Doing Something Useful with Enterprise Library 3.0

1. Doing Something Usefulwith Enterprise Library 3.0 Benjamin Day Level: Intermediate

2. About the speaker • Owner, Benjamin Day Consulting, Inc. • Email: benday@benday.com • Web: http://www.benday.com • Blog: http://blog.benday.com • Trainer • Visual Studio Team System, Team Foundation Server • Microsoft MVP for C# • Microsoft VSTS/TFS Customer Advisory Council • Leader of Beantown.NET INETA User Group

3. Agenda • Overview • Policy Injection • Logging • Exception Handling • Validation

4. Why Enterprise Library? • Why not? • Why write and re-write common application code? • Focus on solving the core business problem • Microsoft solved it for you • Standardized solution • Hooks in nicely with .NET through configs • It’s free • http://codeplex.com/entlib

5. Plug-in Config Helpers & Design Instrumen-tation ObjectBuilder Ent Lib 3.0 – Application Blocks Data Access Logging Caching Core Cryptography Exception Handling Security Policy Injection Validation http://tinyurl.com/3d8xfw

6. Data Access Block • Wraps common actions for database access • Handles closing of connections, IDispose calls • Some degree of database independence • Relatively easy to understand

7. Adopting Enterprise Library • Why is this talk titled“Doing Something Useful…”? • Can be like swimming in the Atlantic at low tide in the spring • What does this have to do with the Data Access Block? • Does it have to be so difficult?

8. My $0.02 on where begin • Start with the Policy Injection Block • Allows you to defer decisions on other blocks • Configure PIB to use logging • Simple way to debug your configuration • Exception Handling Block • (eat your vegetables) • Caching • Fix performance problems

9. Policy Injection Block • Uses magic • Mostly elves • Some wood nymphs for reliability • Just kidding.

10. Policy Injection Block • Layer of abstraction • Lets you hook functionality in at runtime via config • Intercepts calls in to an object’s methods • Think aspect-oriented programming or dependency injection for methods

11. The Overall Design

12. Getting started with the PI block • Two ways to use Policy Injection: • Objects extend from MarshalByRef • Code against interfaces instead of concrete classes • Add references • Microsoft.Practices.EnterpriseLibrary.PolicyInjection • Microsoft.Practices.ObjectBuilder • Microsoft.Practices.EnterpriseLibrary.CallHandlers • Plus, whatever block you’ll reference from PI • Edit app.config/web.config with EntLibConfig.exe

13. Calling into the PI framework • Call PolicyInjection.Create<T>() or one of the overloads • Returns a wrapper to your object • Call your methods through the wrapper

14. Configuration • EntLibConfig.exe • Uses the Remoting Policy Injector • Policy consists of • Matching Rules • Handlers

15. Matching Rules • Tells the framework when to run the policy

16. Handlers • Tells the framework what to do when it finds a policy match

17. Logging Handler • Through policy injection framework, intercepts calls • Writes message to log before and/or after

18. Logging Application Block • Logs activity in your app • Trace Listeners • Where does it get stored? • Formatters • How does it get stored? • Filters • What to write?

19. Logging Block Design

20. Trace Listeners

21. Formatters

22. Demo • Add Policy Injection to an existing app • Configure logging

23. Exception Handling Block • Allows you to define how to treat exceptions • Option: Catch and re-throw different exception • Option: Eat the exception

24. Design of the Exception Block

25. Demo • Add exception handling to our app via Policy Injection • Wrap Handlers • Replace Handlers

26. Demo • Add Exception Handling to a WCF application

27. The Validation Block

28. About the Validation Block • Allows you to validate access to your objects • Validation logic can be stored outside of your objects in the configs • Validation can also be defined via attributes • Similar to a rules engine • Think Windows Workflow Rules “light”

29. Available Validators • And Composite • Contains Characters • Date Time Range • Domain • Enum Conversion • Not Null • Object Collection • Object Validator • Or Composite • Property Compare • Range Validator • RegEx • Relative Date Time • String Length • Type Conversion

30. Common Validator Fields • MessageTemplate • Provides a human-readable error message • Overrides the default implementation • MessageTemplateResourceName • Enables messages in resource files • MessageTemplateResourceType • Negate • If statement evaluates to true  rule fails • false  succeeds • Tag • Category for the validation

31. Message Template Tokens • Think String.Format() • Use these to create custom messages • {0} • Original value being validated • {1} • “Key” for the value • If property or field  name (m_id or Id) • If object  null • {2} • The tag value if available

32. Service Layer Pattern “Defines an application’s boundary with a layer of services that establishes a set of available operations and coordinates the application’s response in each operation.” -Randy Stafford From “Patterns Of Enterprise Application Architecture”by Martin Fowler, Randy Stafford, et al.Chapter 9

33. Demo • Validate Restaurant with the ValidationFactory

34. The Caching Block • Allows you to cache return values from method, properties • Easy to add with the Policy Injection Block

35. Demo • Populate list of states using the caching block

36. Summary • Policy Injection Block Helps Speed Adoption • Logging Block • Exception Handling Block • Exception Handling in WCF • Validation Block • Caching Block

37. About the speaker • Owner, Benjamin Day Consulting, Inc. • Email: benday@benday.com • Web: http://www.benday.com • Blog: http://blog.benday.com • Trainer • Visual Studio Team System, Team Foundation Server • Microsoft MVP for C# • Microsoft VSTS/TFS Customer Advisory Council • Leader of Beantown.NET INETA User Group