Chapter 8 -- Business Service Layer Technologies

Chapter 8

About This Chapter

Business objects tend to encapsulate corporate business rules and application-specific operations. Once the components are designed as described in Chapters 2 and 6, implementing them should be a fairly mechanical coding exercise. However, some specific issues may need to be addressed during the design process to ensure that business objects work well, particularly within the Microsoft Transaction Server (MTS) environment. This chapter focuses on such issues as:

• Using an object context to manage state.
• Using explicitly defined interfaces when possible.
• Composing functionality.
• Maintaining state across transaction boundaries.
• Propagating errors.
• Programmatically controlling security.

These issues are more common to business objects than to data objects.

In addition, this chapter examines using the Microsoft Component Object Model (COM) within the business service of an application's physical design. Business rules and processes are first integrated into a physical design that effectively uses COM technologies. Component-specific network technologies and environmental impacts are then integrated into the physical design.

The majority of this chapter's information is based on our own experience, together with the following sources:

• Mary Kirtland's Designing Component-Based Solutions
• Speeches and white papers from the Microsoft COM group

Upon completion, you will be able to:

• Understand the Microsoft Component Object Model (COM).
• Analyze the role of COM in logical and physical design models.
• Understand COM capabilities in transactional processing using MTS.
• Understand how objects are used throughout a network and enterprise.
• Analyze environmental impacts that affect the business service layer to derive an optimal physical design.