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+Network Working Group                                      R. Siemborski
+Request for Comments: 3656                    Carnegie Mellon University
+Category: Experimental                                     December 2003
+
+
+                     The Mailbox Update (MUPDATE)
+                 Distributed Mailbox Database Protocol
+
+Status of this Memo
+
+   This memo defines an Experimental Protocol for the Internet
+   community.  It does not specify an Internet standard of any kind.
+   Discussion and suggestions for improvement are requested.
+   Distribution of this memo is unlimited.
+
+Copyright Notice
+
+   Copyright (C) The Internet Society (2003).  All Rights Reserved.
+
+Abstract
+
+   As the demand for high-performance mail delivery agents increases, it
+   becomes apparent that single-machine solutions are inadequate to the
+   task, both because of capacity limits and that the failure of the
+   single machine means a loss of mail delivery for all users.  It is
+   preferable to allow many machines to share the responsibility of mail
+   delivery.
+
+   The Mailbox Update (MUPDATE) protocol allows a group of Internet
+   Message Access Protocol (IMAP) or Post Office Protocol - Version 3
+   (POP3) servers to function with a unified mailbox namespace.  This
+   document is intended to serve as a reference guide to that protocol.
+
+
+
+
+
+
+
+
+
+
+
+
+
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+
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+
+Siemborski                    Experimental                      [Page 1]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+Table of Contents
+
+   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
+   2.  Protocol Overview . . . . . . . . . . . . . . . . . . . . . .   3
+       2.1.  Atoms . . . . . . . . . . . . . . . . . . . . . . . . .   4
+       2.2.  Strings . . . . . . . . . . . . . . . . . . . . . . . .   4
+   3.  Server Responses  . . . . . . . . . . . . . . . . . . . . . .   4
+       3.1.  Response: OK  . . . . . . . . . . . . . . . . . . . . .   5
+       3.2.  Response: NO  . . . . . . . . . . . . . . . . . . . . .   5
+       3.3.  Response: BAD . . . . . . . . . . . . . . . . . . . . .   5
+       3.4.  Response: BYE . . . . . . . . . . . . . . . . . . . . .   6
+       3.5.  Response: RESERVE . . . . . . . . . . . . . . . . . . .   6
+       3.6.  Response: MAILBOX . . . . . . . . . . . . . . . . . . .   6
+       3.7.  Response: DELETE  . . . . . . . . . . . . . . . . . . .   7
+       3.8.  Server Capability Response. . . . . . . . . . . . . . .   7
+   4.  Client Commands . . . . . . . . . . . . . . . . . . . . . . .   8
+       4.1.  Command: ACTIVATE . . . . . . . . . . . . . . . . . . .   8
+       4.2.  Command: AUTHENTICATE . . . . . . . . . . . . . . . . .   8
+       4.3.  Command: DEACTIVATE . . . . . . . . . . . . . . . . . .   9
+       4.4.  Command: DELETE . . . . . . . . . . . . . . . . . . . .   9
+       4.5.  Command: FIND . . . . . . . . . . . . . . . . . . . . .   9
+       4.6.  Command: LIST . . . . . . . . . . . . . . . . . . . . .  10
+       4.7.  Command: LOGOUT . . . . . . . . . . . . . . . . . . . .  10
+       4.8.  Command: NOOP . . . . . . . . . . . . . . . . . . . . .  10
+       4.9.  Command: RESERVE. . . . . . . . . . . . . . . . . . . .  10
+       4.10. Command: STARTTLS . . . . . . . . . . . . . . . . . . .  11
+       4.11. Command: UPDATE . . . . . . . . . . . . . . . . . . . .  12
+   5.  MUPDATE Formal Syntax . . . . . . . . . . . . . . . . . . . .  12
+   6.  MUPDATE URL Scheme. . . . . . . . . . . . . . . . . . . . . .  14
+       6.1.  MUPDATE URL Scheme Registration Form. . . . . . . . . .  14
+   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
+   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
+   9.  Intellectual Property Rights. . . . . . . . . . . . . . . . .  16
+   10. References. . . . . . . . . . . . . . . . . . . . . . . . . .  17
+       10.1. Normative References. . . . . . . . . . . . . . . . . .  17
+       10.2. Informative References. . . . . . . . . . . . . . . . .  17
+   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  18
+   12. Author's Address. . . . . . . . . . . . . . . . . . . . . . .  18
+   13. Full Copyright Statement. . . . . . . . . . . . . . . . . . .  19
+
+
+
+
+
+
+
+
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+
+
+Siemborski                    Experimental                      [Page 2]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+1.  Introduction
+
+   In order to support an architecture where there are multiple [IMAP,
+   POP3] servers sharing a common mailbox database, it is necessary to
+   be able to provide atomic mailbox operations, as well as offer
+   sufficient guarantees about database consistency.
+
+   The primary goal of the MUPDATE protocol is to be simple to implement
+   yet allow for database consistency between participants.
+
+   The key words "MUST, "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
+   "RECOMMENDED", and "MAY" in this document are to be interpreted as
+   defined in BCP 14, RFC 2119 [KEYWORDS].
+
+   In examples, "C:" and "S:" indicate lines sent by the client and
+   server respectively.
+
+2.  Protocol Overview
+
+   The MUPDATE protocol assumes a reliable data stream such as a TCP
+   network connection.  IANA has registered port 3905 with a short name
+   of "mupdate" for this purpose.
+
+   In the current implementation of the MUPDATE protocol there are three
+   types of participants: a single master server, slave (or replica)
+   servers, and clients.  The master server maintains an authoritative
+   copy of the mailbox database.  Slave servers connect to the MUPDATE
+   master server as clients, and function as replicas from the point of
+   view of end clients.  End clients may connect to either the master or
+   any slave and perform searches against the database, however
+   operations that change the database can only be performed against the
+   master.  For the purposes of protocol discussion we will consider a
+   slave's connection to the master identical to that of any other
+   client.
+
+   After connection, all commands from a client to server must have an
+   associated unique tag which is an alphanumeric string.  Commands MAY
+   be pipelined from the client to the server (that is, the client need
+   not wait for the response before sending the next command).  The
+   server MUST execute the commands in the order they were received,
+   however.
+
+   If the server supports an inactivity login timeout, it MUST be at
+   least 15 minutes.
+
+
+
+
+
+
+
+Siemborski                    Experimental                      [Page 3]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   MUPDATE uses data formats similar to those used in [ACAP].  That is,
+   atoms and strings.  All commands and tags in the protocol are
+   transmitted as atoms.  All other data is considered to a string, and
+   must be quoted or transmitted as a literal.
+
+   Outside of a literal, both clients and servers MUST support line
+   lengths of at least 1024 octets (including the trailing CR and LF
+   characters).  If a line of a longer length must be transmitted,
+   implementations MUST make use of literals to do so.
+
+2.1.  Atoms
+
+   An atom consists of one or more alphanumeric characters.  Atoms MUST
+   be less than 15 octets in length.
+
+2.2.  Strings
+
+   As in [ACAP], a string may be either literal or a quoted string.  A
+   literal is a sequence of zero or more octets (including CR and LF),
+   prefix-quoted with an octet count in the form of an open brace ("{"),
+   the number of octets, an optional plus sign to indicate that the data
+   follows immediately (a non-synchronized literal), a close brace
+   ("}"), and a CRLF sequence.  If the plus sign is omitted (a
+   synchronized literal), then the receiving side MUST send a "+ go
+   ahead" response, and the sending side MUST wait for this response.
+   Servers MUST support literals of atleast 4096 octets.
+
+   Strings that are sent from server to client SHOULD NOT be in the
+   synchronized literal format.
+
+   A quoted string is a sequence of zero or more 7-bit characters,
+   excluding CR, LF, and the double quote (<">), with double quote
+   characters at each end.
+
+   The empty string is represented as either "" (a quoted string with
+   zero characters between double quotes) or as {0} followed by CRLF (a
+   literal with an octet count of 0).
+
+3.  Server Responses
+
+   Every client command in the MUPDATE protocol may receive one or more
+   tagged responses from the server.  Each response is preceded by the
+   same tag as the command that elicited the response from the server.
+
+
+
+
+
+
+
+
+Siemborski                    Experimental                      [Page 4]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+3.1.  Response: OK
+
+   A tagged OK response indicates that the operation completed
+   successfully.  There is a mandatory implementation-defined string
+   after the OK response.  This response also indicates the beginning of
+   the streaming update mode when given in response to an UPDATE
+   command.
+
+   Example:
+
+C: N01 NOOP
+S: N01 OK "NOOP Complete"
+
+3.2.  Response: NO
+
+   A tagged NO response indicates that the operation was explicitly
+   denied by the server or otherwise failed.  There is a mandatory
+   implementation-defined string after the NO response that SHOULD
+   explain the reason for denial.
+
+   Example:
+
+C: A01 AUTHENTICATE "PLAIN"
+S: A01 NO "PLAIN is not a supported SASL mechanism"
+
+3.3.  Response: BAD
+
+   A tagged BAD response indicates that the command from the client
+   could not be parsed or understood.  There is a mandatory
+   implementation-defined string after the BAD response to provide
+   additional information about the error.  Note that untagged BAD
+   responses are allowed if it is unclear what the tag for a given
+   command is (for example, if a blank line is received by the mupdate
+   server, it can generate an untagged BAD response).  In the case of an
+   untagged response, the tag should be replaced with a "*".
+
+   Example:
+
+C: C01 SELECT "INBOX"
+S: C01 BAD "This is not an IMAP server"
+C:
+S: * BAD "Need Command"
+
+
+
+
+
+
+
+
+
+Siemborski                    Experimental                      [Page 5]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+3.4.  Response: BYE
+
+   A tagged BYE response indicates that the server has decided to close
+   the connection.  There is a mandatory implementation-defined string
+   after the BYE response that SHOULD explain the reason for closing the
+   connection.  The server MUST close the connection immediately after
+   transmitting the BYE response.
+
+   Example:
+
+C: L01 LOGOUT
+S: L01 BYE "User Logged Out"
+
+3.5.  Response: RESERVE
+
+   A tagged RESERVE response may only be given in response to a FIND,
+   LIST, or UPDATE command.  It includes two parameters: the name of the
+   mailbox that is being reserved (in mUTF-7 encoding, as specified in
+   [IMAP]) and a location string whose contents is defined by the
+   clients that are using the database, though it is RECOMMENDED that
+   the format of this string be the hostname of the server which is
+   storing the mailbox.
+
+   This response indicates that the given name is no longer available in
+   the namespace, though it does not indicate that the given mailbox is
+   available to clients at the current time.
+
+   Example:
+
+S: U01 RESERVE "internet.bugtraq" "mail2.example.org"
+
+3.6.  Response: MAILBOX
+
+   A tagged MAILBOX response may only be given in response to a FIND,
+   LIST, or UPDATE command.  It includes three parameters: the name of
+   the mailbox, a location string (as with RESERVE), and a client-
+   defined string that specifies the IMAP ACL [IMAP-ACL] of the mailbox.
+   This message indicates that the given mailbox is ready to be accessed
+   by clients.
+
+   Example:
+
+S: U01 MAILBOX "internet.bugtraq" "mail2.example.org" "anyone rls"
+
+
+
+
+
+
+
+
+Siemborski                    Experimental                      [Page 6]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+3.7.  Response: DELETE
+
+   A tagged DELETE response may only be given in response to an UPDATE
+   command, and MUST NOT be given before the OK response to the UPDATE
+   command is given.  It contains a single parameter, that of the
+   mailbox that should be deleted from the slave's database.  This
+   response indicates that the given mailbox no longer exists in the
+   namespace of the database, and may be given for any mailbox name,
+   active, reserved, or nonexistent.  (Though implementations SHOULD NOT
+   issue DELETE responses for nonexistent mailboxes).
+
+   Example:
+
+S: U01 DELETE "user.rjs3.sent-mail-jan-2002"
+
+3.8.  Server Capability Response
+
+   Upon connection of the client to the server, and directly following a
+   successful STARTTLS command, the server MUST issue a capabilities
+   banner, of the following format:
+
+   The banner MUST contain a line that begins with "* AUTH" and contain
+   a space-separated list of SASL mechanisms that the server will accept
+   for authentication.  The mechanism names are transmitted as atoms.
+   Servers MAY advertise no available mechanisms (to indicate that
+   STARTTLS must be completed before authentication may occur).  If
+   STARTTLS is not supported by the server, then the line MUST contain
+   at least one mechanism.
+
+   If the banner is being issued without a TLS layer, and the server
+   supports the STARTTLS command, the banner MUST contain the line "*
+   STARTTLS".  If the banner is being issued under a TLS layer (or the
+   server does not support STARTTLS), the banner MUST NOT contain this
+   line.
+
+   The last line of the banner MUST start with "* OK MUPDATE" and be
+   followed by four strings: the server's hostname, an implementation-
+   defined string giving the name of the implementation, an
+   implementation-defined string giving the version of the
+   implementation, and a string that indicates if the server is a master
+   or a slave.  The master/slave indication MUST be either "(master)" or
+   an MUPDATE URL that defines where the master can be contacted.
+
+   Any unrecognized responses before the "* OK MUPDATE" response MUST be
+   ignored by the client.
+
+
+
+
+
+
+Siemborski                    Experimental                      [Page 7]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   Example:
+
+S: * AUTH KERBEROS_V4 GSSAPI
+S: * STARTTLS
+S: * OK MUPDATE "mupdate.example.org" "Cyrus" "v2.1.2" "(master)"
+
+4.  Client Commands
+
+   The following are valid commands that a client may send to the
+   MUPDATE server: AUTHENTICATE, ACTIVATE, DEACTIVATE, DELETE, FIND,
+   LIST, LOGOUT, NOOP, RESERVE, STARTTLS, and UPDATE.
+
+   Before a successful AUTHENTICATE command has occurred, the server
+   MUST NOT accept any commands except for AUTHENTICATE, STARTTLS, and
+   LOGOUT (and SHOULD reply with a NO response for all other commands).
+
+4.1.  Command: ACTIVATE
+
+   The ACTIVATE command has 3 parameters: the mailbox name, its
+   location, and its ACL.  This command MUST NOT not be issued to a
+   slave server.
+
+   This command can also be used to update the ACL or location
+   information of a mailbox.  Note that it is not a requirement for a
+   mailbox to be reserved (or even exist in the database) for an
+   ACTIVATE command to succeed, implementations MUST allow this behavior
+   as it facilitates synchronization of the database with the current
+   state of the mailboxes.
+
+4.2.  Command: AUTHENTICATE
+
+   The AUTHENTICATE command initiates a [SASL] negotiation session
+   between the client and the server.  It has two parameters.  The first
+   parameter is mandatory, and is a string indicating the desired [SASL]
+   mechanism.  The second is a string containing an optional BASE64
+   encoded (as defined in section 6.8 of [MIME]) client first send.
+
+   All of the remaining SASL blobs that are sent MUST be sent across the
+   wire must be in BASE64 encoded format, and followed by a CR and LF
+   combination.  They MUST NOT be encoded as strings.
+
+   Clients may cancel authentication by sending a * followed by a CR and
+   LF.
+
+   The [SASL] service name for the MUPDATE protocol is "mupdate".
+   Implementations are REQUIRED to implement the GSSAPI [SASL]
+   mechanism, though they SHOULD implement as many mechanisms as
+   possible.
+
+
+
+Siemborski                    Experimental                      [Page 8]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   If a security layer is negotiated, it should be used directly
+   following the CR and LF combination at the end of the server's OK
+   response (i.e., beginning with the client's next command) Only one
+   successful AUTHENTICATE command may be issued per session.
+
+4.3.  Command: DEACTIVATE
+
+   The DEACTIVATE command takes two parameters, the mailbox name and
+   location data.  The mailbox MUST already exist and be activated on
+   the MUPDATE server.  If the server responds OK, then the mailbox name
+   has been moved to the RESERVE state.  If the server responds NO, then
+   the mailbox name has not been moved (for example, the mailbox was not
+   already active).  Any ACL information that is known about the mailbox
+   MAY be lost when a DEACTIVATE succeeds.  This command MUST NOT be
+   issued to a slave.
+
+   Example:
+
+C: A01 DEACTIVATE "user.rjs3.new" "mail3.example.org!u4"
+S: A01 OK "Mailbox Reserved."
+
+4.4.  Command: DELETE
+
+   The DELETE command takes only a single parameter, the mailbox name to
+   be removed from the database's namespace.  The server SHOULD give a
+   NO response if the mailbox does not exist.  This command MUST NOT be
+   issued to a slave server.
+
+4.5.  Command: FIND
+
+   The FIND command takes a single parameter, a mailbox name.  The
+   server then responds with the current record for the given mailbox,
+   if any, and an OK response.
+
+   Example (mailbox does not exist):
+
+C: F01 FIND "user.rjs3.xyzzy"
+S: F01 OK "Search Complete"
+
+   Example (mailbox is reserved):
+
+C: F01 FIND "user.rjs3"
+S: F01 RESERVE "user.rjs3" "mail4.example.org"
+S: F01 OK "Search Complete"
+
+
+
+
+
+
+
+Siemborski                    Experimental                      [Page 9]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+4.6.  Command: LIST
+
+   The LIST command is similar to running FIND across the entire
+   database.  The LIST command takes a single optional parameter, which
+   is a prefix to try to match against the location field of the
+   records.  Without the parameter, LIST returns every record in the
+   database.
+
+   For each mailbox that matches, either a MAILBOX or a RESERVE response
+   (as applicable) is sent to the client.  When all responses are
+   complete, an OK response is issued.
+
+   Example:
+
+C: L01 LIST
+S: L01 RESERVE "user.rjs3" "mail4.example.org!u2"
+S: L01 MAILBOX "user.leg" "mail2.example.org!u1" "leg lrswipcda"
+S: L01 OK "List Complete"
+C: L02 LIST "mail4.example.org!"
+S: L02 RESERVE "user.rjs3" "mail4.example.org!u2"
+S: L02 OK "List Complete"
+
+4.7.  Command: LOGOUT
+
+   The LOGOUT command tells the server to close the connection.  Its
+   only valid response is the BYE response.  The LOGOUT command takes no
+   parameters.
+
+4.8.  Command: NOOP
+
+   The NOOP command takes no parameters.  Provided the client is
+   authenticated, its only acceptable response is an OK.  Any idle
+   timeouts that the server may have on the connection SHOULD be reset
+   upon receipt of this command.
+
+   If this command is issued after an UPDATE command has been issued,
+   then the OK response also indicates that all pending database updates
+   have been sent to the client.  That is, the slave can guarantee that
+   its local database is up to date as of a certain time by issuing a
+   NOOP and waiting for the OK.  The OK MUST NOT return until all
+   updates that were pending at the time of the NOOP have been sent.
+
+4.9.  Command: RESERVE
+
+   The RESERVE command takes two parameters (just like the RESERVE
+   response), the mailbox name to reserve and location data.  If the
+   server responds OK, then the mailbox name has been reserved.  If the
+   server responds NO, then the mailbox name has not been reserved (for
+
+
+
+Siemborski                    Experimental                     [Page 10]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   example, another server has reserved it already).  This command MUST
+   NOT be issued to a slave.
+
+   The typical sequence for mailbox creation is:
+
+C: R01 RESERVE "user.rjs3.new" "mail3.example.org!u4"
+S: R01 OK "Mailbox Reserved."
+<client does local mailbox create operations>
+C: A01 ACTIVATE "user.rjs3.new" "mail3.example.org!u4" "rjs3 lrswipcda"
+S: A01 OK "Mailbox Activated."
+
+4.10.  Command: STARTTLS
+
+   The STARTTLS command requests the commencement of a [TLS]
+   negotiation.  The negotiation begins immediately after the CRLF in
+   the OK response.  After a client issues a STARTTLS command, it MUST
+   NOT issue further commands until a server response is seen and the
+   [TLS] negotiation is complete.
+
+   The STARTTLS command is only valid in non-authenticated state.  The
+   server remains in non-authenticated state, even if client credentials
+   are supplied during the [TLS] negotiation.  The [SASL] EXTERNAL
+   mechanism MAY be used to authenticate once [TLS] client credentials
+   are successfully exchanged.  Note that servers are not required to
+   support the EXTERNAL mechanism.
+
+   After the [TLS] layer is established, the server MUST re-issue the
+   initial response banner (see Section 3.8).  This is necessary to
+   protect against man-in-the-middle attacks which alter the
+   capabilities list prior to STARTTLS, as well as to advertise any new
+   SASL mechanisms (or other capabilities) that may be available under
+   the layer.  The client MUST discard cached capability information and
+   replace it with the new information.
+
+   After the a successful STARTTLS command, the server SHOULD return a
+   NO response to additional STARTTLS commands.
+
+   Servers MAY choose to not implement STARTTLS.  In this case, they
+   MUST NOT advertise STARTTLS in their capabilities banner, and SHOULD
+   return a BAD response to the STARTTLS command, if it is issued.
+
+   Example:
+
+C: S01 STARTTLS
+S: S01 OK "Begin TLS negotiation now"
+<TLS negotiation, further commands are under TLS layer>
+S: * AUTH KERBEROS_V4 GSSAPI PLAIN
+S: * OK MUPDATE "mupdate.example.org" "Cyrus" "v2.1.2" "(master)"
+
+
+
+Siemborski                    Experimental                     [Page 11]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+4.11.  Command: UPDATE
+
+   The UPDATE command is how a slave initializes an update stream from
+   the master (though it is also valid to issue this command to a
+   slave).  In response to the command, the server returns a list of all
+   mailboxes in its database (the same results as a parameterless LIST
+   command) followed by an OK response.  From this point forward,
+   whenever an update occurs to the master database, it MUST stream the
+   update to the slave within 30 seconds.  That is, it will send
+   RESERVE, MAILBOX, or DELETE responses as they are applicable.
+
+   After a client has issued an UPDATE command, it may only issue NOOP
+   and LOGOUT commands for the remainder of the session.
+
+   Example:
+
+C: U01 UPDATE
+S: U01 MAILBOX "user.leg" "mail2.example.org!u1" "leg lrswipcda"
+S: U01 MAILBOX "user.rjs3" "mail3.example.org!u4" "rjs3 lrswipcda"
+S: U01 RESERVE "internet.bugtraq" "mail1.example.org!u5" "anyone lrs"
+S: U01 OK "Streaming Begins"
+<some time goes by, and another client creates a new mailbox>
+S: U01 RESERVE "user.leg.new" "mail2.example.org!u1"
+<some more time passes, and the create succeeds>
+S: U01 MAILBOX "user.leg.new" "mail2.example.org!u1" "leg lrswipcda"
+<much more time passes, and the slave decides to send a NOOP to reset
+its inactivity timer>
+C: N01 NOOP
+S: U01 DELETE "user.leg.new"
+S: N01 OK "NOOP Complete"
+
+5.  MUPDATE Formal Syntax
+
+   The following syntax specification uses the Augmented Backus-Naur
+   Form (ABNF) notation as specified in [ABNF].  This uses the ABNF core
+   rules as specified in Appendix A of [ABNF].
+
+   Except as noted otherwise, all alphabetic characters are case-
+   insensitive.  The use of upper or lower case characters to define
+   token strings is for editorial clarity only.  Implementations MUST
+   accept these strings in a case-insensitive fashion.
+
+   Note that this specification also uses some terminals from section 8
+   of [ACAP].
+
+   cmd-activate = "ACTIVATE" SP string SP string SP string
+
+   cmd-authenticate = "AUTHENTICATE" SP sasl-mech [ SP string ]
+
+
+
+Siemborski                    Experimental                     [Page 12]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   cmd-delete = "DELETE" SP string
+
+   cmd-find = "FIND" SP string
+
+   cmd-list = "LIST" [ SP string ]
+
+   cmd-logout = "LOGOUT"
+
+   cmd-noop = "NOOP"
+
+   cmd-reserve = "RESERVE" SP string SP string
+
+   cmd-starttls = "STARTTLS"
+
+   cmd-update = "UPDATE"
+
+   command = tag SP command-type CRLF
+
+   command-type = cmd-activate / cmd-authenticate / cmd-delete /
+                  cmd-find / cmd-list / cmd-logout / cmd-noop /
+                  cmd-reserve / cmd-starttls / cmd-update
+
+   response = tag SP response-type CRLF
+
+   response-type = rsp-ok / rsp-no / rsp-bad / rsp-bye / rsp-mailbox /
+                   rsp-reserve / rsp-delete
+
+   rsp-bad = "BAD" SP string
+
+   rsp-bye = "BYE" SP string
+
+   rsp-mailbox = "MAILBOX" SP string SP string SP string
+
+   rsp-no = "NO" SP string
+
+   rsp-ok = "OK" SP string
+
+   rsp-reserve = "RESERVE" SP string SP string
+
+   rsp-delete = "DELETE" SP string
+
+   sasl-mech = 1*ATOM-CHAR
+      ; ATOM-CHAR is defined in [ACAP]
+
+   string = quoted / literal
+      ; quoted and literal are defined in [ACAP]
+
+
+
+
+
+Siemborski                    Experimental                     [Page 13]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   tag = 1*ATOM-CHAR
+      ; ATOM-CHAR is defined in [ACAP]
+
+6.  MUPDATE URL Scheme
+
+   This document defines the a URL scheme for the purposes of
+   referencing MUPDATE resources, according to the requirements in
+   [RFC2717].  This includes both MUPDATE servers as a whole, along with
+   individual mailbox entries on a given MUPDATE server.
+
+   There is no MIME type associated with these resources.  It is
+   intended that a URL consumer would either retrieve the MUPDATE record
+   in question, or simply connect to the MUPDATE server running on the
+   specified host.  Note that the consumer will need to have
+   authentication credentials for the specified host.
+
+   The MUPDATE URL scheme is similar to the IMAP URL scheme [IMAP-URL].
+   However, it only takes one of two possible forms:
+
+      mupdate://<iserver>/
+      mupdate://<iserver>/<mailbox>
+
+   The first form refers to a MUPDATE server as a whole, the second form
+   indicates both the server and a mailbox to run a FIND against once
+   authenticated to the server.  Note that part of <iserver> may include
+   username and authentication information along with a hostname and
+   port.
+
+6.1.  MUPDATE URL Scheme Registration Form
+
+   URL scheme name: "mupdate"
+
+   URL scheme syntax:
+
+      This defines the MUPDATE URL Scheme in [ABNF].  Terminals from the
+      BNF of IMAP URLs [IMAP-URL] are also used.
+
+         mupdateurl = "mupdate://" iserver "/" [ enc_mailbox ]
+            ; iserver and enc_mailbox are as defined in [IMAP-URL]
+
+   Character encoding considerations:
+
+      Identical to those described in [IMAP-URL] for the appropriate
+      terminals.
+
+
+
+
+
+
+
+Siemborski                    Experimental                     [Page 14]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   Intended Usage:
+
+      The form of the URL without an associated mailbox is intended to
+      designate a MUPDATE server only.  If a mailbox name is included in
+      the URL, then the consumer is expected to execute a FIND command
+      for that mailbox on the specified server.
+
+   Applications and/or protocols which use this URL scheme name:
+
+      The protocol described in this document.
+
+   Interoperability Considerations:
+
+      None.
+
+   Security Considerations:
+
+      Users of the MUPDATE URL Scheme should review the security
+      considerations that are discussed in [IMAP-URL].  In particular,
+      the consequences of including authentication mechanism information
+      in a URL should be reviewed.
+
+   Relevant Publications:
+
+      This document and [IMAP-URL].
+
+   Author, Change Controller, and Contact for Further Information:
+
+      Author of this document.
+
+7.  Security Considerations
+
+   While no unauthenticated users may make modifications or even perform
+   searches on the database, it is important to note that this
+   specification assumes no protections of any type for authenticated
+   users.
+
+   All authenticated users have complete access to the database.  For
+   this reason it is important to ensure that accounts that are making
+   use of the database are well secured.
+
+   A more secure deployment might have all read only access go through a
+   slave, and only have accounts which need write access use the master.
+   This has the disadvantage of a marginally longer time for updates to
+   reach the clients.
+
+
+
+
+
+
+Siemborski                    Experimental                     [Page 15]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+   The protocol assumes that all authenticated users are cooperating to
+   maintain atomic operations.  Therefore, all new mailboxes SHOULD be
+   RESERVEd before they are ACTIVATEd, despite the fact that the
+   protocol does not require this, and it is therefore possible for a
+   set of participants which do not obey the provided locking to create
+   an inconsistent database.  RESERVEing the mailbox first is not
+   required to perform an activate because this behavior simplifies
+   synchronization with the actual location of the mailboxes.
+
+8.  IANA Considerations
+
+   The IANA has assigned TCP port number 3905 to "mupdate".
+
+   The IANA has registered a URL scheme for the MUPDATE protocol, as
+   defined in section 6.1 of this document.
+
+   IANA has registered a GSSAPI service name of "mupdate" for the
+   MUPDATE protocol in the registry maintained at:
+
+   http://www.iana.org/assignments/gssapi-service-names
+
+9.  Intellectual Property Rights
+
+   The IETF takes no position regarding the validity or scope of any
+   intellectual property or other rights that might be claimed to
+   pertain to the implementation or use of the technology described in
+   this document or the extent to which any license under such rights
+   might or might not be available; neither does it represent that it
+   has made any effort to identify any such rights.  Information on the
+   IETF's procedures with respect to rights in standards-track and
+   standards-related documentation can be found in BCP-11.  Copies of
+   claims of rights made available for publication and any assurances of
+   licenses to be made available, or the result of an attempt made to
+   obtain a general license or permission for the use of such
+   proprietary rights by implementors or users of this specification can
+   be obtained from the IETF Secretariat.
+
+   The IETF invites any interested party to bring to its attention any
+   copyrights, patents or patent applications, or other proprietary
+   rights which may cover technology that may be required to practice
+   this standard.  Please address the information to the IETF Executive
+   Director.
+
+
+
+
+
+
+
+
+
+Siemborski                    Experimental                     [Page 16]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+10.  References
+
+10.1.  Normative References
+
+   [KEYWORDS]  Bradner, S., "Key words for use in RFCs to Indicate
+               Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+   [IMAP]      Crispin, M., "Internet Message Access Protocol - Version
+               4", RFC 3501, March 2003.
+
+   [ABNF]      Crocker, D., Ed. and P. Overell, "Augmented BNF for
+               Syntax Specifications: ABNF", RFC 2234, November 1997.
+
+   [MIME]      Freed, N. and N. Bornstein, "Multipurpose Internet Mail
+               Extensions (MIME) Part One: Format of Internet Message
+               Bodies", RFC 2045, November 1996.
+
+   [IMAP-ACL]  Myers, J., "IMAP4 ACL extension", RFC 2086, January 1997.
+
+   [SASL]      Myers, J., "Simple Authentication and Security Layer
+               (SASL)", RFC 2222, October 1997.
+
+   [IMAP-URL]  Newman, C., "IMAP URL Scheme", RFC 2192, September 1997.
+
+   [ACAP]      Newman, C. and J. Myers, "ACAP -- Application
+               Configuration Access Protocol", RFC 2244, November 1997.
+
+   [TLS]       Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
+               RFC 2246, January 1999.
+
+10.2.  Informative References
+
+   [POP3]      Myers, J. and M. Rose, "Post Office Protocol - Version
+               3", STD 53, RFC 1939, May 1996.
+
+   [RFC2717]   Petke, R. and I. King, "Registration Procedures for URL
+               Scheme Names", BCP 35, RFC 2717, November 1999.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Siemborski                    Experimental                     [Page 17]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+11.  Acknowledgments
+
+   Lawrence Greenfield and Ken Murchison, for a great deal of input on
+   both the protocol and the text of the documents.
+
+12.  Author's  Address
+
+   Robert Siemborski
+   Carnegie Mellon, Andrew Systems Group
+   Cyert Hall 207
+   5000 Forbes Avenue
+   Pittsburgh, PA  15213
+
+   Phone: (412) 268-7456
+   EMail: rjs3+@andrew.cmu.edu
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Siemborski                    Experimental                     [Page 18]
+
+RFC 3656     MUPDATE Distributed Mailbox Database Protocol December 2003
+
+
+13.  Full Copyright Statement
+
+   Copyright (C) The Internet Society (2003).  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 implementation 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 assignees.
+
+   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.
+
+Acknowledgement
+
+   Funding for the RFC Editor function is currently provided by the
+   Internet Society.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Siemborski                    Experimental                     [Page 19]
+