Warum muss Software weiterentwickelt werden? Was sind die Herausforderungen eines Modernisierungsprojektes? Was sind Vorteil und Nutzen der modellbasierten Migration?

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© itemis AG
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Modernisierung von (Alt-)Anwendungen
Jens Trompeter
26.11.2014

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© itemis AG
Agenda
§ Migration (Warum? Was? Wie?)
§ Modellbasierte Migration
§ Vorteile / Nutzen
2

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© itemis AG
Warum muss Software ständig weiterentwickelt werden?
Die Umwelt ändert sich
3
§ Neue oder geänderte
§ fachliche Anforderungen
§ technische Anforderungen
§ Randbedingungen

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© itemis AG
Software-Entropie
Wartung vs. Modernisierung
4
Lehman, M. M.; Belady, L.A. (1985), Program evolution: processes of software change:
1. A computer program that is used will be modified
2. When a program is modified, its complexity will increase, provided that one does not
actively work against this.
§ Wartung: unterbrechungsfreie
Weiterentwicklung (in kleinen Schritten)
§ Modernisierung: großer Schritt, Plattform-
Wechsel

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© itemis AG
Modernisierung
Was bedeutet das?
5
Wechsel ...
• der Programmiersprache
• Neues Programmierparadigma
• z.B. RPG → Java, Fortan → C#, PL/SQL → Java
• der Laufzeitumgebung
• Oracle Forms à Java-Stack (Eclipse Scout, Spring, EclipseLink, ...)
• RPG-Runtime à Java-Stack (JSF, Spring, Hibernate, ...)
• der Plattform / Betriebssystem
• System z (Host) → Unix
• System i (AS/400) → Unix/Windows

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© itemis AG
Modernisierung – Warum?
6
§ Warum?
§ Technische Zwänge (z.B. auslaufender Support)
§ Steigende Wartungskosten und Betriebskosten
§ „Know-how geht in Rente“
§ Akzeptanz (z.B. User Experience, Erlernbarkeit, ...)
§ Attraktivität und Marktchancen

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© itemis AG
Besondere Herausforderung von Migrationsprojekten
7
§ Große Projekte
§ Fehlende Dokumentation
§ Fehlende (autom.) Tests
§ Bottle-Neck-Ressourcen / Kopfwissen
§ Gewachsene, nicht harmonische Strukturen
§ Parallele Weiterentwicklung / Code-Freeze
§ Weiterbildungsaspekte (Prozesse, Methoden, Technologien, Tools, ...)
§ Neben SW-Migration auch Datenmigration

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© itemis AG
Variante 1 – Manuelle Migration
8
Altsystem Manuelle Migration Zielsystem
Vorteil:
§ Potential zur
Restrukturierung
Nachteile:
§ Parallele Entwicklung von Alt- und Neusystem
§ Zeit-, Personal- und Kostenintensiv
§ Homogenität des Zielsystems schwer sicherzustellen
§ Konsistenz zum Altsystem schwer nachweisbar
Scheitert oft!

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© itemis AG
Variante 2 – Automatisierte Migration mit Standard-Werkzeug
9
Altsystem Standard-Werkzeug Zielsystem
Vorteile:
§ Fertiges Werkzeug
§ Zeitersparnis
§ Ggf. Kostenersparnis
Nachteile:
§ Werkzeug und Zielarchitektur nicht anpassbar
§ Weiterentwicklung sehr aufwendig/nicht
möglich
§ Abhängigkeit vom Werkzeughersteller
Wartbarkeit bleibt schlecht!

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© itemis AG
Variante 3 – Modellbasierte Migration
10
Altsystem Modellbasierte Migration mit
angepassten Werkzeugen
Zielsystem
10
Bester Kompromiss!

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© itemis AG
Modellbasierte Migration
11
4 321

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© itemis AG
JJJJJ
Modellbasierte Migration (Analyse & Extraktion)
12
4 321
Das Altsystem stellt ein
wertvolles Investment dar.
Es gilt möglichst viel des
existierenden Altsystems zu
extrahieren und zur
Erstellung des neuen
Systems zu nutzen.
Zu Beginn der Migration
erfolgt die Analyse des
Altsystems mit dem Ziel,
Strukturen im Code und in
der Datenhaltung zu
erkennen.
1

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© itemis AG
JJJJJ
Modellbasierte Migration (Analyse & Extraktion)
13
4 321
Aus bestimmten Teilen des
analysierten Altsystems
werden formale Modelle mit
höherer Abstraktion
abgeleitet.
Die Modelle decken
unterschiedliche Aspekte
(Frontend, Business-Logik,
Daten, etc.) ab, die aus dem
Altsystem automatisiert
extrahiert werden. Weitere
Modelle zur
Vervollständigung der
Systembeschreibung
können manuell ergänzt
werden.
Die Modelle werden dann
als Input für den Generator
des Zielsystems verwendet.
2

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© itemis AG
JJJJJ
Modellbasierte Migration (Zielarchitektur)
14
4 321
Die (grobe) Zielarchitektur
muss vor dem Anpassen
des Generators feststehen.
Alle Aspekte der
Zielarchitektur werden
manuell in Form einer
Referenzimplementierung
umgesetzt.
Aus der Referenz-
implementierung werden
die Abbildungsvorschriften
(Templates) für den
Generator abgeleitet.
3

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© itemis AG
JJJJJ
Modellbasierte Migration (Generatorbau)
15
4 321
Der Generator erzeugt
mittels der Templates das
Zielsystem.
Das generierte Zielsystem
wird durch manuellen Code
vervollständigt.
Die sukzessive
Verfeinerung des
Zielsystems führt in einem
iterativen Prozess zu einer
entsprechenden
Verfeinerung des
Generators.
4

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© itemis AG
Modellbasierte Migration
16
4 321

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© itemis AG
(Teil-)automatisierte Erstellung des Zielsystems
Qualität und Produktivität
17
§ Effizienzsteigerung, Produktivitätsverbesserungen
§ Automatisierung wiederholbarer Abläufe
§ Wiederverwendung
§ Reduzierung von Routinetätigkeiten
§ Automatisierte Erstellung von Dokumentation und Tests
§ ...
§ Qualitätsverbesserung, Verbesserung der Wartbarkeit
§ Stringente, automatisierte Umsetzung einer wohldefinierten Architektur
§ Weniger Kopfmonopole
§ Trennung von Fachlichkeit und Technik
§ Leichtere, zentrale Fehlerbehebung
§ ...

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© itemis AG
Vorteile und Nutzen modellbasierter Migration
18
Zielarchitektur
Automatisierung
Weiterentwicklung
↪ 100% Freiheit bei der Definition der Zielarchitektur
↪ Konsistente Umsetzung der Zielarchitektur durch Code-Generierung
↪ Fachlich versierte Altsystem-Entwickler leicht einzubinden
Optimierung von
↪ Qualität
↪ Kosten
↪ Zeit
Die moderne Entwicklungsplattform ermöglicht
↪ einfache Anpassungen
↪ kostengünstige Wartung
durch
§ Passgenaue Automatisierung
erzeugt wartbare Software
§ Kurze Freeze-Time
§ Parallele Entwicklung von Alt- und
Neusystem möglich

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© itemis AG
Modellbasierte Migration
Technologien
19

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© itemis AG
itemis AG | Am Brambusch 15-24 | D-44536 Lünen | www.itemis.de
Jens Trompeter
Tel.: +49 231 9860 217
Mobil: +49 151 10860456
jens.trompeter@itemis.de