enterprise application design patterns: improved and applied

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 SoftwareDesign

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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ProblemsFowler 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 ExamplesTrivial 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 ApartLazy Load

Unit of Work


P. Theory Implementation

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Problems SummaryThe 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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ConclusionWe 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 WorkCode 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 AnalogySoftware Development -> Cooking

WEA Development -> Baking


An Analogy

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An Analogy:: StylesLayered Style, Event-based Style, Process

Control, Blackboard

Cakes/Pizza, Cookies/Muffins, Souflé, Omlette/Pancake


An Analogy:: Styles

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An Analogy:: Design PatternsCommand, 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:: FrameworksStruts 1.0 - > Waffle Iron

Hibernate -> Bread Maker


Analogy:: Frameworks

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Cyclic ReferenceWhere to solve it?

• Input Mapper

Common Alternatives• Loading other Domain Objects after


Cyclic Reference Solution

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Cyclic Reference alternativeEasy:


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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 alternativeHarder


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public Person find(long id) {






if(!rs.next) ;//

Person p = new Person(id);


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

p.setPet(pet);

}


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Proxypublic Person find(long id) {






if(!rs.next) ;//

Person p = new Person(id,

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


}


enterprise application design patterns: improved and applied

Documents

interrelation of patterns

architectural patterns

applied stuart

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