Pattern

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Pattern Framework

• ????

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??

• More about Pattern
• Framework
• Comparison

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??

• More about Pattern
• Framework
• Comparison

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More about Pattern

• Patterns of Patterns
• Anti-pattern
• J2EE patterns

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More about Pattern

• Patterns of Patterns
• Anti-pattern
• J2EE patterns

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Working together

• Patterns are often used together and combined
  with the same design solution.
• A compound pattern combines two or more patterns
  into a solution that solves a recurring or
  general problem.

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Example?????????

• ????
• ????
• ???
• ??????
• ??????(look-and-feel)??
• ????????
• ????
• ????????

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??????

• Composite?????????????
• Strategy??????????
• Decorator??????
• Abstract Factory???????
• Bridge????????
• Command????????
• Iterator?????????
• Visitor?????????????????????????

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Duck Example

• Start with a bunch of Quackables..
• A goose came along and wanted to act like a
  Quakable too.
• Then, the Quackologists decided they wanted to
  count quacks.
• But the Quackologists were worried theyd forget
  to add the QuackCounter decorator.
• We had management problems keeping track of all
  those ducks and geese and quackables.
• The Quackologists also wanted to be notified when
  any quackable quacked.

Adapter
Decorator
Abstract factory
Composite
Iterator
Observer
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Compound Patterns

• MVC
• a song about MVC by James Dempsey (lyrics)

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MVC

• MVC is a compound pattern consisting of the
  Observer (model), Strategy (controller) and
  Composite (view) patterns.
• The Adapter pattern can be used to adapt a new
  model to an existing view and controller.

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Pattern Definition Review

• A Pattern is a solution to a problem in a
  context.
• Context the recurring situation in which the
  pattern applies
• Problem the goal you are trying to achieve in
  this context and any constrains that occur in the
  context.
• Solution a general design that anyone can apply
  which resolves the goal and set of constraints

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Pattern Categories I -- Goal

• Creational Patterns involve object instantiation
  and all provide a way to decouple a client from
  the objects it needs to instantiate.
• Structural Patterns compose classes or objects
  into larger structures.
• Behavioral Patterns concerned with how classes
  and objects interact and distribute responsibility

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Pattern Categories II -- Scope

• Class Patterns
• Describe how relationships between classes are
  defined via inheritance.
• Relationships in class patterns are established
  at compile time.

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Pattern Categories II -- Scope

• Object Patterns
• Describe relationships between objects and are
  primarily defined by composition.
• Relationships in object patterns are typically
  created at runtime and are more dynamic and
  flexible

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More about Pattern

• Patterns of Patterns
• Anti-pattern
• J2EE patterns

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Anti-Patterns

• Andrew Koenig 1995, Michael Akroyd 1996
• An anti-pattern (????) tells you how to go from a
  problem to a BAD solution.
• Tell you why a bad solution is attractive.
• Tell you why that solution in the long term is
  bad.
• Suggest other patterns that are applicable which
  may provide good solutions.

Wiki
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??????

• ?????????
• ?????????
• ?????????
• ?????????
• ?????????
• ???????????
• ???????
• ?????????
• ??????
• ????????

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Example

• ?????
• ???????????????,??????????????????????????????????
  ,??????????????
• ?????
• ??????????????
• ??????????????????????
• ??????????????????????
• ?????????,???????????????????
• ??????????,????????
• ?????????????????????
• ????????????????????

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Example

• ???? (Refactor)
• ?????????????????????,??????????????
• ????????????????,???????????????
• ??????????????????,?????????
• ?????????????????????
• ??,??????????
• ??,????????????????,???????????????,??????????????
  ?,??????????

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More about Pattern

• Patterns of Patterns
• Anti-pattern
• J2EE patterns

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J2EE Patterns

• ??
• ????????,????J2EE?????Java????????
• ??????????,?J2EE??????????????????????????
• ????????,??????????????,?????
• ???????

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J2EE Patterns Classification

• ??????SJC?????TheServerSide???????
• J2EE JSP, Servlet, EJB, JMS, JDBC, JNDI
• SJC (Sun Java Center)????
• Web???JSP,Servlet
• Intercepting Filter, Front Controller, View
  Helper
• ?????EJB
• Business Delegate, Value Object, Session Façade
• ?????JMS,JDBC
• Data Access Object, Service Activator

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J2EE Patterns Classification

• TheServerSide????
• EJB???????
• Session Façade, Message Façade, EJB Command
• ????????
• Data Transfer Object, Data Transfer HashMap
• ????????
• Version Number, JDBC for Reading
• ???EJB????
• EJB Home Factory, Business Delegate

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Example

• EJB??????????
• ??EJB ??EJBHome em JNDIServer.getRemoteHome(EJ
  B-JNDI-NAME) EJBObject myEJB em.create()
• em.create()??Afactory.create()
• EJBObject ???

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Example

• ?? Bean???Bean Façade??
• ????Bean???????Bean
• ???Bean???Façade?/Manager?
• ??Façade ??Bean??
• ????,???????????Bean?????
• ????,???????

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Example

• DTO(Data Transfer Object)??
• DTO?????????????JavaBeans,?J2EE?????????
• DTO????,???????Message
• ?JavaBeans?????????Model

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Example

• MVC??
• MVC???J2EE Web??????

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Example

• Proxy??
• ???????????????????????????????
• ???????????????(Access Proxy)????????????
• ??Proxy??
• ??????Java???(Reflect)??,?????????????????????????
  ?????????
• ???????????????????????????????,??????????????????
  ?

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J2EE Anti-Pattern

• ?EJB??J2EE
• ????
• ???????
• ????????Session Bean
• ????
• ??Servlet????JSP

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NowOO Design Toolbox

• OO Basics
• OO Principles
• OO Patterns
• Your patterns here!

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??

• More about Pattern
• Framework why, what, how
• Comparison

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Forms of design-level reuse

• Sharing of consistency programming and scripting
  language
• Sharing concrete solution fragments libraries
• Sharing contracts interfaces
• Sharing individual architecture patterns
• Sharing subsystem architectures frameworks
• Sharing overall structure system architectures.

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Framework

• GoF A framework is a set of cooperating
  classes, some of which may be abstract, that make
  up a reusable design for a specific class of
  software.
• A software framework is an abstraction in which
  common code providing generic functionality can
  be selectively overridden or specialized by user
  code, thus providing specific functionality.
• Frameworks are a special case of software
  libraries in that they are reusable abstractions
  of code wrapped in a well-defined API, yet they
  contain some key distinguishing features that
  separate them from normal libraries.

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Framework

• ??,????????????,??????,???????????????????????????
  ,????????,????????,????????
• ????????????(?J2EE)??????????????

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Framework
????
??????
????
???????
?????
????
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Framework

• First commercial application framework MacApp by
  Apple Computer for Macintosh
• Well-known frameworks
• MFC
• Struts, Spring, Avalon, PicoContainer
• Hibernate
• Jdon

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Framework ??

• Inversion of control - The overall program's
  flow of control is not dictated by the caller,
  but by the framework.
• Default behavior - A framework has a default
  behavior. This default behavior must actually be
  some useful behavior and not a series of no-ops.
• Extensibility - A framework can be extended by
  the user usually by selective overriding or
  specialized by user code providing specific
  functionality.
• Non-modifiable framework code - The framework
  code, in general, is not allowed to be modified.
  Users can extend the framework, but not modify
  its code.

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How to design a good framework?

• ?????? (Domain Driven Design)
• ????IoC (Inversion of Control) or ????DI
  (Dependence Injection)
• AOP (Aspect Oriented Programming)

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Domain Driven Design

• ??DDD http//domaindrivendesign.org/
• The premise of domain-driven design is two-fold
• For most software projects, the primary focus
  should be on the domain and domain logic and
• Complex domain designs should be based on a
  model.

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DDD Background

• ????????Java??Web????,????????
• Ruby on Rails (RoR)?Web???????Java??????????????
  ????????????
• ?Java??????DDD??(RoR)??,????Java??????,?????????,
  ????IoC/AOP??????

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DDD

• Domain-driven design is not a technology or a
  methodology. It is a way of thinking and a set of
  priorities, aimed at accelerating software
  projects that have to deal with complicated
  domains.

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???DDD
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DDD

• ????
• ??????(Domain Model)??,?????????????,??????????
  ,??????????????
• ??
• ????????,????Delphi/VB?????????????

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DDD??

• ??????????(ubiquitous )???,????????????????????,?
  ?????????????????
• ??????????????????????,??????????????????
• ???????????????????,?????? ?????????

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??????????
Persistence
Domain Service
Domain Model
GUI
Logging
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?????????

• ????MVC?????,???????????????Controller?,?Struts?Ac
  tion?????Action?????
• ????SOA???,????????????????
• ????????,?????setter/getter????????????????????,??
  ????????
• ???????????????,?????????????????????,???????

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?????????????

• ?????OrderItemId, OrderId, ProductId ? Qty?
• ???? MinDeliveryQty ? PendingQty??,??????????
• ????????????,???????????????????
• ?????OO??,????????????????????
• DDD????????????????? ?

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????????????

• ?????????????,??????????????
• ???????????????,????????????,???????
• ??????????,????,?ER????,???????,???domain
  model???????,???????

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DDD advantage

• ?????? ???Model??????

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?Jdon Framework (JF)??

• http//www.jdon.com/jdonframework/

• Domain Model?JF?????????????
• ??Model??????????????
• ?Domain Model????????????

?Domain???
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??JF?DDD????
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Model Configuration

• ????????MVC??Controller??

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IoC

• ???? Inversion of Control
• Review
• Design Principles DIP (dependence inversion)
• Hollywood Principle Dont call us, well call
  you.
• ???? Dependence Injection (by Martin Fowler)
• http//www.martinfowler.com/articles/injection.htm
  l

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IoC Motivation

• First
• We knew from basic Java tutorial, that all
  objects should be created first before use.
• Then
• We knew how to create objects by usage of factory
  patterns.
• Now
• We will study how to get an object from an IoC
  container and use it without creating it by
  ourselves.

abc new ABC()
abc Factory.createInstanceOfABC()
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Example
http//today.java.net/pub/a/today/2004/02/10/ioc.h
tml
public class JDBCDataManger public void
accessData() DataSource dataSource new
DataSource() //access data ...
public class JDBCDataManger public void
accessData() DataSource dataSource
ApplciationResources.getDataSource() //access
data ...
In either case, the JDBCDataManager has to fetch
the DataSource itself!
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IoC Motivation

• ??????,?????????,?????????????????,???????????,???
  ??????,????????????,?????,????????????????????,???
  ?????

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IoC Approach I

• Interface Injection / Contextualized Dependency
  Lookup (Type 1)
• components implement specific interfaces provided
  by their containers in order to be configured

Avalon
import org.apache.avalon.framework. public
class JDBCDataManger implements Serviceable
DataSource dataSource public void service
(ServiceManager sm) throws ServiceException
dataSource (DataSource)sm.lookup("dataSource
") public void getData()
//use dataSource for something
The requirement to implement specific interfaces
can give code a "bloated" feel, while at the same
time coupling your application code to the
underlying framework.
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IoC Approach II

• Setter Injection (Type 2)
• some external metadata is used to resolve
  dependencies.

Spring
public class JDBCDataManger private
DataSource dataSource public void
setDataManager(DataSource dataSource
this.dataSource dataSource public void
getData() //use dataSource for something

Looks like a normal bean!
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IoC Approach II

• Metadata takes the form of an XML configuration
  file in Spring.

ltbean id"myDataSource" class"org.apache.commo
ns.dbcp.BasicDataSource" gt ltproperty
name"driverClassName"gt ltvaluegtcom.mydb.jdbc.D
riverlt/valuegt lt/propertygt ltproperty
name"url"gt ltvaluegtjdbcmydb//serverport/myd
blt/valuegt lt/propertygt ltproperty
name"username"gt ltvaluegtrootlt/valuegt
lt/propertygt lt/beangt
Metadata can be reused by multiple components!
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IoC Approach II

• define an instance of our manager and pass in a
  reference to the data source

ltbean id"dataManager" class"example.JDBCDataM
anger"gt ltproperty name"dataSource"gt ltref
bean"myDataSource"/gt lt/propertygt lt/beangt
Make unit test easier! Application code is not
tied to the container.
Potential downsides Component relationship
unclear Encapsulation broken
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IoC Approach III

• Constructor Injection (Type 3)
• Based on the principle of Good Citizen
• Register an object with the framework, specify
  the parameters to use (which can in turn be
  created by the framework itself) and then just
  request an instance.
• The components being registered just have to
  implement a constructor, which can be used to
  inject the dependencies.

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IoC Approach III

• Need a constructor

public class JDBCDataManger private
DataSource dataSource public
JDBCDataManger(DataSource dataSource)
this.dataSource dataSource public
void getData() //use dataSource for
something
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IoC Approach III
PicoContainer

• //create a datasource bean
• BasicDataSource dataSource new
  BasicDataSource()
• dataSource.setDriverClassName("com.mydb.jdbc.Drive
  r")
• dataSource.setUrl("jdbcmysql//localhost3306/myd
  b")
• dataSource.setUsername("Bob")
• //create the container
• MutablePicoContainer pico new
  DefaultPicoContainer()
• //register components with container
• ConstantParameter dataSourceParam new
  ConstantParameter(dataSource)
• String key "DataManager"
• Parameter params dataSourceParam
• // Now each request for a DataManager will
  instantiate a JDBCDataManager object with our
  defined
• // dataSource object
• pico.registerComponentImplementation (key,
  JDBCDataManger.class,params)

Use old-fashioned Java code to glue everything
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IoC Approach III

• To get instances of the JDBCDataManager object,
  we just have to reference the class by its key

JDBCDataManger dm (JDBCDataManger)pico.getCo
mponentInstance(key)
Application code is independent of the framework
itself only a constructor is needed.
Potential downsides using constructors to
maintain the dependencies can become more complex
when using inheritance
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Comparison
Type 1 ?JNDI?ServiceManager??????? 1. EJB/J2EE2. Avalon
Type 2 ??JavaBeans?setter?? 1. Spring Framework,2. WebWork/XWork
Type 3 ?????????? 1. PicoContainer,2. HiveMind
???????IoC??????
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IoC Timeline
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Spring vs. PicoContainer

• Different work required to set up your IoC
  bindings
• Spring can be configured either by an XML
  configuration file or directly in Java
• PicoContainer requires a Java binding
• Both are fairly lightweight framework
• PicoContainer is smaller
• Spring is not just an IoC framework it also
  provides web application and AOP frameworks, as
  well as some general support classes

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Aspect-Oriented Programming

• Separation of Concerns
• Crosscutting Concerns
• Aspects
• Weaving

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Aspect-Oriented Programming

• Complexity of enterprise software systems
• JBoss 4.0????AOP?????????????Authentication ??
  Caching ??Context passing ???? Error handling
  ????Lazy loading ??? Debugging ??logging,
  tracing, profiling and monitoring ???? ??
  ??Performance optimization ????Persistence
  ??? Resource pooling ???Synchronization
  ?? Transactions ??

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??

• More about Pattern
• Framework why, what, how
• Comparison

72
Comparison

• ???????
• ???????????????????
• ???????????,?????????????????
• ?????
• ???????

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Comparison

• ??????????
• ????????????,??????
• ????????,??????????
• ?????????????????
• ??????????????????,????
• ????????????
• ???????????????
• ???OO???????????,???OO????????????????

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Comparison

• ?????,????????????,?????????

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More Comparison

• ?? vs. ????
• ?? vs. ???,??
• ?? vs. ??????

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??(????????)

• ????(container)???,?????????,??????????
• ??????,??Spring??????IoC??
• Ref
• ????Presentation????????email??,OO????/????/??????
  ?