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ABSTRACT

Object/Relational Mapping (ORM) provides a methodology and mechanism for object-oriented systems to hold their long-term data safely in a database, with transactional control over it, yet have it expressed when needed in program objects. Instead of bundles of special code for this, ORM encourages models and use of constraints for the application, which then runs in a context set up by the ORM. Today's web applications are particularly well-suited to this approach, as they are necessarily multithreaded and thus are prone to race conditions unless the interaction with the database is very carefully implemented. The ORM approach was first realized in Hibernate, an open source project for Java systems started in 2002, and this year is joined by Microsoft's Entity Data Model for .NET systems. Both are described here.

REFERENCES

• 1: Atul Adya , José A. Blakeley , Sergey Melnik , S. Muralidhar, Anatomy of the ADO.NET entity framework, Proceedings of the 2007 ACM SIGMOD international conference on Management of data, June 11-14, 2007, Beijing, China [doi>10.1145/1247480.1247580]
• 2: Ambler, S., 2003. Agile Database Techniques, Wiley
• 3: Christian Bauer , Gavin King, Java Persistence with Hibernate, Manning Publications Co., Greenwich, CT, 2006
• 4: BEA 2006, Kodo Developer's Guide for JPA/JDO http://e-docs.bea.com/kodo/docs41/full/html/index.html
• 5: Philip A. Bernstein , Sergey Melnik, Model management 2.0: manipulating richer mappings, Proceedings of the 2007 ACM SIGMOD international conference on Management of data, June 11-14, 2007, Beijing, China [doi>10.1145/1247480.1247482]
• 6: Peter Pin-Shan Chen, The entity-relationship model—toward a unified view of data, ACM Transactions on Database Systems (TODS), v.1 n.1, p.9-36, March 1976 [doi>10.1145/320434.320440]
• 7: Hibernate, http://www.hibernate.org
• 8: IBM, 2007 Feature Pack for EJB 3.0 for WebSphere Application Server V6.1http://www-1.ibm.com/support/docview.wss?rs=177&uid=swg21287579
• 9: Sergey Melnik , Atul Adya , Philip A. Bernstein, Compiling mappings to bridge applications and databases, Proceedings of the 2007 ACM SIGMOD international conference on Management of data, June 11-14, 2007, Beijing, China [doi>10.1145/1247480.1247532]
• 10: MSDN Library, 2006 The ADO.NET Entity Framework Overview, http://msdn2.microsoft.com/en-us/library/aa697427(VS.80).aspx
• 11: Oracle, 2008, Oracle TopLink 11g Preview, http://www.oracle.com/technology/products/ias/toplink/preview/index.html
• 12: Unified Modeling Language. http://www.uml.org/

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.2 DATABASE MANAGEMENT
      H.2.1 Logical Design
          Subjects: Data models

Additional Classification:
  D. Software
  D.2 SOFTWARE ENGINEERING
        D.2.11 Software Architectures
            Subjects: Data abstraction
      D.2.2 Design Tools and Techniques
          Subjects: Object-oriented design methods

  H. Information Systems
  H.2 DATABASE MANAGEMENT
      H.2.3 Languages
          Subjects: Database (persistent) programming languages
      H.2.8 Database applications

General Terms:
Algorithms, Design, Languages

Keywords:
data model, entity data model, hibernate, impedance mismatch, object-relational mapping, persistence, schema mapping