department of computer science and software engineering concordia university e nterprise a...

Department of Computer Science and Software

EngineeringConcordia University

ENTERPRISE APPLICATION DESIGN PATTERNS:IMPROVED AND APPLIED

Stuart [email protected]

February 11, 2010

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Enterprise Application Design Patterns: Improved and Applied

Outline

A Brief Overview of Development

Problems for Software Engineers

A Progression Through Fowler’s Patterns

Domain Objects and Improved Patterns

Applying Patterns with the SoenEA

Framework

February 2010 Stuart Thiel

Outline

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Developers Work With Software

Design

Implement

Test

Maintain


Developers Work With Software

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Developer Aids/Tools• Programming Languages

• Integrated Development Environments

• Processes / Artifacts

• Patterns / Styles


Developer Tools

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Problems

Fowler describes architectural patterns, but no overall

usage guidelines

• High level patterns lack broad examples

• Guidance on interrelation of patterns is sparse

• Pattern theory / implementation separation ambiguous

Cooking Analogy


Problems

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Problems:: Few Simple Examples

Trivial examples for Fowler’s patterns, usually

covering only a piece of functionality


P. Few Simple Examples

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Problems:: Interrelation Not

Described

Not usually covering more than one or two

patterns at a time

Discussion of interrelation limited


P. Interrelation Not Described

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Problems:: Theory Mixes with

Implementation, or is Kept Apart

Lazy Load

Unit of Work


P. Theory Implementation

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Problems Summary

The components of a solution are available

We can readily identify patterns in existing

software

There is no description of what to

do


Problem Summary

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Enterprise Application Design Patterns: Improved and AppliedSolutions

Solutions

Review of Existing Patterns

An Additional Patterns

Refined Patterns

SoenEA


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Enterprise Application Design Patterns: Improved and AppliedExisting Patterns

Review of Existing Patterns

Fowler identifies important patterns

They need context wrt each other

Transaction Script to complex Domain Model


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Enterprise Application Design Patterns: Improved and AppliedAdditional Patterns

Additional Pattern

Domain Object

Front Command

Dispatcher

List Proxy


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Enterprise Application Design Patterns: Improved and AppliedRefined Patterns:: Mappers

Refined Patterns

Data Mapper / Table Data GatewayInput MapperOutput MapperTable Data GatewayFinder


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Enterprise Application Design Patterns: Improved and AppliedRefined Patterns:: Others

Refined Patterns

Front Controller

Lazy Load

Identity Map

Unit of Work


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Enterprise Application Design Patterns: Improved and AppliedSoenEA:: advantages

SoenEA

help eliminate tedious tasks,

help programmers to make fewer mistakes, and

give guidance on proper practices.


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Enterprise Application Design Patterns: Improved and AppliedSoenEA:: provides

SoenEA

Patterns

Utility components

Default Implementations of Typical Components (DITCs)

Test components


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SoenEA Summary• Developers can use our contribution to build on their

understanding of existing patterns• They can use SoenEA to quickly develop software• SoenEA is like a jigsaw puzzle


Summary


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Conclusion

We have brought together a lot of other people’s good ideas

Our approach has been used in commercial applications

Our approach has allowed consistent and reliable

development

Our approach is readily communicable


Conclusion

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Future Work

Code Generation

Testing

Application Level Patterns

Validator Pattern

Refining Data Gateway Implementations

Integration with other artefacts0


Future Work

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Thank You!

Thank You

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An Analogy

Software Development -> Cooking

WEA Development -> Baking


An Analogy

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An Analogy:: Styles

Layered Style, Event-based Style, Process

Control, Blackboard

Cakes/Pizza, Cookies/Muffins, Souflé,

Omlette/Pancake


An Analogy:: Styles

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An Analogy:: Design Patterns

Command, Factory, Adapter, Proxy

Mixing, Chopping, Heating, Greasing,

Measuring


An Analogy:: Design Patterns

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An Analogy:: Architectural

Patterns

Lazy Load, Pessimistic Offline Lock , Unit Of

Work

Mixing Dry Ingredients vs. Wet, Checking That

All Ingredients Are Available Before Starting,

Preparing All Ingredients


An Analogy:: Architectural Patterns

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An Analogy:: Frameworks

Struts 1.0 - > Waffle Iron

Hibernate -> Bread Maker


Analogy:: Frameworks

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Cyclic Reference

Where to solve it?

• Input Mapper

Common Alternatives

• Loading other Domain Objects after


Cyclic Reference Solution

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Cyclic Reference alternative

Easy:


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public Person find(long id) {

//Check Identity Map and return if found

if(IdentityMap.has(id,Person.class))

return IdentityMap.get(id,Person.class);

//Not in Identity Map

ResultSet rs = PersonFinder.find(id);

if(!rs.next) ;//

Person p = new Person(id);

UoW.getCurrent.registerClean(p);

Person buddy = find(rs.getLong("buddy"));

p.setBuddy(buddy);

}


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Cyclic Reference alternative

Harder


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if(!rs.next) ;//

Person p = new Person(id);


Pet pet = find(rs.getLong("pet"));

p.setPet(pet);

}


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Proxy







if(!rs.next) ;//

Person p = new Person(id,

new PersonProxy(rs.getLong("buddy")));


}


department of computer science and software engineering concordia university e nterprise a...

Documents

improved patterns

interrelation of patterns

patterns soenea

important patterns

architectural patterns

stuart thiel slide

stuart thiel problems

stuart thiel outline