Errors occasionally occur when saving data using the FlightInfoContext ADO.NET Entity
Framework context. Updates to the data are being lost when an error occurs.

You need to ensure that data is still saved when an error occurs by retrying the operation.
No more than five retries should be performed.
With which code segment should you replace the body of the SaveChanges() method in the
FlightInfoContext.es file?

A.
Option A

B.
Option B

C.
Option C

D.
Option D

Explanation:

EntitySqlException: Represents errors that occur when parsing Entity SQL command text.
This exception is thrown when syntactic or semantic rules are violated. SqlException: The
exception that is thrown when SQL Server returns a warning or error. This class cannot be
inherited. EntityCommandExecutionException : Represents errors that occur when the
underlying storage provider could not execute the specified command. This exception
usually wraps a provider-specific exception.

Case Study: 2
Scenario 2
Background
You are developing an ASP.NET MVC application in Visual Studio 2012 that will be used
to process orders.
Business Requirements
The application contains the following three pages:
A page that queries an external database for orders that are ready to be
processed. The user can then process the order.
A page to view processed orders.
A page to view vendor information.
The application consumes three WCF services to retrieve external data.
Technical Requirements
Visual Studio Solution:
The solution contains the following four projects.
ExternalQueue: A WCF service project used to communicate with the external order
database.
OrderProcessor: An ASP.NET MVC project used for order processing and logging order
metadata.
OrderUpload: A WCF service project used to submit order data to an external data
source.
Shipping: A WCF service project used to acquire shipping information.
ExternalQueue Project:
Entity Framework is used for data access. The entities are defined in the
ExternalOrders.edmx file as shown in the following diagram.

The project contains two services defined in the following files.

✑ IExternalQueueService.es
✑ ExternalQueueService.svc.
The ExternalQueue.Helpers namespace contains a definition for a class named
OrderNotFound Exception.
OrderProcessor Project:
Entity Framework is used for data access. The entities are defined in the
ProcessedOrders.edmx file as shown in the following diagram.

The classes are contained in the OrderProcessor.Entities namespace. The project
contains the following two controllers.
InboundQueueController.es ProcessedOrderController.es
WCF service proxies to the ExternalQueue, Shipping and OrderUpload services have
been generated by using the command prompt. The ExecuteCommandProcedure()
method in the ExternalQueueService.svc file must run asynchronously.
The ProcessedOrderController controller has the following requirements. The
GetVendorPolicy() method must enforce a 10 minute absolute cache expiration policy.
The GetProcessedOrders() method must return a view of the 10 most recently
processed orders.
OrderUpload Project:
The project contains two services defined in the following files:
IUploadCallbackService.es UploadCallbackService.svc
Data Access is maintained in a file named UploadOrder.es.
Shipping Project:
Entity Framework is used for data access. The entities are defined in the
ExternalOrders.edmx file as shown in the following diagram.

The Custom Tool property for ExternalOrders.edmx has been removed.
POCO classes for the Entity Model are located in the ShippingAddress.es file. The
POCO entity must be loaded by using lazy loading. The project contains two services
defined in the following files.
IShippingService.es ShippingService.svc.
The IShippingService contract must contain an operation that receives an order number
as a parameter. The operation must return a class named ShippingInfo that inherits from
a class named State.

Application Structure