Sanierung grosser !Software Systeme!Sibylle Peter, Dr. Dieter Holz!Canoo Engineering AG!Basel, Switzerland!

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Sibylle Peter Dieter Holz

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Inhalt

๏  Einführung

๏  Die Fallstudie: Investionsberatung für Kundenberater

๏  Die Sanierung

๏  Wie wir arbeiten

๏  Wie wird ein Sanierungsprojekt ein Erfolg?

Einführung

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Sanierungsprojekte

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Sanierungsprojekte

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Definition (Martin Fowler, Refactoring, pg. 53):

Refactoring (noun): a change made to the internal structure of software to make it easier to understand and cheaper to modify without changing its observable behavior.

Refactor (verb): To restructure software by applying a series of refactorings without changing it‘s observable behavior

Sanierung durch Refactoring

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Software Entropie

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Software Entropie

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Software Entropie

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Die Fallstudie

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Facts

๏  Produktiv und erfolgreich seit 2004

๏  Kontinuierlich weiterentwickelt

๏  320 JSP Dateien, 1800 Klassen

๏  Ca 70. funktionale Tests

๏  Wenig Unit Tests

๏  Wenig Dokumentation

๏  Hohe Fluktation, hohe Kosten, Change Requests können nicht mehr implementiert werden.

Start: Erste Analyse

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Abhängigkeiten

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Objekttypen

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Action

Java Beans

JSP

ServiceInvoker

Service

Worker

Controller Helper

Mapper

Container

HttpServlet

BusinessObject

HttpServlet

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Masterplan

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Action

Java Beans

JSP

Container

HttpServlet

BusinessObject

Facade TransferObject

HttpServlet

Util

Service Mapper

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Masterplan

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Java Beans

Service Mapper

Validator

Facade TransferObject

Action

JSP HttpServlet

Formatter

Aggregating Facade

Refactoring Teil 1

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Ziel: Neues Service Layer

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1. Schritt Strukturierung in Fassaden

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2. Schritt: Einführung von Transfer Objekten (TO)

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Presentation!Layer!

transfer objects!

JSP Java Bean Action HttpRequest

BusinessObject Converter

TransferObject

Facade

Service

Service!Layer!

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public class User extends CoreObject { private String id; private Employee userIdentity; private RoleBUManager m_roleBUManager = new RoleBUManager(); private boolean isAllowed = false; private String eMailTask; private Timestamp mutTimestamp; private String mutId;

public final class UserTO { private final String fId; private final String fEamCode; private final String fBuCode; private final String fDepartment;

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Presentation!Layer!JSP Java Bean Action HttpRequest

BusinessObject Converter

TransferObject Service!Layer!

ServiceObject

EJB Proxy

simple!

complex!

1:1!

1:n! Mapper

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Presentation!Layer!JSP Java Bean Action HttpRequest

BusinessObject Converter

TransferObject Service!Layer!

ServiceObject

EJB Proxy

simple!

complex!

structural logic m:n!

1:1! Mapper

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Validierung

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public final class AARefCurrencyTO { ... public AARefCurrencyTO(UID<AARefCurrencyTO2> uid, String eamCode, final BigDecimal manual, BUCode buCode, MutSeqNr mutSeqNr, BigDecimal sortOrder, Long language, String name) { // Preconditions: if (uid == null) throw new IllegalArgumentException(...); ... if (language > 4) throw new IllegalArgumentException(...);

// Assignments: this.uid = uid; ... }

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Fassaden Interface

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public static FrontpageText getFrontpageText (CriteriaToGetFrontpageText criteria)

throws CoreException

public CriteriaToGetFrontpageText(String buCode, User user, int entryFrom)

public static FrontpageTextTO getFrontpageText (String buCode, UserTO user)

throws CoreException

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3. Schritt: Neues Service Layer

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inTO! outTO!

Service!

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Service Interface und AbstractService

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public interface IService<TOI, TOO> { public TOO execute(TOI toi) throws CoreException; }

public abstract class AbstractService<TOI, SOI, SOO, TOO> implements IService<TOI, TOO> { public final TOO execute(final TOI toi)

throws CoreException { if (toi == null) { throw new IllegalArgumentException(“'toi' must not

be null"); } SOI soi = mapInput(toi); SOO soo = innerExecute(soi); return mapOutput(soo); }

protected abstract SOI mapInput(TOI toi); protected abstract SOO innerExecute(SOI soi)

throws CoreException; protected abstract TOO mapOutput(SOO soo); }

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Aggregierende Service Klassen

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inTO! outTO!

Services!

inTO A! outTO A!

Service A!

Service!

inTO B! outTO B!

Service B!

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4. Schritt: Einführung von Basis Typen

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// Usage example: BUCode buCode = BUCode.getFlyweight("0012");

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Fassaden Interface

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public static FrontpageTextTO getFrontpageText(BUCode buCode, EAMCode eamCode, UserTO user) throws CoreException

public static FrontpageTextTO getFrontpageText(String buCode, String eamCode, UserTO user) throws CoreException

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Resultat nach Teil 1

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Old Presentationlayer

Converter

New Servicelayer Architecture!

Design Guidelines for - Services

- TransferObjects - Basetypes

New Feature:!

RiskAnalyzer!

Change Request:!CoSa!

Refactoring von Komponenten

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Current State

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New Servicelayer Architecture!

New Business Layer

Old Presentationlayer

Converter Presentation Layer

Domain Layer

Refactored Components New Features

Old GUI Framework

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Domain Model Adapters

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public class MonitoredHoldingDO extends AbstractHoldingDO implements IMonitoredHoldingDO {

public MonitoredHoldingDO(final Holding holding) { super(holding); }

@Override protected BOInfo getBOInfo() { return new BOInfo(getHolding().getWorkingTIS(), getAssetsFromHolding (), getSafekeepingAccountsFromHolding()); }

private ImmutableMap<Integer, Asset> getAssetsFromHolding() { return HoldingDOBuilderUtil.getTisIncludedAssetsFromHolding

(getHolding(), getHolding().getWorkingTIS()); } … }

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Komponente Load Partner

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Vorgehen

๏  Code aufräumen ‣  IDE Vorschläge umsetzen (Remove unused code etc)

๏  Überschaubare Einheiten erstellen ‣ Mit Extract Method Refactoring Methoden herausziehen ‣  Abhängigkeiten zu Attributen entfernen (static methods) ‣ Move Refactoring benutzen, um diese Methoden in einer Hilfklasse

zwischenzulagern

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Vorgehen

๏  Analyse der neuen Einheiten und Design gemäss der Zielarchitektur

๏  Akzeptanz Tests definieren und mit BBD Frameworks implementieren

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Akzeptanztest

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scenario "DictionaryService can find the word 'Griffon'", { given "an instance of DictionaryService is available", { service = new DictionaryService() }

when "the word 'Griffon' is used as parameter", { result = service.findDefinition('Griffon') }

then "the definition should be found", { assert result == "Grails inspired desktop application development platform.” } }

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Akzeptanztest mit EasyB

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Vorgehen

๏  Refactoring ‣ Wenn noch nötig, Mikado Methode anwenden

๏  Messen der Code Qualität

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Sonar Dashboard

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Voraussetzungen für erfolgreiche Sanierungsprojekte?

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Wie wir arbeiten

Daily standup meeting!

Regular workshops with the customer‘s lead engineer!

Retrospective in regular

intervalls!

Lightweigth, but intensive testing process with test

team

Monthly meeting with the project manager of the

customer

Weekly reporting with the lead engineer and

architect of the customer

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Team

Experienced, dedicated developers

motivation

A disciplined approach

team size.

A lead engineer of the customers

side

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Authorität und Flexibilität

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Management support

Accepted by the team

The customers trust Flexible,

iterative planning

Involved in system design

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Weitere Voraussetzungen

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Continuous Integration

Assessment Master Plan

Automated Integration

Tests

Good Analysis Tools

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Erkenntnisse oder Best Practices

๏  Entweder technisches oder logisches Refactoring

๏  Analyse – Implementierung – Stabilisation

๏  Früher Wissenstransfer zum Core Team

๏  Investition in automatische Regressionstest

๏  Abhängigkeiten zu anderen Systemen reduzieren

๏  Automatische Qualitätssicherung

๏  Manuelles Testing braucht Zeit – genügend Zeit einplanen

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Nachhaltigkeit

๏  Code verbessern ist nicht genug

๏  Professionelle Ethik einführen

๏  Technische Schulden überwachen und ggf. beseitigen

๏  Continous Improvement: Retrospektiven

๏  Core Team muss unterstützt werden, damit neue Funktionalität in guter Qualität ausgeliefert wird.

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Warum Sanierungsprojekte?

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Bücher und Links

๏  Martin Fowler, Refactoring: Improving the Design of Existing Code

๏  Stephan Ducasse, Oscar Nierstrasz, Object Oriented Reengineering Patterns PDF: http://www.win.ua.ac.be/~sdemey/

๏  Joshua Kerievsky, Refactoring to Patterns

๏  Martin Lippert, Stefan Rook, Refactoring in Large Software Projects

๏  Behaviour Driven Development: ‣ EasyB: http://www.easyb.org/ ‣ Spock: http://code.google.com/p/spock/

๏  Sonar: http://www.sonarsource.org/

๏  Mikado Method: http://pragprog.com/magazines/2010-06/the-mikado-method

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Master Thesis @ Canoo

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Master Thesis @ Canoo

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