ISAMET Inc.

5001 Baum Blvd. Suite 650 Pittsburgh PA 15213 US daboo@isamet.com http://www.isamet.com/

Oracle Corporation

600 Blvd. de Maisonneuve West 19th Floor Montreal QC H3A 3J2 CA bernard.desruisseaux@oracle.com http://www.oracle.com/

Open Source Application Foundation

2064 Edgewood Dr. Palo Alto CA 94303 US lisa@osafoundation.org http://www.osafoundation.org/

Applications calsched calsch caldav calendar calendaring scheduling webdav iCal iCalendar text/calendar HTTP This document specifies a set of methods, headers, message bodies, properties, and reports that define calendar access extensions to the WebDAV protocol. The new protocol elements are intended to make WebDAV-based calendaring and scheduling an interoperable standard that supports single-user calendar access, calendar management, calendar sharing, and calendar publishing.

The concept of using HTTP and WebDAV as a basis for a calendaring server is by no means a new concept: it was discussed in the IETF CALSCH working group as early as 1997 or 1998. Several companies have implemented calendaring servers using HTTP PUT/GET to upload and download iCalendar objects, and using WebDAV PROPFIND to get listings of resources. However, those implementations do not interoperate because there are many small and big decisions to be made in how to model calendaring data as WebDAV resources, as well as how to implement required features that aren't already part of WebDAV. This document proposes a standard way of modeling calendar data in WebDAV, with additional features to make calendar access work well. Discussion of this Internet-Draft is taking place on the mailing list <http://lists.osafoundation.org/mailman/listinfo/ietf-caldav>.

The augmented BNF used by this document to describe protocol elements is described in Section 2.1 of . Because this augmented BNF uses the basic production rules provided in Section 2.2 of , those rules apply to this document as well. 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 . The term "protected" is used in the Conformance field of property definitions as defined in Section 1.4.2 of RFC3253. When XML element types in the namespaces "DAV:" and "urn:ietf:params:xml:ns:caldav" are referenced in this document outside of the context of an XML fragment, the string "DAV:" and "CALDAV:" will be prefixed to the element type names respectively.

Definitions of XML elements in this document use XML element type declarations (as found in XML Document Type Declarations), described in Section 3.2 of . The namespace "urn:ietf:params:xml:ns:caldav" is reserved for the XML elements defined in this specification, its revisions, and related CalDAV specifications. It MUST NOT be used for proprietary extensions. Note that the XML declarations used in this document are incomplete, in that they do not include namespace information. Thus, the reader MUST NOT use these declarations as the only way to create valid CalDAV properties or to validate CalDAV XML element type. Some of the declarations refer to XML elements defined by WebDAV which use the "DAV:" namespace. Wherever such elements appear, they are explicitly given the "DAV:" prefix to help avoid confusion. Also note that some CalDAV XML element names are identical to WebDAV XML element names, though their namespace differs. Care MUST be taken not to confuse the two sets of names.

A "precondition" of a method describes the state of the server that must be true for that method to be performed. A "postcondition" of a method describes the state of the server that must be true after that method has been completed. If a method precondition or postcondition for a request is not satisfied, the response status of the request MUST be either 403 (Forbidden) if the request should not be repeated because it will always fail, or 409 (Conflict) if it is expected that the user might be able to resolve the conflict and resubmit the request. In order to allow better client handling of 403 and 409 responses, a distinct XML element type is associated with each method precondition and postcondition of a request. When a particular precondition is not satisfied or a particular postcondition cannot be achieved, the appropriate XML element MUST be returned as the child of a top-level DAV:error element in the response body, unless otherwise negotiated by the request. In a 207 Multi-Status response, the DAV:error element would appear in the appropriate DAV:responsedescription element.

This section lists what functionality is required of a CalDAV server. To advertise support for CalDAV, a server: MUST support WebDAV Class 1. MUST support WebDAV ACL with the privilege defined in of this document. MUST support transport over TLS as defined in RFC2818. MUST support strong ETags to support disconnected operations. MUST support all required calendaring REPORTs defined in this document. MUST advertise calendaring REPORTs via the DAV:supported-report-set property as defined in Versioning Extensions to WebDAV. In addition, a server: SHOULD support the MKCALENDAR method defined in of this document.

If a server supports the CalDAV features described in this document, it MUST include "calendar-access" as a field in the DAV response header from an OPTIONS request on any resource that supports any calendar properties, reports, methods, or privilege. A value of "calendar-access" in the DAV header MUST indicate that the server supports all MUST level requirements and REQUIRED features specified in this document.

>> Request <<

>> Response <<

In this example, the OPTIONS response indicates that the server supports CalDAV on this collection, therefore the "/home/bernard/" collection may be used as a parent for calendar collections as the MKCALENDAR method is available, and as a possible target for REPORT requests for calendaring reports.

One of the features which has made WebDAV a successful protocol is its firm data model. This makes it a useful framework for other applications such as calendaring. This specification follows the same pattern by developing all features based on a well-described data model. In the CalDAV data model, every VEVENT, VTODO, VJOURNAL, and VFREEBUSY component is contained in an individual resource, referred to as a "calendar object resource". Each calendar object resource may be individually locked and have individual WebDAV properties. These resources are placed into WebDAV collections with a mostly-fixed structure.

A CalDAV server is a calendaring-aware engine combined with a WebDAV repository. A WebDAV repository is a set of WebDAV collections, containing other WebDAV resources, within a unified URL namespace. For example, the repository "http://www.example.com/webdav/" may contain WebDAV collections and resources, all of which have URLs beginning with "http://www.example.com/webdav/". Note that the root URL "http://www.example.com/" may not itself be a WebDAV repository (for example, if the WebDAV support is implemented through a servlet or other Web server extension). A WebDAV repository MAY include calendar data in some parts of its URL namespace, and non-calendaring data in other parts. A WebDAV repository can advertise itself as a CalDAV server if it supports the functionality defined in this specification at any point within the root of the repository. That might mean that calendaring data is spread throughout the repository and mixed with non-calendar data in nearby collections (e.g., calendar data may be found in /home/lisa/calendar/ as well as in /home/bernard/calendar/, and non-calendar data in /home/lisa/contacts/). Or, it might mean that calendar data can be found only in certain sections of the repository (e.g., /caldav/). Calendaring features are only required in the repository sections that are or contain calendaring objects. So a repository confining calendar data to the /caldav/ collection would only need to support the CalDAV required features within that collection. The CalDAV server or repository is the canonical location for calendar data and state information. Both CalDAV servers and clients MUST ensure that the data is consistent and compliant. Clients may submit requests to change data or download data. Clients may store calendar objects offline and attempt to synchronize at a later time. However, clients MUST be prepared for calendar data on the server to change between the time of last synchronization and when attempting an update, as calendar collections may be shared and accessible via multiple clients. HTTP ETags and other features help this work.

Recurrence is an important part of the data model because it governs how many resources are expected to exist. This specification models a recurring calendar component and its recurrence exceptions as a single resource. In this model, recurrence patterns, recurrence dates, exception dates, and exception information are all part of the data in a single calendar object resource. This model avoids problems of limiting how many recurrence instances to store in the repository, how to keep instances in synch with the recurring calendar component, and how to link recurrence exceptions with the recurring calendar component. It also results in less data to synchronize between client and server, and makes it easier to make changes to all recurrence instances or to a recurrence pattern. It makes it easier to create a recurring calendar component, and easier to delete all recurrence instances. Clients are not forced to retrieve information about all recurrence instances of a recurring component. The CALDAV:calendar-query and CALDAV:calendar-multiget REPORTs defined in this document allow clients to retrieve only recurrence instances that overlap a given time range.

Calendar home collections are manifested to clients as a WebDAV resource collection, identified by a URL. A calendar home collection MUST report the DAV:collection and CALDAV:calendar-home XML elements in the value of the DAV:resourcetype property. The element type declaration for CALDAV:calendar-home is:

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Typically, calendar users will group all the calendar collections that they own under a common calendar home collection. Grouping a user's calendar collections under a common calendar home collection allow one to obtain free-busy time information for all this user's calendar with a single CALDAV:free-busy-query REPORT request targetted at the calendar home collection. Creation of calendar home collections is viewed as an administrative task and is not covered by this specification. Calendar home collections MUST NOT contain other calendar home collections. Multiple calendar home collections MAY be children of the same WebDAV collection. A calendar home collection MAY contain additional collections and non-collection resources of types not defined here. How such items are used is not defined by this specification. However, additional collections contained in a calendar home collection MUST NOT contain calendar home collections.

Calendar collections are manifested to clients as a WebDAV resource collection, identified by a URL. A calendar collection MUST report the DAV:collection and CALDAV:calendar XML elements in the value of the DAV:resourcetype property. The element type declaration for CALDAV:calendar is:

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A calendar collection contains resources that represent the iCalendar objects within a calendar. A calendar collection may be created through provisioning (e.g., automatically created when a user's account is created), or it may be created through MKCALENDAR (see ). This can be useful for a user to create a second calendar (e.g., soccer schedule) or for users to share a calendar (e.g., team events or conference room). Note however that this document doesn't define what extra calendar collections are for, users must rely on non-standard cues to find out what a calendar collection is for, or use the CALDAV:calendar-description property defined in to provide such a cue. Calendar collections MUST NOT contain other calendar collections. Multiple calendar collections MAY be children of the same WebDAV collection. A calendar collection MAY contain additional collections and non-collection resources of types not defined here. How such items are used is not defined by this specification. However, additional collections contained in a calendar collection MUST NOT contain calendar collections.

This section defines properties that may be defined on calendar home collections and/or calendar collections.

calendar-description urn:ietf:params:xml:ns:caldav Provides a human-readable description of what this calendar home or calendar collection represents. This property MAY be protected and SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 12.14.1 of ). Servers MUST indicate the human language of the description using the xml:lang attribute and SHOULD consider the HTTP Accept-Language request header when selecting one of multiple available languages. The CALDAV:calendar-description property MAY be defined on any calendar home or calendar collection. If present, the property contains a description of the calendar home or calendar collection that is suitable for presentation to a user.

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Calendrier de Bernard Desruisseaux ]]>

calendar-component-restriction-set urn:ietf:params:xml:ns:caldav Specifies the type of calendar component types (e.g., VEVENT, VTODO, etc.) that calendar object resources may contain in a calendar collection. This property MAY be protected and SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 12.14.1 of ). The CALDAV:calendar-component-restriction-set property MAY be defined on any calendar collection to specify the calendar component types that the CalDAV server support in the calendar object resources contained in the calendar collection. CalDAV servers MAY allow users to set this property on any calendar collection by using PROPPATCH to allow them to restrict the calendar component types themselves. The element <C:comp name="VTIMEZONE"> MUST only be specified if support for calendar object resources that only contains VTIMEZONE components is provided or desired. Support for VTIMEZONE components in calendar object resources that contain VEVENT or VTODO components is always assumed.

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CalDAV servers that will allow users to modify this property will require a way to advertise what they are capable of supporting. Perhap they could return a calendar-component-restriction-set element as part of the value of the calendar-restrictions property.

calendar-restrictions urn:ietf:params:xml:ns:caldav Specifies restrictions on a calendar collection. This property MAY be protected and SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 12.14.1 of ). The CALDAV:calendar-restrictions property MAY be defined on any calendar collection to specify restrictions a CalDAV server may have on a calendar collection.

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Calendar object resources contained in calendar collections MUST NOT contain more than one type of calendar component (e.g., VEVENT, VTODO, etc.) with the exception of VTIMEZONE components which MUST be specified for each unique TZID parameter value specified in the iCalendar object. For instance, a calendar object resource can contain two VEVENT components and one VTIMEZONE component, but it cannot contain one VEVENT component and one VTODO component. The UID property value of the calendar components contained in a calendar object resource MUST be unique in the scope of the calendar collection, and all its descendant collections, in which the calendar object resource is contained. Calendar components in a calendar collection that have different UID property values MUST be stored in separate calendar object resources. Calendar components with the same UID property value, in a given calendar collection, MUST be contained in the same calendar object resource. This ensures that all components in a recurrence "set" are contained in the same calendar object resource. In that case there will be one component without a RECURRENCE-ID property (the component that defines the recurrence pattern) and all the rest will have that property (these are the recurrence exceptions). For example, given the following iCalendar object:

The VEVENT component with the UID value "1@example.com", would be stored in its own calendar object resource. The two VEVENT components with the UID value "2@example.com", which represent a recurring event where one recurrence instance has been overridden, would be stored in the same calendar object resource.

The creation of calendar collections and calendar object resources may be initiated by either a CalDAV client or by the CalDAV server. For example, a server might come preconfigured with a user's calendar collection, or the CalDAV client might request the server to create a new calendar collection for a given user. Servers might populate events as calendar objects inside a calendar collection, or clients might request the server to create events. Either way, both client and server MUST comply with the requirements in this document, and MUST understand objects appearing in calendar collections or according to the data model defined here.

An HTTP request using the MKCALENDAR method creates a new calendar collection resource. A server MAY restrict calendar collection creation to particular collections. Support for MKCALENDAR on the server is OPTIONAL because some calendar stores only support one calendar per user (or principal) and those are typically pre-created for each account. However, servers and clients are strongly encouraged to support MKCALENDAR whenever possible to allow users to create multiple calendar collections to better help organize their data. Clients SHOULD use the DAV:displayname property for a human-readable name of the calendar. This requires the clients to issue a PROPPATCH request to change the DAV:displayname property to the appropriate value immediately after issuing the MKCALENDAR request. Clients SHOULD NOT set the DAV:displayname property to be the same as any other calendar collection at the same URI "level". When displaying calendar collections to users, clients SHOULD check the DAV:displayname property and use that value as the name of the calendar. In the event that the DAV:displayname property is empty, the client MAY use the last part of the calendar collection URI as the name. If a MKCALENDAR request fails, the server state preceding the request MUST be restored. Marshalling: If a request body is included, it MUST be a CALDAV:mkcalendar XML element.

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If a response body for a successful request is included, it MUST be a CALDAV:mkcalendar-response XML element.

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The response MUST include a Cache-Control:no-cache header. Preconditions: (DAV:resource-must-be-null): A resource MUST NOT exist at the Request-URI. (CALDAV:calendar-collection-location-bad): The Request-URI MUST identify a location where a calendar collection can be created. (CALDAV:insufficient-privilege): The DAV:bind privilege MUST be granted to the current user. Postconditions: (CALDAV:initialize-calendar-collection): A new calendar collection exists at the Request-URI. The DAV:resourcetype of the calendar collection MUST contain both DAV:collection and CALDAV:calendar XML elements.

201 (Created) - The calendar collection resource was created in its entirety. 403 (Forbidden) - This indicates at least one of two conditions: 1) the server does not allow the creation of calendar collections at the given location in its namespace, or 2) the parent collection of the Request-URI exists but cannot accept members. 405 (Method Not Allowed) - MKCALENDAR can only be executed on a null resource. 409 (Conflict) - A collection cannot be made at the Request-URI until one or more intermediate collections have been created. 415 (Unsupported Media Type)- The server does not support the request type of the body. 507 (Insufficient Storage) - The resource does not have sufficient space to record the state of the resource after the execution of this method.

>> Request <<

>> Response <<

In this example, a new calendar collection is created at http://cal.example.com/home/lisa/calendar/.

Clients typically populate calendar collections with calendar object resources. The URL for each calendar object resource is entirely arbitrary, and does not need to bear a specific relationship (but might) to the calendar object resource's subject, scheduled time, UID or other metadata. A new calendar object resource must have a unique URL, otherwise the new component would instead be an update to an existing calendar object resource. When servers create new resources, it's not hard for the server to choose a unique URL. It's slightly tougher for clients, because a client might not want to examine all resources in the collection, and might not want to lock the entire collection to ensure that a new one isn't created with a name collision. However, there are http features to mitigate this. If the client intends to create a new non-collection resource, such as a new VEVENT, the client SHOULD use the HTTP header "If-None-Match: *" on the PUT request. The Request-URI on the PUT request MUST include the target collection, where the resource is to be created, plus the name of the resource in the last path segment. The last path segment could be a random number, or it could be a sequence number, or a string related to the object's SUMMARY property. No matter how the name is chosen, the "If-None-Match" header ensures that the client cannot overwrite an existing resource even if it has accidentally chosen a duplicate resource name. Servers SHOULD return an ETag header containing the actual ETag of the newly created resource on a successful creation.

>> Request <<

>> Response <<

The request to change an existing event is the same, but with a specific ETag in the "If-Match" header, rather than the "If-None-Match" header. As indicated in Section 3.10 of RFC 2445, the URL of calendar object resources containing (an arbitrary set of) calendaring and scheduling information may be suffixed by ".ics", and the URL of calendar object resources containing free or busy time information may be suffixed by ".ifb". Preconditions for PUT within calendar collections: (CALDAV:uid-already-exists): The component UID chosen is not unique and the client must choose another if it attempts again. (CALDAV:invalid-calendar-resource): The iCalendar object syntax or structure was invalid. (Note that the server MAY support upload formats other than iCalendar but then the server MUST validate each component uploaded according to the chosen format syntax.)

A CalDAV server MUST support WebDAV ACL. WebDAV ACL provides a framework for an extensible list of privileges on WebDAV collections and ordinary resources. A CalDAV server MUST also support the calendaring privilege defined in this section.

Calendar users often wish to allow other users to see their busy time information, without viewing the other details of the calendar components (location, summary, attendees). This allows a significant amount of privacy while still allowing those other users to schedule meetings at times when the calendar user is likely to be free. The CALDAV:read-free-busy privilege controls which calendar collections and calendar object resources are examined when a free-busy-query REPORT is run (see ). This privilege can be granted on calendar collections or calendar object resources. Servers MUST support this privilege on calendar collections and any calendar object resources within those collections.

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The CALDAV:read-free-busy privilege is aggregated in the DAV:read privilege. Note that if an ACL grants the privilege CALDAV:read-free-busy, the client may not expect to be granted access to GET, HEAD, OPTIONS and PROPFIND.

In the WebDAV ACL standard, servers MUST support the DAV:supported-privilege-set property to show which privileges are abstract, which privileges are supported, how the privileges relate to another, and to provide text descriptions (particularly useful for custom privileges). The relationships between privileges involves showing which privilege is a subset or a superset of another privilege. For example, because reading the ACL property is considered a more specific privilege than the DAV:read privilege (a subset of the total set of actions are allowed), it may be aggregated under the DAV:read privilege. Although the list of supported privileges MAY vary somewhat from server to server (the WebDAV ACL specification leaves room for a fair amount of diversity in server implementations), the following restriction MUST hold for a CalDAV server: The server MUST support the CALDAV:read-free-busy privilege. The CALDAV:read-free-busy privilege MUST be non-abstract, and MUST be aggregated under the DAV:read privilege.

This is a partial example of how the DAV:supported-privilege-set property could look on a server supporting CalDAV. Note that aggregation is shown in the structure of the DAV:supported-privilege elements containing each other.

Any operation Read any object Read ACL Read current user privilege set Read busy time information Write any object ... ]]>

This section defines additional properties for WebDAV principal resources as defined in RFC3744.

calendar-home-URL urn:ietf:params:xml:ns:caldav Identify the URL of any calendar home collections owned by the associated principal resource. This property MAY be protected and SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 12.14.1 of ). Support for this property is RECOMMENDED.

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http://cal.example.com/home/bernard/ ]]>

calendar-address-set urn:ietf:params:xml:ns:caldav Identify the calendar addresses of the associated principal resource. This property MAY be protected and SHOULD NOT be returned by a PROPFIND allprop request (as defined in Section 12.14.1 of ). Support for this property is RECOMMENDED. This property SHOULD be searchable using the DAV:principal-property-search REPORT. The DAV:principal-search-property-set REPORT SHOULD identify this property as such. This property is mostly meant to discover the calendar home collection URLs of the principal associated with a given calendar address by using the DAV:principal-property-search REPORT.

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mailto:bernard@example.com mailto:bernard.desruisseaux@example.com ]]>

In this example, the client request the CALDAV:calendar-home-URL of the principal resources whose CALDAV:calendar-address-set property contains the substring "mailto:bernard@example.com". In addition, the client request the DAV:displayname to be returned with the matching principals. The response shows that only one principal resource meet the search specification, "Bernard Desruisseaux".

>> Request << mailto:bernard@example.com ]]>

>> Response << http://cal.example.com/users/bernard http://cal.example.com/home/bernard/ Bernard Desruisseaux HTTP/1.1 200 OK ]]>

This section defines the reports which a CalDAV server MUST support on calendar collections and calendar object resources. CalDAV servers MUST advertise support for those reports with the DAV:supported-report-set property defined in RFC3253. Some of these reports allow calendar data (from possibly multiple resources) to be returned. Clients SHOULD request the DAV:getetag property whenever executing reports that return calendar data, to ensure that any local cache used for synchronization is kept up to date with the latest changes on the server

The REPORT method (defined in Section 3.6 of RFC3253) provides an extensible mechanism for obtaining information about a resource. Unlike the PROPFIND method, which returns the value of one or more named properties, the REPORT method can involve more complex processing. REPORT is valuable in cases where the server has access to all of the information needed to perform the complex request (such as a query), and where it would require multiple requests for the client to retrieve the information needed to perform the same request. A server that supports calendar-access MUST support the DAV:expand-property report (defined in Section 3.8 of RFC3253).

A WebDAV collection which contains one or more calendar collections is not a new type of resource, but it may support these new REPORT. If so, then the REPORT is expected to have the semantics of including information from all the calendar data contained in the collection, and its children, recursively. These collections may contain more than only calendar related resources. It's up to the server, if it supports this REPORT on a normal WebDAV collection, to find calendar object resources and decide what to do with non-calendar resources and whether those may also appear in the collection or its children. If these reports are supported on ordinary collections the server advertises the capability with the DAV:supported-report-set property as already described.

Some of the reports defined in CalDAV can be targetted at calendar object resources within a specific time range. To determine whether a calendar object resource matches the time range filter element, the start and end times for the particular type of object are determined and then compared to the requested time range. If the start and end overlap the requested time range, then the calendar object resource matches the filter element. The rules defined in for determining the actual start and end times of calendar components MUST be used. When such time range filtering is used, special consideration must be given to recurring calendar components such as VEVENT and VTODO components. The server MUST expand recurring items to determine. whether any one or more recurrence instances overlap the requested time range. If any one instance overlaps the time range, then the calendar object resource matches the filter element. In addition, CalDAV provides three ways to determine which recurrence instances are returned from the recurrence set. The three options are: Return all the calendar components contained in the calendar object resources. This includes the recurrence instance that defines the recurrence pattern, referred to as the "master instance", as well as the recurrence instances that define exceptions to the recurrence pattern, referred to as the "overriden instances". Because of the rules defined in all recurrence instances of a recurring component will always be in the same calendar object resource. Return the "master" instance and only the "overridden instances" that overlap the specified time range. This avoids the need for clients to process recurrence instances outside of the time range they are interested in. Return an "expanded" set of calendar components that represent only those instances in the recurrence set that overlap the specified time range. This avoids the need for clients to do any recurrence processing themselves as the server does the expansion for them and provides the list of instances.

The CALDAV:calendar-query REPORT performs a search for all calendar object resources that match a specified search filter. The response of this report will contain all the WebDAV properties and calendar object resource data specified in the request. In the case of the CALDAV:calendar-data XML element, one can explicitly specify the calendar components and properties that should be returned in the calendar object resource data that matches the search filter. The format of this report is modeled on the PROPFIND method. The request and response bodies of the CALDAV:calendar-query report use XML elements that are also used by PROPFIND. In particular the request can include XML elements to request WebDAV properties to be returned. When that occurs the response should follow the same behavior as PROPFIND with respect to the DAV:multistatus response elements used to return specific property results. For instance, a request to retrieve the value of a property which does not exist is an error and MUST be noted with a response XML element which contains a 404 (Not Found) status value. Support for the calendar-query REPORT is REQUIRED. Marshalling: The request body MUST be a CALDAV:calendar-query XML element as defined in . The response body for a successful request MUST be a DAV:multistatus XML element (i.e., the response uses the same format as the response for PROPFIND). In the case where there are no response elements, the returned multistatus XML element is empty. The response body for a successful calendar-query REPORT request MUST contain a DAV:response element for each iCalendar object that matched the search filter. The declaration of the DAV:response element from Section 12.9.1 of RFC2518 has been modified to allow the CALDAV:calendar-data element within the DAV:response element, see Preconditions: None. Postconditions: (DAV:number-of-matches-within-limits): The number of matching calendar object resources must fall within server-specific, predefined limits. For example, this condition might be triggered if a search specification would cause the return of an extremely large number of responses.

In this example, the client requests the server to return specific components and properties of the VEVENT components that overlap the time range from September 2nd, 2004 at 00:00:00 am UTC to September 2nd, 2004 at 11:59:59 pm UTC. In addition the DAV:getetag property is also requested and returned as part of the response. Note that the third calendar object returned is a recurring event whose first instance lies outside of the requested time range, but whose second instance does overlap the time range.

>> Request << ]]>

>> Response << http://cal.example.com/home/bernard/calendar/ev102.ics "23ba4d-ff11fb" HTTP/1.1 200 OK BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Example Corp.//CalDAV Client//EN BEGIN:VEVENT DTSTART:20040902T100000Z DTEND:20040902T120000Z SUMMARY:Design meeting UID:34222-232@example.com X-ABC-GUID:E1CX4zp-0005Ld-21@example.com END:VEVENT END:VCALENDAR http://cal.example.com/home/bernard/calendar/mtg103.ics "ff11fb-23ba4d" HTTP/1.1 200 OK BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Example Corp.//CalDAV Client//EN BEGIN:VEVENT DTSTART:20040902T130000Z DTEND:20040902T150000Z SUMMARY:Design meeting - Part II UID:63409-868@example.com X-ABC-GUID:E1CX5Dr-0007ym-Hz@example.com END:VEVENT END:VCALENDAR http://cal.example.com/home/bernard/calendar/mtg104.ics "7834cd-63fd2c" HTTP/1.1 200 OK BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Example Corp.//CalDAV Client//EN BEGIN:VEVENT DTSTART:20040901T130000Z DTEND:20040901T150000Z RRULE:FREQ=DAILY;COUNT=2 SUMMARY:Design meeting - Part III UID:63409-451@example.com X-ABC-GUID:E1CX5Dr-0008ym-Hz@example.com END:VEVENT END:VCALENDAR ]]>

Todo: Example with CALDAV:limit-recurrence-set.

Todo: Example with CALDAV:expand-recurrence-set.

In this example, the client requests the server to return the VTODO components that have an alarm trigger scheduled in the specified time range.

>> Request << ]]>

In this example, the client requests the server to return the VEVENT component that has the UID property set to "20041121-FEEBDAED@foo.org".

>> Request << 20041121-FEEBDAED@foo.org ]]>

In this example, the client requests the server to return the VEVENT components that have the ATTENDEE property with the value "mailto:bernard@example.com" and for which the PARTSTAT parameter is set to "NEEDS-ACTION".

>> Request << mailto:bernard@example.com NEEDS-ACTION ]]>

In this example, the client requests the server to return all VEVENT components.

>> Request << ]]>

The CALDAV:calendar-multiget REPORT is used to retrieve specific calendar object resources from within a collection, if the Request-URI is a collection, or to retrieve a specific calendar object resource, if the Request-URI is a calendar object resource. This report is similar to the CALDAV:calendar-query REPORT (see ), except that it takes a list of DAV:href elements instead of a CALDAV:filter element to determine which calendar object resources to return. Support for the calendar-multiget REPORT is REQUIRED. Marshalling: The request body MUST be a CALDAV:calendar-multiget XML element (see , which MUST contain at least one DAV:href XML element, and one optional CALDAV:calendar-data element as defined in . If the Request-URI is a collection resource, then the DAV:href elements MUST refer to resources within that collection, and they MAY refer to resources at any depth within the collection. As a result the "Depth" header MUST be ignored by the server and SHOULD NOT be sent by the client. If the Request-URI refers to a non-collection resource, then there MUST be a single DAV:href element that is equal to the Request-URI. The response body for a successful request MUST be a DAV:multistatus XML element. In the case where there are no response elements, the returned multistatus XML element is empty. The response body for a successful CALDAV:calendar-multiget REPORT request MUST contain a DAV:response element for each calendar object resource referenced by the provided set of DAV:href elements. The DAV:response element is as defined in . In the case of an error accessing any of the provided DAV:href resources, the server MUST return the appropriate error status code in the DAV:status element of the corresponding DAV:response element. Preconditions: None. Postconditions: None.

In this example, the client requests the server to return specific properties of the VEVENT components references by specific URIs. In addition the DAV:getetag property is also requested and returned as part of the response. Note that in this example, the resource at http://cal.example.com/home/bernard/calendar/mtg1.ics does not exist, resulting in an error status response.

>> Request << http://cal.example.com/home/bernard/calendar/ev102.ics http://cal.example.com/home/bernard/calendar/mtg1.ics ]]>

>> Response << http://cal.example.com/home/bernard/calendar/ev102.ics "23ba4d-ff11fb" HTTP/1.1 200 OK BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Example Corp.//CalDAV Client//EN BEGIN:VEVENT DTSTART:20040902T100000Z DTEND:20040902T120000Z SUMMARY:Design meeting UID:34222-232@example.com END:VEVENT END:VCALENDAR http://cal.example.com/home/bernard/calendar/mtg1.ics HTTP/1.1 404 Resource not found ]]>

The CALDAV:free-busy-query REPORT generates a VFREEBUSY component containing free busy information for all relevant calendar components within calendar collections which have the CALDAV:read-free-busy or DAV:read privilege granted for the current user. Only VEVENT components, without a TRANSP property or with the TRANSP property set to a value other than "TRANSPARENT", and VFREEBUSY components are used to generate the free busy time information. Support for the CALDAV:free-busy-query REPORT is REQUIRED. Marshalling: The request body MUST be a CALDAV:free-busy-query XML element (see , which MUST contain at least one CALDAV:time-range XML element, as defined in . The response body for a successful request MUST be a DAV:multistatus XML element. In the case where there are no response elements, the returned multistatus XML element is empty. The response body for a successful CALDAV:free-busy-query REPORT request MUST contains a DAV:response element for each calendar collection for which free-busy information has been computed. Each DAV:response element contains a single CALDAV:calendar-data XML element as defined in . The CALDAV:calendar-data XML element MUST contain an iCalendar object with a single VFREEBUSY component, with zero or more FREEBUSY property values that describe the busy time intervals for the calendar object resources being targeted, and with other properties set according to the rules of iCalendar. This report only returns busy time information. Applications desiring free time information MUST infer this from available busy time information. When the Request-URI for a CALDAV:free-busy-query REPORT is a calendar collection, the free-busy data is implicitly determined from the calendar object resources containing VEVENT and VFREEBUSY components within the calendar collection, irrespective of the value of any Depth header included in the REPORT request. Only calendar object resources containing VEVENT or VFREEBUSY components that have the CALDAV:read-free-busy privilege granted to the current user will be computed in the response. When the Request-URI for a CALDAV:free-busy-query REPORT is a non-calendar collection, the scope of the report is governed by the value of the Depth header in the request as follows: Depth: 0 - an empty VFREEBUSY component will be returned as there is no valid calendar data to be scanned on the collection. Depth: 1 - free-busy data for any calendar collections immediately within the target collection is returned. Depth: infinity - free-busy data for all calendar collections within any sub-collections of the target collection is returned. Note that as per the requirements of the server MUST expand any recurring items to determine whether any instances contribute to the free busy information in the requested time range. Preconditions: None. Postconditions: (DAV:number-of-matches-within-limits): The number of matching calendar object resources must fall within server-specific, predefined limits. For example, this condition might be triggered if a search specification would cause the return of an extremely large number of responses.

In this example, the client requests the server to return free-busy information on the calendar collection /home/bernard/calendar/, between 9:00 AM and 5:00 PM on 2nd September 2004. The server responds indicating three busy time intervals of one hour, two hours and 30 minutes during the course of the time interval being examined.

>> Request << ]]>

>> Response << http://cal.example.com/home/bernard/calendar/ HTTP/1.1 200 OK BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Example Corp.//CalDAV Client//EN BEGIN:VFREEBUSY DTSTAMP:20050125T090000Z DTSTART:20040902T090000Z DTEND:20040902T170000Z FREEBUSY:20040902T090000Z/PT1H, 20040902T120000Z/PT2H, 20040902T160000Z/PT30M END:VFREEBUSY END:VCALENDAR ]]>

There are a number of actions clients can take which will be legal (the server will not return errors) but which can degrade interoperability with other client implementations accessing the same data. For example, a recurrence rule could be replaced with a set of recurrence dates, a single recurring event could be replaced with a set of independent resources to represent each recurrence, or the start/end time values can be translated from the original timezone to another timezone. Although these are iCalendar interoperability best practices and not limited only to CalDAV usage, interoperability problems are likely to be more evident in CalDAV use cases.

WebDAV already provides functionality required to synchronize a collection or set of collections, make changes offline, and a simple way to resolve conflicts when reconnected. Strong ETags are the key to making this work, but these are not required of all WebDAV servers. Since offline functionality is more important to Calendar applications than to other WebDAV applications, CalDAV servers MUST support strong ETags.

The reports provided in CalDAV can be used by clients to optimize their performance in terms of network bandwidth usage, and resource consumption on the local client machine. Both of those issues are certainly major considerations for mobile or handheld devices with limited capacity, but they are also relevant to desktop client applications in cases where the calendar collections contain large amounts of data. Typically clients present calendar data to users in views that span a finite time interval, so whenever possible clients should only retrieve calendar items from the server using CALDAV:calendar-query report combined with a time-range element to limit the scope of returned items to just those needed to populate the current view.

Typically in a calendar, historical data (events, to-dos etc. that have completed prior to the current date) do not change, though they may be deleted. As a result, a client can speed up the synchronization process by only considering data for the present time and the future up to a reasonable limit (e.g., one week, one month). If the user then tries to examine a portion of the calendar outside of the range that has been synchronized, the client can perform another synchronization operation on the new time interval being examined. This "just-in-time" synchronization can minimize bandwidth for common user interaction behaviors.

If a client wants to support calendar data synchronization, as opposed to downloading calendar data each time it is needed, it needs to cache the component resources URI and ETag along with the actual calendar data. Whilst the URI remains static for the lifetime of the component, the ETag will change with each successive change to the component data. Thus to synchronize a local data cache with the server, the client can first fetch the URI/ETag pairs for the time interval being considered, and compare those results with the cached data. Any cached component whose ETag differs from that on the server needs to be synchronized. In order to properly detect the changes between the server and client data, the client will need to keep a record of which items have been created, changed or deleted since the last synchronization operation so that it can reconcile those changes with the data on the server. An example of how to do that would be the following: The client issues a CALDAV:calendar-query REPORT request for a specific time range, and asks for only the DAV:getetag property to be returned:

]]>

The client then uses the results to determine which components have changed, been created or deleted on the server and how those relate to locally cached components that may have changed, been created or deleted. If the client determines that there are items on the server that need to be fetched, the client issues a CALDAV:calendar-multiget report to fetch the actual data:

http://cal.example.com/home/bernard/calendar/evt1.ics http://cal.example.com/home/bernard/calendar/mtg1.ics ]]>

Clients may not need all the properties in a calendar component when presenting information to the user. Since some property data can be large (e.g., ATTACH or ATTENDEE lists) clients can choose to ignore those by only requesting the specific items it knows it will use, through use of the CALDAV:calendar-data XML element in the relevant reports. However, if a client needs to make a change to a component, it can only change the entire component data via a PUT request. There is no way to incrementally make a change to a set of properties within a calendar component resource. As a result the client will have to cache the entire set of properties on a resource that is being changed.

WebDAV locks can be used to prevent two clients modifying the same resource from either overwriting each others' changes (though that problem can also be solved by using ETags) and also to prevent the user from making changes that will conflict with another set of changes. In a multi-user calendar system, the calendar client could lock an event while the user is editing the event, and unlock the event when the user finishes or cancels. Locks can also be used to prevent changes while data is being reorganized. For example, a calendar client might lock two calendar collections prior to moving a bunch of calendar resources from one to another. Clients may request a lock timeout period that is appropriate to the use case. When the user explicitly decides to reserve a resource and prevent other changes, a long timeout might be appropriate, but in cases when the client automatically decides to lock the resource the timeout should be short (and the client can always refresh the lock should it need to). A short lock timeout means that if the client is unable to remove the lock, the other calendar users aren't prevented from making changes.

Much of the time a calendar client (or agent) will discover a new calendar's location by being provided directly with the URL. E.g. a user will type his or her own calendar location into client configuration information, or cut and paste a URL from email into the calendar application. The client need only confirm that the URL points to a resource which is a calendar. The client may also be able to browse WebDAV collections to find calendar collections. The choice of HTTP URLs means that calendar object resources are backward compatible with existing software, but does have the disadvantage that existing software does not usually know to look at the OPTIONS response to that URL to determine what can be done with it. This is somewhat of a barrier for WebDAV usage as well as with CalDAV usage. This specification does not offer a way through this other than making the information available in the OPTIONS response should this be requested. For calendar sharing and scheduling use cases, one might wish to find the calendar belonging to another user. If the other user has a calendar in the same repository, that calendar can be found by using the principal namespace required by WebDAV ACL support. For other cases, the authors have no universal solution but implementors can consider whether to use vCard or LDAP standards together with calendar attributes.

calendar-query urn:ietf:params:xml:ns:caldav Defines a report for querying calendar data See .

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calendar-data-only urn:ietf:params:xml:ns:caldav Specifies that only calendar object resources may be contained in a calendar collection. The CALDAV:calendar-data-only element MUST be specified in the CALDAV:calendar-restrictions property of calendar collection that only provide support for calendar object resources.

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calendar-data urn:ietf:params:xml:ns:caldav Used to define which parts of a calendar component object should be returned by the report that uses this element. When used in a request, the CALDAV:calendar-data element specifies the iCalendar components and properties to be returned in the iCalendar objects part of the response. If this element doesn't contain any CALDAV:comp element, iCalendar objects will be returned with all their components and properties. When used inside a response, the CALDAV:calendar-data element contains an iCalendar object that matched the search filter specified in the request.

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comp urn:ietf:params:xml:ns:caldav Defines which component types to return The name value is a calendar component name (e.g., "VEVENT") NOTE: The CALDAV:prop and CALDAV:allprop elements used here have the same name as elements defined in WebDAV. However, the elements used here have the "urn:ietf:params:xml:ns:caldav" namespace, as opposed to the "DAV:" namespace used for elements defined in WebDAV.

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allcomp urn:ietf:params:xml:ns:caldav Specifies that all components shall be returned This element can be used when the client wants all types of components returned by a report.

]]>

allprop urn:ietf:params:xml:ns:caldav Specifies that all properties shall be returned. This element can be used when the client wants all properties of components returned by a report. NOTE: The CALDAV:allprop element defined here has the same name as the DAV:allprop element defined in WebDAV. However, the CALDAV:allprop element defined here uses the "urn:ietf:params:xml:ns:caldav" namespace, as opposed to the "DAV:" namespace used for the DAV:allprop element defined in WebDAV.

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prop urn:ietf:params:xml:ns:caldav Defines which properties to return in the response. The "name" attribute specifies the name of the calendar property to return (e.g., "ATTENDEE"). The "novalue" attribute can be used by clients to request that the actual value of the property not be returned (if the "novalue" attribute is set to "yes"). In that case the server will return just the iCalendar property name and any iCalendar parameters and a trailing ":" without the subsequent value data. NOTE: The CALDAV:prop element defined here has the same name as the DAV:prop element defined in WebDAV. However, the CALDAV:prop element defined here uses the "urn:ietf:params:xml:ns:caldav" namespace, as opposed to the "DAV:" namespace used for the DAV:prop element defined in WebDAV.

]]>

expand-recurrence-set urn:ietf:params:xml:ns:caldav Forces the server to expand recurring components into separate instances. The CALDAV:expand-recurrence-set element specifies that recurring components shall be returned as individual components with no recurrence properties (i.e., EXDATE, EXRULE, RDATE and RRULE). The required "start" and "end" attributes contain iCalendar format DATE-TIME (always specified in UTC) or DATE values that define the time interval over which the recurrence expansion should take place. The start value is inclusive and the end value is exclusive of the interval as per iCalendar DTSTART and DTEND properties. The server MUST return only those expanded components whose time interval intersects the interval specified by the start and end attributes.

]]>

limit-recurrence-set urn:ietf:params:xml:ns:caldav Specifies a time range to limit the set of recurrence instances returned by the server. The CALDAV:limit-recurrence-set XML element specifies that a server MUST only return information about the recurrence instances whose scheduled time intersect a specified time range for a given calendaring REPORT request. The required "start" and "end" attributes specify DATE or DATE-TIME iCalendar values in UTC that defines the actual time range. The server MUST use the same logic as defined for CALDAV:time-range to determine if a recurrence instance intersect a given time range.

]]>

filter urn:ietf:params:xml:ns:caldav Determines which matching components are returned. The "filter" element specifies the search filter used to match components that should be returned by a report.

]]>

comp-filter urn:ietf:params:xml:ns:caldav Limits the search to only the chosen component types. The "name" attribute is a calendar component type (e.g., "VEVENT"). When this element is present, the server should only return a component if it matches the filter, which is to say:

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prop-filter urn:ietf:params:xml:ns:caldav Limits the search to specific properties. The "name" attribute MUST contain an iCalendar property name (e.g., "ATTENDEE"). When the CALDAV:prop-filter executes, a property matches if:

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param-filter urn:ietf:params:xml:ns:caldav Limits the search to specific parameters. The "param-filter" element limits the search result to the set of resources containing properties with parameters that meet the parameter filter rules. When this filter executes, a parameter matches if:

]]>

is-defined urn:ietf:params:xml:ns:caldav Causes a search to match a resource if a component type, property or parameter name exists. The CALDAV:is-defined XML element limits the filter to resources where the named component, property or parameter is defined.

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text-match urn:ietf:params:xml:ns:caldav Specifies a substring match on a property or parameter value. The specified text is used for a substring match against the property or parameter value specified in a report. The "caseless" attribute indicates whether the match is case-sensitive (value set to "no") or case-insensitive (value set to "yes"). The default value is server-specified. Caseless matching SHOULD be implemented as defined in section 5.18 of the Unicode Standard (). Support for the "caseless" attribute is optional. A server should respond with a status of 422 if it is used but cannot be supported.

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time-range urn:ietf:params:xml:ns:caldav Specifies a time interval for testing components against. The CALDAV:time-range element allows for a single time range to be defined, in order to limit all the results of the search to the set of resources that contain a component which overlap that time range. The value of the "start" and "end" attributes MUST follow the syntax of the DATE or DATE-TIME iCalendar value type, with any time specified in UTC. While the "start" and "end" attributes are not required to allow time ranges opened at one end, at least one of them MUST be specified in the CALDAV:time-range element. We need to clarify the logic when the DTSTART, DTEND, DURATION, or DUE properties are not defined in the calendar component. A VEVENT component overlaps a given time-range if:

start) OR (DTSTART <= start AND DTSTART+DURATION > start) OR (DTSTART >= start AND DTSTART < end) OR (DTEND > start AND DTEND <= end) ]]>

A VTODO component overlaps a given time-range if:

= start) OR (DTSTART <= start AND DTSTART+DURATION > start) OR (DTSTART >= start AND DTSTART < end) OR (DUE >= start AND DUE < end) ]]>

A VJOURNAL component overlaps a given time-range if:

= start AND DTSTART < end ]]>

A VALARM component overlaps a given time-range if:

= start AND trigger-time < end ]]>

Any property of value type DATE-TIME or DATE (e.g., DTSTAMP) will match a given time-range if:

= start AND value < end ]]>

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response DAV: Response that includes calendar data. Modifies the standard WebDAV response element to include calendar data in the response if required by the report type.

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calendar-multiget urn:ietf:params:xml:ns:caldav CalDAV report used to retrieve specific calendar component items via their URIs. See .

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free-busy-query urn:ietf:params:xml:ns:caldav CalDAV report used to generate a VFREEBUSY to determine busy time over a specific set of time ranges. See .

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HTTP protocol transactions are sent in the clear over the network unless protection from snooping is negotiated. This can be accomplished by use of TLS as defined in RFC2818. In particular, HTTP Basic authentication MUST NOT be used unless TLS is in effect. Servers MUST take adequate precautions to ensure malicious clients cannot consume excessive server resources (CPU, memory, disk, etc.) through carefully crafted reports. For example, a client could upload an event with a recurrence rule that specifies a recurring event occurring every second for the next 100 years which would result in approximately 3 x 10^9 instances! A report that asks for recurrences to be expanded over that range would likely constitute a denial-of-service attack on the server. We should make an explicit reference to the security considerations mentionned in iCalendar, iTIP and iMIP.

In addition to the namespaces defined by RFC2518 for XML elements, this document uses a URN to describe a new XML namespace conforming to a registry mechanism described in RFC3688. All other IANA considerations mentioned in RFC2518 also apply to this document.

Registration request for the CalDAV namespace: URI: urn:ietf:params:xml:ns:caldav Registrant Contact: See the "Author's Address" section of this document. XML: None. Namespace URIs do not represent an XML specification.

The authors would like to thank the following individuals for contributing their ideas and support for writing this specification: Michael Arick, Mario Bonin, Chris Bryant, Scott Carr, Mike Douglass, Helge Hess, Dan Mosedale, Kervin L. Pierre, Julian F. Reschke, Mike Shaver, Simon Vaillancourt, and Jim Whitehead. The authors would also like to thank the Calendaring and Scheduling Consortium for advice with this specification, and for organizing interoperability testing events to help refine it.

Harvard University

1350 Mass. Ave. Cambridge MA 02138 - +1 617 495 3864 sob@harvard.edu

General keyword 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. Authors who follow these guidelines should incorporate this phrase near the beginning of their 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 RFC 2119. Note that the force of these words is modified by the requirement level of the document in which they are used. Certicom

tdierks@certicom.com

Certicom

callen@certicom.com

This document specifies Version 1.0 of the Transport Layer Security (TLS) protocol. The TLS protocol provides communications privacy over the Internet. The protocol allows client/server applications to communicate in a way that is designed to prevent eavesdropping, tampering, or message forgery. Lotus Development Corporation

6544 Battleford Drive Raleigh NC 27613-3502 USA +1-919-676-9515 +1-919-676-9564 Frank_Dawson@Lotus.com http://home.earthlink.net/~fdawson

Microsoft Corporation

One Microsoft Way Redmond WA 98052-6399 USA +1-425-936-5522 +1-425-936-7329 deriks@Microsoft.com

Applications calendaring scheduling PIM There is a clear need to provide and deploy interoperable calendaring and scheduling services for the Internet. Current group scheduling and Personal Information Management (PIM) products are being extended for use across the Internet, today, in proprietary ways. This memo has been defined to provide the definition of a common format for openly exchanging calendaring and scheduling information across the Internet. This memo is formatted as a registration for a MIME media type per . However, the format in this memo is equally applicable for use outside of a MIME message content type. The proposed media type value is 'text/calendar'. This string would label a media type containing calendaring and scheduling information encoded as text characters formatted in a manner outlined below. This MIME media type provides a standard content type for capturing calendar event, to-do and journal entry information. It also can be used to convey free/busy time information. The content type is suitable as a MIME message entity that can be transferred over MIME based email systems, using HTTP or some other Internet transport. In addition, the content type is useful as an object for interactions between desktop applications using the operating system clipboard, drag/drop or file systems capabilities. This memo is based on the earlier work of the vCalendar specification for the exchange of personal calendaring and scheduling information. In order to avoid confusion with this referenced work, this memo is to be known as the iCalendar specification. This memo defines the format for specifying iCalendar object methods. An iCalendar object method is a set of usage constraints for the iCalendar object. For example, these methods might define scheduling messages that request an event be scheduled, reply to an event request, send a cancellation notice for an event, modify or replace the definition of an event, provide a counter proposal for an original event request, delegate an event request to another individual, request free or busy time, reply to a free or busy time request, or provide similar scheduling messages for a to-do or journal entry calendar component. The iCalendar Transport-indendent Interoperability Protocol (iTIP) defined in is one such scheduling protocol. Microsoft Corporation

One Microsoft Way Redmond WA 98052-6399 yarong@microsoft.com

Dept. Of Information and Computer Science, University of California, Irvine

Irvine CA 92697-3425 ejw@ics.uci.edu

Netscape

685 East Middlefield Road Mountain View CA 94043 asad@netscape.com

Novell

1555 N. Technology Way M/S ORM F111 Orem UT 84097-2399 srcarter@novell.com

Novell

1555 N. Technology Way M/S ORM F111 Orem UT 84097-2399 dcjensen@novell.com

This document specifies 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, namespace manipulation, and resource locking (collision avoidance). Department of Information and Computer Science

University of California, Irvine Irvine CA 92697-3425 +1(949)824-1715 fielding@ics.uci.edu

World Wide Web Consortium

MIT Laboratory for Computer Science, NE43-356 545 Technology Square Cambridge MA 02139 +1(617)258-8682 jg@w3.org

Compaq Computer Corporation

Western Research Laboratory 250 University Avenue Palo Alto CA 94305 mogul@wrl.dec.com

World Wide Web Consortium

MIT Laboratory for Computer Science, NE43-356 545 Technology Square Cambridge MA 02139 +1(617)258-8682 frystyk@w3.org

Xerox Corporation

MIT Laboratory for Computer Science, NE43-356 3333 Coyote Hill Road Palo Alto CA 94034 masinter@parc.xerox.com

Microsoft Corporation

1 Microsoft Way Redmond WA 98052 paulle@microsoft.com

World Wide Web Consortium

MIT Laboratory for Computer Science, NE43-356 545 Technology Square Cambridge MA 02139 +1(617)258-8682 timbl@w3.org

The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. It is a generic, stateless, protocol which can be used for many tasks beyond its use for hypertext, such as name servers and distributed object management systems, through extension of its request methods, error codes and headers . A feature of HTTP is the typing and negotiation of data representation, allowing systems to be built independently of the data being transferred. 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 . This memo describes how to use Transport Layer Security (TLS) to secure Hypertext Transfer Protocol (HTTP) connections over the Internet. This memo provides information for the Internet community. Rational Software

20 Maguire Road Lexington MA 02421 US geoffrey.clemm@rational.com

IBM

3039 Cornwallis Research Triangle Park NC 27709 US jamsden@us.ibm.com

IBM

Hursley Park Winchester S021 2JN UK tim_ellison@uk.ibm.com

Microsoft

One Microsoft Way Redmond WA 90852 US ckaler@microsoft.com

UC Santa Cruz, Dept. of Computer Science

1156 High Street Santa Cruz CA 95064 US ejw@cse.ucsc.edu

This document specifies a set of methods, headers, and resource types that define the WebDAV (Web Distributed Authoring and Versioning) versioning extensions to the HTTP/1.1 protocol. WebDAV versioning will minimize the complexity of clients that are capable of interoperating with a variety of versioning repository managers, to facilitate widespread deployment of applications capable of utilizing the WebDAV Versioning services. WebDAV versioning includes automatic versioning for versioning-unaware clients, version history management, workspace management, baseline management, activity management, and URL namespace versioning. This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. IBM

20 Maguire Road Lexington MA 02421 geoffrey.clemm@us.ibm.com

greenbytes GmbH

Salzmannstrasse 152 Muenster NW 48159 Germany julian.reschke@greenbytes.de

Oracle Corporation

500 Oracle Parkway Redwood Shores CA 94065 eric.sedlar@oracle.com

U.C. Santa Cruz, Dept. of Computer Science

1156 High Street Santa Cruz CA 95064 ejw@cse.ucsc.edu

This document specifies a set of methods, headers, message bodies, properties, and reports that define Access Control extensions to the WebDAV Distributed Authoring Protocol. This protocol permits a client to read and modify access control lists that instruct a server whether to allow or deny operations upon a resource (such as HyperText Transfer Protocol (HTTP) method invocations) by a given principal. A lightweight representation of principals as Web resources supports integration of a wide range of user management repositories. Search operations allow discovery and manipulation of principals using human names. Textuality and Netscape

tbray@textuality.com

Microsoft

jeanpa@microsoft.com

University of Illinois at Chicago and Text Encoding Initiative

cmsmcq@uic.edu

Sun Microsystems

eve.maler@east.sun.com

francois@yergeau.com

The Unicode Consortium ISBN 0321185781 Critical Angle Inc.

4815 W Braker Lane #502-385 Austin TX 78759 USA +1 512 372-3160 M.Wahl@critical-angle.com

Netscape Communications Corp.

501 E. Middlefield Rd. MS MV068 Mountain View CA 94043 USA +1 650 937-3419 howes@netscape.com

Isode Limited

The Dome The Square Richmond TW9 1DT UK +44-181-332-9091 S.Kille@isode.com

Applications LDAP ITU directory service protocol directory lightweight directory access protocol This RFC contained boilerplate in this section which has been moved to the RFC2223-compliant unnumbered section "Status of this Memo." This document describes a directory access protocol that provides both read and update access. Update access requires secure authentication, but this document does not mandate implementation of any satisfactory authentication mechanisms. In accordance with RFC 2026, section 4.4.1, this specification is being approved by IESG as a Proposed Standard despite this limitation, for the following reasons: a. to encourage implementation and interoperability testing of these protocols (with or without update access) before they are deployed, and b. to encourage deployment and use of these protocols in read-only applications. (e.g. applications where LDAPv3 is used as a query language for directories which are updated by some secure mechanism other than LDAP), and c. to avoid delaying the advancement and deployment of other Internet standards-track protocols which require the ability to query, but not update, LDAPv3 directory servers. Readers are hereby warned that until mandatory authentication mechanisms are standardized, clients and servers written according to this specification which make use of update functionality are UNLIKELY TO INTEROPERATE, or MAY INTEROPERATE ONLY IF AUTHENTICATION IS REDUCED TO AN UNACCEPTABLY WEAK LEVEL. Implementors are hereby discouraged from deploying LDAPv3 clients or servers which implement the update functionality, until a Proposed Standard for mandatory authentication in LDAPv3 has been approved and published as an RFC. Lotus Development Corporation

6544 Battleford Drive Raleigh NC 27613 USA +1-919-676-9515 frank_dawson@lotus.com

Netscape Communications Corp.

501 East Middlefield Rd. Mountain View CA 94041 USA +1.415.937.3419 howes@netscape.com

Applications MIME audio content-type directory multipurpose internet mail extensions This memo defines the profile of the MIME Content-Type for directory information for a white-pages person object, based on a vCard electronic business card. The profile definition is independent of any particular directory service or protocol. The profile is defined for representing and exchanging a variety of information about an individual (e.g., formatted and structured name and delivery addresses, email address, multiple telephone numbers, photograph, logo, audio clips, etc.). The directory information used by this profile is based on the attributes for the person object defined in the X.520 and X.521 directory services recommendations. The profile also provides the method for including a representation of a white-pages directory entry within the MIME Content-Type defined by the 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 . XpertSite.Com ISOCOR Lotus When scheduling a calendar entity, such as an event, it is a prerequisite that an organizer has the calendar address of each attendee that will be invited to the event. Additionally, access to an attendee's current "busy time" provides an a priori indication of whether the attendee will be free to participate in the event. In order to meet these challenges, a calendar user agent (CUA) needs a mechanism to locate (URI) individual user's calendar and free/busy time. This memo defines three mechanisms for obtaining a URI to a user's calendar and free/busy time. These include: - Manual transfer of the information; - Personal data exchange using the vCard format; and - Directory lookup using the LDAP protocol.

The following table extend the WebDAV Method Privilege Table specified in Appendix B of WebDAV ACL. METHODPRIVILEGES MKCALENDARDAV:bind REPORTDAV:read or CALDAV:read-free-busy (on all referenced resources)

Various editorial changes. Added properties calendar-restrictions and calendar-component-restriction-set on calendar collections. Added properties calendar-home-URL and calendar-address-set on principal resources. Removed property calendar-URL on principal resources. Added pre- and postconditions to reports. Added new XML elements calendar-data-only and limit-recurrent-set. Modified calendar-data XML element to support the attributes content-type and version. Reorganised sections 3, 4, 5 & 6 into two sections and re-ordered sub-sections. Added comment about client not setting a duplicate displayname. Removed three CalDAV OPTIONS requests. Changed "authenticated user" to "user" in various places. Rewrote section on calendar object resource restrictions for better clarity.

Reworded section "Recurrence and the Data Model". Removed timezone collection feature. Removed ability for a server to return the Location header on a successful PUT request. Clarified restrictions on calendar object resources contained in calendar collections. Added preconditions on PUT in calendar collections. Added informative "Guidelines" section, with information on locking and how to find calendar collections. Moved "Sychronization Operations" section in the "Guidelines" section.

Removed a lot of non-normative text. Removed property promotion/demotion requirements. Removed calendar-owner and cal-scale properties. Removed 'ical' prefix/text from element names. Relaxed WebDAV Class 2 (locking) requirement to a MAY. Relaxed MKCALENDAR requirement to a SHOULD. Moved the XML Namespace section in the Introduction. Added CALDAV: prefix to CalDAV XML elements in the text. Added CALDAV:calendar-multiget report. Added CALDAV:free-busy-query report. Added CALDAV:calendar-description property. Changed CALDAV:calendar-query-result element name to CALDAV:calendar-data Added description and examples of handling timezones. Added mandatory "start" and "end" attributes to the CALDAV:expand-recurrence-set element. Added three CalDAV OPTIONS requests. Grouped XML Element declarations in a separate section.

Added a note about the HTTP Location response header. Added report calendar-query. Removed reports calendar-property-search and calendar-time-range. Removed section on CalDAV and timezones. Added requirement to return ETag on creation. Revised data model to remove sub-collections from calendar collection. Added informative references section. Removed dependencies on DASL.

Removed Calendar Containers (simplification that doesn't seem to remove much functionality) Added MKCALENDAR to create calendars and all sub-collections Added cal-scale property to calendars

Basically still adding major sections of content: Defined new field values to the OPTIONS "DAV:" response header Added new resource properties Added new principal properties Added new SCHEDULE method and related headers Added new privileges for scheduling

Added section on privileges for calendaring, extending WebDAV ACL privilege set Defined what to do with unrecognized properties in the bodies of iCalendar events, with respect to property promotion/demotion