Case Study: 1
Scenario 1
Background
You are developing a flight information consolidation service. The service retrieves flight information from a
number of sources and combines them into a single data set. The consolidated flight information is stored in a
SQL Server database. Customers can query and retrieve the data by using a REST API provided by the
service. The service also offers access to historical flight information. The historical flight information can be
filtered and queried in an ad hoc manner. The service runs on a Windows Azure Web Role. SSL is not used.
Business Requirements
A new data source for historical flight information is being developed by a contractor located on another
continent.
If a time zone is not specified, then it should be interpreted as Coordinated Universal Time (UTC).
When you upgrade a service from a staging deployment to a production deployment, the time that the service
is unavailable must be minimized.
The default port must be used for HTTP.
Technical Requirements
The existing sources of flight information and the mechanism of exchange are listed below.
Blue Yonder Airlines provides flight information in an XML file.
Consolidated Messenger provides flight information in a Microsoft Access database that is uploaded every 12
hours to the service using SFTP. The company uses port 22 for SFTP.
Margie’s Travel provides and consumes flight information using serialized ADO.NET DataSets. Data is
periodically synced between the service and Margie’s Travel.
Trey Research provides data from multiple sourcesserialized in proprietary binary formats. The datamust be
read by using .NET assemblies provided by Trey Research. The assemblies use a common set of
dependencies. The current version of the Trey Research assemblies is 1.2.0.0. All assemblies provided by
Trey Research are signed with a key pair contained in a file named Trey.snk, which Trey Research also
supplies.
The application specification requires that any third-party assemblies must have strong names.
Application Structure
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You need to recommend a data access technology to the contractor to retrieve data from the new data source.
Which data access technology should you recommend?
A.
LINQ to XML
B.
ADO.NET Entity Framework
C.
ADO.NET DataSets
D.
WCF Data Services
Why WCF?
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Because the new data source is from other continent and I understand it retrieve data on internet, so the answer should be WCF.
There isn’t a lot of info in the requirements.
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Answer is D. WCF can transfer data in JSON format.
Linq to XML implies transfer of XML. This has a large overhead compared to JSON.
Datasets are very expensive for transferring over the internet.
Entity framework implies accessing a SQLServer server. Again this has a large overhead compared to WCF.
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The contractor does not have access to the server. Thus it must be a “Service” technology => WCF is here the only choice, the others are server side only
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