Coldewey Consulting Publications on Database Access

Using a database is much more than just decide on a product and start to program. Rather there are certain technical problems you have to solve over and over again. In my work together with Wolfgang Keller I have analyzed the popular access techniques and described them, mostly using the pattern paradigm. These techniques apply regardless of the overall architecture to components as well as to persistency services and to good old layered architectures.

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Database Technology

I also recommend Wolfgang Keller's "Object/Relational Access Layers - A Roadmap, Missing Links and More Patterns", which still is the most detailled and comprehensive overview over the subject I'm aware of.

Wolfgang Keller, Jens Coldewey:

Relational Database Access Layer

in Robert C. Martin, Dirk Riehle, Frank Buschmann (Eds.): Pattern Language of Programm Design 3, Addison-Wesley, 1997

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This pattern language for relational database access layers helps you to design database applications that reflect relational calculus at a business object level. Such applications are known as data-driven or representational. These systems need not be object-oriented; you may also use a 3GL. Hence the pattern language does not cover mapping, inheritance and polymorphism. ...

Designing an application that uses a relational database means coping with an array of problems. How do you ensure adequate performance? How and where in your system should you code SQL statements? How do you deal with performance optimizations like denormalization of the data model that might cause a partial rewrite of your SQL code? What interface should an application kernel object use to access the data stores?

In a three-layer architecture, it is a proven technique to encapsulate aspects of database access in a database access layer. This paper presents a framework and a set of patterns that help you to design database access layers for relational databases.

Available as zipped MS Word from Wolfgang Keller's Website

Jens Coldewey:

An Access Layer for Object Databases

in Mary Loomis, Akmal B. Chaundhri (Eds.): Object Databases in Practice, Prentice-Hall, 1997

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Is it a good idea to employ a database access layer for object databases? This article describes a database access layer that has been successfully implemented for a single-user CAD system. It outlines the forces and sketches the design

There is no online version available

Jens Coldewey, Wolfgang Keller:

Objektorientierte Datenintegration - ein Migrationsweg zur Objekttechnologie

Objekt Spektrum Juli/August 1996, Nr. 4, Seite 20-28. (available in German only)

Viele Unternehmen versprechen sich von einem Einstieg in objektorientierte Technologie verbesserte Möglichkeiten zur Wiederverwendung und die einfachere Entwicklung von verteilten Systemen. Gerade bei Großanwendern, wie Banken und Versicherungen, werden dabei häufig bestehende Systeme abgelöst, die eine monolithische, transaktionsorientierte Architektur aufweisen. Eine "Stichtagsablösung" ist riskant und meist auch nicht durchführbar.

Der Artikel diskutiert die objektorientierte Datenintegration als Migrationsstrategie, bei der Altsysteme und neue Applikationen auf den gleichen Datenbeständen arbeiten. Die typischen Probleme werden erläutert und Lösungswege skizziert.

Available in German as HTML from Wolfgang Keller's Website

Jens Coldewey:

Choosing a Database Technology

Tutorial held at Object World 98, Frankfurt, Germany on October 1st 1998

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One of the important issues facing many companies today is their choice of strategy for Object Data Management. Since a database plays such a crucial role within a company, it is vital to evaluate the alternatives and make an informed choice. This tutorial analyses the important factors and forces that need to be observed in the decision for a particular technology. Rather than analyzing existing products it shows how to assemble decision matrices in large IT organizations. Thanks to Akmal Chaundhri for his support in compiling this tutorial.

Available as Acrobat PDF file [3.7 MB]

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Author: Jens ColdeweyLast change: March 12th 2001