In 2000 Barnes & Noble asked us to help design and implement a back office email system that would be used to notify internal staff of various events occurring within the ordering process. I developed the service using component architecture with the intent of reuse for multiple developers.
By giving real-time notifications to staff they were able to react to ordering events quicker increasing customer satisfaction.
This system was developed as a clustered service on Windows NT 5.0 using SQL Server 6.5 as the back-end. The service received messages off of an MSMQ message queue, formatted the emails, then sent them out via SMTP through Microsoft Exchange.
The service itself was done in such a way as to allow other developers to easily create their own services based upon a set of base classes and interfaces. A developer needed only to develop a COM component and pass in the identifier to the service on the command line. The queuing logic and transactions were all orchestrated from within the service itself so developers didn’t need to understand the nuances of MSMQ, transaction boundaries, etc.