COM+ is a programming model based on Component Object Model
(COM). COM+ does not replace the COM. In fact, COM+ technology uses the COM by
extending its features to provide enterprise level services.
COM was the very first methodologies to facilitate object oriented
software implementation. It is mainly used to encapsulate business task and
logic into one business object, called COM component in the distributed
environment which can be shared and accessed by different applications.
In the real world scenario, more than one COM component work
altogether to achieve a high density task. To manage the integrity and security
among different components, COM uses another service of Microsoft, called
Microsoft Transaction Server (MTS).
In other words, COM+ is nothing but a combination of both
COM and MTS. It means COM+ = COM + MTS. COM+ was first introduced in Microsoft
Windows 2000 Server. COM+ also includes additional features like object
pooling, load balancing, component queuing, etc. These services were being
known as the COM+ Component Services. When multiple components are grouped
together it is referred to as COM+ applications.