The Dublo Architecture Pattern for Smooth Migration of Business Information Systems: An Experience Report

ABSTRACT

While the importance of multi-tier architectures for enterpriseinformation systems is widely accepted and theirbenefits are well published, the systematic migration frommonolithic legacy systems toward multi-tier architectures isknown to a much lesser extent. In this paper we present apattern on how to re-use elements of legacy systems withinmulti-tier architectures, which also allows for a smooth migrationpath. We report on experience we made with migratingexisting municipal information systems towards a multitierarchitecture. The experience is generalized by describingthe underlying pattern such that it can be re-used forsimilar architectural migration tasks. The emerged Dublopattern is based on the partial duplication of businesslogic among legacy system and newly deployed applicationserver. While this somehow contradicts the separation-of-concernsprinciple, it offers a high degree of flexibility inthe migration process and allows for a smooth transition.Experience with the combination of outdated databasetechnology with modern server-side component and webservices technologies is discussed. In this context, we alsoreport on technology and architecture selection processes.

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Index Terms

• Applied computing

  • Enterprise computing

    • Business process management

• Information systems

  • Information systems applications

• Software and its engineering

  • Software creation and management

    • Software post-development issues

      • Software reverse engineering

  • Software notations and tools

    • General programming languages

      • Language features

        • Patterns

  • Software organization and properties

    • Software system structures

      • Distributed systems organizing principles

        • Client-server architectures

      • Software architectures