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Migrating from the Exchange 2000 Sample Gateway to Exchange 2007

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Topic Last Modified: 2007-09-24

By Ray Dixon, Programming Writer

Microsoft Exchange Server 2007 does not support the Exchange 2000 Sample Gateway sample application. In this article, I will explain how to implement your own Foreign connector to replace the basic functionality of a gateway that is based on the Exchange 2000 Sample Gateway. This article does not cover reporting, error handling, or other advanced features of the Exchange 2000 Sample Gateway.

Primary Functions of a Gateway

Gateways perform the following three basic functions:

  • Message transfer
  • Address mapping
  • Message content translation

A gateway must transfer messages to and from a foreign messaging system and an Exchange system. The address mapping and message content translation functions facilitate the transfer of messages between the systems.

The gateway converts each recipient address from the format of the originating system to the format of the receiving system. For example, if the message is coming from a foreign system that uses an X.400 address, the gateway must map each X.400 recipient address to a Simple Mail Transfer Protocol (SMTP) address in the Exchange system. Similarly, if the message is going the other direction, from the Exchange system to the foreign messaging system, the gateway must map the Exchange SMTP address for each recipient to the corresponding X.400 address in the foreign system.

The gateway also converts the contents of each message from the content format that is supported by the foreign system to a format that Exchange understands, and converts message contents from the content formats that are supported by Exchange to the format that the foreign system supports.

Exchange 2007 and the Exchange 2000 Sample Gateway

The following features that are required for the Exchange 2000 Sample Gateway are not included in Exchange 2007:

  • X.400 message transfer agent (MTA)
  • Routing Groups
  • Link State Routing
  • Routing Objects
  • Proxy Address Generators

For more information about features that are deprecated and deemphasized in Exchange 2007, see Discontinued Features and De-Emphasized Functionality.

Exchange 2007 does not provide direct migration paths for all the features that the Exchange 2000 Sample Gateway requires. You can, however, use the following features of Exchange 2007 to achieve the same results:

  • Foreign connector
  • Replay directory
  • Content converters
  • Transport agents

Foreign Connector

To transfer messages from Exchange 2007 to a foreign messaging system, you must create a Foreign connector for your gateway on an Exchange server that has the Hub Transport server role installed. When you create the Foreign connector, you define a Drop directory that your gateway will monitor for new messages. The gateway will process messages in the Drop directory of the Foreign connector as incoming messages from Exchange 2007 to the foreign system. For more information, see How to Create a New Foreign Connector.

Replay Directory

The Exchange 2007 Replay directory transfers messages from the foreign system to Exchange 2007. You can implement the gateway so that it puts messages from the foreign system in the Replay directory. Exchange 2007 processes each message in the Replay directory. For more information, see How to Configure the Replay Directory.

Content Converters

The content conversion features that are provided in the Microsoft .NET Framework Extensions for Exchange 2007 convert the contents of messages that are transferred between Exchange 2007 and the foreign system. The Encoders, MIME, TexConverters, and TNEF namespaces provide classes, methods, and properties that enable you to convert message content between many different formats. For information about these namespaces, see.NET Framework Extensions for Exchange 2007.

Transport Agents

Transport agents perform content conversion and address mapping. You will need two transport agents: one for outgoing messages and one for incoming messages. The outgoing transport agent acts on messages that are sent to the Foreign connector. The outgoing transport agent must perform content conversion and address mapping on each message that is destined for the foreign system.

The incoming transport agent acts on messages that are received from the Replay directory. The incoming transport agent must examine each message to determine whether it came from the foreign system, and perform content conversion and address mapping so that Exchange 2007 can then correctly route the message.

For more information about Exchange 2007 transport agents, see Transport Agents.

Migrating Your Gateway to Exchange 2007

The following procedures list the steps that are required in order to provide Exchange 2000 Sample Gateway functionality in an Exchange 2007 system.

To send messages from Exchange 2007 to the foreign system

  1. Create and configure a Foreign connector to which Exchange 2007 will deliver messages that are destined for the foreign system.

  2. Implement and install a Transport agent that acts on messages that are destined for the Foreign connector and performs address mapping and content conversion.

  3. Configure the foreign system to read and act on messages that are delivered to the directory that you specified when you created the Foreign connector.

To send messages from the foreign system to Exchange 2007

  1. Configure the Replay directory on a Hub Transport server so that the Replay directory is available to the foreign system.

  2. Implement or configure the foreign system so that it puts outgoing (from the foreign system) messages in the Replay directory.

  3. Implement and install a transport agent that acts on messages that are received from the foreign system in the Replay directory. Implement this agent so that it performs address mapping and content conversion from the foreign system to formats that Exchange 2007 supports (for example, SMTP for addressing and MIME for content).

Conclusion

Although there is no direct route to porting the Exchange 2000 Sample Gateway to Exchange 2007, you can achieve the same functionality by taking advantage of Exchange 2007 features. You do have to implement most of the conversion logic yourself. However, you get to implement that logic by using the.NET Framework, and the result will not require extensions to the Active Directory directory service.