A Step beyond Object to Data Mapping

Richard Deadman


As Java moves beyond cute dancing applets to become a platform for distributed multi-platform computing, the race to supply the infrastructure services is starting.  This includes not only distributed "CORBAish" management services (Naming, Event Channel, Security, Trader, Administration) but also facilities for managing the data which is centric to corporate applications.  Several Object to Relational Database mapping frameworks are now becoming available, but The Object People's "TOPLink/J"tm goes beyond just mapping the data to also managing it.

You assign your best modellers to designing the logical object model and sit down yourself to solve the physical issues -- object mapping, transactions, caching, object handle faulting, object identity.  Suddenly you realize that you are going to have to build your own one-off proprietary pseudo-OO database on top of JDBC.  And doing so will involve 40-60% of the non-gui coding effort.  Surely, hopefully, someone else has run into this before.

A sure indicator of the seriousness which with Java is entering the corporate IT market are the number of Java Object to JDBC table mapping tools that are emerging on the market (Sun's upcoming JavaBlend, Thought's CocoBase, Novera's EPIC dbBlend, ChiMu's FORM, O2's JRB, Objectmatter's BSF, Software Tree's JDX, 2Link Consulting's dbGen, CrossLogic's Universe).  Some are new, some available for free, but one of the most complete turns out to be a product that isn't new at all, not at its roots anyway.  The Object People's TOPLink/Jtm is a both new and old.  While not perfect, it offers a wealth of features that makes the management of data in serious corporate applications much easier.  Presently in Beta (as of February, 1998), TOPLink/J, if priced similarly to its Smalltalk cousin, will not be a cheap product but will pay for itself in development time, effort, stability and maintainability.  The key to it's advanced standing is that The Object People have done it all before.

Before Java was a coined name for Sun's Oak project, The Object People were mentoring the building of pure OO Smalltalk systems by large corporate customers.  They saw a need for a tool to map objects into and out of the legacy relational databases that were firmly entrenched in many customer's sites.  And so, for over five years, they have been selling a tool for the Smalltalk market called TOPLink.  In this time, they extended the tool and its framework to support the management of objects as well as the mapping of them to database tables.  As a result, TOPLink supports not only object mapping, but caching, object identity, faulting, transactions, units of work and some three tier support.

Object Mapping

Caching and Object Identity


Transactions and Units of Work

Three Tier Support

Limitations and Drawbacks