You are designing a Windows Forms application that allows users to search a product catalog and place orders.
You have the following requirements:
- Display a progress indicator while the application is searching the catalog. - Ensure that users can cancel search operations.
You need to recommend an approach that meets the requirements.
What should you recommend?

• A. Use a BackgroundWorker component to perform the search.
• B. Execute the search on the user interface thread. Provide a Cancel button to cancel the search.
• C. Implement the search as a duplex service.
• D. Implement the search as a Windows Communication Foundation (WCF) service by using the AsyncPattern property of the OperationContractattribute.

You are evaluating an existing Windows Presentation Foundation (WPF) application. The WPF application runs in a Web browser as a XAML browser application (XBAP). The WPF application runs in the Intranet zone with Full Trust. A client certificate for the WPF application has been generated.
Users are unable to access the WPF application. You locate the following message in the security log: "User has refused to grant required permissions to the application." Users state that they are clicking OK in all message boxes that appear.
You need to recommend an approach for ensuring that the WPF application runs correctly on all client computers.
Which two actions should you recommend? (Each correct answer presents part of the solution. Choose two.)

• A. Import the client certificate to the Trusted Root store.
• B. Modify the ClickOnce manifest for the WPF application to grant the appropriate permissions.
• C. Sign the ClickOnce manifest for the WPF application.
• D. Use the Code Access Security Policy Tool to grant the appropriate permissions.

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You are designing a distributed Windows Presentation Foundation (WPF) application. You have the following requirements:
Ensure that all errors are logged in a central location.
Ensure that the WPF application logs related errors within a single transaction.
Secure error information during transmission.
You need to recommend a strategy for collecting error information.
What should you recommend?

• A. Create a Windows Communication Foundation (WCF) service. Use the basicHttpBinding protocol to transport the information.
• B. Write the information to the Windows Application log on each client system. Use Windows Management Instrumentation (WMI) to collect the results.
• C. Write the information to the Windows Application log on each client system. Use Windows Error Reporting to collect the results.
• D. Create a Windows Communication Foundation (WCF) service. Use the wsHttpBinding protocol to transport the information.

You are designing an application by using Windows Presentation Foundation (WPF), Microsoft .NET Framework 4, and Microsoft SQL Server 2008.
The application will contain several forms that include custom data validators.
You need to ensure that data is validated before the database updates occur. You also need to ensure that the validation logic can be reused.
How should you design the validation?

• A. Subscribe to the MouseLeave event for all user interface (UI) components of the application.
  Perform data validation in the event handler and alert users when a data entry error occurs.
• B. Subscribe to the TextChanged event for all user interface (UI) components of the application.
  Perform data validation in the event handler and alert users when a data entry error occurs.
• C. Implement the IDataErrorlnfo interface in the data class of the application.
• D. Implement the INotifyPropertyChanged interface in the data class of the application.