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Articles from Jinal Desai .NET
Enterprise Library Interview Questions
2014-01-27 11:01:55 Jinal Desai
1. What is Enterprise Library?
Ans. Enterprise Library is class library delivered freely by Microsoft Patterns
and Practices group. It is made up of series of application blocks, each aimed
at managing specific crosscutting concerns for example writing entries to
system log or Windows Event Log, caching and validating user input, etc.
2. What are application blocks?
Ans. Application blocks are pluggable and reusable software components
designed to assist developers with common enterprise development
challenges.
3. What are the advantages of Enterprise Library? Why to use Enterprise
Library?
Ans. First thing first Enterprise Library contains standard and proven code
practices and components which can save considerable amount of
development time in turn minimize costs, reduce the use of test resources
and also decrease overall maintenance effort.
Enterprise library is continuously evolving with the capabilities of the .NET
Framework to utilize new features of .NET Framework and language
capabilities.
Enterprise library embodies many design patterns, and demonstrates good
architectural and coding techniques which are proven over the time.
And finally it’s free.
4. How many application blocks are there in Enterprise Library?
Ans. There are total nine application blocks in Enterprise Library. Among nine
application blocks seven are functional blocks which actually targets specific
cross-cutting concerns and two are designed to help in implementing more
loosely coupled, testable, and maintainable systems.
5. Can you describe all it’s application blocks in one line?
Ans. Caching: It is used for local in-memory caching or database caching or
isolated storage caching.
Credential Management: It provides common authorization related
functionalities such as user’s authentication and authorization data caching
and integrating with .NET framework security features.
Data Access: It provides facility to perform common data access tasks such
as reading data, passing data through application layers and submitting
changed data back to database system.
Encryption: It makes easy to incorporate cryptographic functionalities such
as encrypting and decrypting data, creating a hash from data, and comparing
hash values to verify data has not been altered into application.
Exception Handling: It is used to implement unified model of exception
handling through out various architectural layers of the application.
Logging: It is used to implement common logging functions such as writing
informations to the Windows Event Log or an email message or a database or
Windows Message Queue, a text file, a Windows Management
Instrumentation (WMI) event, or a custom location.
Validation: It is used to implement structured and easy-to-maintain validation
mechanisms using attributes and rule sets.
6. Why we need to configure Enterprise Library? What is configuration
tool?
Ans. Enterprise Library uses configuration sources to expose configuration
information to the application blocks and the core features of the library. The
configuration sources can read configuration from standard .NET
configuration files (such as App.config and Web.config), from other files, from
a database, and can also take into account Group Policy rules for a machine
or a domain.
Enterprise Library includes a stand-alone configuration console (GUI tool) that
integrates with Microsoft Visual Studio. We can access configuration console
by right clicking on configuration file and click on “Edit Enterprise Library V(5/6)

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Configuration” menu item.
7. Can you describe mechanism behind instantiating Enterprise Library
objects?
Ans. Enterprise Library 5.0 uses dependency injection container to generate
instances. There are two approaches recommended to creating instances.
First and simple approach of obtaining instances is using Enterprise Library
service locator. It provides access to the Unity container that holds the
Enterprise Library configuration information. Alternatively, if we are already a
DI convert, we can take charge of the entire process by creating and
populating a container and using it to create and manage both Enterprise
Library objects and your own custom types.
8. Can you write down simple example of both?
Ans. Yes sure. First one is simple approach, using Enterprise Library service
locator.
//To instantiate LogWriter
var writer = EnterpriseLibraryContainer.Current.GetInstance<LogWriter>();
writer.Write("I'm a log entry created by the Logging block!");
//To instantiate specific database object
var customerDb = EnterpriseLibraryContainer.Current.GetInstance<Database>("Customers");
Second one is using DI convert.
//To initialize and populate the default Unity container
var theContainer = new UnityContainer().AddNewExtension<EnterpriseLibraryCoreExtension>();
//To instantiate LogWriter
var writer = theContainer.Resolve<LogWriter>();
//To instantiate specific database object
var customerDb = theContainer.Resolve<Database>("Customers");
9. What’s new in Enterprise Library 5.0?
Ans. In Enterprise Library 5.0 following are major enhancement provided.
Major architectural refactoring to provide improved testability and
maintainability through dependency injection style of development. You
can even replace Unity (that ships with Enterprise Library) with a
container of your choice.
Asynchronous data access support.
Integration with WPF validation mechanism.
Optimized cache scavenging.
Support for the .NET 4.0 Framework and integration with Microsoft Visual
Studio 2010.
Data accessors for more intuitive processing of data query results.
Programmatic configuration support, including a fluent configuration
interface and an XSD schema to enable IntelliSense.
Enterprise Library Interview Questions
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