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Versions: 00 01 02 03                                                   
Network Working Group                               Andre Coutemanche/CS&T
Internet Draft                                      Steve Mansour/Netscape
<draft-ietf-calsch-irip-02.txt                      Pete O'Leary/Amplitude
Expires six months from:                                 November 19, 1998


         ICalendar Real-time Interoperability Protocol (IRIP)

Status of this Memo

This document is an Internet-Draft.  Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, and
its working groups. Note that other groups may also distribute working
documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months.
Internet-Drafts may be updated, replaced, or made obsolete by other
documents at any time.  It is not appropriate to use Internet-Drafts as
reference material or to cite them other than as a "working draft" or
"work in progress".

To learn the current status of any Internet-Draft, please check the
1id-abstracts.txt listing contained in the Internet-Drafts Shadow
Directories on ftp.ietf.org (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).
Distribution of this document is unlimited.

Abstract

This document specifies a binding from the iCalendar
Transport-independent Interoperability Protocol [ITIP] to a real-time
transport. Calendaring entries defined by the iCalendar Object Model
[ICAL] are composed using constructs from [RFC-2045], [RFC-2046],
[RFC-2047], [RFC-2048] and [RFC-2049].

This document is based on the calendaring and scheduling model defined
by [ICMS].

This document is based on discussions within the Internet Engineering
Task Force (IETF) Calendaring and Scheduling (CALSCH) working group.
More information about the IETF CALSCH working group activities can be
found on the IMC website at http://www.imc.org, the IETF website at
http://www.ietf.org/html.charters/calsch-charter.html. Refer to the
references within this document for further information on how to
access these various documents.

Distribution of this document is unlimited. Comments and suggestions
for improvement should be sent to the authors.













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1 Introduction

This binding document provides the transport specific information
necessary convey iCalendar Transport-independent Interoperability
Protocol [ITIP] over a real-time transport.

1.1 Related Memos

Implementers will need to be familiar with several other memos that,
along with this memo, form a framework for Internet calendaring and
scheduling standards.

This document - specifies a real-time binding for [ITIP].

-  [ICAL] specifies a core specification of objects, data types,
   properties and property parameters;

-  [ITIP] specifies an interoperability protocol for scheduling between
   different implementations;

-  [IMIP] specifies a messaging-based protocol binding for [ITIP].

This document does not attempt to repeat the specification of concepts
or definitions from these other memos. Where possible, references are
made to the memo that provides for the specification of these concepts
or definitions.

1.2 Formatting Conventions

The mechanisms defined in this memo are defined in propose. In order to
refer to elements of the calendaring and scheduling model, core object
or interoperability protocol defined in [ICMS], [ICAL] and [ITIP] some
formatting conventions have been used.

Calendaring and scheduling roles defined by [ICMS] are referred to in
quoted-strings of text with the first character of each word in upper
case. For example, "Organizer" refers to a role of a "Calendar User"
within the scheduling protocol defined by [ITIP].

Calendar components defined by [ICAL] are referred to with capitalized,
quoted-strings of text. All calendar components start with the letter
"V". For example, "VEVENT" refers to the event calendar component,
"VTODO" refers to the to-do calendar component and "VJOURNAL" refers to
the daily journal calendar component.

Scheduling methods defined by [ITIP] are referred to with capitalized,
quoted-strings of text. For example, "REQUEST" refers to the method for
requesting a scheduling calendar component be created or modified,
"REPLY" refers to the method a recipient of a request uses to update
their status with the "Organizer" of the calendar component.

Properties defined by [ICAL] are referred to with capitalized,
quoted-strings of text, followed by the word "property". For example,
"ATTENDEE" property refers to the iCalendar property used to convey the
calendar address of a calendar user.

Property parameters defined by [ICAL] are referred to with lower case,
quoted-strings of text, followed by the word "parameter". For example,


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"VALUE" parameter refers to the iCalendar property parameter used to
override the default data type for a property value.

2 Architecture

[IRIP] enables real-time interoperability between scheduling systems
using the iCalendar [ICAL] format for information exchange. [IRIP] is
designed primarily to allow Calendar Services (CS) as defined in [ICSM]
to forward real-time requests on behalf of Calendar User Agents (CUA)
and receive real-time responses. The goal of [IRIP] is to allow two or
more CS's to establish connections with each other. However, the design
of [IRIP] does not preclude its use from CUA directly to CS. [IRIP]
allows a CS to initiate a session and perform operations on behalf of
multiple CUA's without the need to reauthenticate the session for each
CUA.

The sections and examples below refer to a "user", a "sender", and a
"receiver". For purposes of this document these terms are defined as
follows:

user - the CU that initiates a request.
sender - the agent used to contact a receiving device, send commands,
and receive replies.

receiver - the agent that accepts commands and sends replies.

The sender and receiver can take on varying roles of CUA and CS as
described in [ICMS].

[IRIP] allows two CS's to establish different levels of trust. When an
[IRIP] connection is first established, both parties to the connection
authenticate one another using the AUTHENTICATE command. The Sender can
then initiate commands that the Receiver MUST interpret relative to the
Sender's access control. The AUTHENTICATE command supports proxy
operations via [SASL].

1.3 State Diagram

An [IRIP] session begins when a TCP/IP connection is made on port 5228.
The protocol begins in the Connected state. The AUTHENTICATE command,
when successful, begins the Authenticated state. From the Authenticated
state, the sender can initiate a request using the RECIPIENT command.
The Sender can then issues as many RECIPIENT commands as the operation
in progress requires until sending an ICALDATA command. After
completing the ICALDATA command, the Sender must wait for a response
from the receiver. The Receiver's response can indicate that the
request has been completed or that the request could not be completed
in the time specified by the Sender. When the response has ended, the
Sender returns to the Authenticated state where another request can be
initiated.  Implementations should be prepared to handle a DISCONNECT
at any point in this state diagram.










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      +---------SWITCH-----------+                +------------+
      |                          |  +-DISCONNECT->| TERMINATED |
      |                          |  |             +------------+
      V                          |  |                      A
+------------+                 +---------------+           |
| Connected  |--AUTHENTICATE-->| Authenticated |----ERROR--+
+------------+                 |               |<--------+
 +--------------ABORT--------->|   (Proxy)     |         |
 |                       +---->|               |<---+    |
 |                       |     +---------------+    |    |
 |  +--RECIPIENT--+      |                |  |      |    |
 |  |             |      +--AUTHENTICATE--+  |      |    |
+----------+      V                          |      | COMPLETE
|   Send   |<---------------RECIPIENT--------+      |   or
+----------+                                        |  ABORT
   |         +--------COMPLETE or ERROR-------------+    |
ICALDATA     |                                           |
   |         |                                           |
   |  +---------+                           +--------+   |
   +->| Receive |--(Response from Server)-->|  Idle  |---+
      +---------+                           +--------+
           A                                     |
           |                                     |
           +--------------CONTINUE---------------+

1.4 Calendar Address

Calendar addresses are URIs. IRIP uses the following forms of URI.

irip://<host>:<port>/<relativeCALID>

where:

    <host> is address of the computer on which the IRIP server is
           running

    <port> is optional. Its default value is 5228.

<relativeCALID> is an identifier that uniquely identifies the calendar.
There is no implied structure in a relativeCALID, it is an arbitrary
string of characters. It may refer to the calendar of a user or of a
resource such as a conference room.

Examples:

    irip://calendar.example.com/user1
    irip://calendar.example.com/conferenceRoomA
    irip://calendar.example.com/89798-098-zytytasd

1.5 Bounded Latency

[IRIP] is designed so that the Sender can either obtain an immediate
response from a request or discover within a known amount of time that
the request cannot be completed. When the Sender initiates a command
that the Receiver cannot complete within a given amount of time, the
Receiver can return an error code to the Sender indicating this
condition. The Sender then issues either a CONTINUE or ABORT command.


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The ABORT command immediately terminates the command in progress. The
CONTINUE command instructs the Receiver to continue processing the
command. The ABORT command causes the Receiver to discard the current
command and return to the Authenticated state.

3 Protocol

3.1 Commands

Reply codes MAY be followed by arbitrary text. The length of the reply
code, any subsequent text, and the terminating <CRLF> MUST be 1024
characters or less. The length of a RECIPIENT command and its single
argument, and the terminating <CRLF> MUST be l024 characters or less.
Implementations may truncate RECIPIENT lines or reply code lines that
exceed 1024 characters.

In the examples below, lines preceded with "S:" refer to the Sender and
lines preceded with "R:" refer to the Receiver.

3.1.1 ABORT

The ABORT command is issued by the Sender to stop an ICALDATA request
from being processed further. When the latency time is specified on the
ICALDATA command, the Receiver must issue a reply to the Sender within
the specified time.  The reply may be a reply code indicating that the
server has not yet processed the request.  The Sender must then tell
the server whether to continue or abort.

The Sender can issue the ABORT command at any time after the ICALDATA
command has been completed but before the Sender receives a reply.

Example:

...
S: ICALDATA:10
R: 2.0.1
S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: quoted-printable
S:
S: BEGIN:VCALENDAR
S: ...
S: END:VCALENDAR
S: .
<10 seconds elapse...>
R: .
R: 2.0.2
S: ABORT
R: 2.0.3
S: <sender can now begin another command or it can disconnect>

The Receiver will issue the 8.2 reply code if it receives an ABORT when
the ICALDATA command is not in progress. This could happen if the
Sender issues an ABORT command at a point in time after the Receiver
has completed the operation and issued the reply code but before the
Sender has actually received the reply code. For example:

S: ICALDATA:10
S: <an ICAL object>
S: .


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<10 seconds elapse...>
S: ABORT
R: 2.0
R: 8.2
In this case, the reply code 2.0 is in response to the [ICAL] object
and the reply code 8.2 is in response to the ABORT command.

3.1.2 AUTHENTICATE

The authentication mechanism used in [IRIP] is based on [SASL]. This
allows the [IRIP] senders and receivers to dynamically negotiate
authentication and encryption mechanisms. [SASL] defines authentication
methods such as ANONYMOUS and encapsulates concepts of PROXY used in
[IRIP].

The AUTHENTICATE command is used by the client to identify itself to
the server. Authentication is required before the following commands
can be issued:

ABORT
AUTHENTICATE
CONTINUE
DISCONNECT
ICALDATA
RECIPIENT
SWITCH

The format of the command is of the following:

AUTHENTICATE <mechanism> <initial data>

from which the standard [SASL] interchange will take place as defined
in the [SASL] profile. Authentication mechanisms will differ from one
server to the other, from one version to another. The CAPABILITY
command must be used by the sender to determine the best authentication
mechanism to use.

Example of an authentication session with kerberose version 4:

R: 2.0 Welcome IRIP Server
S: AUTHENTICATE KERBEROS_V4 744RTU3r#
S: sfdkjgs;lfdjg s;ldfkj gslkfdjgwrt949jsl4ns.dlngsdf
S: slkfjgsdlfjg;dslfjgdsfg
S: ;lasfgsdfg  45243 z!$14325dc
R: 2.0

3.1.2.1 Authentication with Proxy Access

The proxy mechanism is the ability to have data posted by an indirect
source. To handle this requirement, [SASL] mechanisms have a separate
"Authentication" and "authorization" identity. Thus, server A could
authenticate to server B using server A's credentials with the
authorization identity of user X. This effectively allows PROXY
operations between servers.  Some older [SASL] mechanisms do not
support both authentication and authorization and therefore cannot be
used when PROXY operations are required.  As per the [SASL] profile,
the authorization identity is the one used to determine if the
operation should be allowed or not. The authentication identity ensures
the transaction is originating from a trusted sender.


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3.1.2.2 Authentication for Anonymous Access

SASL defines an ANONYMOUS authentication mechanism that must be used if
anonymous access is to be implemented by an [IRIP] capable server. This
is done by using the standard [SASL] authentication method and
requesting the ANONYMOUS mechanism. The mechanism consists of a single
message from the client to the server. The client sends optional trace
information in the form of a human readable string. It is recommended
that the trace information take one of three forms: An [RFC-822]
Internet e-mail address, an opaque ASCII string which does not contain
the "@" character and can be interpreted by the system administrator of
the client's domain or nothing. Anonymous authentication is further
described in [ANON-SASL].

The following is an example of anonymous access using an opaque ASCII
string:

R: <listen on TCP port 5228>
S: <establish a connection to TCP port 5228>
R: 2.0
S: AUTHENTICATE ANONYMOUS
R: +
S: c21yaGM
R: 2.0

3.1.3 CAPABILITY

The CAPABILITY command tells the server to return a list of
capabilities it supports.  The server must return a CAPABILITY response
with "IRIPrev1" as one of the listed capabilities.  The CAPABILITY
command can be issued in any connection state. The response may differ
depending on the current state of the connection. The responses may
also differ depending upon the authenticated user.

The format of the capabilities response is a series of lines with the
form <name>[=<value>]. Each name-value pair is delimited by a <CRLF>
character sequence. The sequence <CRLF>.<CRLF> followed by a reply code
terminates the response.

Example:

S: CAPABILITY
R: CAPABILITY IRIPrev1
R: AUTH=KERBEROS_V4
R: AUTH=PLAIN
R: .
R: 2.0

The table below summarizes the information available response to a
CAPABILITY command.

Capability            Occurs  Description
--------------------- ------- ----------------------------------
IRIPrev1                  1   Revision of IRIP, must be
                              "IRIPrev1"

AUTH                      0+  Authentication mechanism(s)
                              supported


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MAXICALOBJECTSIZE     0 or 1  An integer value that specifies
                              The largest ICAL object the server
                              will accept. Objects larger than
                              this will be rejected.

MAXDATE               0 or 1  The datetime value beyond which
                              the server cannot accept.

MINDATE               0 or 1  The datetime value prior to which
                              the server cannot accept.

3.1.4 CONTINUE

The CONTINUE command is issued by the Sender to allow an ICALDATA
request to continue being processed. When the latency time is specified
on the ICALDATA command, the Receiver must issue a reply to the Sender
within the specified time.  The reply could be a reply code indicating
that the server has not yet processed the request.  The Sender must
then tell the server whether to continue or abort the command in
progress.

The CONTINUE has the following form:

        CONTINUE[:latencyTime]

If the optional latencyTime is present, it is a positive integer that
specifies the maximum number of seconds the client will wait for the
next response. If it is omitted, the receiver waits an indefinite
period of time for the response.

In this example, the Sender requests some sort of response from the
server every 10 seconds.

...
S: ICALDATA:10
R: 2.0.1
S: BEGIN:VCALENDAR
<etc>
S: END:VCALENDAR
S: .
<after 10 seconds...>
R: .
R: 2.0.2  Reply Pending
S: CONTINUE:10
R: BEGIN:VCALENDAR
<etc>
R: END:VCALENDAR
R: .
R: 2.0
3.1.5 DISCONNECT

The DISCONNECT command signals the end of communication between the
Sender and Receiver. It can be sent from any state.

Example:

S: DISCONNECT
R: 2.0


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3.1.6 ICALDATA

The ICALDATA command is used specify the iCalendar Object that is to be
delivered to one or more recipients specified in the RECIPIENT
command.  The format of the command is:


S: ICALDATA[:latencyTime]
R: 2.0.1
S: <MIME encapsulated ITIP Message>
S: .
R: <MIME encapsulated ITIP Message>
R: .
R: <reply code>

The optional latencyTime value specifies the maximum number of seconds
the Sender can wait for a reply.  If it is not present, the client
places no time limit on the server for a reply. A reply code of 2.0.1
indicates that the [ITIP] message data can be sent.  When the entire
message has been sent, the sender terminates sending data with the
special sequence <CRLF>.<CRLF>. The receiver reply may optionally
contain an ITIP message followed by the special sequence <CRLF>.<CRLF>
followed by a reply code. Only the [ITIP] message is optional in the
reply, the <CRLF>.<CRLF> sequence must be present.

S: ICALDATA
R: 2.0.1
S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: 7bit
S:
S: BEGIN:VCALENDAR
<etc.>
S: END:VCALENDAR
S: .
R: .
R: 2.0

3.1.7 RECIPIENT

The RECIPIENT command is used to identify a recipient of the iCalendar
Object.  Use multiple RECIPIENT commands to specify multiple
recipients.  The command format is

RECIPIENT <calendar address>

A response code of 2.0 indicates that the calendar address is available
for [ITIP] messages. If the receiver does not accept [ITIP] messages
for the specified calendar address, it may respond with [ITIP] reply
code 5.3 to indicate that the calendar address is unknown or the IRIP
referral reply code, 10.1, and supply the new calendar address. In
either case, the IRIP server does not deliver the [ITIP] message when
the reply code is 5.3 or 10.1.

3.1.8 SWITCH

The SWITCH command is used to allow the Sender and Receiver to change
roles.  Its format is:



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    SWITCH

The SWITCH command is useful in environments where the firewall of a
Sender would not allow the Receiver to initiate a connection. The
SWITCH command is issued by the Sender to give the Receiver the
opportunity to take the role of the Sender.  The Sender must be in the
authenticated state before the SWITCH command can be used.


The Receiver must respond in one of the following fashions:

* send an OK reply and take on the role of  Sender
* send a error reply indicating refusal and retain the role of Receiver

If program-A is currently the Sender and sends the SWITCH command and
receives an OK reply then program-A becomes the Receiver.  Program-A is
then in its initial state and sends a service ready greeting message.

If program-B is currently the Receiver and sends an OK reply in
response to a SWITCH command then program-B becomes the Sender.
Program-B is then in the initial state (connected) as if the
transmission channel just opened, and expects to receive a service
ready greeting.

3.2 Fanout and Queued Transactions

An IRIP server must be able to fanout requests targeted at other IRIP
servers. An IRIP server may queue information targeted at other IRIP
servers. There are several reasons for queing requests. One reason is
that firewall issues may prevent one server from contacting another.
IRIP provides a SWITCH command described later in this document to help
address this situation.

IRIP servers can establish trust relationships between each other. A
trusted relationship means:

-  one server must authenticate with the other
-  authenticated calendars on one server are trusted and treated as
   authenticated on the other.

The trusted relationship need not be bi-directional. That is, the fact
that IRIP server A trusts IRIP server B does not necessarily mean that
B trusts A.

A trusted relationship between two IRIP servers means that one server
can queue transactions for the other server and deliver them some time
later. If IRIP server B trusts A, then A can queue requests for B. If A
does not trust B then B cannot accumulate requests for A.

Certain requests may need to be delivered and replied to in real-time.
In fact, a requester may wish to cancel the request if the reply cannot
be delivered in real-time. In IRIP it is possible to detect whether or
not a reply will be made in real-time and cancel the request if
necessary.

3.3 Reply Codes

[IRIP] error codes follow the format defined for Status Replies in
[ITIP]. All Status Replies as defined in [ITIP] are valid error codes


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when returned by an [IRIP] command.

In addition to those defined in [ITIP], [IRIP] defines the following
error codes:

REPLY
CODE   DESCRIPTOR              MEANING
------ ----------------------  --------------------------------------
2.0.1  START-ICALDATA          Start ICAL input; end with
                               <CRLF>.<CRLF>

2.0.2  REPLY-PENDING           A timeout has occurred. The server is
                               still working on the reply. Use
                               CONTINUE to continue waiting for the
                               reply or ABORT to terminate the
                               command.

2.0.3 ABORTED                  In response to the client issuing an
                               ABORT command, this reply code
                               indicates that any command currently
                               underway was successsfully aborted.

2.0.4  TRUSTED-WILL-ATTEMPT    The specified Calendar is not here
                               but a trust relationship exists
                               between this server and the server
                               on which the Calendar exists. An
                               attempt will be made to deliver the
                               request or reply to the Calendar
                               anyway.

2.0.5  TRUSTED-WILL-QUEUE      The specified Calendar cannot be
                               contacted directly. The request or
                               reply will be queued and delivered to
                               the target calendar when its IRIP
                               server contacts this server and issues
                               the SWITCH command.

2.0.6  WILL-ATTEMPT            The specified Calendar is not here
                               but an attempt will be made to deliver
                               the request or reply to the Calendar
                               anyway.

2.0.7  QUEUED                  The request or reply has been queued
                               for delivery.


8.0    GENERAL FAILURE         A failure has occurred in the Receiver
                               that prevents the operation from
                               succeeding.

8.1    SERVER TOO BUSY         Sent when a session cannot be
                               established because the [IRIP]
                               Receiver is too busy.

8.2    ICAL OBJECT TOO BIG     Used to signal that an ICAL object has
                               exceeded the server's size limit.

8.3    DATE TOO LARGE          A DATETIME value was too large to be
                               represented on this Calendar.


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8.4    DATE TOO SMALL          A DATETIME value was too far in the
                               past to be represented on this
                               Calendar.

9.0    INVALID IRIP COMMAND    An unrecongnized command was received.

10.1   REFERRAL                Accompanied by an alternate address.
                               The RECIPIENT specified should be
                               contacted at the given alternate
                               address. The referral address MUST
                               follow the reply code.

10.2   SERVER SHUT DOWN        The server is shutting down.

10.3   SERVER STOPPING FLOOD

10.4   EXCEEDED QUOTAS

10.5   QUEUED TOO LONG         The ITIP message has been queued too
                               too long. Delivery has been aborted.


4 Implementation Considerations

It is strongly recommended that when an IRIP implementation encounters
an error requiring the communication channel between the Sender and
Receiver to be dropped that the DISCONNECT command be issued rather
than simply breaking the communication channel.

[Editors note: What is the expectation for calstore recipients that
don't exist on this server?]

5 Security Considerations

The security of [IRIP] with [SASL] support is highly dependent on the
mechanism used to authenticate the client and whether or not the
security layer is further negotiated. Without a robust security layer,
[IRIP] transactions are subject to eavesdropping and the integrity of
[IRIP] transactions may be compromised. Since [IRIP] is designed
specifically for real time Internet transactions, it is recommended
that implementations use the highest degree of authentication and
transmission security possible.

Authentication is fundamental to [IRIP]. It is the basis for granting
and denying access. Without a robust security layer [IRIP] will be
subject to many possible attacks and the full contents of the server
itself may be at risk.

5.1 SASL ANONYMOUS Mechanism

Implementing support for the Anonymous [SASL] significantly increases
the vulnerability of the calendar server and its data. Refer to
[ANON-SASL] for further information on many threats specific to
Anonymous [SASL] access.

5.2 SASL Profile Definition for the protocol

The implementation of [SASL] in [IRIP] requires the server and client


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to comply with the following profile extension:

-  AUTHENTICATE command.
-  Full description of the challenge/response definition.
-  Starting octet.
-  Authorization identity supplied by the sender must the one used to
   grant or denied the requested operation.

5.3 Security Threats

5.3.1 Eavesdropping

If [SASL] is used to negotiate a security layer with the server, then
traffic is no longer in the clear and eavesdropping will not be
restricted.

5.3.2 Connection Flooding

Connections that have not been authenticated within a configurable
number of seconds should be disconnected.

5.3.3 Denial of Service Attacks

[Editors note: need explanation and recommendation: ???]

6 Examples

6.1 Unauthenticated Freebusy Request

This examples shows an anonymous request for the freebusy time of
irip://cal.example.com/sman.  Note that once xyz is authenticated on
the irip server either the fully qualified IRIP CALID or the relative
CALID can be used to reference a Calendar.  That is,
"irip://cal.example.com/xyz" and "xyz" refer to the same calendar and
can be used interchangeably.

R: <listen on TCP port 5228>
S: <establish a TCP connection to cal.example.com port 5228>
R: 2.0
S: AUTHENTICATE ANONYMOUS xyz
R: 2.0
S: RECIPIENT:sman
R: 2.0
S: ICALDATA
R: 2.0.1
S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: 7bit
S:
S: BEGIN:VCALENDAR
S: PRODID:-//ACME/DesktopCalendar//EN
S: METHOD:REQUEST
S: VERSION:2.0
S: BEGIN:VFREEBUSY
S: ORGANIZER:xyz
S: ATTENDEE:sman
S: DTSTAMP:19971113T190000Z
S: DTSTART:19971115T160000Z
S: DTEND:19971116T040000Z
S: UID:www.example.com-873970198738777@host.com


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S: END:VFREEBUSY
S: END:VCALENDAR
S: .

<server looks up the freebusy time and builds a reply>

R: Content-Type:text/calendar; method=REPLY; charset=US-ASCII
R: Content-Transfer-Encoding: 7bit
R:
R: BEGIN:VCALENDAR
R: PRODID:-//EXAMPLE/DesktopCalendar//EN
R: METHOD:REPLY
R: VERSION:2.0
R: BEGIN:VFREEBUSY
S: ORGANIZER:irip://cal.example.com/xyz
R: ATTENDEE:irip://cal.example.com/sman
R: DTSTAMP:19971113T190005Z
R: DTSTART:19971115T160000Z
R: DTEND:19971116T040000Z
R: UID:www.example.com-873970198738777@host.com
R: FREEBUSY:19971113T230000Z/PT1H,19971114T210000Z/PT30M
R: END:VFREEBUSY
R: END:VCALENDAR
R: .
R: sman 2.0
R: .
S: DISCONNECT
R: 2.0
R: <disconnect>
S: <disconnect>

6.2 Using Switch

This session demonstrates how a poll can be accomplished using the
SWITCH command.  In this case, the sender (S) becomes the receiver (R)
after issuing the switch command.


R: <listen on TCP port 5228>
S: <establish a connection to TCP port 5228>
R: 2.0
S: AUTHENTICATE KERBEROS_V4 93407205
S: <more authentication information>
R: 2.0
S: SWITCH
R: 2.0
<sender now becomes the receiver>
S: 2.0
R: AUTHENTICATE KERBEROS_V4  27367ao986pq8u98u9e8w0-0--0--0werg
S: 2.0
<receiver can now authenticate and send anything pending for the
sender>

6.3 Queued Requests

In the diagram below, sender S has authenticated to the IRIP server
B.foo.com.  C.foobar.com, D.bar.com, and E.barfoo.com all have IRIP
servers. B has a trusted relationship with both C and D. A firewall is
in place that prohibits B from initiating a connection to D. However, D


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can connect to B.

                                  +--------------+
                           +------| C.foobar.com |
                           |      +--------------+
                           |
            +-----------+  |      +-----------+
 S ---------| B.foo.com |------#--| D.bar.com |
            +-----------+  |      +-----------+
                           |
                           |      +--------------+
                           +------| E.barfoo.com |
                                  +--------------+
6.3.1 Meeting Invitation

In this example, S sends an event request to the IRIP server on B for
calendars on B, C, D, and E.

R: <listen on TCP port 5228>
S: <establish a TCP connection to b.foo.com port 5228>
R: 2.0
S: AUTHENTICATE KERBEROS_V4 93407205
S: <more authentication information>
R: 2.0
S: RECIPIENT:irip://B.foo.com/bill
R: 2.0
S: RECIPIENT:irip://C.foobar.com/cathy
R: 2.0.4
S: RECIPIENT:irip://D.bar.com/david
R: 2.0.5
S: RECIPIENT:irip://E.barfoo.com/eddie
R: 2.0.6
S: ICALDATA: 16
R: 2.0.1
S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: 7bit
S:
S: BEGIN:VCALENDAR
S: PRODID:-//ACME/DesktopCalendar//EN
S: METHOD:REQUEST
S: VERSION:2.0
S: BEGIN:VEVENT
S: ORGANIZER:irip://B.foo.com/bill
S: ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:irip://B.foo.com/bill
S: ATTENDEE;RSVP=TRUE;TYPE=INDIVIDUAL:irip://C.foobar.com/cathy
S: ATTENDEE;RSVP=TRUE;TYPE=INDIVIDUAL:irip://D.bar.com/david
S: ATTENDEE;RSVP=TRUE;TYPE=INDIVIDUAL:irip://E.barfoo.com/eddie
S: DTSTAMP:19981011T190000Z
S: DTSTART:19981101T200000Z
S: DTEND:19981101T2100000Z
S: SUMMARY:Conference
S: UID:calsrv.example.com-873970198738777@example.com
S: SEQUENCE:0
S: STATUS:CONFIRMED
S: END:VEVENT
S: END:VCALENDAR
S: .
R: .
R: irip://B.foo.com/bill 2.0


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R: irip://C.foobar.com/cathy 2.0
R: irip://D.bar.com/david 2.0.7
R: irip://E.barfoo.com/eddie 2.0
S: DISCONNECT
R: 2.0
R: <disconnect>
S: <disconnect>

The invitation is written to the calendar B.foo.com/bill. IRIP server
B.foo.com authenticates to C.foobar.com and sends the event request,
which is successfully written to C.foobar.com/cathy. The IRIP server on
B.foo.com cannot contact D.bar.com, but a trust relationship exists
between them and the request is queued for delivery. This request will
be delivered the next time the IRIP server on D.bar.com connects to the
IRIP server on B.foo.com and issues a SWITCH command. The IRIP server
on B.foo.com connects to the IRIP server on E.barfoo.com and
authenticates as anonymous since it has no trust relationship with
E.barfoo.com. If the anonymous authentication is successful, the event
request is delivered to E.barfoo.com/eddie.

[Editors note: in the case of the anonymous authentication, B could
also provide E with the same credentials as S provided to B]

6.3.2 Busy Time Request

In this example, the sender S sends a Freebusy request to B for
calendars on B, C, D, and E. S needs the information immediately and
will abort any attempt to queue requests.

R: <listen on TCP port 5228>
S: <establish a TCP connection to cal.example.com port 5228>
R: 2.0
S: AUTHENTICATE KERBEROS_V4 93407205
S: <more authentication information>
R: 2.0
S: RECIPIENT:irip://B.foo.com/bill
R: 2.0
S: RECIPIENT:irip://C.foobar.com/cathy
R: 2.0.4
S: RECIPIENT:irip://D.bar.com/david
R: 2.0.5
S: RECIPIENT:irip://E.barfoo.com/eddie
R: 2.0.6

<the sender cannot accept a queued request and response. The
 current operation will be canceled. The operation will be tried
 again with all attendees that have requests queued dropped from the
 RECIPIENT list...>

S: ABORT
R: 2.0.3
S: RECIPIENT:irip://B.foo.com/bill
R: 2.0
S: RECIPIENT:irip://C.foobar.com/cathy
R: 2.0.4
S: RECIPIENT:irip://E.barfoo.com/eddie
R: 2.0.6
S: ICALDATA
R: 2.0.1


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S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: 7bit
S:
S: BEGIN:VCALENDAR
S: PRODID:-//ACME/DesktopCalendar//EN
S: METHOD:REQUEST
S: VERSION:2.0
S: BEGIN:VFREEBUSY
S: ORGANIZER:irip://B.foo.com/bill
S: ATTENDEE:irip://B.foo.com/bill
S: ATTENDEE:irip://C.foobar.com/cathy
S: ATTENDEE:irip://D.bar.com/david
S: ATTENDEE:irip://E.barfoo.com/eddie
S: DTSTAMP:19971113T190000Z
S: DTSTART:19971115T160000Z
S: DTEND:19971116T040000Z
S: UID:www.example.com-873970198738777@host.com
S: END:VFREEBUSY
S: END:VCALENDAR
S: .

<server looks up the freebusy time for B.foo.com/bill,
 requests and receives the freebusy time for
 irip://C.foobar.com/cathy and irip://E.barfoo.com/eddie. Then it
 builds a reply>

R: Content-Type:multipart/mixed;boundary="--FEE3790DC7E35189CA67CE2C"
R:
R: This is a multi-part message in MIME format.
R:
R:----FEE3790DC7E35189CA67CE2C
R: Content-Type:text/calendar; method=REPLY; charset=US-ASCII
R: Content-Transfer-Encoding: 7bit
R:
R: BEGIN:VCALENDAR
R: PRODID:-//EXAMPLE/DesktopCalendar//EN
R: METHOD:REPLY
R: VERSION:2.0
R: BEGIN:VFREEBUSY
S: ORGANIZER:irip://B.foo.com/bill
R: ATTENDEE:irip://B.foo.com/bill
R: DTSTAMP:19971113T190005Z
R: DTSTART:19971115T160000Z
R: DTEND:19971116T040000Z
R: UID:www.example.com-873970198738777@host.com
R: FREEBUSY:19971115T200000Z/PT1H,19971116T170000Z/PT30M
R: END:VFREEBUSY
R: END:VCALENDAR
R:
R:----FEE3790DC7E35189CA67CE2C
R: Content-Type:text/calendar; method=REPLY; charset=US-ASCII
R: Content-Transfer-Encoding: 7bit
R:
R: BEGIN:VCALENDAR
R: PRODID:-//EXAMPLE/DesktopCalendar//EN
R: METHOD:REPLY
R: VERSION:2.0
R: BEGIN:VFREEBUSY
S: ORGANIZER:irip://B.foo.com/bill


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R: ATTENDEE:irip://C.foobar.com/cathy
R: DTSTAMP:19971113T190005Z
R: DTSTART:19971115T160000Z
R: DTEND:19971116T040000Z
R: UID:www.example.com-873970198738777@host.com
R: FREEBUSY:19971115T230000Z/PT1H,19971116T210000Z/PT30M
R: END:VFREEBUSY
R: END:VCALENDAR
R:
R:----FEE3790DC7E35189CA67CE2C
R: Content-Type:text/calendar; method=REPLY; charset=US-ASCII
R: Content-Transfer-Encoding: 7bit
R:
R: BEGIN:VCALENDAR
R: PRODID:-//EXAMPLE/DesktopCalendar//EN
R: METHOD:REPLY
R: VERSION:2.0
R: BEGIN:VFREEBUSY
S: ORGANIZER:irip://B.foo.com/bill
R: ATTENDEE:irip://E.barfoo.com/eddie
R: DTSTAMP:19971113T190005Z
R: DTSTART:19971115T160000Z
R: DTEND:19971116T040000Z
R: UID:www.example.com-873970198738777@host.com
R: FREEBUSY:19971115T230000Z/PT1H,19971116T210000Z/PT30M
R: END:VFREEBUSY
R: END:VCALENDAR
R:
R:----FEE3790DC7E35189CA67CE2C
R: .
R: irip://B.foo.com/bill 2.0
R: irip://C.foobar.com/cathy 2.0
R: irip://E.barfoo.com/eddie 2.0
S: DISCONNECT
R: 2.0
R: <disconnect>
S: <disconnect>

Since each reply is delivered immediately, the reply is sent as a
Multipart/Mixed. Transport reply codes for each recipient are returned
after the Multipart/Mixed data.

6.4 Resource Scheduling

R: <listen on TCP port 5228>
S: <connect to port 5228>
R: 2.0
S: AUTHENTICATE KERBEROS_V4 7SF8S3&#
S: <more authentication information>
R: 2.0
S: RECIPIENT Large_Conference_Room
R: 2.0
S: RECIPIENT Overhead_Projector_1
R: 2.0
S: ICALDATA: 10
S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: 7bit
S:
S: BEGIN:VCALENDAR


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S: PRODID:-//Foo Corporation//Inlet MIMEDIR//EN
S: VERSION:2.0
S: METHOD:REQUEST
S: BEGIN:VEVENT
S: ORGANIZER:irip://cal.example.com/xyz
S: ATTENDEE:irip://cal.example.com/Large_Conference_Room
S: ATTENDEE:irip://cal.example.com/Overhead_Projector_1
S: DTSTART:19980706T190000Z
S: DTEND:19980706T203000Z
S: LOCATION:Large Conference Room
S: DESCRIPTION:Big customer meeting in Large Conference room.
S: SUMMARY:Customer meeting
S: PRIORITY:1
S: END:VEVENT
S: END:VCALENDAR
S: .
R: <looks up availability in database>
R: .
R: 2.0 Large_Conference_Room
R: 2.0 Overhead_Projector_1
S: RECIPIENT Large_Conference_Room
R: 2.0
S: RECIPIENT Overhead_Projector_1
R: 2.0
S: ICALDATA: 10
S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: 7bit
S:
S: BEGIN:VCALENDAR
S: PRODID:-//Foo Corporation//Insight MIMEDIR//EN
S: VERSION:2.0
S: METHOD:REQUEST
S: BEGIN:VEVENT
S: ORGANIZER:irip://cal.example.com/xyz
S: ATTENDEE:irip://cal.example.com/Large_Conference_Room
S: ATTENDEE:irip://cal.example.com/Overhead_Projector_1
S: DTSTART:19980708T220000Z
S: DTEND:19980708T230000Z
S: LOCATION:Large Conference Room
S: DESCRIPTION:Another big customer meeting in Large Conference room.
S: SUMMARY:Customer meeting
S: PRIORITY:1
S: END:VEVENT
S: END:VCALENDAR
S: .
R: <looks up availability in database>
R: .
< Large_Conference_Room not available, thus the response code is...>
R: 4.0
S: RECIPIENT Large_Conference_Room
R: 2.0
S: RECIPIENT Overhead_Projector_1
R: 2.0
S: ICALDATA: 10
S: Content-Type:text/calendar; method=REQUEST; charset=US-ASCII
S: Content-Transfer-Encoding: 7bit
S:
S: BEGIN:VCALENDAR
S: PRODID:-//Foo Corporation//Insight MIMEDIR//EN


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S: VERSION:2.0
S: METHOD:REQUEST
S: BEGIN:VEVENT
S: ORGANIZER:irip://cal.example.com/xyz
S: ATTENDEE:irip://cal.example.com/Large_Conference_Room
S: ATTENDEE:irip://cal.example.com/Overhead_Projector_1
S: DTSTART:19980708T160000Z
S: DTEND:19980708T170000Z
S: LOCATION:Large Conference Room
S: DESCRIPTION:Another big customer meeting in Large Conference room.
S: SUMMARY:Customer meeting
S: PRIORITY:1
S: END:VEVENT
S: END:VCALENDAR
S: .
R: <looks up availability in database>
<10 seconds pass>
R: .
<Database too busy, thus the response code is...>
R: 2.0.2
S: ABORT
R: 2.0
S: DISCONNECT
R: 2.0
R: <drops TCP connection>

7 Acknowledgments

The following have participated in the drafting and discussion of this
memo:

Bruce Kahn, Doug Royer, Mugino Saeki

8 Bibliography

[ ICAL] "Internet Calendaring and Scheduling Core Object Specification
- iCalendar", Internet-Draft, July 1997,
ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-ical-10.txt.

[ICMS] "Internet Calendaring Model Specification", Internet-Draft, July
1997, ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-mod-00.txt.

[ITIP] "iCalendar Transport-Independent Interoperability Protocol
(iTIP) : Scheduling Events, Busy Time, To-dos and Journal Entries ",
Internet-Draft, October 1997,
http://www.imc.org/draft-ietf-calsch-itip-06.txt.

[IMIP] "iCalendar Message-based Interoperability Protocol (iMIP),
Internet-Draft, October 1997,
http://www.imc.org/draft-ietf-calsch-imip-05.txt.

[ID-UTF8] "UTF-8, a transformation format of Unicode and ISO 10646",
Internet-Draft, July,1996,
ftp://ftp.ietf.org/internet-drafts/draft-yergeau-utf8-01.txt.

[RFC-822] Crocker, D., "Standard for the Format of ARPA Internet Text
Messages", STD 11, RFC 822, August 1982.

[RFC-1847]. J. Galvin, S. Murphy, S. Crocker & N. Freed, "Security


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Multiparts for MIME: Multipart/Signed and Multipart/Encrypted", RFC
1847, October 1995.

[RFC-2112] Levinson, E., "The MIME Multipart/Related Content-type," RFC
2112, March 1997.

[RFC-2015] M. Elkins, "MIME Security with Pretty Good Privacy (PGP),"
RFC 2015, October 1996.

[RFC-2045] Freed, N., Borenstein, N., " Multipurpose Internet Mail
Extensions (MIME) - Part One: Format of Internet Message Bodies", RFC
2045, November 1996.

[RFC-2046] Freed, N., Borenstein, N., " Multipurpose Internet Mail
Extensions (MIME) - Part Two: Media Types", RFC 2046, November 1996.

[RFC-2047] Moore, K., "Multipurpose Internet Mail Extensions (MIME) -
Part Three: Message Header Extensions for Non-ASCII Text", RFC 2047,
November 1996.

[RFC-2048] Freed, N., J. Klensin, J. Postel, "Multipurpose Internet
Mail Extensions (MIME) - Part Four: Registration Procedures", RFC 2048,
January 1997.

[RFC-2222] J. Meyers, Simple Authentication and Security Layer (SASL)",
RFC 2222, October 1997.

9 Open Issues

Registration of the [SASL] profile for [IRIP] with the IANA.
Port Number registration
10 Author's Address

The following address information is provided in a vCard v2.1,
Electronic Business Card, format.


BEGIN:VCARD
FN:Andre Courtemanche
ORG:CS&T
ADR;WORK;POSTAL;PARCEL:;;3333 Graham Boulevard;Montreal;QC;H3R
3L5;Canada

TEL;WORK;MSG:+1-514-733-8500
TEL;WORK;FAX:+1-514-733-8788
EMAIL;INTERNET:andre@cst.ca
END:VCARD

BEGIN:VCARD
VERSION:2.1
FN:Steve Mansour
ORG:Netscape Communications Corporation
ADR;WORK;POSTAL;PARCEL:;;501 East Middlefield Road;Mountain
  View;CA;94043;USA
TEL;WORK;MSG:+1-650-937-2378
TEL;WORK;FAX:+1-650-937-2103
EMAIL;INTERNET:sman@netscape.com
END:VCARD



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BEGIN:VCARD
FN:Pete O'Leary
ORG:Amplitude
ADR;WORK;POSTAL;PARCEL:;;
TEL;WORK;MSG:+1-415-659-3511
TEL;WORK;FAX:+1-415-659-0006
EMAIL;INTERNET:pete@amplitude.com
END:VCARD

The iCalendar object is a result of the work of the Internet
Engineering Task Force Calendaring and scheduling Working Group. The
chairman of that working group is:

BEGIN:VCARD
FN:Anik Ganguly
ORG:Open Text, Inc.
ADR;WORK;POSTAL;PARCEL:;;38777 West Six Mile Road Suite 101;
    Livonia;MI;48152;USA
TEL;WORK;MSG:+1-734-542-5955
EMAIL;INTERNET:ganguly@acm.org
END:VCARD

The co-chairman of that working group is:

BEGIN:VCARD
VERSION:2.1
FN:Robert Moskowitz
EMAIL;INTERNET: rgm-ietf@htt-consult.com
END:VCARD

11 Full Copyright Statement

"Copyright (C) The Internet Society (date).  All Rights Reserved.

This document and translations of it MAY be copied and furnished to
others, and derivative works that comment on or otherwise explain it or
assist in its implmentation MAY be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are
included on all such copies and derivative works.  However, this
document itself MAY NOT be modified in any way, such as by removing the
copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of developing
Internet standards in which case the procedures for copyrights defined
in the Internet Standards process MUST be followed, or as required to
translate it into languages other than English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.





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