INFO: Active Messaging and Collaboration Data Objects (CDO)

• Collaboration Data Objects (CDO), versions 1.0a, 1.1, 1.2

SUMMARY

Microsoft has released several different object models that provide Messaging functionality. These object libraries are OLE Messaging, Active Messaging, and Collaboration Data Objects (CDO). This article briefly describes each object library and how they relate to each other.

MORE INFORMATION

OLE Messaging, Active Messaging, and CDO are first, second, and third generation (respectively) of Microsoft's Messaging object library.

OLE Messaging

OLE Messaging is installed with the Exchange 4.0 client and server and Windows Messaging System (WMS). OLE Messaging is an out-of-process OLE server called Mdisp[32].exe which is available in both 16-bit and 32-bit builds. OLE Messaging is now called CDO 1.0.

Active Messaging

Active Messaging is installed with the Exchange 5.0 client and server. Active Messaging is an in-process OLE server called Olemsg[32].dll, which is available in both 16-bit and 32-bit builds. There were a few feature enhancements in Active Messaging, but the core functionality of the library remains mostly unaltered. Active Messaging is now called CDO 1.1.

CDO 1.1 is available for free download from the Microsoft website as documented in the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q171440
   TITLE     : Where to Acquire the Active Messaging Library

Collaboration Data Objects (CDO)

CDO version 1.2 is installed with Exchange Server 5.5. The object library consists of the in-process OLE servers called Cdo.dll.

CDO is Microsoft's first Messaging offering specifically targeted at satisfying the increasing developer community request for more richly featured inter-application collaboration. Some of the added functionality over CDO 1.1 includes support for scheduling meetings and appointments. More detailed information on the feature set of CDO 1.2 can be found in the CDO online documentation.

Collaboration Data Objects for NTS (CDONTS)

CDONTS is a Simple Mail Transfer Protocol (SMTP) specific OLE server that is specifically designed to provide Messaging functionality to Web-based applications. The object library consists of the in-process OLE server called Cdonts.dll. For more information on CDONTS, please see the product documentation.

REFERENCES

Exchange Server, 5.5; search on: "CDO" and "CDONTS" CDO Help File: CDO.HLP (for both CDO and CDONTS)