Mobile Gateway Architecture for Service Providers
The Mobile Gateway 4.0 provides push email and synchronization to consumers and business users on any handset without requiring additional client software.
The multiprotocol gateway combines industry-standard LEMONADE and OMA EMN push email with Email to SMS, WAP Push, and Email to MMS to provide the best possible user experience from high-end smartphones to entry-level devices. Address book and calendar synchronization using SyncML completes the service offering for business users, as well as consumers.
The architecture of Synchronica Mobile Gateway is based entirely on open industry standards and is designed to operate a highly scalable, fault-tolerant environment tightly integrated with the existing infrastructure. It includes support for automatic failover and load balancing, providing near-linear scalability and has been proven in carrier-grade deployments.
Synchronica Mobile Gateway Overview
Synchronica Mobile Gateway provides synchronization of email, contacts, calendar, notes, and tasks between corporate or ISP back-ends and OMA DS-, IMAP-, and Push IMAP-enabled smartphones, as well as mass market mobile handsets, providing both business users and consumers with access to email and PIM information through their handset.
Business customers using Microsoft Exchange, IBM Lotus Domino, or Sun Java System Communication Suite can receive mobile email and synchronize calendar and contact data over the air, staying up to date with critical business information at all times.
Consumer and professional consumers can receive and send ISP email to and from friends and colleagues, using their mobile phone.
The solution is based on the winning combination of the dominant industry standards SyncML (OMA DS), Push IMAP (LEMONADE), and OMA EMN (push email notification). While SyncML is ideal for synchronization of calendar and contacts, IMAP IDLE and OMA EMN are the best options for delivering push email to mass market devices.
Thanks to its industry-standard approach, Mobile Gateway does not require any additional client software to be installed on the device. While other solutions are limited to the small segment of smartphones, Mobile Gateway is compatible with hundreds of SyncML-/IMAP-enabled devices from all leading manufacturers.
Further expanding its reach, Synchronica supplies clients for non-SyncML-supported handsets including Windows Mobile and Palm OS.
Main Components Overview
The following section covers the high-level overview of the architecture of Synchronica Mobile Gateway.
Synchronica Mobile Gateway architecture overview
Synchronization Engine
The synchronization engine manages the synchronization process of calendar, tasks, contacts, and notes data between the back-end PIM store and the mobile handset, using the Open Mobile Alliance Data Synchronization (OMA DS) protocol.
IMAP / POP3 and SMTP Engine
The IMAP / POP3 and SMTP engine manages the email receipt and delivery processes between the back-end email server and the mobile handset, using the IMAP / POP3 and SMTP protocols.
WAP Interface
The WAP interface manages the email receipt and delivery processes between the back-end email server and the mobile handset, using the WAP 1.0 and WAP 2.0 protocols.
SMS / MMS Interface
The SMS / MMS interface manages the connection between the notification and client provisioning services and the mobile network for delivery of notification and provisioning messages to the mobile handset. The interface uses the SMPP protocol to connect to the network SMSC.
User Interface
The user interface elements allow the end user and administration users to access the account and service settings via separate HTML interfaces.
Transcoding Engine
The transcoding engine converts and resizes email attachments so that mobile phones can display them properly. Various document formats, such as Word and PDF, as well as images, are transformed to fit best the capabilities of the given mobile device.
Email to Messaging Service (Email to MS) Engine
The email-to-MS engine converts regular email messages into MMS or SMS formats so that the email messages can be delivered to even the simplest handsets. The conversion depends on device capabilities to ensure the best possible user experience.
Content Model
The content model defines the internal representation of each content type and maps it to JCR nodes and properties in the Universal Data Connector (UDC).
Dynamic Device Configuration
Although Synchronica Mobile Gateway is based on the IMAP / SMTP and OMA DS industry standards, individual device implementations of the standards vary. Dynamic device configuration allows different device implementations to be managed correctly within Mobile Gateway.
To support the regular launch of new devices and platform versions in the market, Mobile Gateway operates an automatic update process for handsets and device configurations, allowing new handsets to be added to the service simply and easily without upgrades to the core Mobile Gateway server.
Observation and Notification
This section covers how changes on both front- and back-ends are detected and handled, how Synchronica Mobile Gateway synchronizes emails and PIM information.
Observation
The observation engine monitors the back-end PIM and email store for new events and triggers a notification when a new event is identified.
As standard, the observation engine utilizes a scheduled polling mechanism to identify new events. However, it is also capable of accepting notification of new events from the PIM or email back-end store.
Notification
The notification engine is triggered by a new event being identified by the observation engine. This then notifies the mobile device of the new event, using the following protocols:
- Open Mobile Alliance Data Synchronization Server Alert (OMA DS)
An SMS-based notification protocol for PIM content which triggers the mobile handset OMA DS client to initiate a synchronization session with the server - Open Mobile Alliance Email Notification (OMA EMN)
An SMS-based notification protocol for email content which triggers the mobile handset IMAP email client to initiate a connection to the server - IMAP IDLE
A constant connection between the Mobile Gateway server and the mobile handset, allowing notification of new events to be transmitted to the mobile handset and triggering the mobile handset IMAP client to initiate a connection to the server - WAP Push
A WAP Push message is sent to the mobile phone. The message contains a link that opens the email message in the phone's WAP browser. This enables feature phones to have the best user experience with regular email messages - Email to MMS
Email messages are automatically converted into MMS format by the email-to-MS engine and are delivered to MMS-capable mobile handsets. This way, feature phones can also display pictures in email messages - Email to SMS
Email messages are automatically converted into SMS format by the email-to-MS engine and are delivered to mobile phones. Even the simplest and feature-poor mobile phones (including legacy 2G mobile devices) that have a screen can display emails transformed into SMS messages
Universal Data Connector and Back-Ends
This section describes what back-ends are supported by Synchronica Mobile Gateway and how these back-ends are integrated into the architecture.
Universal Data Connector
The Universal Data Connector provides a Java Content Repository-based (JCR) interface which allows back-ends to be plugged into the Mobile Gateway service.
The JCR-based API for back-ends enables easy development of connectors for proprietary email and PIM services.
Back-Ends
Synchronica Mobile Gateway ships with a number of standard connectors allowing connectivity into the following standard email and PIM service back-ends:
- Microsoft Exchange 2003 and 2007
- Sun Java Communications Suite 4 and 5
- IBM Lotus Domino 6 and 7
- Google (email, calendar, and contacts)
- Hotmail / Windows Live (email and contacts)
- Web feeds (RSS)
- Any IMAP back-end
- Any POP3 back-end
Client Provisioning
The client provisioning module compiles and submits OMA DS, IMAP, POP3, SMTP, APN, WAP, and MMS settings to the SMS interface for delivery to the mobile handset. This enables easy, automated configuration of the mobile handset, significantly reducing customer support calls relating to errors in manual configuration.
Implementation Overview and Scenarios
Synchronica Mobile Gateway features a unique zero footprint architecture which results in a faster take-up rate for mobile email and synchronization than competing solutions. Unlike those other solutions, Mobile Gateway requires no installation of adapters behind the corporate firewall - users simply register at a web site and instantly synchronize their corporate data with mobile devices.
Synchronica Mobile Gateway is primarily designed to be deployed in a carrier network or service provider environment. However, it can be installed behind a company firewall and connected directly to the company groupware server.
Operator Implementation
Synchronica Mobile Gateway operator deployment overview
Security
Synchronica takes all efforts to ensure a secure operation of the Synchronica Mobile Gateway. For authentication and encryption, Synchronica Mobile Gateway conforms to the industry standards as defined by OMA DS and IMAP standards and supports SSL and TLS for data encryption and MD5 for encrypted authentication.
All traffic flowing through the public internet is encrypted with SSL, ensuring user data is at no time exposed to prying eyes.
For security reasons, the service does not duplicate the user's data to a local database, but stores only metadata required during the synchronization process. In addition, Synchronica Mobile Gateway creates a separate back-end connection for every user with the user's credentials, therefore operating under the permissions assigned to that user.
Scalability and Resilience
Synchronica Mobile Gateway has been designed to meet carrier-grade requirements for performance, scalability, and stability. It has demonstrated to support thousands of concurrent sessions per server CPU and provides near-linear scalability in a load-balanced environment. Support for clustered deployments and automatic failover ensures continuous operation of the system in case of a hardware or software failure (see the Synchronica Mobile Gateway Load Test Report).
IMAP / POP3 and SMTP Engine
Synchronica Mobile Gateway supports both the IMAP / SMTP standards, as well as the OMA DS standard for email communication between a back-end and a mobile handset.
IMAP / POP3 / SMTP is by far the most available email protocol on mobile handsets, with OMA DS email being supported on only very few handsets. In addition, the majority of push email standards are being developed based on handsets using IMAP clients, for example, IMAP IDLE and OMA EMN.
Mobile Gateway is therefore able to offer a very strong combination of mobile email and PIM synchronization by offering access to both IMAP / POP3 / SMTP and OMA DS for communication of the relevant data types with the mobile handset. By offering a fully functional IMAP engine, Mobile Gateway service is able to address a very wide range of mobile handsets in the market.
Synchronica Mobile Gateway IMAP and SMTP engine overview
IMAP / POP3 Gateway
Towards the mobile device, the IMAP / POP gateway appears to be a fully functional IMAP / POP3 server. When a connection arrives, the gateway performs the necessary authentication, Secure Sockets Layer (SSL) negotiation. It then translates the folder and message operations into the appropriate UDC commands which, using the appropriate connector, allows the mobile device to retrieve and exchange messages with their configured back-end email store
New Email Notification
Synchronica Mobile Gateway provides support for both available industry standards for push email notification.
IMAP IDLE
The IMAP IDLE mechanism is part of the LEMONADE profile (License to Enhanced Mobile Oriented and Diverse Endpoints) and is an extension of the of IMAP protocol, enabling the server to notify the client of new messages. The standard provides a constant connection between the client and server which allows the server to notify the client of new email events. The IDLE command works like a keep-alive message to ensure the client stays connected. The server responds to the IDLE command when there is a new message to indicate to the client that there is new data available.
The bandwidth usage of the IDLE command is very small, making it very efficient.
OMA EMN
The OMA EMN (Open Mobile Alliance Email Notification) standard is a binary SMS-based protocol which allows the server to send an SMS notification of a new email. The supporting email client will silently accept the binary message and initiate an IMAP connection to the server to collect the email. Once collected, the device will alert the user.
Although the network usage for IMAP IDLE is very low, the battery life and GPRS network limitations may affect the decision on which notification strategy to use.
SMTP Gateway
While the IMAP gateway enables users to receive emails on their phone, the SMTP Gateway enables them to send emails from their devices via Mobile Gateway. Towards the device, the SMTP gateway is completely transparent and appears to be a standard RFC 2821 SMTP Server.
When an SMTP connection arrives, the SMTP gateway performs the authentication and SSL negotiation, followed by the necessary operations to allow the connected client to transmit new messages for delivery. Next, the SMTP gateway passes these new messages to the UDC layer which relays the messages to the configured back-end messaging server.
After sending, the message appears in the folder Sent Items on the user's messaging server as if it was sent from the user's desktop PC.
Note: The capability of appending messages to a mail server's sent items folder depends on the functionality being supported by the mail server. Standard POP3 and SMTP mail servers, for example, do not support this functionality.
Mobile Gateway Synchronization Engine
There are two ways to initiate the synchronization process. The user can trigger it manually by selecting the appropriate menu item in the device's synchronization client, or the server can initiate the process (push). As defined by the Open Mobile Alliance (OMA), for DS Push, the server sends a notification message to the device, causing the client to connect back to the server which then transmits the changes to the device. To the end-user, this process is completely transparent.
During the synchronization session, Mobile Gateway receives either an XML byte array or the compressed format WAP Binary XML (WBXML) which it then converts to XML. The XML or WBXML document is interpreted as a SyncML request that is part of the SyncML session. The sync core takes the SyncML requests and sends the client modifications to the back-end via the Universal Data Connector and collects any server modifications. After matching all the modifications (the main activity of synchronization), the server modifications are sent back to the client.
Synchronica Mobile Gateway synchronization engine overview
Once the synchronization process has started, there are two types of synchronization. Fast sync is the normal type; the synchronization only updates items modified since the previous synchronization. Slow sync is when all items are sent; this is normally only required for the initial synchronization session.
Client Mapping / Conflict Resolution (Slow Sync)
During a slow sync, the client sends all its data to Synchronica Mobile Gateway, and the server sends all its data to the device. The server maintains a client mapping database, associating each client data entry with its corresponding server entry.
Slow Synchronization overview
Client Mapping / Conflict Resolution (Fast Sync)
Fast sync relies on the client / server mapping in the database which contains the client and server keys. Only the modifications are compared and synchronized between server and client, resulting in short synchronization sessions. A conflict is detected when the same item is modified on the client and the server side. In automatic conflict resolution mode, the server modification wins and is sent to the client, overriding the client changes.
Fast Synchronizaton overview
Synchronica Mobile Gateway Clients
While a large percentage of mobile handsets offer built-in synchronization and email clients, not all manufacturers have committed to OMA DS support. Synchronica offers a complete and homogenized end-to-end solution by providing support for the most important device platforms that are not shipping with built-in synchronization clients:
- Palm OS
- Microsoft Windows Mobile
In addition, clients are available for Windows, (Outlook and Outlook Express / Windows Mail) and Mac OS desktop platforms to allow the user case where users do not have a direct connection to their server PIM stores and require the PIM data on their desktop PCs.
Synchronica Mobile Gateway clients overview
Palm OS - Synchronica offers a synchronization client for the Palm OS-based PDAs and smartphones, enabling synchronization of emails, contacts, appointments, and tasks via Synchronica Mobile Gateway.
Windows Mobile - Synchronica offers a synchronization client for Windows Mobile for Pocket PC and Windows Mobile for Smartphones to enable wireless synchronization of emails, contacts, appointments, and tasks including support for Windows Mobile 2003, 2005, and 2006.
