Data Binding and Asynchronous Business Objects

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Data Binding and Asynchronous Business Objects
Or... AJAX for Windows Forms

• Paul Stovell
• www.paulstovell.net

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Before we begin

• Data Binding

! DataSets
Bad ?
Good ?
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Trial Balance

• Personal Project
• Reason for this presentation
• Designed to teach basic double-entry accounting
  to high school and university students.
• Uses multiple data providers Access, XML, SQL
  Server
• Windows Presentation Foundation UI
• Available at www.paulstovell.net

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Principals
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ErrorProvider The most abused component?

• Detects and displays errors from data sources
• Data Sources should implement
• IDataErrorInfo (System.ComponentModel)
• INotifyPropertyChanged (System.ComponentModel)

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The Problem

• Lots of accounts
• Each account shows an Opening and Closing
  Balance, which must be calculated

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Step 1

• Using a BackgroundWorker to calculate the Opening
  and Closing balance
• Drawbacks
• Duplicated code.
• Still have to wait for accounts to load.

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Step 2

• Anonymous delegates and inheritance to reduce
  code duplication.
• Drawbacks
• Duplicated code.
• Still have to wait for accounts to load.

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Step 3

• Custom collection class for lazy loading.
• Drawbacks
• Duplicated code.
• Still have to wait for accounts to load.
• w0ot!!

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Extras

• Custom DataGridView Column/Cell
• Filtering

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Principals
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Conclusion

• INotifyPropertyChanged
• ErrorProvider and IDataErrorInfo
• BackgroundWorker
• Easy peasy lemon-squeezie!
• Suggested uses
• Complex database queries
• Legacy systems/licensing problems
• Web services/remoting
• Calling Java systems ?
• Data Binding rocks!

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Links and Resources

• Brian Noyes
• .NET Rocks! - Brian Noyes on Data Binding in .NET
  2.0http//shrinkster.com/gjq (G J Q)
• Amazon Data Binding with Windows Forms
  2.0http//shrinkster.com/gjr (G J R)
• Delegates and Business Objects (more
  ErrorProvider information)
• http//shrinkster.com/gpk (G P K)
• SSW Rules to Better Windows Forms
• http//shrinkster.com/gpl (G P L)
• Trial Balance
• http//shrinkster.com/gpm (G P M)
• Interfaces Related to Data Binding
• http//shrinkster.com/gpn (G P N)