 13] Internet-Draft jCal February 2014 3.6.7. Float (RFC5545 section 3.3.7) Description: iCalendar "FLOAT" property values are represented by a property with the type identifier "float". The value elements are JSON primitive number values. Example: ["x-grade", {}, "float", 1.3] 3.6.8. Integer (RFC5545 section 3.3.8) Description: vCard "INTEGER" property values are represented by a property with the type identifier "integer". The value elements are JSON primitive number values which MUST resolve to an integer value in the range specified in [RFC5545], Section 3.3.8. Thus a fractional and/or exponential part are only allowed under limited circumstances. Examples: ["percent-complete", {}, "integer", 42] 3.6.9. Period of Time (RFC5545 section 3.3.9) Description: iCalendar "PERIOD" property values are represented by a jCal property with the type identifier "period". The value element is an array of JSON strings, with the first element representing the start of the period and the second element representing the end of the period. As in [RFC5545], the start of the period is always formatted as a date-time value and the end of the period MUST be either a date-time or duration value. Any date, date-time or duration values contained in the period value MUST be formatted in accordance to the rules for date, date-time or duration values specified in this document. Example: ["freebusy", { "fbtype": "FREE" }, "period", ["1997-03-08T16:00:00Z", "P1D"] ] Kewisch, et al. Expires August 22, 2014 [Page 14] Internet-Draft jCal February 2014 3.6.10. Recurrence Rule (RFC5545 section 3.3.10) Description: iCalendar "RECUR" property values are represented by a property with the type identifier "recur". The value elements are objects describing the structured data as specified by [RFC5545]. Each rule part is described by the combination of key and value. The key specifies the name of the rule part and MUST be converted to lowercase. The value of the rule part MUST be mapped by the following rules: * The value of the "freq" and "wkst" rule parts MUST be a string as specified in [RFC5545], with case preserved. * The value of the "until" rule part MUST be a date or date-time value formatted in accordance to the rules for date or date- time specified in this document. * The "count" and "interval" rule parts MUST be specified as a single JSON number value. * The following rule parts can have one or more numeric values: "bysecond", "byminute", "byhour", "bymonthday", "byyearday", "byweekno", "bymonth", and "bysetpos". If a rule part contains multiple values, an array of numbers MUST be used for that rule part. Single-valued rule parts can be represented either using a single number value, omitting the array completely, or an array with one number element. A jCal parser MUST be able to understand both data types. * Similarly, the "byday" rule part can have one or more string values. If it contains multiple values, an array of strings MUST be used. As before, a single-valued rule part can be represented either using a single string value or an array with one string element, both of which a jCal parser MUST be able to understand. Example 1: Kewisch, et al. Expires August 22, 2014 [Page 15] Internet-Draft jCal February 2014 ["rrule", {}, "recur", { "freq": "YEARLY", "count": 5, "byday": [ "-1SU", "2MO" ], "bymonth": 10 } ] Example 2: ["rrule", {}, "recur", { "freq": "MONTHLY", "interval": 2, "bymonthday": [ 1, 15, -1 ], "until": "2013-10-01" } ] 3.6.11. Text (RFC5545 section 3.3.11) Description: iCalendar "TEXT" property values are represented by a property with the type identifier "text". The value elements are JSON strings. Example: ["comment", {}, "text", "hello, world"] 3.6.12. Time (RFC5545 section 3.3.12) Description: iCalendar "TIME" property values are represented by a property with the type identifier "time". The value elements are JSON strings with the same time value specified by [RFC5545], but represented using the extended format of the complete representation specified in [ISO.8601.2004], Section 4.2.2.2. Other variations, for example representation with reduced accuracy, MUST NOT be used. The same restrictions with respect to leap seconds, time fractions, and timezone offsets as specified in [RFC5545] Section 3.3.12 apply. Kewisch, et al. Expires August 22, 2014 [Page 16] Internet-Draft jCal February 2014 ABNF Schema: time-complete = hour ":" minute ":" second [zone] ; HH:MM:SS Example: ["x-time-local", {}, "time", "12:30:00"], ["x-time-utc", {}, "time", "12:30:00Z"], ["x-time-offset", { "tzid": "Europe/Berlin" }, "time", "12:30:00"] 3.6.13. URI (RFC5545 section 3.3.13) Description: iCalendar "URI" property values are represented by a property with the type identifier "uri". The value elements are JSON strings representing the URI. Example: ["tzurl", {}, "uri", "http://example.org/tz/Europe-Berlin.ics"] 3.6.14. UTC Offset (RFC5545 section 3.3.14) Description: iCalendar "UTC-OFFSET" property values are represented by a property with the type identifier "utc-offset". The value elements are JSON strings with the same UTC offset value specified by [RFC5545], with the exception that the hour and minute components are separated by a ":" character, for consistency with the [ISO.8601.2004] timezone offset, extended format. Example: ["tzoffsetfrom", {}, "utc-offset", "-05:00"], ["tzoffsetto", {}, "utc-offset", "+12:45"] 3.7. Extensions Kewisch, et al. Expires August 22, 2014 [Page 17] Internet-Draft jCal February 2014 iCalendar extension properties and property parameters (those with an "X-" prefix in their name) are handled in the same way as other properties and property parameters: the property is represented by an array, the property parameter represented by an object. The property or parameter name uses the same name as for the iCalendar extension, but in lowercase. For example, the "X-FOO" property in iCalendar turns into the "x-foo" jCal property. See Section 5 for how to deal with default values for unrecognized extension properties or property parameters. 4. Converting from jCal into iCalendar When converting component, property and property 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 [RFC5545]. Character escaping and line folding MUST be applied to the resulting iCalendar data as required by [RFC5545] and [RFC6868]. Non-binary value types MUST NOT be base64 encoded. When converting to iCalendar, the VALUE parameter MUST be added to properties whose default value type is unknown, but do not have a jCal type identifier "unknown". The VALUE parameter MAY be omitted for properties using the default value type. The VALUE parameter MUST be omitted for properties which have the jCal type identifier "unknown". 5. Handling Unrecognized Properties or Parameters In iCalendar, properties can have one or more value types as specified by their definition, with one of those values being defined as the default. When a property uses its default value type, the "VALUE" property parameter does not need to be specified on the property. For example, "DTSTART"'s default value type is "DATE- TIME", so "VALUE=DATE-TIME" need not be set as a property parameter. However, "DTSTART" also allows a "DATE" value to be specified, and if that is used, "VALUE=DATE" has to be set as a property parameter. When new properties are defined or "X-" properties used, an iCalendar to jCal converter might not recognize them, and not know what the appropriate default value types are, yet they need to be able to preserve the values. A similar issue arises for unrecognized property parameters. In jCal, a new "unknown" property value type is introduced. Its purpose is to allow preserving unknown property values when round- Kewisch, et al. Expires August 22, 2014 [Page 18] Internet-Draft jCal February 2014 tripping between jCal and iCalendar. To avoid collisions, this specification reserves the UNKNOWN property value type in iCalendar. It MUST NOT be used in any iCalendar as specified by [RFC5545], nor any extensions to it. The type is hence registered to the iCalendar Value Data Types registry in Section 7.1. 5.1. Converting iCalendar into jCal Any property that does not include a "VALUE" property parameter and whose default value type is not known, MUST be converted to a primitive JSON string. The content of that string is the unprocessed value text. Also, value type MUST be set to "unknown". To correctly implement this format, it is critical that if the default type is not known that the type "unknown" is used. If this requirement is ignored and for example "text" is used, additional escaping may occur which breaks round-tripping values. Any unrecognized property parameter MUST be converted to a string value, with its content set to the property parameter value text, treated as if it were a "TEXT" value. 5.2. Converting jCal into iCalendar In jCal the value type is always explicitly specified. It is converted to iCalendar using the iCalendar VALUE parameter, except in the following two cases: o If the value type specified in jCal matches the default value type in iCalendar, the VALUE parameter MAY be omitted. o If the value type specified in jCal is set to "unknown", the VALUE parameter MUST NOT be specified. The value MUST be taken over in iCalendar without processing. 5.3. Examples The following is an example of an unrecognized iCalendar property (that uses a "DATE-TIME" value as its default), and the equivalent jCal representation of that property. iCalendar: X-COMPLAINT-DEADLINE:20110512T120000Z jCal: Kewisch, et al. Expires August 22, 2014 [Page 19] Internet-Draft jCal February 2014 ["x-complaint-deadline", {}, "unknown", "20110512T120000Z"] The following is an example of how to cope with jCal data where the parser was unable to identify the type. Note how the "unknown" value type is not added to the iCalendar data and escaping, aside from standard JSON string escaping, is not processed. jCal: ["x-coffee-data", {}, "unknown", "Stenophylla;Guinea\\,Africa"] iCalendar: X-COFFEE-DATA:Stenophylla;Guinea\,Africa The following is an example of a jCal property (where the corresponding iCalendar property uses a "INTEGER" value as its default), and the equivalent iCalendar representation of that property. jCal: ["percent-complete", {}, "integer", 95] iCalendar: PERCENT-COMPLETE:95 The following is an example of an unrecognized iCalendar property parameter (that uses a "FLOAT" value as its default) specified on a recognized iCalendar property, and the equivalent jCal representation of that property and property parameter. iCalendar: DTSTART;X-SLACK=30.3;VALUE=DATE:20110512 jCal: ["dtstart", { "x-slack": "30.3" }, "date", "2011-05-12"] Kewisch, et al. Expires August 22, 2014 [Page 20] Internet-Draft jCal February 2014 6. Security Considerations This specification defines how iCalendar data can be "translated" between two different data formats - the original text format and JSON - with a one-to-one mapping to ensure all the semantic data in one format (properties, parameters and values) are preserved in the other. It does not change the semantic meaning of the underlying data itself, or impose or remove any security considerations that apply to the underlying data. The use of JSON as a format does have its own inherent security risks as discussed in Section 7 of [RFC4627]. Even though JSON is considered a safe subset of JavaScript, it should be kept in mind that a flaw in the parser processing JSON could still impose a threat which doesn't arise with conventional iCalendar data. With this in mind, a parser for JSON data should be used for jCal that is aware of the security implications. For example, the use of JavaScript's eval() function is only allowed using the regular expression in Section 6 of [RFC4627]. A native parser with full awareness of the JSON format should be preferred. In addition, it is expected that this new format will result in iCalendar data being more widely disseminated (e.g., with use in web applications rather than just dedicated calendaring applications). In all cases, application developers have to conform to the semantics of the iCalendar data as defined by [RFC5545] and associated extensions, and all of the security considerations described in Section 7 of [RFC5545], or any associated extensions, are applicable. 7. IANA Considerations This document defines a MIME media type for use with iCalendar in JSON data. This media type SHOULD be used for the transfer of calendaring data in JSON. Type name: application Subtype name: calendar+json Required parameters: none Optional parameters: "method", "component" and "optinfo" as defined for the text/calendar media type in [RFC5545], Section 8.1. Encoding considerations: Same as encoding considerations of application/json as specified in [RFC4627], Section 6. Kewisch, et al. Expires August 22, 2014 [Page 21] Internet-Draft jCal February 2014 Security considerations: See Section 6. Interoperability considerations: This media type provides an alternative format for iCalendar data based on JSON. 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. Similarly, Applications that use the application/ json media type to transfer calendaring data can use this to further specify the content. Fragment identifier considerations: N/A Additional information: Deprecated alias names for this type: N/A Magic number(s): N/A File extension(s): N/A Macintosh file type code(s): N/A Person & email address to contact for further information: calsify@ietf.org 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 7.1. UNKNOWN iCalendar Value Data Type IANA is asked to add the following entry to the iCalendar Data Types registry: Value name: UNKNOWN Purpose: To allow preserving property values whose default value type is not known during round-tripping between jCal and iCalendar. Kewisch, et al. Expires August 22, 2014 [Page 22] Internet-Draft jCal February 2014 Format definition: (Not applicable) Description: The UNKNOWN value data type is reserved for the exclusive use of the jCal format. Its use is described in Section 5 of this document. Example: As this registration serves as a reservation of the UNKNOWN type so that it is not used in iCalendar, there is no applicable iCalendar example. Examples of its usage in jCal can be found in this document. IANA is asked to make the "Status" column for this entry in the registry say, "Reserved - Do not use" and to make the "Reference" column refer to Section 5 of this document. 8. Acknowledgments The authors would like to thank the following for their valuable contributions: William Gill, Erwin Rehme, and Dave Thewlis, Simon Perreault, Michael Angstadt, Peter Saint-Andre, Bert Greevenbosch, Javier Godoy. This specification originated from the work of the XML-JSON technical committee of the Calendaring and Scheduling Consortium. 9. References 9.1. Normative References [ISO.8601.2004] International Organization for Standardization, ""Data elements and interchange formats -- Information interchange -- Representation of dates and times" ", ISO 8601, 12 2004. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, October 2006. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. Kewisch, et al. Expires August 22, 2014 [Page 23] Internet-Draft jCal February 2014 [RFC5545] Desruisseaux, B., "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", RFC 5545, September 2009. [RFC6321] Daboo, C., Douglass, M., and S. Lees, "xCal: The XML Format for iCalendar", RFC 6321, August 2011. [RFC6868] Daboo, C., "Parameter Value Encoding in iCalendar and vCard", RFC 6868, February 2013. 9.2. Informative References [RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006. [RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running Code: The Implementation Status Section", RFC 6982, July 2013. [calconnect-artifacts] The Calendaring and Scheduling Consortium, "Code Artifacts and Schemas", , . Appendix A. Implementation Status (to be removed prior to publication as an RFC, as well as the reference to RFC6982) This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in [RFC6982]. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist. According to [RFC6982], "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit". Kewisch, et al. Expires August 22, 2014 [Page 24] Internet-Draft jCal February 2014 1. ICAL.js - Philipp Kewisch, James Lal. A JavaScript parser for iCalendar (rfc5545) Source: https://github.com/mozilla-comm/ical.js/ Maturity: production Coverage: All aspects of this draft, up to version 01. Includes an online validator. (as of rev 847c67c501, 2013-02-14) Licensing: MPL, Mozilla Public License 2.0 2. Py Calendar - Cyrus Daboo. iCalendar/vCard Library Source: https://svn.calendarserver.org/repository/calendarserver /PyCalendar/branches/json/ Maturity: production Coverage: All aspects of this draft, up to version 01. Licensing: Apache License, Version 2.0 Additionally, interoperability testing of this draft is an ongoing effort under members of calconnect, the Calendaring and Scheduling Consortium. CalDAV Vendors are looking into supporting this draft. Appendix B. ABNF Schema Below is an ABNF schema as per [RFC5234] for iCalendar in JSON. ABNF Symbols not described here are taken from [RFC4627]. The schema is non-normative and given for reference only. The numeric section numbers given in the comments refer to section in [RFC5545]. Additional semantic restrictions apply, especially regarding the allowed properties and sub-components per component. Details on these restrictions can be found in this document and [RFC5545]. Additional schemas may be available on the internet at [calconnect-artifacts]. ; A jCal Object is a component with the component-name "vcalendar". ; Restrictions to which properties and sub-components may be ; specified are to be taken from RFC5545. jcalobject = component ; A jCal component consists of the name string, properties array and Kewisch, et al. Expires August 22, 2014 [Page 25] Internet-Draft jCal February 2014 ; component array component = begin-array DQUOTE component-name DQUOTE value-separator properties-array value-separator components-array end-array components-array = begin-array [ component *(value-separator component) ] end-array ; A jCal property consists of the name string, parameters object, ; type string and one or more values as specified in this document. property = begin-array DQUOTE property-name DQUOTE value-separator params-object value-separator DQUOTE type-name DQUOTE propery-value *(value-separator property-value) end-array properties-array = begin-array [ property *(value-separator property) ] end-array ; Property values depend on the type-name. Aside from the value types ; mentioned here, extensions may make use of other JSON value types. ; The non-terminal symbol structured-prop-value covers the special ; cases for GEO and REQUEST-STATUS property-value = simple-prop-value / structured-prop-value simple-prop-value = string / number / true / false structured-prop-value = begin-array [ structured-element *(value-separator structured-element) ] end-array structured-element = simple-prop-value ; The jCal params-object is a JSON object which follows the semantic ; guidelines described in this document. params-object = begin-object [ params-member *(value-separator params-member) ] end-object params-member = DQUOTE param-name DQUOTE name-separator param-value param-value = string / param-multi param-multi = begin-array [ string *(value-separtor string) ] end-array ; The type MUST be a valid type as described by this document. New ; value types can be added by extensions. Kewisch, et al. Expires August 22, 2014 [Page 26] Internet-Draft jCal February 2014 type-name = "binary" / "boolean" / "cal-address" / "date" / "date-time" / "duration" / "float" / "integer" / "period" / "recur" / "text" / "time" / "uri" / "utc-offset" / x-type ; Component, property, parameter and type names MUST be lowercase. ; Additional semantic restrictions apply as described by this ; document and RFC5545. component-name = lowercase-name property-name = lowercase-name param-name = lowercase-name x-type = lowercase-name lowercase-name = 1*(%x61-7A / DIGIT / "-") Appendix C. Examples This section contains two examples of iCalendar objects with their jCal representation. C.1. Example 1 C.1.1. 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 C.1.2. jCal Data ["vcalendar", [ ["calscale", {}, "text", "GREGORIAN"], ["prodid", {}, "text", "-//Example Inc.//Example Calendar//EN"], ["version", {}, "text", "2.0"] ], [ ["vevent", Kewisch, et al. Expires August 22, 2014 [Page 27] Internet-Draft jCal February 2014 [ ["dtstamp", {}, "date-time", "2008-02-05T19:12:24Z"], ["dtstart", {}, "date", "2008-10-06"], ["summary", {}, "text", "Planning meeting"], ["uid", {}, "text", "4088E990AD89CB3DBB484909"] ], [] ] ] ] C.2. Example 2 C.2.1. iCalendar Data BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Example Corp.//Example Client//EN BEGIN:VTIMEZONE LAST-MODIFIED:20040110T032845Z TZID:US/Eastern BEGIN:DAYLIGHT DTSTART:20000404T020000 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4 TZNAME:EDT TZOFFSETFROM:-0500 TZOFFSETTO:-0400 END:DAYLIGHT BEGIN:STANDARD DTSTART:20001026T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZNAME:EST TZOFFSETFROM:-0400 TZOFFSETTO:-0500 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20060206T001121Z DTSTART;TZID=US/Eastern:20060102T120000 DURATION:PT1H RRULE:FREQ=DAILY;COUNT=5 RDATE;TZID=US/Eastern;VALUE=PERIOD:20060102T150000/PT2H SUMMARY:Event #2 DESCRIPTION:We are having a meeting all this week at 12 pm fo r one hour\, with an additional meeting on the first day 2 h ours long.\nPlease bring your own lunch for the 12 pm meetin gs. Kewisch, et al. Expires August 22, 2014 [Page 28] Internet-Draft jCal February 2014 UID:00959BC664CA650E933C892C@example.com END:VEVENT BEGIN:VEVENT DTSTAMP:20060206T001121Z DTSTART;TZID=US/Eastern:20060104T140000 DURATION:PT1H RECURRENCE-ID;TZID=US/Eastern:20060104T120000 SUMMARY:Event #2 bis UID:00959BC664CA650E933C892C@example.com END:VEVENT END:VCALENDAR C.2.2. jCal Data ["vcalendar", [ ["prodid", {}, "text", "-//Example Corp.//Example Client//EN"], ["version", {}, "text", "2.0"] ], [ ["vtimezone", [ ["last-modified", {}, "date-time", "2004-01-10T03:28:45Z"], ["tzid", {}, "text", "US/Eastern"] ], [ ["daylight", [ ["dtstart", {}, "date-time", "2000-04-04T02:00:00"], ["rrule", {}, "recur", { "freq": "YEARLY", "byday": "1SU", "bymonth": 4 } ], ["tzname", {}, "text", "EDT"], ["tzoffsetfrom", {}, "utc-offset", "-05:00"], ["tzoffsetto", {}, "utc-offset", "-04:00"] ], [] ], ["standard", [ ["dtstart", {}, "date-time", "2000-10-26T02:00:00"], Kewisch, et al. Expires August 22, 2014 [Page 29] Internet-Draft jCal February 2014 ["rrule", {}, "recur", { "freq": "YEARLY", "byday": "1SU", "bymonth": 10 } ], ["tzname", {}, "text", "EST"], ["tzoffsetfrom", {}, "utc-offset", "-04:00"], ["tzoffsetto", {}, "utc-offset", "-05:00"] ], [] ] ] ], ["vevent", [ ["dtstamp", {}, "date-time", "2006-02-06T00:11:21Z"], ["dtstart", { "tzid": "US/Eastern" }, "date-time", "2006-01-02T12:00:00" ], ["duration", {}, "duration", "PT1H"], ["rrule", {}, "recur", { "freq": "DAILY", "count": 5 } ], ["rdate", { "tzid": "US/Eastern" }, "period", "2006-01-02T15:00:00/PT2H" ], ["summary", {}, "text", "Event #2"], ["description", {}, "text", // Note that comments and string concatenation are not // allowed per JSON specification and is used here only // to avoid long lines. "We are having a meeting all this week at 12 pm for one " + "hour, with an additional meeting on the first day 2 " + "hours long.\nPlease bring your own lunch for the 12 pm " + "meetings." ], ["uid", {}, "text", "00959BC664CA650E933C892C@example.com"] ], [] ], Kewisch, et al. Expires August 22, 2014 [Page 30] Internet-Draft jCal February 2014 ["vevent", [ ["dtstamp", {}, "date-time", "2006-02-06T00:11:21Z"], ["dtstart", { "tzid": "US/Eastern" }, "date-time", "2006-01-02T14:00:00" ], ["duration", {}, "duration", "PT1H"], ["recurrence-id", { "tzid": "US/Eastern" }, "date-time", "2006-01-04T12:00:00" ], ["summary", {}, "text", "Event #2"], ["uid", {}, "text", "00959BC664CA650E933C892C@example.com"] ], [] ] ] ] Appendix D. Change History (to be removed prior to publication as an RFC) draft-kewisch-et-al-icalendar-in-json-01 * Added information on how to handle multi-value parameter. The decision leads to a cleaner draft for a similar proposal for vcard. * Removed the open discussion point section regarding the mime media type in favor of adding one. * Minor corrections in wording and typo fixes. draft-kewisch-et-al-icalendar-in-json-02 * Added implementation status section. * Removed various text tables that just show a conversion from uppercase to lowercase. * Changed value format for RECUR and PERIOD types * Minor corrections in wording and typo fixes. Kewisch, et al. Expires August 22, 2014 [Page 31] Internet-Draft jCal February 2014 draft-ietf-jcardcal-jcal-00 * Publication as a WG draft draft-ietf-jcardcal-jcal-01 * Changed handling of GEO and REQUEST-STATUS to align with jCard * Corrections and additions to the ABNF Section * Added a further sentence on preprocessing and escaping to clarify that JSON escaping must be used. draft-ietf-jcardcal-jcal-02 * Changed handling of unknown property parameter types. * Minor corrections and fixing typos. draft-ietf-jcardcal-jcal-03 * Changed wording around RECUR value handling. * Minor corrections and fixing typos. draft-ietf-jcardcal-jcal-04 * Changed wording around RECUR value handling again. draft-ietf-jcardcal-jcal-05 * Added reference to rfc6868 for both directions * Resolved a few MAY/SHOULD conflicts * Improved UNKNOWN registration by only putting iCalendar related information into the registration template. * Removed the stream construct, replaced with general information on how to handle iCalendar streams. * Corrected some examples and ABNF draft-ietf-jcardcal-jcal-06 * Corrected trailing commas in some examples. * Corrected rrule examples to use object syntax. Kewisch, et al. Expires August 22, 2014 [Page 32] Internet-Draft jCal February 2014 * Corrected "request-status" example to use an array. * Updated UNKNOWN registration text as per iCalendar expert suggestion. draft-ietf-jcardcal-jcal-07 * Minor fix in an example. draft-ietf-jcardcal-jcal-08 * Editorial changes for alignment with draft-ietf-jcardcal-jcard. draft-ietf-jcardcal-jcal-09 * Editorial changes in preparation for IETF last call. * Removed reference to jcard draft * Made more clear that parsers MUST be able to understand both single-valued and array data types. Authors' Addresses Philipp Kewisch Mozilla Corporation 650 Castro Street, Suite 300 Mountain View, CA 94041 USA EMail: mozilla@kewis.ch URI: http://www.mozilla.org/ Cyrus Daboo Apple Inc. 1 Infinite Loop Cupertino, CA 95014 USA EMail: cyrus@daboo.name URI: http://www.apple.com/ Kewisch, et al. Expires August 22, 2014 [Page 33] Internet-Draft jCal February 2014 Mike Douglass Rensselaer Polytechnic Institute 110 8th Street Troy, NY 12180 USA EMail: douglm@rpi.edu URI: http://www.rpi.edu/ Kewisch, et al. Expires August 22, 2014 [Page 34]