This document describes a RESTful web service for calendar access and update.
ws-calendar-wd19 — Originally contributed by Mike Douglass as part of WS-Calendar v1.0 Specification. See full history in that document.
Ported to separate document. “Promoted” all section headers.
Added Intro, updated namespaces to meet OASIS standard
Additional namespace clean-up in response to Cover comments.
Consistent capitalization of calWS when used as a namespace identifier
Clean-up of CalWS discussion in appendix
Types, capitalization, missing XRD reference
© 2012 The Calendaring and Scheduling Consortium, Inc.
This document is not a CalConnect Standard. It is distributed for review and comment, and is subject to change without notice and may not be referred to as a Standard. Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.
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This document describes a RESTful web service for calendar access and update.
This document was editorially updated to ensure synchronization with the OASIS WS-Calendar publication of CalWS-SOAP as V1.0 for public review and contains the same content.
This document is copyright ©2012 by The Calendaring and Scheduling Consortium and is licensed under the Creative Commons 3.0 Unported License:
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Michael Douglass
This specification is related to:
WS-Calendar Version 1.0. Latest version.
The CalWS REST protocol is built upon and makes the same assumptions about structure as the CalDAV protocol defined in
Calendar resources, for example events and tasks are stored as named resources (files) inside special collections (folders) known as “Calendar Collections”.
This specification can be looked upon as a layer built on top of CalDAV and defines the basic operations which allow creation, retrieval, update and deletion. In addition, query and freebusy operations are defined to allow efficient, partial retrieval of calendar data.
This does not mean that a CalWS service must be built on CalDAV, merely that a degree of conformity is established such that services built in that manner do not have a significant mismatch. It is assumed that some CalWS REST services will be built without any CalDAV support.
The keywords “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in
XML namespaces and prefixes used in this standard:
| Prefix | Namespace |
| xcal | urn:ietf:params:xml:ns:icalendar-2.0 |
| calWS | |
| xrd |
The Service interactions are built upon and make the same assumptions about structure as the CalDAV protocol defined in
Calendar resources, for example events and tasks are stored as named resources (files) inside special collections (folders) known as “Calendar Collections”.
These services can be looked upon as a layer built on top of CalDAV and defines the basic operations which allow creation, retrieval, update and deletion. In addition, query, and free-busy operations are defined to allow efficient, partial retrieval of calendar data.
These services assume a degree of conformity with CalDAV is established such that services built in that manner do not have a significant mismatch. It is assumed that some WS-Calendar services will be built without any CalDAV support.
The protocol is an HTTP based RESTfull protocol using a limited set of methods. Each request may be followed by a response containing status information. The following methods are specified in the protocol description, PUT, POST, GET, DELETE. To avoid various issues with certain methods being blocked clients may use the X-HTTP-Method-Override: header to specify the intended operation. Servers SHOULD behave as if the named method was used.
A service or resource will have a number of properties which describe the current state of that service or resource. These properties are accessed through a GET on the target resource or service with an ACCEPT header specifying application/xrd+xml. See
The following operations are defined by this specification:
Retrieval and update of service and resource properties
Creation of a calendar object
Retrieval of a calendar object
Update of a calendar object
Deletion of a calendar object
Query
Free-busy query
The same restrictions apply to Calendar Object Resources as specified in CalDAV
It is assumed that the client and server each have access to a full set of up to date timezone information. Timezones will be referenced by a timezone identifier from the full set of Olson data together with a set of well-known aliases defined [TZDB]. CalWS services may advertise themselves as timezone servers through the server properties object.
A number of issues are not addressed by this version of the specification, either because they should be addressed elsewhere or will be addressed at some later date.
It is assumed that the targeted server will set an appropriate level of access based on authentication. This specification will not attempt to address the issues of sharing or Access Control Lists (ACLs).
The protocol will not provide any explicit provisioning operations. If it is possible to authenticate or address a principals calendar resources then they MUST be automatically created if necessary or appropriate
These operations are not yet defined for this version of the CalWS protocol. Both operations raise a number of issues. In particular implementing a move operation through a series of retrievals, insertions and deletions may cause undesirable side-effects. Both these operations will be defined in a later version of this specification.
We will not address the issue of creating collections within the address space. The initial set is created by provisioning.
This operation is currently undefined. A GET on a collection may fail or return a complete calendar object representing the collection.
These operations are not defined in this version of the specification. In the future it will be possible to define or set the properties for the service or resources within the service.
An href is a URI reference to a resource, for example
The URL above reflects a possible structure for a calendar server. All URLs should be absolute or path-absolute following the rules defined in
A calendar object resource is an event, meeting or a task. Attachments are resources but NOT calendar object resources. An event or task with overrides is a single calendar resource entity.
A folder only allowed to contain calendar object resources.
A folder only allowed to contain calendar resources which is also used for scheduling operations. Scheduling events placed in such a collection will trigger implicit scheduling activity on the server.
The collection under which all the resources for a given principal are stored. For example, for principal “fred” the principal home might be “/user/fred/”
Each operation on the calendar system has a number of pre-conditions and post-conditions that apply.
A “precondition” for a method describes the state of the server that must be true for that method to be performed. A “post-condition” of a method describes the state of the server that must be true after that method has been completed. Any violation of these conditions will result in an error response in the form of a CalWS XML error element containing the violated condition and an optional description.
Each method specification defines the preconditions that must be satisfied before the method can succeed. A number of post-conditions are generally specified which define the state that must exist after the execution of the operation. Preconditions and post-conditions are defined as error elements in the CalWS XML namespace.
In the XRD entity returned properties and related services and entities are defined by absolute URIs which correspond to the extended relation type defined in
Certain of these property URIs correspond to CalDAV preconditions. Each URL is prefixed by the CalWS relations and properties namespace . Those properties which correspond to CalDAV properties have the additional path element “caldav/”, for example
corresponds to
In addition to those CalDAV properties, the CalWS specification defines a number of other properties and link relations with the URI prefix of .
This property defines the features supported by the target. All resources contained and managed by the service should return this property. The value is a comma separated list containing one or more of the following
calendar-access — the service supports all MUST requirements in this specification
Defines the maximum number of attendees allowed per event or task.
Defines the maximum date/time allowed on an event or task
Defines the maximum number of instances allowed per event or task
Provides a numeric value indicating the maximum size of a resource in octets that the server is willing to accept when a calendar object resource is stored in a calendar collection.
Provides a DATE-TIME value indicating the earliest date and time (in UTC) that the server is willing to accept for any DATE or DATE-TIME value in a calendar object resource stored in a calendar collection.
Provides some descriptive text for the targeted collection.
The location of a timezone service used to retrieve timezone information and specifications. This may be an absolute URL referencing some other service or a relative URL if the current server also provides a timezone service.
Provides the URL to the user home for the currently authenticated principal.
Provides the URL to use as a target for freebusy requests for the current authenticated principal.
Provides the URL to use as a target for freebusy requests for a different principal.
Provides information about a child collections for the target. The href attribute gives the URI of the collection. The element should only have CalWS child elements giving the type of the collection, that is the calWS:collection link property and the CalWS-calendar-collection link property. This allows clients to determine the structure of a hierarchical system by targeting each of the child collections in turn.
The xrd:title child element of the link element provides a description for the child-collection.
Appears within a link relation describing collections or entities. The value is a date-time as defined in
Appears within an xrd object describing collections or entities. The value is the same format as would appear in the Last-Modified header and is defined in
Appears within an xrd object describing collections or entities. The value is a localized name for the entity or collection.
Appears within an xrd object describing collections. The value is a text timezone identifier.
Appears within an xrd object describing collections or entities. The value is a server specific URI.
Appears within a link relation describing collections or entities. The property takes no value and indicates that this child element is a collection.
Appears within a link relation describing collections or entities. The property takes no value and indicates that this child element is a calendar collection.
Appears within a link relation describing collections or entities and specifies the set of privileges allowed to the current authenticated principal for that collection or entity.
Each privilege element defines a privilege or access right. The following set is currently defined
calWS: Read — current principal has read access
calWS: Write — current principal has write access
Properties, related services and locations are obtained from the service or from service resources in the form of an XRD document as defined by
Given the URL of a CalWS service a client retrieves the service XRD document through a GET on the service URL with an ACCEPT header specifying application/xrd+xml.
Retrieving resource properties is identical to obtaining service properties, that is, execute a GET on the target URL with an ACCEPT header specifying application/xrd+xml.
The service properties define the global limits and defaults. Any properties defined on collections within the service hierarchy override those service defaults. The service may choose to prevent such overriding of defaults and limits when appropriate.
None
200: OK
403: Forbidden
404: Not found
Creating calendar object resources is carried out by a POST on the parent collection. The body of the request will contain the resource being created. The request parameter “action=create” indicates this POST is a create. The location header of the response gives the URL of the newly created object.
action=create
201: created
403: Forbidden — no access
calWS:target-exists: The target of a PUT must exist. Use POST to create entities and PUT to update them.
calWS:not-calendar-data: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST be a supported media type (i.e., iCalendar) for calendar object resources;
calWS:invalid-calendar-data: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST be valid data for the media type being specified (i.e., MUST contain valid iCalendar data);
calWS:invalid-calendar-object-resource: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST obey all restrictions specified in Calendar Object Resources (e.g., calendar object resources MUST NOT contain more than one type of calendar component, calendar object resources MUST NOT specify the iCalendar METHOD property, etc.);
calWS:unsupported-calendar-component: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST contain a type of calendar component that is supported in the targeted calendar collection;
calWS:uid-conflict: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST NOT specify an iCalendar UID property value already in use in the targeted calendar collection or overwrite an existing calendar object resource with one that has a different UID property value. Servers SHOULD report the URL of the resource that is already making use of the same UID property value in the calWS:href element
calWS:invalid-calendar-collection-location: In a COPY or MOVE request, when the Request- URI is a calendar collection, the Destination-URI MUST identify a location where a calendar collection can be created;
calWS:exceeds-max-resource-size: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST have an octet size less than or equal to the value of the CalDAV:max-resource-size property value on the calendar collection where the resource will be stored;
calWS:before-min-date-time: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST have all of its iCalendar DATE or DATE-TIME property values (for each recurring instance) greater than or equal to the value of the CalDAV:min-date-time property value on the calendar collection where the resource will be stored;
calWS:after-max-date-time: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST have all of its iCalendar DATE or DATE-TIME property values (for each recurring instance) less than the value of the CalDAV:max-date-time property value on the calendar collection where the resource will be stored;
calWS:too-many-instances: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST generate a number of recurring instances less than or equal to the value of the CalDAV:max-instances property value on the calendar collection where the resource will be stored;
calWS:too-many-attendees-per-instance: The resource submitted in the PUT request, or targeted by a COPY or MOVE request, MUST have a number of ATTENDEE properties on any one instance less than or equal to the value of the CalDAV:max-attendees-per-instance property value on the calendar collection where the resource will be stored;
A simple GET on the href will return a named resource. If that resource is a recurring event or task with overrides, the entire set will be returned. The desired format is specified in the ACCEPT header. The default form is application/xml+calendar
none
200: OK
403: Forbidden — no access
406 The requested format specified in the accept header is not supported.
Resources are updated with the PUT method targeted at the resource href. The body of the request contains a complete new resource which effectively replaces the targeted resource. To allow for optimistic locking of the resource use the if-match header.
When updating a recurring event all overrides and master must be supplied as part of the content.
Preconditions as specified in
200: OK
304: Not modified — entity was modified by some other request
403: Forbidden — no access, does not exist etc. See error response
Delete is defined in
Delete for collections may or may not be supported by the server. Certain collections are considered undeletable. On a successful deletion of a collection all contained resources to any depth must also be deleted.
200: OK
403: Forbidden — no access
404: Not Found
Querying provides a mechanism by which information can be obtained from the service through possibly complex queries. A list of iCalendar properties can be specified to limit the amount of information returned to the client. A query takes the parts
Limitations on the data returned
Selection of the data
Optional timezone id for floating time calculations.
The current specification uses CalDAV multiget and calendar-query XML bodies as specified in
The POST method is used for all requests, the action being identified by the outer element.
While CalDAV servers generally only support
The CalDAV query allows the specification of a number of DAV properties. Specification of these properties, with the exception of DAV:getetag, is considered an error in CalWS.
The CalDAV:propnames element is invalid
With those differences, the CalDAV specification is the normative reference for this operation.
This is achieved by specifying one of the following
CalDAV:allprop return all properties (some properties are specified as not being part of the allprop set so are not returned)
CalDAV:prop An element which contains a list of properties to be returned. May only contain DAV:getetag and CalDAV:calendar-data
Of particular interest, and complexity, is the calendar-data property which can contain a time range to limit the range of recurrences returned and/or a list of calendar properties to return.
The preconditions as defined in
This example shows the time-range limited retrieval from a calendar which results in 2 events, one a recurring event and one a simple non-recurring event.
Freebusy queries are used to obtain freebusy information for a calendar-collection or principals. The result contains information only for events to which the current principal has sufficient access.
When targeted at a calendar collection the result is based only on the calendaring entities contained in that collection. When targeted at a principal freebusy URL the result will be based on all information which affect the principals freebusy status, for example availability.
The possible targets are:
A calendar collection URL
The XRD link with relation CalWS/current-principal-freebusy
The XRD link with relation CalWS/principal-freebusy with a principal given in the request.
The query follows the specification defined in
Freebusy information is returned by default as xcalendar VFREEBUSY components, as defined by
Since a Freebusy query can only refer to a single user, a client will already know how to match the result component to a user. A server MUST only return a single VFREEBUSY component.
The Accept header is used to specify the format for the returned data. In the absence of a header the data should be returned as specified in
None of these parameters are required except for the conditions noted below. Appropriate defaults will be supplied by the server.
The default value is left up to the server. It may be the current day, start of the current month, etc.
Specifies the start date for the Freebusy data. The server is free to ignore this value and return data in any time range. The client must check the data for the returned time range.
A profile of an
2007-01-02T13:00:00-08:00
It is up to the server to interpret local date/times.
2007-02-03T15:30:00-0800
2007-12-01T10:15:00Z
Specifying only a start date/time without specifying an end-date/time or period should be interpreted as in
Date-only values are disallowed as the server cannot determine the correct start of the day. Only UTC or date/time with offset values are permitted.
Same as start
Specifies the end date for the Freebusy data. The server is free to ignore this value.
Same as start
Same as start
The default value is left up to the server. The recommended value is “P42D”.
Specifies the amount of Freebusy data to return. A client cannot specify both a period and an end date. Period is relative to the start parameter.
A duration as defined in
P42D
none
Specifies the principal when the request is targeted at the XRD CalWS/principal-freebusy. Specification of this parameter is an error otherwise.
Server specific
The server is free to ignore the start, end and period parameters. It is recommended that the server return at least 6 weeks of data from the current day.
A client MUST check the time range in the VFREEBUSY response as a server may return a different time range than the requested range.
The server SHOULD return an Etag response header for a successful GET request targeting a Freebusy read URL. Clients MAY use the Etag response header value to do subsequent “conditional” GET requests that will avoid re-sending the Freebusy data again if it has not changed.
Below are the typical status codes returned by a GET request targeting a Freebusy URL. Note that other HTTP status codes not listed here might also be returned by a server.
200 OK
302 Found
400 Start parameter could not be understood / End parameter could not be understood / Period parameter could not be understood
401 Unauthorized
403 Forbidden
404 The data for the requested principal is not currently available, but may be available later.
406 The requested format in the accept header is not supported.
410 The data for the requested principal is no longer available
500 General server error
The following are examples of URLs used to retrieve Freebusy data for a user:
Some Request/Response Examples:
The last numbered section in the specification must be the Conformance section. Conformance Statements/Clauses go here.
The following individuals have participated in the creation of this specification and are gratefully acknowledged
Participants:
Bruce Bartell, Southern California Edison
Brad Benson, Trane
Edward Cazalet, Individual
Toby Considine, University of North Carolina at Chapel Hill
William Cox, Individual
Sharon Dinges, Trane
Mike, Douglass, Rensselaer Polytechnic Institute
Craig Gemmill, Tridium, Inc.
Girish Ghatikar, Lawrence Berkeley National Laboratory
Gerald Gray, Southern California Edison
David Hardin, ENERNOC
Gale Horst, Electric Power Research Institute (EPRI)
Gershon Janssen, Individual
Ed Koch, Akuacom Inc.
Benoit Lepeuple, LonMark International*
Carl Mattocks, CheckMi*
Robert Old, Siemens AG
Alexander Papaspyrou, Technische Universitat Dortmund
Joshua Phillips, ISO/RTO Council (IRC)
Jeremy J. Roberts, LonMark International
David Thewlis, CalConnect
The Calendaring and Scheduling Consortium (CalConnect) TC-XML committee worked closely with WS1013 Calendar Technical Committee, bridging to developing IETF standards and contributing the services definitions that make up Services in Section 4. The Technical Committee gratefully acknowledges their assistance and cooperation as well. Contributors to TC XML include:
Cyrus Daboo, Apple
Mike Douglass, Rensselaer Polytechnic Institute
Steven Lees, Microsoft
Tong Li, IBM
The WS-Calendar Technical Committee thanks CalConnect for contributing this overview of iCalendar and its use.
The iCalendar specification was first produced by the IETF in 1998 as
Alongside iCalendar is the iTIP specification (
iCalendar itself is a text-based data format. However, an XML format is also available, providing a one-to1034 one mapping to the text format (
iCalendar data files typically have a .ics file name extension. Most desktop calendar clients can import or export iCalendar data, or directly access such data over the Internet using a variety of protocols.
The iCalendar data format has a well defined data model. “iCalendar objects” encompass a set of “iCalendar Components” each of which contains a set of “iCalendar properties” and possibly other sub- Components. An iCalendar property consists of a name, a set of optional parameters (specified as “key1041 value” pairs) and a value.
iCalendar Components include:
“VEVENT” which represents an event
“VTODO” which represents a task or to-do
“VJOURNAL” which represents a journal entry
“VFREEBUSY” which represents periods of free or busy time information
“VTIMEZONE” which represents a timezone definition (timezone offset and daylight saving rules)
“VALARM” is currently the only defined sub-Component and is used to set alarms or reminders on events or tasks.
Properties include:
“DTSTART” which represents a start time for a Component
“DTEND” which represents an end time for a Component
“SUMMARY” which represents a title or summary for a Component
“RRULE” which can specify rules for repeating events or tasks (for example, every day, every week on Tuesdays, etc.)
“ORGANIZER” which represents the calendar user who is organizing an event or assigning a task
“ATTENDEE” which represents calendar users attending an event or assigned a task
In addition to this data model and the pre-defined properties, the specification defines how all those are used together to define the semantics of calendar objects and scheduling. The semantics are basically a set of rules stating how all the Components and properties are used together to ensure that all iCalendar products can work together to achieve good interoperability. For example, a rule requires that all events must have one and only one “DTSTART” property. The most important part of the iCalendar specification is the semantics of the calendaring model that it represents. The 1063 use of text or XML to encode those is secondary.
The iTIP specification defines how iCalendar objects are exchanged in order to accomplish the key task needed to schedule events or tasks. An example of a simple workflow is as follows:
To schedule an event, an organizer creates the iCalendar object representing the event and adds calendar users as attendees.
The organizer then sends an iTIP “REQUEST” message to all the attendees.
Upon receipt of the scheduling message, each attendee can decide whether they want to attend the meeting or not.
Each attendee can then respond back to the organizer using an iTIP “REPLY” message indicating their own attendance status.
iTIP supports other types of scheduling messages, for example, to cancel meetings, add new instances to a repeating meeting, etc.
iCalendar was designed to be extensible, allowing for new Components, properties and parameters to be defined as needed. A registry exists to maintain the list of standard extensions with references to their definitions to ensure anyone can use them and work well with others.
An Internet calendar subscription is simply an iCalendar data file made available on a web server. Users can use this data in two ways:
The data can be downloaded from the web server and then imported directly into an iCalendar aware client. This solution works well for calendar data that is not likely to change over time (for example the list of national holidays for the next year).
Calendar clients that support “direct” subscriptions can use the URL to the calendar data on the web server to download the calendar data themselves. Additionally, the clients can check the web server on a regular basis for updates to the calendar data, and then update their own cached copy of it. This allows calendar data that changes over time to be kept synchronized.
CalDAV is a calendar access protocol and is defined in
CalDAV is used in a variety of different environments, ranging from very large internet service providers, to large and small corporations or institutions, and to small businesses and individuals.
CalDAV clients include desktop applications, mobile devices and browser-based solutions. It can also be used by “applets”, for example, a web page panel that displays a user’s upcoming events.
One of the key aspects of CalDAV is its data model. Simply put, it defines a “calendar home” for each calendar user, within which any number of “calendars” can be created. Each “calendar” can contain any number of iCalendar objects representing individual events, tasks or journal entries. This data model ensures that clients and servers can interoperate well.
In addition to providing simple operations to read, write and delete calendar data, CalDAV provides a querying mechanism to allow clients to fetch calendar data matching specific criteria. This is commonly used by clients to do “time-range” queries, i.e., find the set of 1106 events that occur within a given start/end time period.
CalDAV also supports access control allowing for features such as delegated calendars and calendar sharing.
CalDAV also specifies how scheduling operations can be done using the protocol. Whilst it uses the semantics of the iTIP protocol, it simplifies the process by allowing simple calendar data write operations to trigger the sending of scheduling messages, and it has the server automatically process the receipt of scheduling messages. Scheduling can be done with other users on the CalDAV server or with calendar users on other systems (via some form of “gateway”).
ActiveSync and SyncML are technologies that allow multiple devices to synchronize data with a server, with calendar data being one of the classes of data supported. These have typically been used for low1118 end and high-end mobile devices.
CalWS refers to a set of web services calendar access APIs developed under a cooperative agreement between The Calendaring and Scheduling Consortium (CalConnect) and OASIS, and being published as a work product of the WS-Calendar Technical Committee. CalWS defines an API to access and manipulate calendar data stored on a server. It follows a similar data model to CalDAV and has been designed to co-exist with a CalDAV service offering the same data.
This specification is part of the CalWS set.
iSchedule is a protocol to allow scheduling between users on different calendaring systems and across different internet domains. It transports iTIP scheduling messages using HTTP between servers. Servers use DNS and various security mechanisms to determine the authenticity of messages received.
It has been specifically designed to be independent of any calendar system in use at the endpoints, so that it is compatible with many different systems. This allows organizations with different calendar systems to exchange scheduling messages with each other, and also allows a single organization with multiple calendar systems (for example due to mergers, or different departmental requirements) to exchange scheduling messages between users of each system.
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.
This document defines extensions to the Web Distributed Authoring and Versioning (WebDAV) protocol to specify a standard way of accessing, managing, and sharing calendaring and scheduling information based on the iCalendar format. This document defines the “calendar-access” feature of CalDAV. [STANDARDS-TRACK]
Web Distributed Authoring and Versioning (WebDAV) consists of a set of methods, headers, and content-types ancillary to HTTP/1.1 for the management of resource properties, creation and management of resource collections, URL namespace manipulation, and resource locking (collision avoidance).
RFC 2518 was published in February 1999, and this specification obsoletes RFC 2518 with minor revisions mostly due to interoperability experience. [STANDARDS-TRACK]
This document defines a date and time format for use in Internet protocols that is a profile of the ISO 8601 standard for representation of dates and times using the Gregorian calendar.
HTTP has been in use by the World-Wide Web global information initiative since 1990. This specification defines the protocol referred to as “HTTP/1.1”, and is an update to RFC 2068. [STANDARDS-TRACK]
This document defines a standardized form of Freebusy read URL to improve interoperability between client and server implementations, while extending the functionality and utility through the use of optional parameters.
This memo has been defined to provide the definition of a common format for openly exchanging calendaring and scheduling information across the Internet. [STANDARDS-TRACK]
This document specifies how calendaring systems use iCalendar objects to interoperate with other calendar systems. It does so in a general way so as to allow multiple methods of communication between systems. [STANDARDS-TRACK]
This document, “iCalendar Message-Based Interoperability Protocol (iMIP)”, specifies a binding from the iCalendar Transport-independent Interoperability Protocol (iTIP) to Internet email-based transports. Calendaring entries defined by the iCalendar Object Model (iCalendar) are wrapped using constructs from RFC 5322 and MIME (RFC 2045, RFC 2046, RFC 2047, and RFC 2049), and then transported over SMTP. [STANDARDS-TRACK]
This document defines the iCalendar data format for representing and exchanging calendaring and scheduling information such as events, to-dos, journal entries, and free/busy information, independent of any particular calendar service or protocol. [STANDARDS-TRACK]
This document specifies a protocol that uses the iCalendar object specification to provide scheduling interoperability between different calendaring systems. This is done without reference to a specific transport protocol so as to allow multiple methods of communication between systems. Subsequent documents will define profiles of this protocol that use specific, interoperable methods of communication between systems.
The iCalendar Transport-Independent Interoperability Protocol (iTIP) complements the iCalendar object specification by adding semantics for group scheduling methods commonly available in current calendaring systems. These scheduling methods permit two or more calendaring systems to perform transactions such as publishing, scheduling, rescheduling, responding to scheduling requests, negotiating changes, or canceling. [STANDARDS-TRACK]