CDOSys

Collaboration Data Objects (CDO) for Microsoft® Windows® 2000 (Cdosys.dll), which implements the 2.0 version of the Collaboration Data Objects API specification, is a Component Object Model (COM) component designed to simplify writing programs that create or manipulate Internet messages. CDO for Windows 2000 is one in a suite of collaborative COM components referred to collectively as CDO. CDO for Windows 2000 is an integral part of the Windows 2000 series of operating systems.

CDO for Windows 2000 provides COM classes that expose dual interfaces that you can use in applications written in languages supporting COM and Automation, such as Microsoft Visual Basic®, Microsoft Visual C++®, Microsoft Visual J++®, and scripting languages such as Visual Basic, Scripting Edition. It is designed for creating both client and server applications for computers running Windows 2000, and supports creating and managing messages formatted and sent using Internet standards such as the Multipurpose Internet Mail Extensions (MIME) standard. The CDO for Windows 2000 component supports sending messages using both the SMTP and NNTP protocols, as well as through a local SMTP/NNTP service pickup directory.

Upgrading to Microsoft Exchange 2000 Server

When you upgrade a computer running Microsoft® Windows® 2000 with Microsoft® Exchange® 2000 server, a new COM component, Microsoft CDO for Exchange 2000 replaces the Microsoft CDO for Windows 2000 component. The CDO for Windows 2000 component is a proper subset of the functionality offered by CDO for Exchange 2000, so all applications, including transport event sinks, will continue to function properly. When Microsoft Exchange 2000 is installed, the CDO for Windows 2000 component is unregistered from the system and COM runtime.

Both components share a common set of GUID values, interface definitions, enumerations, module constants and so on. Applications written in Microsoft Visual Basic, Microsoft J++, or Microsoft Visual C++ do not need to be re-compiled. The application will simply load the new CDO for Exchange 2000 component at runtime.

You need to redesign any application using CDO for Windows 2000 if it uses the drop directory provided by the SMTP or NNTP services on the machine. When Microsoft Exchange 2000 is installed, the Exchange Web Store becomes the drop location for messages and NNTP posted files on the server; the SMTP and NNTP services no longer drop messages to the SMTP/NNTP drop directory.

CDO and ADO

CDO for Windows 2000 integrates with the Microsoft® ActiveX® Data Objects (ADO) Version 2.5 component to present a consistent mechanism for managing data that comprises a message. Additionally, the CDO for Windows 2000 Message and BodyPart COM classes expose the OLE DB 2.5 interfaces required by the TRow CoType. C++ programmers can access the data using these OLE DB 2.5 interfaces. These CDO objects are polymorphs of the standard OLE DB Row object and the ADO Record object.