P-IMAP Draft Overview(http://www.ietf.org/internet-drafts/draft-maes-lemonade-p-imap-02.txt)

Stéphane H. Maes – stephane.maes@oracle.com

Oracle Corporation

IETF Lemonade Face-to-Face MeetingDallas, TXJune 2004

PIMAP: Goals and Motivations

1. Support the mobile e-mail:1. End-to-end secure, quasi real-time 2-way propagation of e-mail events

between messaging servers and mobile devices, allowing bothstores to remain synchronized

2. Mobile e-mail usage scenario3. Bandwidth optimization

• Not as much overhead as a session-based SyncML approach• Not so much chattiness as IMAPv4 Rev1

• Leveraging compression to ensure bandwidth conservation• Group commands to reduce round-trips

2. Take into account the variety of available network bearers in order toadjust the message flows accordingly

3. Extend message delivery capabilities to obviate the need for SMTP4. Directly interfaces and interoperates with IMAPv4 Rev1 Message Store5. Basis to support generic event-based synchronization:

1. Draft proposes sections to contain PIM events if desired

High Level Use Cases for Mobile E-mail

• An e-mail arrives at the corporate server of a mobile worker. • The client on the terminal is notified of the new email without excessive

delay (based on preferences) and in a secure manner. • Based on the preferences of the user, the notification is made available to

the user or, the client securely fetches the new e-mail or portions of it (e.g., header, few first kB, whole body without attachment or whole e-mail).

• The mobile user experience of delay should be comparable to desktop email.

• The user downloads and views attachments in ways adapted to its device.• An e-mail is composed by a mobile worker.

• Upon selecting to send the e-mail, it is immediately securely sent from the corporate e-mail server of the user (and not another server, e.g., operator provided SMTP server).

• Changes performed by the mobile worker in his e-mail client (e.g., deleting an e-mail or moving it from one e-mail folder to another) are properly reflected to the user mail box in the corporate server, as prescribed by the user.

• While mobile, a user can set and change filtering rules that specify when a new e-mail arriving at the corporate e-mail must be reflected in the mobile client.

High Level Use Cases for Mobile E-mail

• Depending on the network / service provider available to the mobile worker (e.g., underlying network technology, roaming, cost etc…), he or she can change behaviour of the mobile e-mail and appropriately provision for :• Secure notification of all or filtered new e-mails (and possibly other events)

through separate messaging mechanisms (e.g. SMS, MMS, Push) followed by:• Automated secure retrieval in a data session• Manual secure retrieval in a data session• [Secure browsing access (e.g., WAP, Web, Voice) -- out of scope of

work on Mobile Profile]• An always on connection with notification of all or filtered new e-mails (and

possibly other events) followed by automated or manual retrieval within the same session.

• Same or new sessions to send e-mail• [The user can synchronize his e-mail over the air as mobile e-mail, using a

pass through connection with another computer (e.g., cradle, Bluetooth, IRDA …) or over a direct LAN connection -- out of scope of work on Mobile Profile]

High Level Requirements1. Push e-mail experience or quasi-instantaneous synchronization between client

and server e-mail:1. Bi-directional event-based synchronization2. Manageability of email messages and folders including attachments from

the client while mobile2. Offline usage (e.g. not limited to browser-based access which is today still

often the only available model for mobile users)3. Cost structure:

1. Manageability (e.g. to be able to adapt to manage cost by setting what email to receive, how to be notified, when to synchronize, what to do with attachments, etc…)

4. Security:1. End-to-end between mobile client and e-mail server/proxy2. E-mail sent from the e-mail server (e.g., corporate e-mails server) instead

of other servers3. No intermediate storage outside enterprise domains.

5. Support of intermittent connectivity inherent to mobile network6. Content Adaptation7. Efficient exchanges of e-mail messages between client and server to optimize

mobile data costs and mobile data transfer delays8. Support of different underlying network technologies9. Interworking with IMAPv4 Rev1

PIMAP: Protocol Highlights

1. Extension commands allowing clients to:1. Set notification mode (in-band, out-band) and device address –

XSETPIMAPPREF/XGETPIMAPPREF2. Set view and notification filters - XFILTER3. Send out messages - XDELIVER4. Exchange compression capabilities:

• Leveraging compression to ensure bandwidth conservation5. Encryption – XENCRYPTED

• Payload encryption2. Combine often-used groups of commands into macros:

• Group commands to reduce round-trips3. Support for various bindings to underlying protocols, for instance:

1. PIMAP over HTTPS [Mandatory]2. PIMAP over TCP.3. Any other network optimizations can be used

4. Support for multiple notifications mechanisms:1. Based on OMA-EN specifications2. Supports

1. In-band notifications (e.g. within HTTP or TCP bindings).2. Out-band notifications (e.g. SMS, WAP Push, …).

PIMAP: Flows1. Keep-Alive HTTP binding, in-band notifications

HTTPS Listener

PIMAP Dispatcher

IMAPv4 Rev1 Message Store

Events

TCP Listener

PIMAP Client

Events/Commands

SMS

WAP Push

Out-bandNotifications

PIMAP Messaging Server

CommandProcessing

EventHandling

EventQueuing

1. Client establishes and authenticates a PIMAP session over a long-lived HTTPS request. It performs an IMAP state comparison for subscribed folders.

2. It uses this request to propagate client-originated events (send, delete, etc.)3. Server uses long-lived response to notify of server originated events.

1. Server receives notifications from the Message Store in different ways:1. Message Store has notification rules capabilities and can actively notify the PIMAP

dispatcher2. PIMAP dispatcher opens an IDLE session to the Message Store in behalf of the user

4. Client reacts to notifications if needed (e.g. fetches body of new message)5. If request/response ends, server maintains session and queues events.6. Client re-establishes HTTPS request within session lifetime and retrieves events without the need

for a full state comparison.

Ses

sion

PIMAP: Flows

HTTPS Listener

PIMAP Dispatcher

IMAPv4 Rev1 Message Store

Events

TCP Listener

PIMAP Client

Events/Commands

SMS

WAP Push

Out-bandNotifications

PIMAP Messaging Server

CommandProcessing

EventHandling

EventQueuing

1. Client establishes and authenticates a PIMAP session over a TCP connection. 2. It performs an IMAP state comparison for subscribed folders. 3. Client-originated events (send, delete, etc.) are propagated.4. Server uses connection to notify of server originated events.

1. Server receives notifications from the Message Store in different ways:1. Message Store has notification rules capabilities and can actively notify the PIMAP

dispatcher.2. PIMAP dispatcher opens an IDLE session to the Message Store in behalf of the user.

5. Client reacts to notifications if needed (e.g. fetches body of new message).6. Notifications may be missed when the client suddenly drops connection.

1. In this case, the server sends a RESYNC untagged response whenever the client reconnects.

Ses

sion

2. TCP binding, in-band notifications

PIMAP: Flows

HTTPS Listener

PIMAP Dispatcher

IMAPv4 Rev1 Message Store

Events

TCP Listener

PIMAP Client

Commands

SMS

WAP Push

Out-bandNotifications

PIMAP Messaging Server

CommandProcessing

EventHandling

EventQueuing

1. Client establishes and authenticates a PIMAP session over HTTPS.2. It performs an IMAP state comparison for subscribed folders. 3. Client-originated events (send, delete, etc.) are propagated as requests.4. Server uses SMS to notify of server originated events.5. Client reacts to notifications if needed (e.g. fetches body of new message) over additional

requests. The server maintains (cookie-based) a long-lived session and queues server events, reducing the need for full state comparisons.

6. If notifications are lost (out of coverage, etc.) the client retrieves pending events when one finally reaches its destination.

7. It is also possible that the client connects to server without even receiving the SMS. In this case, the server pushes pending events to the client in-band.

Ses

sion

3. HTTPS binding, out-band notifications (e.g. SMS)

Events

Future Work on P-IMAP

1. Allow support for a client device to track changes in multiple folders at once. 2. Enhance XZIP so that a client device can zip requests to the server. 3. Have an N most recent messages filter. 4. Allow support in out-band notifications to contain message events.5. Complete empty sections (e.g. folder events, PIM events, …)

Proposal for next steps at Lemonade

1. Initiate a Lemonade IETF draft of IMAP-MP (Mobile Profile)1. Starting from draft-maes-lemonade-p-imap-02.txt2. Incorporating additional comments from Lemonade WG3. Generate internet draft 00 for IETF-60 (san Diego)

2. Discuss comments, issues and next steps at IETF-60 for Mobile Profile:1. E.g. complete future work2. Consider specifying other bindings?

3. Consider deriving a notification IETF draft beyond mobile for IETF-614. Initiate a liaison with OMA on Mobile e-mail (New OMA Work Item) describing

plans and status for Mobile Profile:1. Hopefully OMA would re-use and point at IETF Lemonade Mobile Profile

PIMAP: Protocol Revision History1. Updates for Release 02

1. Throughout this document - took out references to mailbox since its definition was ambiguous. Now, the terms folder, email account, and repository are used instead.

2. Section 1.2.2 - took out message events, which is now described in new section 3. 3. Section 1.4 - removed attachments behavior 4. Section 3 - new section containing event payloads 5. Old section 3.1.3 - removed this section on forwarded flags 6. Old section 3.1.4 - added resync, folder, and session untagged response syntax 7. Old section 3.1.5 - UID becomes should instead of must requirement 8. Old section 3.1.7 - took out resync, which is now in login section 9. New section 4.1.6 - a new section concerning untagged XENCRYPTED responses in place of untagged

FETCH responses. 10. Old 3.2.1 - XPROVISION now just returns what XFILTERS are supported and what values some PIMAP

Prefs can take on 11. Old 3.2.2

1. Took out PIMAP_OUTBAND_NEW_FORMAT 2. Added in PIMAP_INBAND_PUSH format 3. valid values for some preferences are given in XPROVISION 4. XGETPIMAPPREF -> XGETPIMAPPREFS 5. defined XGETPIMAPPREFS untagged response

12. Old 3.2.3 - defined XFILTER untagged response 13. Old 3.2.4 - dropped this section on XTERSE 14. Old 3.2.6 - changed syntax so only V & N can be given for get. 15. Old 3.2.7

1. XUIDCONVERT -> UID CONVERT 2. added untagged response syntax

16. Security Considerations section - added in that there are additional security considerations when the server is implemented through a proxy on a distrusted operator network.

17. Appendix B.2 - changed example where client gets events in response to a login command (instead of noop) 18. Appendix C - new appendix to cover security issues for proxy-based deployments of P-IMAP. 19. Appendix E.2 on further considerations, which are things to add in the upcoming releases.

PIMAP: Protocol Revision History2. Updates for Release 01

1. Sections 1.1, 1.3, 2.2.1, 2.2.2, and 2.2.31. Added diagrams to better explain P-IMAP concepts

2. Section 1.4 1. Point 1 - changed term definition to Compression2. Added points 5 and 6 regarding Attachment Handling

3. Section 3.1.41. Updated minimal P-IMAP server requirements

4. Section 3.1.51. Fixed the title – P-IMAP Session/Login2. Added examples for “First Login” and “Login after Logout” cases

5. Added Section 3.1.7 1. RESYNC untagged response to solve problems with missed notifications

6. Section 3.2.21. XSETPREF and XGETPREF becomes XSETPIMAPPREF and XGETPIMAPPREF2. Reduced the number of preference parameters

7. Section 3.2.31. Added a Days Before Today filter

8. Removed section 49. References

1. Added references to IMAP-DISC and RFC 21802. Removed references to MIMAP, NSMS

10. Appendix B1. added example of outband notification and explained client's responsibilities

11. Appendix C1. Removed completely, as attachment conversion is described in XCONVERT command and

ways of retrieving it are discussed in RFC 26833. Release 00

1. Initial release published on Feb. 8th 2004