Layered Architecture Issues

The following links are views into sections of the Duwamish Books articles. For a full list of the articles, look under each individual phase in the Contents pane of this Help file.

These logical layers, which can be found in most business applications, are referenced throughout the Duwamish sample. For an introduction, see our introduction to application layers.

Presentation layer

• Visual Basic forms that present business objects (Phase 1)
  
  
• Preparation of a purchase order (Phase 1)
  
  
• Three browser client types in Phase 4
  
  
• And workflow (Phase 4)

Workflow layer

• Preparation of a purchase order (Phase 1)
  
  
• Preparation of a sale (Phase 1)
  
  
• Workflow (client-side business rules) name clarified
  
  
• Workflow as a consumer of BLL services in client applications (Phase 3)
  
  
• Workflow design in Phase 4
  
  
• And presentation (Phase 4)
  
  
• Caching HTML and XML (Phase 4)
  
  
• The Phase 4 Cache component API
  
  
• The Phase 4 Workflow component API

Business logic layer

• InsertSale transaction code (Phase 1)
  
  
• InsertSale using updated DAL (Phase 2)
  
  
• Business Logic Layer (BLL) component justified
  
  
• Business logic layer (server-side business rules) defined (Phase 3)
  
  
• Use of BLL programming model
  
  
• BLL code distributed between COM component and SQL database
  
  
• Visual C++ BLL design
  
  
• Visual C++ ATL wizard project settings for BLL
  
  
• Stored procedure names coupled to business logic code
  
  
• Visual C++ BLL reusable core processing
  
  
• Visual C++ BLL parameters and commands
  
  
• Visual C++ BLL class hierarchy
  
  
• Implementing ISupportErrorInfo in the Visual C++ BLL
  
  
• Calling own interface method in the Visual C++ BLL
  
  
• Increased robustness in the Visual C++ BLL
  
  
• Executing SQL Server 6.5 stored procedures in BLL
  
  
• Phase 4 compatibility with legacy clients
  
  
• The Phase 4 Business Logic Layer API

Data access layer

• Providing cached data records with Visual Basic object collections (Phase 1)
  
  
• InsertSale transaction code (Phase 1)
  
  
• InsertSale using updated DAL (Phase 2)
  
  
• Data Access Layer (DAL) component justified (Phase 2)
  
  
• ADO disconnected recordsets as data containers (Phase 2)
  
  
• Transaction control (Phase 2)
  
  
• ODBC connection management (Phase 2)
  
  
• ODBC connection pooling and MTS
  
  
• DAL API (Phase 2)
  
  
• DAL API changes (Phase 3 )
  
  
• DAL API changes (Phase 3.5)