Information Management

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Collaboration Data Objects (CDO) is a technology for implementing messaging capabilities. CDO is an object library that exposes the interfaces of the Messaging Application Programming Interface (MAPI), but instead of requiring the C/C++ language as MAPI does, CDO can be programmed using any development tool that creates COM objects, such as Microsoft Active Sever Pages (ASP), Microsoft Visual Basic, and Microsoft Visual C++.

CDO has had several incarnations, and previous versions shipped with different names and functionality. For example, in Microsoft Exchange Server version 4.0, CDO was named OLE Messaging, and in Exchange Server 5.0, CDO was named Active Messaging. With the advent of Exchange Server version 5.5 and Microsoft Outlook 98, the library was renamed Collaboration Data Objects to better describe its services—CDO provides much more than messaging functionality. Even though the names have changed from version to version, any older applications using a previous version of CDO are compatible with the latest version of the library. (At the time this book goes to press, the latest released version of CDO is version 1.21.)

You install CDO by installing either Microsoft Outlook 98 on your machine or Microsoft Outlook Web Access on your web server. CDO is actually divided into two DLLs: CDO.dll and CDOHTML.dll. CDO.dll contains the core collaborative functionality of CDO, such as sending messages, accessing the directory, and viewing free/busy calendar information. CDOHTML.dll, is the CDO Rendering library. This library allows you to automatically convert information stored inside Exchange Server to HTML by using custom views, colors, and formats. The CDO Rendering library is installed when you install Outlook Web Access on your web server.

This section of the "Programming Microsoft Outlook and Microsoft Exchange Supplement" covers many of the objects in the CDO library and discusses the typically used methods and properties of these objects. For additional information on CDO, consult the CDO help file (cdo.chm) on the companion CD, as well as the MSDN Library.