Reza Alirezaei

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How to build 3-tier applications in MOSS 2007
Reza Alirezaei Eidenai Innovations reza_at_devhorizo
n.com http//blogs.devhorizon.com/reza
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Session Prerequisites

• Experience with
• WSS and/or MOSS
• Web Part Development
• Some exposures to Data Access Programming
• Experience with biz and data-driven Apps
• Level 300

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Agenda

• Summary of multi-tier design
• Typed DataSets
• ObjectDataSource
• SPROC
• Demo

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• For most business applications the heart of the
  design revolves around the data and business
  tiers. There is no one design fits all , only
  trade-offs

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Multi-Tier Design

• Business applications with gt 1 tier
• Standard Design contains
• Presentation
• Business
• Data access
• Data store
• Logical Design VS Physical Design

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To layer or not to layer?

• Separation, Separation and Separation
• Increases Team Productivity
• Mix language development,
• Parallel Dev
• Reusability
• Across multiple front-ends
• DAL as a execution engine

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Interactions between BLL and DAL

• 1) BLL as pure interface
• Delegation of most of the work to DAL
• DAL is tied to the business (Reusability ?)
• Northwind.SharePoint.DAL spDataSource
• .
• public void update (Product p)
• // DAL must be aware of Product
  object
• spDataSource.UpdateProduct(p)

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• 2) DAL as an execution engine
• BLL responsible for some data storage
• Low-level interface
• BLL is tied to database schema ( watch out !)
• Northwind.SharePoint.DAL spDataSource
• .
• public void update (Product p)
• string sqlCommand
• sqlCommand .. // properly format SQL
  statement
• spDataSource.Execute(sqlCommand)

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Typed DataSet

• Very capable generic data container
• Vender Generic / Schema Specific
• Built-in functionalities like filtering, search,
  sort
• Extending DataSet using .Net 2.0s new partial
  class concept (Demo)

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• Intellisense in VS IDE
• No string literals - No Implicit assumption
• Automatic Database validation pick up
• Type safe wrapper NorthwindTDS.Products0.Name
  42 ? Compiler Error
• Automatically generated from DB schema

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ObjectDataSource

• Supports a three-tier architecture
• Uses reflection
• Exposes a number of Helper properties
• NOT a generic data access layer control
• Pre- /Post- level event handlers

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Sproc - A great way to go!

• Wraps your schema
• Layer of decoupling schema from your application
• Additional access control (Security)
• Force transactional executions
• Encapsulates complex SQL/performance boost

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Instrumentation

• System.Diagnostics.Trace
• Redirecting the trace output
• Old-School way VS dynamic approach
• A lot of work
• Other instrumentation facilities

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Topics not covered today!

• 1) Physical Design and Trade-offs
• 2) Security (Broad subject)
• Think about STRIDE
• Authentication, Authorization
• how and where to implement Security

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• 3) Validation
• Field Level validation _at_ database
• PL first level validation
• e.g. Credit Card must not contain letters
• BLL Additional validation
• e.g. Is Credit Card valid ?
• 4)Optimistic Concurrency

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