Lemonade Internet Draft: Mobile E-mai S. H. Maes Document: draft-maes-lemonade-mobile-email-01.txt Oracle Corporation Expires: April 2005 October 2004 Lemonade and Mobile e-mail Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document describes the challenges with mobile e-mail in order to identify the challenges that are within the mobile profile of Lemonade. Maes [Page 1] October 2004 Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. An implementation is not compliant if it fails to satisfy one or more of the MUST or REQUIRED level requirements for the protocol(s) it implements. An implementation that satisfies all the MUST or REQUIRED level and all the SHOULD level requirements for a protocol is said to be "unconditionally compliant" to that protocol; one that satisfies all the MUST level requirements but not all the SHOULD level requirements is said to be "conditionally compliant." When describing the general syntax, some definitions are omitted as they are defined in [RFC3501]. Table of Contents Status of this Memo...............................................1 Abstract..........................................................1 Conventions used in this document.................................2 Table of Contents.................................................2 1. Introduction...................................................3 1.1. Definitions...............................................3 1.2. Main Expectations.........................................3 1.3. Additional Considerations.................................3 1.4. Main actors...............................................4 1.5. Other players in Ecosystem................................4 2. Challenges.....................................................4 2.1. Devices...................................................4 2.2. Networks and operators....................................5 2.3. Enterprises and other e-mail service providers............6 3. Deployment models..............................................6 4. Scope, objectives of Lemonade Mobile Profile: Recommendations..8 Security Considerations...........................................9 Authors Addresses.................................................9 Intellectual Property Statement...................................9 Acknowledgment...................................................10 Full Copyright Statement.........................................10 Maes Expires - April 2005 [Page 2] October 2004 1. Introduction This document describes the challenges associated to mobile e-mail. 1.1. Definitions Mobile e-mail is defined as "Access to e-mail while mobile". 1.1. Main Expectations The main expectations for mobile e-mail are: - To receive quasi-instantaneous notification of new e-mails when within coverage (if setup this way) - To reflect quasi-instantaneously new e-mail or e-mail server events in the mobile client when within coverage - To send quasi-instantaneously e-mail composed on mobile client from appropriate e-mail server when within coverage or as soon that coverage is established otherwise - To efficiently manipulate e-mails / drafts / attachment as needed or as preferred - End-to-end secure when needed (e.g. e-mails may at no point be in clear outside enterprise domain) - Low or at least bearable cost of usage (e.g. traffic / bandwidth optimization, predictable cost, manageable traffic, ...) Note that the notion of quasi-instantenous refers to the impression of the user and not to a particular precise duration: the user has the feeling that something happens in a way that is quasi-instantenous. This may be equivalent to some desktop user experience or sometimes be faster or slower than desktop. That is not important as the user can usually not compare. On the other hand, some overall behavior clearly violate this principle (e.g. if the client waits for the user to "browse" its mailbox with a client to download the headers or even the whole messages). 1.3. Additional Considerations The following considerations are also important for mobile e-mail - Need for graceful degradation and server-to-client notifications (that client can display instead if acting on and that informs the user). - Format adaptation (attachments, page, ...) - DRM rules: how to respect DRM rules like forward lock - Provisioning / setup: These are extremely challenging on mobile devices with limited or challenging input capabilities. Also average users are more easily confused and unable to correctly setup mobile phones - Charging: Operator want to maintain charging to create a viable business model. They may prevent the deployment of mobile email solutions that do not permit charging for e-mail services. - Synchronization with other clients: - e.g. Peer to peer vs. with server (SyncML / OMA DS, ActiveSync, ...) - Relationship to PIM (agenda / Address Book) Maes Expires - April 2005 [Page 3] October 2004 1.4. Main Actors The main actors are: - User - Operators of the mobile network - E-mail service provider: - Service provider (e.g. Operator, other e-mail server provider) - Enterprise 1.4. Other players in ecosystem Other actors influence decisions related to mobile e-mail: - Device Manufacturers - Client software providers - E-mail server manufacturers: - E-mail server - Mobile e-mail enablement server 2. Challenges 2.1. Devices Devices present the following challenges that directly impact mobile e-mail: - Constrained memory / processing power (always improving): - Wide range to support - Limited battery life (will remain a problem for a long time): - Constrains processing capability - Constrains connectivity patterns (not always fully connected but may be awaken via outband notifications...) - Notifications / wake-up are to be supported by mobile e-mail - Constraints acceptable bandwidth - More exotic platforms: - Sometimes proprietary or closed - Challenging or controlled software distribution channels: - Installing, provisioning, supporting, upgrading,... - E.g. DRM trusted clients - Wide range of control models by: - device manufacturer, operator, enterprise, user Maes Expires - April 2005 [Page 4] October 2004 2.2. Networks and operators Mobile networks and operators impose additional constraints that must be taken into account when designing mobile e-mail solutions: - Different underlying network technologies / bearers with different behavior / capabilities - Intermittent connectivity: - Loss of coverage - Nature of mobility (e.g. radio turned off in planes) - Temporary IP addresses - Unreliable delivery (Connection) - Underlying network layer (up to transport) may drop at any time. Even if then re-established, sessions at the transport level are maintained only if the transport protocol provide mechanisms to maintain it when the network connection is re-established. Otherwise, additional mechanisms are needed at the application protocol layer to establish and maintain/recover session if a session is needed or assumed. - Out band notification schemes - Unreliable - But can be used as "wake up / notification scheme" - Limited bandwidth: - Limited capabilities shared across all users - Roaming within and across domain / operators / technologies - Cost: - Multiple cost models (free, unlimited, per packet, per service / type of service, ...) - In general, ... Costly and in need of optimization to maintain cost acceptable enough to user and to allow operator to share network with enough users. - Controlled: - Walled garden: - Inbound and outbound traffic - Internal traffic - With itĘs own authentication mechanisms etc... - Regulated: - QoS - Privacy - Exchanged data - Reachability - Logging - Accountability - ... Maes Expires - April 2005 [Page 5] October 2004 2.3. Enterprises and other e-mail service providers Enterprises must reconcile mobile e-mail deployments with the following requirements: - Walled garden intranets: - Firewalls, VPN, ... - IT Corporate security guidelines: - Wide range - in general VERY conservative e.g. - Require end-to-end security - Allowed applications / usages / content - Firewalls / ports / protocols - (e.g. only HTTP or HTTPS; no SSL/TLS) - No storage of company data outside intranet (in clear or not). This is why MMS solutions are not acceptable - Regulated: - E.g. Journaling / Storage of all corporate e-mails - Control usage costs - Need to integrate with existing IT infrastructure (instead of replacing them). 3. Deployment models The generic logical architecture and protocol to support mobile e-mail include: - Mobile e-mail server (backend e.g. IMAP server) - Connected (e.g. via IMAP) through a "connector" - to a mobile e-mail enabling server - Connected: - Via mobile e-mail protocol to a mobile e-mail client - Via other protocols to mobile enablers that support functions like: - Outband notifications - Provisioning - ... Firewalls may exist: - 1) Between connectors and mobile e-mail enabling server - 2) Between: - Mobile client and mobile e-mail enabling server - Mobile enablers and mobile e-mail enabling server Possible deployments include: A: Mobile e-mail by operators: "operator hosted e-mail service" - Device in network - Mobile "enabled" email server in OperatorĘs Domain - Roaming across compatible networks / operators B: Mobile e-mail by E-mail service provider (enterprise, ISP): - Device in operator network (including roaming) - Mobile "enabled" email E-mail server in service provider Maes Expires - April 2005 [Page 6] October 2004 C: Outsourced mobile enablement of E-mail service provider: 1. By Operator (operator hosted) 2. By other third party service provider - Device in operator network (including roaming) - E-mail server in other domain Deployment A is characterized by: * In operator(s) domain: - Mobile e-mail server (backend e.g. IMAP server) - Connected (e.g. via IMAP) through a "connector" - to a mobile e-mail enabling server - Connected: - Via mobile e-mail protocol to a mobile e-mail client - Via other protocols to mobile enablers that support functions like: - Outband notifications - Provisioning - ... Firewalls may exist: - Between: - Mobile client and mobile e-mail enabling server - Mobile enablers and mobile e-mail enabling server Deployment B is characterized by: * In E-mail Service Provider domain: - Mobile e-mail server (backend e.g. IMAP server) - Connected (e.g. via IMAP) through a "connector" - to a mobile e-mail enabling server - Connected: * In Operator(s) domain: - Via mobile e-mail protocol to a mobile e-mail client - Via other protocols to mobile enablers that support functions like: - Outband notifications - Provisioning - ... Firewalls may exist: - 1) Between connectors and mobile e-mail enabling server - 2) Between: - Mobile client and mobile e-mail enabling server - Mobile enablers and mobile e-mail enabling server Deployment C.1 is characterized by: * In E-mail Service Provider domain: - Mobile e-mail server (backend e.g. IMAP server) - Connected (e.g. via IMAP) through a "connector" Maes Expires - April 2005 [Page 7] October 2004 * In Operator(s) domain: - to a mobile e-mail enabling server - Connected: - Via mobile e-mail protocol to a mobile e-mail client - Via other protocols to mobile enablers that support functions like: - Outband notifications - Provisioning - ... Firewalls may exist: - 1) Between connectors and mobile e-mail enabling server - 2) Between: - Mobile client and mobile e-mail enabling server - Mobile enablers and mobile e-mail enabling server Deployment C.2 is characterized by: * In E-mail Service Provider domain: - Mobile e-mail server (backend e.g. IMAP server) - Connected (e.g. via IMAP) through a "connector" * In third party service provider: - to a mobile e-mail enabling server - Connected: * In Operator(s) domain: - Via mobile e-mail protocol to a mobile e-mail client - Via other protocols to mobile enablers that support functions like: - Outband notifications - Provisioning - ... Firewalls may exist: - 1) Between connectors and mobile e-mail enabling server - 2) Between: - Mobile client and mobile e-mail enabling server - Mobile enablers and mobile e-mail enabling server 4. Scope, objectives of Lemonade Mobile Profile: Recommendations Will lemonade specify the mobile e-mail protocol or specify a set of optimizations "inspired" from mobile e-mail but not necessarily addressing all these issues? We recommend: - That Lemonade aims at addressing all the problems identified that are within the scope of IETF. - That Lemonade MUST design its protocol to allow use of its messages and principles with other transport mechanisms (e.g. HTTP, Outband notification mechanisms, ...) when needed to address some of the mobile e-mail challenges identified in this document. Maes Expires - April 2005 [Page 8] October 2004 Accordingly, Lemonade must not make assumptions on the underlying network transport or design choices that would prevent addressing all these issues even if their resolution is outside the scope of IETF (network neutrality). This implies in particular allowing: compression and encryption at the application level and possibility to bind Lemonade to HTTP/HTTPS. Security Considerations The Mobile e-mail protocols must address / support security issues raised by: - The different deployment models identified in section 3. In particular: - End-to-end security with no message in the clear when the mobile e-mail enabling server is outside the e-mail service provider domain. - No storage of e-mail (in the clear or not) outside the control and domain of the e-mail service provider - Secure notifications when relevant information is carried the notifications. - Support for the restrictions introduced by the presence of firewalls with constraints typically met in such firewall deployments (e.g. corporate guidelines that open only HTTP or HTTPS ports). - On bandwidth limited mobile networks where users pay per data volumes and/or notifications, spam may become an important issue. It can be mitigated with appropriate filters and server-side spam prevention tools. Authors Addresses Stephane H. Maes Oracle Corporation 500 Oracle Parkway M/S 4op634 Redwood Shores, CA 94065 USA Phone: +1-650-607-6296 Email: stephane.maes@oracle.com Intellectual Property Statement 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 Maes Expires - April 2005 [Page 9] October 2004 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. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Full Copyright Statement Copyright (C) The Internet Society 2004. This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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