Extending a Base Product For Multiple Customers

ESUG 2012

Extending a Base Product for Multiple Customers

Denis DefreyneMediaGeniX NG

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“ Your product is cool,but it’s missing feature X!

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— CUSTOMER

“Yes, feature X would be nice…for you, but nobody else!

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— YOU

“Why did you notimplement feature X? :(

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— CUSTOMER

“Ugh, this product isgetting bloated! :(

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— OTHER CUSTOMER

Contents

1. Customisations2. Techniques3. Modules

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1. Customisations

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Customisation =extra bits of code

for a single customer

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Customisations

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‣ New functionalitye.g. new issue checks (no porn at noon)

‣ Extended functionalitye.g. extra metadata on films, contracts, …

‣ Changed functionalitye.g. parental rating management in UK, Finland

Integrations

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‣ Playout server‣ Commercial scheduling system‣ Music scheduling system‣ …

unique for every customer!

Customisations areonly possible if you

have FEW customers

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Requirements

‣ Be customer-specific‣ Be fine-grained‣ Allow merging bugfixes‣ Be decoupled

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Why?

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‣ Talk to other devicesYou’ll have static on your TV otherwise

‣ Cater to a diverse marketNo two broadcasters have the same workflow

‣ Resolve conflicting requirementsDon’t compromise, let them both have it their way

‣ Make customers happy!But don’t over-do it :)

2. Techniques

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Techniques

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1. Site classes2. Behaviors3. Convenience methods

Techniques

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Site classes – example

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Site class =subclass for one

specific customer

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Site = customer

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Site classes

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Film

Site classes

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Film

FilmMTV

MTV

Site classes

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Film class >> siteClassForMTV

^FilmMTV

BASE

Site classes

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newAustinPowersFilm

^Film siteClass newtitle: 'Adventures at ESUG';duration: (Duration fromMinutes: 93);yourself

WHATS’On code for MTV only

Packages

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MTV

BASE

FRAMEWORK

WHATS’On code shared between customers

MediaGeniX framework code

Packages

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MTV

VTM

VRT

TV2NRK

SBS FI NPO

VPRO

PRO7

FOX FTO …

Extensions in packages

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PACKAGE A

MusicClipMusicClip>>titleMusicClip>>videoFileMusicClip>>audioFileMusicClip>>is16Plus

PACKAGE B

MusicClip>>contractMusicClip>>agency

ContractAgreement

MTV

Site classes

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Film class >> siteClassForMTV

^FilmMTV

Site classes

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BASE

FilmMusicClipCommercial

MTV

FilmMTV

Film>>siteClassForMTV

Film >> siteClassForMTV

Film siteClass new

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FRAMEWORK

Site classes

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Class >> siteClass^Site current siteClassOf: self

MTV

Site classes

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SiteMTV >> siteClassOf: aClass^aClass siteClassForMTV

BASE

Site classes

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Site >> siteClassOf: aClass^aClass

BASE


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Film class >> buildSuperModelWith: aBuilder

super buildSuperModelWith: aBuilder.

aBuilderaddString: #title name: 'Title';addDuration: #duration name: 'Duration'

BASE


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aBuilderaddString: #title name: 'Title';addDuration: #duration name: 'Duration'

MTV


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FilmMTV class >> buildSuperModelWith: aBuilder


aBuilderaddString: #idForMTV name: 'ID for MTV'


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BASE


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FilmEditor class >> form

^self newFormaddFormField: #title;addFormField: #duration;yourself

MTV


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FilmEditor >> siteClassForMTV

^FilmEditorMTV

FilmEditorMTV class >> form

^super formaddFormField: #idForMTV;yourself


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BASE


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^self newFormaddFormField: #title;addFormField: #duration;addFormField: #imdbRating;yourself


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BASE


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Film >> openInEditor

^FilmEditor siteClassopenWithEditee: self

Call #siteClass everywhere?

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YES!It’s not as bad as you may think…

PRO TIPAvoid long methods

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Techniques

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Behaviors

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Product

Film Commercial MusicClip

Product

ProductMTV

Behaviors

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Behaviors

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Product


Behaviors

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Product


ProductBehavior

ProductBehaviorMTV

Behavior class =siteclassable class with

behavior from original class

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FRAMEWORK

Behaviors

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BehaviorObject class >> newOn: anObject

^self neworig: anObject;yourself

BASE

Behaviors – example

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Product >> hasValidCertForTx: aTx

^self certification isOkayForTx: aTx

BASE


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ProductBehavior >> hasValidCertForTx: aTx

^self orig certification isOkayForTx: aTx

MTV


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ProductBehaviorMTV >> hasValidCertForTx: aTx

^self orig videoFiles allSatisfy:[:f | f certification isOkayForTx: aTx]

BASE


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Product >> hasValidCertForTx: aTx

^self behavior hasValidCertForTx: aTx

BASE


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Product >> behavior

behavior ifNil: [behavior := ProductBehavior siteClass newOn: self].^behavior

PRO TIP

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Prefer compositionover inheritance

Techniques

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Convenience method =commonly implemented

or overridden method

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Convenience methods

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buildSuperModelWith: aBuilder

addToolsMenuItemsTo: aMenu

addCommandsToToolBar: aToolBar

Convenience methods

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buildSuperModelWith: aBuilderbuildSuperModelForMTVWith: aBuilder

addToolsMenuItemsTo: aMenuaddToolsMenuItemsForMTVTo: aMenu

addCommandsToToolBar: aToolBaraddCommandsToToolBarForMTV: aToolBar

MTV

Convenience methods

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FilmMTV class >> buildSuperModelWith: aBuilder



MTV

Convenience methods

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Film class >> buildSuperModelForMTVWith: aBuilder

super buildSuperModelForMTVWith: aBuilder.


FRAMEWORK

Convenience methods

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Site >> buildSuperModelWith: aBuilder for: aClass

aClass buildSuperModelWith: aBuilder

MTV

Convenience methods

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SiteMTV >> buildSuperModelWith: aBuilder for: aClass

super buildSuperModelWith: aBuilder for: aClass.

aClass buildSuperModelForMTVWith: aBuilder.

PRO TIP

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Use convenience methods for common methods only

Techniques to avoid

‣ BranchesUse them, but not for customer-specific code

‣ VisualWorks “overrides”They prevent access to original code

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Techniques

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3. Modules

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Module =pluggable componentthat provides a set ofrelated functionalities

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Example modules

‣ Contract management‣ Secondary events (logos)‣ Video on demand

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BASE

Super models in modules

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superbuildSuperModelWith: aBuilder.

aBuilder" … other attributes here … "addReference: #contract

to: Contract name: 'Contract'

WR

ON

G

MTV

Activating modules

SiteMTV >> moduleClasses

^OrderedCollection newadd: ContractModule;add: SecondaryEventsModule;yourself

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BASE


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Film class >>buildSuperModelForContractModuleWith: aBuilder

superbuildSuperModelForContractModuleWith: aBuilder.

aBuilderaddReference: #contract

to: Contract name: 'Contract'

FRAMEWORK


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aClass buildSuperModelWith: aBuilder.

FRAMEWORK


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aClass buildSuperModelWith: aBuilder.

self modules do:[:m |m buildSuperModelWith: aBuilder for: aClass].

FRAMEWORK


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Module >> buildSuperModelWith: aBuilder for: aClass

"nothing by default"

BASE


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ContractPresentModule >> buildSuperModelWith: aBuilder for: aClass

aClass buildSuperModelForContractModuleWith:aBuilder.

Extensions in modules

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BASE


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form := self newForm.form addFormField: #title.form addFormField: #duration.^form

BASE


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form := self newForm.form addFormField: #title.form addFormField: #duration.form addFormField: #contract.^form

WR

ON

G

BASE


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form := self newForm.form addFormField: #title.form addFormField: #duration.ContractModule current

addFieldsTo: form for: self.^form

BASE


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ContractPresentModule >> addFieldsTo: aForm for: anEditor

anEditor addContractFieldsTo: aForm

BASE


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FilmEditor >> addContractFieldsTo: aForm

aForm addFormField: #contract.

BASE


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ContractAbsentModule >> addFieldsTo: aForm for: aSender

"nothing by default"


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CONTRACT


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CONTRACT

Site classes vs. modules

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‣ Modules can be shared across sites

‣ Modules require hooks

Recap

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Techniques

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‣ Use site classeswhenever possible

‣ Use behaviorswhen site classes fail (inheritance trees)

‣ Use moduleswhen you need more separation

Requirements

‣ Be customer-specific (with packages)‣ Be fine-grained (with site classes)‣ Allow merging bugfixes (with packages)‣ Be decoupled (with site classes and modules)

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“ Your product is cool,but it’s missing feature X!

— CUSTOMER

“ Do not worry.We’ll implement it for you!

— YOU

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? MAIL [email protected] TWITTER @ddfreyne GITHUB github.com/ddfreyne

Extra Slides

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FRAMEWORK

Site classing modules

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Site >> modules

^self moduleClasses collect:[:c | c siteClass new]

FRAMEWORK

Site classing modules

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SuperModellary >> buildSuperModelFor: aClass

builder := SuperModelBuilder new.

Site current buildSuperModelWith: builder for: aClass.

supermodels at: aClass put: builder superModel.

BASE


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form := self newForm.form addFormField: #title.form addFormField: #duration.ContractModule current

addFieldsTo: form for: self.^form

BASE


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form := self newForm.form addFormField: #title.form addFormField: #duration.ContractModule current isAvailable ifTrue:

[form addFormField: #contract].^form

BASE


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Film >> isLegallyBroadcastable

^ContractModule current isAvailableifFalse: [true]ifTrue: [self contract isSigned].

BASE


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^ContractModule current isAvailableifFalse: [true]ifTrue: [self contract isSigned].

BASE


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^ContractModule currentisFilmLegallyBroadcastable: self

BASE


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ContractPresentModule >> isFilmLegallyBroadcastable: aFilm

^aFilm contract isSigned

BASE


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ContractAbsentModule >> isFilmLegallyBroadcastable: aFilm

^true

Extending a Base Product For Multiple Customers

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