Transcript Session Title

Doing Something Useful
with Enterprise Library
3.0
Benjamin Day
Level: Intermediate
About the speaker
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Owner, Benjamin Day Consulting, Inc.
– Email: [email protected]
– Web: http://www.benday.com
– Blog: http://blog.benday.com
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Trainer
– Visual Studio Team System, Team Foundation Server
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Microsoft MVP for C#
Microsoft VSTS/TFS Customer Advisory
Council
Leader of Beantown.NET INETA User Group
Agenda
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Overview
Policy Injection
Logging
Exception Handling
Validation
Why Enterprise Library?
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Why not?
– Why write and re-write common application code?
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Focus on solving the core business problem
Microsoft solved it for you
– Standardized solution
– Hooks in nicely with .NET through configs
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It’s free
http://codeplex.com/entlib
Ent Lib 3.0 – Application Blocks
Data
Access
Caching
Logging
Core
Cryptography
Config
Helpers
& Design
Plug-in
Instrumentation
Exception
Handling
Object
Builder
Security
Policy Injection
Validation
http://tinyurl.com/3d8xfw
Data Access Block
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Wraps common actions for database access
Handles closing of connections, IDispose calls
Some degree of database independence
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Relatively easy to understand
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Adopting Enterprise Library
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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?
My $0.02 on where begin
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Start with the Policy Injection Block
– Allows you to defer decisions on other blocks
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Configure PIB to use logging
– Simple way to debug your configuration
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Exception Handling Block
– (eat your vegetables)
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Caching
– Fix performance problems
Policy Injection Block
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Uses magic
Mostly elves
Some wood nymphs for reliability
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Just kidding.
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Policy Injection Block
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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
The Overall Design
Getting started with the PI block
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Two ways to use Policy Injection:
– Objects extend from MarshalByRef
– Code against interfaces instead of concrete classes
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Add references
– Microsoft.Practices.EnterpriseLibrary.PolicyInjection
– Microsoft.Practices.ObjectBuilder
– Microsoft.Practices.EnterpriseLibrary.CallHandlers
– Plus, whatever block you’ll reference from PI
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Edit app.config/web.config with
EntLibConfig.exe
Calling into the PI framework
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Call PolicyInjection.Create<T>() or one of the
overloads
Returns a wrapper to your object
Call your methods through the wrapper
Configuration
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EntLibConfig.exe
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Uses the Remoting
Policy Injector
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Policy consists of
– Matching Rules
– Handlers
Matching Rules
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Tells the framework when to run the policy
Handlers
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Tells the framework what to do when it finds
a policy match
Logging Handler
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Through policy injection framework,
intercepts calls
Writes message to log before and/or after
Logging Application Block
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Logs activity in
your app
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Trace Listeners
– Where does it get
stored?
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Formatters
– How does it get
stored?
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Filters
– What to write?
Logging Block Design
Trace Listeners
Formatters
Demo
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Add Policy Injection to an existing app
Configure logging
Exception Handling Block
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Allows you to define how to treat exceptions
Option: Catch and re-throw different
exception
Option: Eat the exception
Design of the
Exception Block
Demo
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Add exception handling to our app via Policy
Injection
Wrap Handlers
Replace Handlers
Demo
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Add Exception Handling to a WCF application
The Validation Block
About the Validation Block
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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”
Available Validators
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And Composite
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Object Validator
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Contains
Characters
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Or Composite
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Property Compare
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Date Time Range
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Domain
Range Validator
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Enum Conversion
RegEx
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Not Null
Relative Date Time
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Object Collection
String Length
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Type Conversion
Common Validator Fields
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MessageTemplate
– Provides a human-readable error message
– Overrides the default implementation
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MessageTemplateResourceName
– Enables messages in resource files
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MessageTemplateResourceType
Negate
– If statement evaluates to true  rule fails
– false  succeeds
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Tag
– Category for the validation
Message Template Tokens
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Think String.Format()
Use these to create custom messages
{0}
– Original value being validated
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{1}
– “Key” for the value
– If property or field  name (m_id or Id)
– If object  null
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{2}
– The tag value if available
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
Demo
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Validate Restaurant with the ValidationFactory
The Caching Block
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Allows you to
cache return
values from
method, properties
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Easy to add with
the Policy Injection
Block
Demo
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Populate list of states using the caching block
Summary
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Policy Injection Block Helps Speed Adoption
Logging Block
Exception Handling Block
Exception Handling in WCF
Validation Block
Caching Block
About the speaker

Owner, Benjamin Day Consulting, Inc.
– Email: [email protected]
– 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