Enterprise Library for .NET Framework 2.0: Core Architecture

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Enterprise Library for .NET Framework 2.0Core
Architecture
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Enterprise Library for .NET Framework 2.0

• Major new release of Enterprise Library
• Designed for Microsoft .NET Framework 2.0
• Leverages key new capabilities provided by the
  platform
• Certain features from Enterprise Library v1.x
  have been deprecated in favor of the platform
• Scenarios and features largely unchanged
• Public application programming interfaces (APIs)
  not identical, but changes are minor
• but many improvements are hiding under the
  covers!

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Key Changes from Enterprise Library 1.x

• Configuration now built on System.Configuration
• Configuration Application Block no longer exists
• Easier to use blocks with or without
  configuration files
• Instrumentation configurable and disabled by
  default
• Much improved Logging Application Block
• Flexibility and performance
• Simpler and more powerful Data Access Application
  Block
• Use with OLE-DB, Open Database Connectivity
  (ODBC) or any managed provider
• Most of the Security Application Block has been
  removed
• Deprecated in favor of .NET Membership and
  Profile features

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Enterprise Library for .NET Framework 2.0
Caching
Data Access
Logging
Core
Cryptography
Exception Handling
Security
Optional ProviderDependency
Block Dependency
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Enterprise Library for .NET Framework 2.0
Caching
Data Access
Logging
Core
Plug-in
Config Helpers Design
Instrumen-tation
Cryptography
ObjectBuilder
Exception Handling
Security
Optional ProviderDependency
Block Dependency
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Core Architecture

• Configuration runtime
• Configuration design and tooling
• Instrumentation
• Factories and object builder

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Configuration in Enterprise Library

• All Enterprise Library blocks are configurable
• Controls how the blocks work in your application
• Specifies which plug-ins you are using
• Previous versions of Enterprise Library included
  a Configuration Application Block
• Supported reading/writing complex configuration
  objects from pluggable storage
• Used by all Enterprise Library blocks, and can be
  used by customer code
• In Enterprise Library for .NET Framework 2.0, the
  requirements are the same but the solution is
  different

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System.Configuration in .NET 2.0

• Much more powerful than the Microsoft .NET
  Framework 1.x classes
• Supports reading and writing rich graphs of
  objects
• Automatic serialization and deserialization
  between configuration classes and XML using
  ConfigurationSection and ConfigurationElement
• Some Enterprise Library 1.x features are not
  directly supported
• Storing configuration somewhere other than XML
  Files
• Monitoring external changes to configuration

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Configuration Runtime

• Enterprise Library for .NET Framework 2.0 uses
  System.Configuration, but provides additional
  helper classes to provide more functionality
• All blocks provide ConfigurationSections which
  are stored in app.config / web.config by default
• All System.Configuration features such as
  encryption and using external files are supported
• Configuration Runtime helper classes are in the
  Common assembly
• Used by all Enterprise Library application blocks
• Can be used by your apps, but you generally wont
  need to

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Configuration Sources
app.config / web.config Default ConfigurationSour
ce
Application Blocks or Custom Code
IConfigurationSource
SystemConfiguration Source
FileConfiguration Source
SqlConfiguration Source
System.Configuration
foo.config
app.config / web.config
File Watcher
File Watcher
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Configuration Sources

• Abstract interface that supports loading/saving
  configuration and monitoring for changes
• Two implementations included in the core
• SystemConfigurationSource defers to
  System.Configuration to read from default
  configuration file (plus adds file watchers)
• FileConfigurationSource defers to
  System.Configuration but reads from arbitrary
  files
• SqlConfigurationSource included as a sample
• Requires that sections derive from
  SerializableConfigurationSection

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Choosing a Configuration Source

• Several ways of choosing a configuration source
  when using Enterprise Library
• If you access blocks using static façades or
  factories (Examples DatabaseFactory, Logger),
  you will always use the applications default
  ConfigurationSource
• If you define a ConfigurationSources section in
  your default.config file, you can specify which
  type of source should be used
• If you dont have this section,
  SystemConfigurationSource is used
• If you use the instance factories
  (ExamplesDatabaseProviderFactory,
  LogWriterFactory) you can specify a configuration
  source of your choosing
• Instantiated directly or using ConfigurationSource
  Factory

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Configuration Source Examples
selectedSource"fileSource"
nterpriseLibrary.Common.Configuration.FileConfigur
ationSource, Microsoft.Practices.EnterpriseLibrary
.Common" filePath"test.config"/ name"systemSource" type"Microsoft.Practices.Ente
rpriseLibrary.Common.Configuration.SystemConfigura
tionSource, Microsoft.Practices.EnterpriseLibrary.
Common"/ figurationSource

• // Use default source specified in the app.config
  / web.config file
• Database db1 DatabaseFactory.CreateDatabase(Sal
  es)
• // Use the specified source you dont need an
  app.config / web.config file
• FileConfigurationSource fileSource new
  FileConfigurationSource(tom.config)
• DatabaseProviderFactory factory new
  DatabaseProviderFactory(fileSource)
• Database db2 factory.Create(Sales)

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Change Notifications

• IConfigurationSource supports monitoring
  configuration data for changes
• AddSectionHandler(string sectionName,
  ConfigurationChangedEventHandler handler)
• RemoveSectionHandler(string sectionName,
  ConfigurationChangedEventHandler handler)
• Any code can register for changes and respond
  accordingly
• In Enterprise Library, only the Logging
  Application Block currently registers to receive
  change notification events

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Configuration Design and Tooling

• Configuration tool eliminates the need to edit
  the blocks XML configuration files
• Quickly add default configuration for a block
• Strongly-typed properties and providers
• Validate configuration before you save
• No major changes to configuration tool user
  experience from previous versions of Enterprise
  Library
• Configuration design-time subsystem can be used
  in your own applications and blocks to provide a
  similar experience for your users

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Configuration Design-Time

• Improved API
• Simple base configuration design manager
• Better node registration and command registration
• 3 to 4 simple classes to register your custom
  provider
• No more OnSited ?
• One configuration design manager per section
• Dependent configuration design managers
• Easy to interop with any .NET configuration

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Instrumentation

• All Enterprise Library blocks include
  instrumentation to assist in development, testing
  and operations
• Event Log events
• Performance Counters
• Microsoft Windows Management Instrumentation
  (WMI) events
• All instrumentation is disabled by default, but
  each type can be individually enabled using the
  configuration tool
• Instrumentation code contained in common assembly
  can be reused in your apps

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Enabling Instrumentation

• Run the installer classes to create the
  instrumentation artifacts
• Run installservices.bat (using an admin account),
  or
• Run installutil.exe over each Enterprise Library
  assembly (using an admin account), or
• Create your own installers/MSI that do this
• Configure instrumentation for your app using the
  tool

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Instrumentation Architecture
Event Log

• Event-driven architecture

Application or Block
calls
Perf Counters
Instrumentation Listener Class(es)
Instrumentation Provider Class(es)
Event
WMI
Wires up
Instrumentation Configuration Settings
ObjectBuilder
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Instrumentation Attributes

• Instrumentation is wired up using attributes
• InstrumentationListener
• Defined on a type within the block or application
• Specifies which listener will deal with
  instrumentation events
• InstrumentationProvider
• Defined on an event within the block or
  application
• Specifies the name of the event being fired
• InstrumentationConsumer
• Defined on a method within the instrumentation
  listener
• The method contains the instrumentation logic,
  and the name must match the one used in an
  InstrumentationProvider declaration

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Instrumentation Example
public class Database IInstrumentationEventProvi
der DbConnection OpenConnection()
// Do stuff instrumentationProvider.FireCo
nnectionOpenedEvent() public object
GetInstrumentationEventProvider()
return instrumentationProvider

• InstrumentationListener( typeof(DataInstrumentati
  onListener), typeof(DataInstrumentationListenerBin
  der))
• public class DataInstrumentationProvider
• InstrumentationProvider("ConnectionOpened")
• public event EventHandler
• connectionOpened
• public void FireConnectionOpenedEvent()
• connectionOpened(this, new EventArgs())

internal class DataInstrumentationListener
InstrumentationListener public
DataInstrumentationListener(string instanceName,
bool perfCountersEnabled, bool eventLogEnabled,
bool wmiEnabled) base(perf, event, wmi)
InstrumentationConsumer( ConnectionOpened")
public void ConnectionOpened(object sender,
EventArgs e) if (PerformanceCountersEnabled)
connectionOpenedCounter.Increment()
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Instrumentation Installation Attributes

• Running installutil over an instrumented class
  should install all required event log sources,
  WMI schemas and performance counters
• Enterprise Library provides a ReflectionInstaller
  which uses reflection to find these, with the
  help of some attributes
• HasInstallableResources
• Indicates that there is instrumentation to
  install
• PerformanceCountersDefinition
• Defines the counters used by the block or app
• EventLogDefinition
• Defines the event log sources used by the block
  or app

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Factories and Object Builder

• Objects inside application blocks need to be
  constructed and configured
• There are different ways you can construct
  objects depending on what you want to do
• Use a default configuration source
• Use a custom configuration source
• Dont use any configuration at all
• Inject instrumentation
• Although each block is different, all rely on
  similar types of factories for construction

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Object Builder

• New subsystem shared between EntLib and Composite
  UI Application Block
• Responsible for building objects inside the
  application blocks
• Invoking the necessary custom factory using data
  from configuration
• Configuring instrumentation for the blocks
• Can be leveraged from your own apps, but
  understanding ObjectBuilder is not required to
  use Enterprise Library

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Factories
Core
Application Block
Static Factory or façade
Configuration Source
User Code
Instance Provider Factory
Enterprise Library Factory
Custom Factory
Object Builder
Strategies
Block Objects
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Using Static Facades and Factories

• Easiest way to use the blocks
• Configuration is retrieved from the default
  configuration source
• Instrumentation is wired up (but may be disabled)
• Results in a call to an instance factory behind
  the scenes
• Examples
• Dim db As Database DatabaseFactory.CreateDatabas
  e(Sales)
• Logger.Write(My message, My Category)

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Using Instance Provider Factories

• You get slightly more control on how objects are
  created
• You can choose your own configuration source
• Instrumentation is wired up (but may be disabled)
• Examples
• Dim factory As New DatabaseProviderFactory(configS
  ource) Dim db As Database factory.Create(Sales
  )
• Dim factory As New LogWriterFactory(configSource)
  Dim writer As LogWriter factory.Create()

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Creating Objects Directly

• New up the object and any dependent objects
  yourself
• Configuration sources are not used
• Object Builder is not involved
• Instrumentation will not be automatically wired
  up (but you can add it yourself)
• Example
• Dim db As SqlDatabase New SqlDatabase("server(l
  ocal)\SQLEXPRESSdatabaseEntLibQuickStartsIntegr
  ated Securitytrue")

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Resources

• Download Enterprise Library and related resources
  from
• http//msdn.microsoft.com/practices
• Join the Enterprise Library Community at
• http//practices.gotdotnet.com/projects/entlib
• Read blogs from the Enterprise Library team at
• http//msdn.microsoft.com/practices/Comm/EntLibBlo
  gs/

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