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Wrapper-based evolution of legacy information systems. Philippe Thiran Jean-Luc Hainaut Djamal Benslimane. By:- Kiran Yayavaram. Introduction . Legacy data-Intensive Applications Data management Systems Wrappers Data Integrity Data Consistency.
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Wrapper-based evolution of legacy information systems Philippe Thiran Jean-Luc Hainaut Djamal Benslimane By:- Kiran Yayavaram
Introduction • Legacy data-Intensive Applications • Data management Systems • Wrappers • Data Integrity • Data Consistency
Wrapper Based Strategies for Information Systems Evolution & Migration • Role of Wrappers in Systems Evolution & Migration • Translate Data & Queries from the legacy data model and interface to those expected by the new component. • Take Charge of Validation logic that ensures data integrity. • Database is migrated first. New Components are developed on this new database, while the legacy components are interfaced through wrappers
Types of Wrappers • Forward Wrappers • Validation logic that ensures data Integrity. These emulate the new technology based on the legacy one. • Backward Wrappers • Model Conversion is the only responsibility. These emulate the legacy technology on top of the new one
Approaches for wrapper Implementation • Wrapper Transparency • Update Facilities
Wrappers…. • Building Wrappers • Wrapper Schema Definition • Mapping Definition
Wrapper Architecture • Wrapper Architecture
…[Wrapper Architecture] • Wrapper Query/Update Analysis • Error Reporting • Query/Update and Data Translation
Abstract specification of a Wrapper • Model and Schema Specification • Transformational Mapping Specification • Implicit Constraints and Schema Interpretation
Wrapper Development • Generic Methodology • Database Reverse Engineering for Schema Definition [DBRE] • Wrapper Generation • Tool Support
Metrics of wrapper development cost Factors • Underlying DBMS to which the wrapper is dedicated • Size of the database and wrapper schemas • Number and the type of schema transformation of the sequence
Conclusion Wrappers….. • Proves to be the core technology that allows a smooth transition to modern architectures. • Easier integration of a legacy database into current large applications • They relieve modern client components from the responsibility of controlling data integrity • Error Recovery & Transaction management