Improvements in Exchange Server 2003
Exchange 2003 provides improved functionality in the following areas:
Support for Volume Shadow Copy service
Support for Outlook 2003 Cached Exchange Mode
Outlook Web Access for Exchange 2003
Mobile Device Support for Exchange 2003
Some of the improvements in these areas depend on whether you are running Windows Server 2003 or Outlook 2003. The following sections discuss these improvements and their dependencies.
In Exchange 2000, routing improvements over Exchange 5.5 helped you to move away from hub-and-spoke routing architectures. For example, you may have had to establish a hub-and-spoke routing architecture for Exchange 5.5 to support hard-wired routing paths. To accomplish this, you probably deployed a number of servers dedicated to message routing in the hub site.
Link state routing introduced in Exchange 2000 made it possible for sending servers to determine the best routing path by the state of the link. This change enabled a move toward peer-to-peer networks between routing groups because messages from any routing group can find a direct route to the receiving group over your network backbone.
Exchange 2003 further improves upon the link state routing features of Exchange 2000 by reducing the amount of link state traffic in two ways.
Performance is improved over what are commonly known as oscillating links, or links that are intermittently available and unavailable. Exchange 2003 reduces link state traffic by attempting to determine if the connector is oscillating. If there are multiple conflicting state changes in the link state queue for a connector in a given interval, the connector is considered an oscillating link and its link state remains up (in service or available for that period). Leaving an oscillating connector up rather than continually changing the link state reduces the amount of link state traffic that is replicated between servers.
Performance is improved in the case of a site to which there is only one route. In this case, Exchange 2003 reduces link state traffic by determining that no alternate path exists and suppressing the link state information. If no alternate path exists for a link, the link state is always marked as up (in service). Exchange lets mail queue for delivery and sends it when the route becomes available.
Both of these changes enhance performance because they reduce the propagation of link state information.
Volume Shadow Copy Service
One of the practical limits to the number of users supported on a single server is the time it takes to back up the mail storage. To significantly reduce this limit, you need the ability to quickly back up and restore your mailbox stores and public folder stores. Exchange 2003 works with the Volume Shadow Copy service in Windows Server 2003 to help you quickly create backups of Exchange data at a specific point in time.
The Volume Shadow Copy service backup method solves several problems with previous backup methods. When an Exchange database is connected, e-mail transactions can continue to occur at any time. If you try to make a quick backup of the data at a particular point in time (a shadow copy), e-mail transactions may still occur while the backup is progressing. As a result, when the backup finishes, it may contain an inconsistent copy of the data. In addition, because it is recommended that you store Exchange database files (.edb files), transaction log files, and Multipurpose Internet Mail Extensions (MIME) content (.stm files) on separate volumes, data may be inconsistent. For example, if you make a shadow copy of the data undergoing a change, and it has not yet been written to the log file, the files do not match.
Without Volume Shadow Copy service, the way to work around this problem is to conduct backups while the database is offline, which means that backups must be performed during downtime. In other words, Exchange has to be shut down so you can perform a consistent backup. But this approach poses scheduling problems and negates any benefit of shadow copy backups. This approach also makes it difficult to complete backups because of the increasing demand for systems to be available 24 hours a day, 7 days a week.
Volume Shadow Copy service, however, creates a consistent point-in-time shadow copy of data while the system is online. After receiving a backup request, Volume Shadow Copy service notifies Exchange services that a backup is about to occur. Exchange then prepares for the backup by cleaning up on-disk structures and flushing caches and log files.
Support for Outlook 2003 Cached Exchange Mode
Exchange 2003 supports Outlook 2003 Cached Exchange Mode, which gives users access to Exchange information from a local cache in the form of an .ost file. Exchange ensures that the mailbox on the server and the .ost file on the client computer remain synchronized as long as the network connection is available. If the network connection is intermittent or is lost entirely, the user can continue to work by accessing e-mail data from the information stored in the local .ost file. Requests for updates from the client computer to the Exchange server are eliminated, so Outlook 2003 users will no longer see the message indicating that data is being requested from the Exchange server during periods of intermittent or no connectivity. The elimination of update requests from the client computer also results in less data traffic from the client computer to the server.
For more information about Cached Exchange Mode, see "Improvements in Outlook 2003."
Outlook Web Access 2003 Improvements
The new version of Outlook Web Access in Exchange Server 2003 contains improvements such as forms based authentication, rules, spell checking, and the ability to send and receive digitally signed and encrypted e-mail messages. The user interface has also been significantly redesigned to provide a user experience similar to that provided with Outlook 2003, including a right-hand preview pane and improved navigation pane.
Outlook Web Access for Exchange 2003 has the ability to perform faster, especially over slow connections, and therefore will be far more responsive to user interactions.
The following list briefly describes the significant new features for Outlook Web Access for Exchange 2003:
Bytes over the wire The speed of Outlook Web Access has been improved by reducing the amount of information that must travel from the server to the browser. Fewer bytes are sent over the wire from server to browser. However, be aware that the logon process involves more bytes than the logon process in Outlook 2003.
Compression support Administrators can configure compression support for Outlook Web Access and provide a performance improvement of nearly 50 percent for most actions on slow network connections. User performance for Outlook Web Access has been optimized for slow network connections with support for data compression. Outlook Web Access compression works by compressing either static or dynamic or both types of web pages, depending on the compression setting you are using. With data compression, your users can see performance increases of up to 50 percent on slower network connections such as traditional dial-up access. You can enable compression from Exchange System Manager.
**Forms Based Authentication **You can enable a new logon page for Outlook Web Access that will store the user's name and password in a cookie instead of in the browser. When a user closes his or her browser, the cookie is cleared. Additionally, after a period of inactivity, the cookie is cleared automatically. The new logon page requires users to enter their domain, user name, and password, or their full user principal name (UPN) e-mail address and password. To enable the Outlook Web Access logon page, you must enable forms-based authentication on the server.
The improvements in features, functionality, and performance may affect decisions about how your users should primarily access their Exchange information. For example, in remote sites, Outlook Web Access may be the primary choice, which is a consideration when planning WAN connections and server placement.
Mobile Device Support for Exchange Server 2003
Exchange 2003 provides mobile device support by providing two applications that can support both Microsoft Windows Mobile™ 2003 powered devices and other mobile devices. You can deploy mobile device support to Exchange to provide your users the ability to access their Exchange information from a variety of mobile devices. You deploy your Exchange server to use Exchange ActiveSync® and Outlook Mobile Access in the same way that you deploy your Exchange server to use Outlook Web Access 2003. By default, when you install Exchange, all of your users are enabled for synchronization and for browse access with Outlook Mobile Access.
Synchronization Synchronizing a device to an Exchange server gives your users access to their Exchange information without their being constantly connected to a mobile network. Users can use their mobile carrier connection to synchronize their Exchange information to their Pocket PC 2003 Phone Edition or Smartphone device and then access this information while offline.
Up-to-Date Notification Up-to-date notifications are automatically generated SMS messages that are sent to a user's Windows Mobile device when a new e-mail message, calendar appointment, or contact arrives in the user's mailbox. Users must configure their devices to receive up-to-date notifications.
Mobile browse access Exchange Server 2003 includes the Outlook Mobile Access application, which makes it possible for users to access their Exchange server to view e-mail messages, contacts, calendar, and tasks with mobile devices.