This chapter begins by covering a few more important aspects of Microsoft Transaction Server (MTS). It explains how MTS extends COM security with its own role-based security model, and it shows you how to share global data among MTS objects using the shared property manager. The chapter also explains how to create Web-based applications that leverage the COM and MTS techniques that you've learned in this book. I describe the IIS/ASP architecture and show you how to create Visual Basic objects from an Active Server Pages (ASP) page. You can create ASP applications that allow Web clients to run your MTS transactions. I also show you some techniques for programming against the built-in ASP objects from inside a Visual Basic DLL.
The chapter concludes with a description of important design issues that you should consider when you build a distributed application. As you know, MTS provides a transaction processing monitor and a few other critical middle-tier services. However, you must provide many other essential pieces of middleware yourself. This chapter explains how to create a scalable event-based notification system and a middle-tier application that monitors a queue for incoming messages. It also explains how to design a system that balances the processing load for hundreds of client applications across a group of servers. You'll learn about some of the high-level design issues involved and examine some of the new services that will be available in COM+.