Caveats

Topic Last Modified: 2008-09-02

This topic provides information about how the different technologies compare with regard to caveats.

Technology	Is there anything I need to be aware of?
Active Directory Services Interfaces (ADSI)
Collaboration Data Objects for Windows 2000 (CDOSYS)
CDOSYS SMTP/NNTP Event Sinks	CDOSYS event sinks do not have all the capabilities of the SMTP transport event sinks, but CDOSYS event sinks are easier to develop.
Collaboration Data Objects for Exchange 2000 Server(CDOEX)	CDOEX can only be run on a computer on which Exchange has been installed. On a computer on which Exchange is installed, CDOEX replaces CDOSYS. Exchange must be running before you can access the CDOEX-specific functionality. However, applications can use the basic CDOSYS functionality without running Exchange.
Collaboration Data Objects for Exchange Management (CDOEXM)	CDOEXM can only be run on a computer on which the Exchange 2000 or Exchange 2003 Administrative Tools have been installed. The computer that is running the CDOEXM application and the computer that is running Exchange 2000 or Exchange 2003 must be in the same Active Directory organization. Important: Because of issues with multiple-hop authentication and unexpected results observed in multithreaded runtime environments, the use of CDOEXM in Microsoft ASP.NET pages, ASP Web pages, or Web services is not supported. To create Web-based Exchange management applications that use CDOEXM functionality, we recommend wrapping CDOEXM in a Distributed Component Object Model (DCOM) package and calling that package from your application.
Collaboration Data Objects for Exchange Workflow (CDOWF)	Consider using Microsoft BizTalk Server for more complex workflow process implementations, especially those that require a more complex workflow processing, must cross organizational boundaries, or are not messaging-related.
Exchange OLE DB Provider (ExOLEDB)	The ExOLEDB provider can only be used on a computer on which Exchange is running, and only to access stores located on that computer. ExOLEDB cannot be used on Exchange front-end servers. To access remote public stores and mailbox stores, use the WebDAV protocol, MAPI, or CDO 1.2.1.
Exchange Store Event Sinks	To use script-based event sinks, the Script Host Sink COM component must be registered on the Exchange server. Doing this allows script-based event registrations on any folder by any user who already has write-permission on the folder.
Exchange Web Forms	Microsoft currently supports Exchange Web forms for use with Exchange 2000 and 2003. However, for long-term compatibility, we recommend that you render the Web forms by using standard ASP tags, instead of using the Exchange form rendering tags. Exchange Web Forms do not ship in Exchange Server 2007.
Exchange Web Services	EWS messages are sent via HTTP, and HTTPS and might be blocked by Internet firewalls.
HTTP/Web Distributed Authoring and Versioning (WebDAV)	When you are creating applications that use WebDAV to transmit sensitive information or that communicate over the Internet, we strongly recommend that the IIS virtual server use SSL/TLS encryption for increased security. Within an intranet, NTLM or Kerberos authentication of WebDAV requests can also be used for authentication, but those do not provide data encryption.
WebDAV Notifications	WebDAV notifications sent from the server to the subscribing client use UDP packets (HTPU), sent on the port specified in the subscription. Depending on your network configuration, notifications generated for subscriptions with HTTP URLs across the Internet might be blocked by the Internet firewall.
Incremental Change Synchronization (ICS)	ICS agents can only be created by using C/C++.
Lightweight Directory Access Protocol (LDAP)
Messaging Application Programming Interface (MAPI)	MAPI is a mature mechanism used to access information in Exchange, and provides some capabilities that are not available in any other API. However, MAPI does not work well outside of an intranet, maintains an open connection for the duration of the MAPI session, and can be difficult to learn.
Outlook Object Model (OOM)	To access data stored in an Exchange mailbox, Microsoft Outlook must be installed and configured on the client computer on which the application is running.
Outlook Web Access	Support and documentation for customizing Outlook Web Access and reusing Outlook Web Access components is available from Microsoft. Microsoft improves and adds features to Outlook Web Access with new releases of Exchange, and the Outlook Web Access internal workings and architecture may change without notice.
Exchange Rules	Documentation for using the Exchange Rules library, rule.dll, was contained in the Exchange Server 5.5 SDK, and is no longer available.
SMTP Event Sinks	CDOSYS event sinks do not have all the capabilities of the SMTP protocol event sinks, but may be simpler to use. Microsoft Transaction Server does not support SMTP event sinks. SMTP event sinks cannot be included in COM+ applications. Event notification filtering is not available for messages submitted by using MAPI clients when the event sink is registered on the same computer from which the message was submitted.
Windows Management Instrumentation (WMI) providers for Exchange	Be aware that complex queries over the message tracking logs can take quite a long time to process.
Exchange Backup and Restore API	The backup API is based on storage groups. Currently, only one backup per storage group is allowed at one time. There may be backups of different storage groups occurring at the same time, but only one database in a storage groups may be backed up at a time.
Exchange writer for the Windows Volume Shadow Copy Service (VSS)	VSS backups are only performed at the storage group level. VSS cannot back up individual databases. The restore of an individual database from a VSS backup is supported; however, the entire storage group must be offline during the restore. Although VSS can back up multiple Exchange storage groups at one time, only one backup can be performed at a time.