Data Modeling with DODS

Part of the Enhydra server, DODS tries to bridge object andrelational databases.

DODS is better than Alzabo at providing a nice object layer above the SQL. Moreover, it seems to provide a better and more stable set of methods for creating queries and working with their results. However, DODS suffers from several of the same problems as Alzabo and other relational-object mapping tools. Some problems include having to learn a new way to execute all of those SQL queries you've been working with for years and complex queries that can be frustrating to write, since you have to rephrase them as method calls. Also, the generic nature of a tool like DODS means that you won't get the specific benefits of your favorite database. In the case of PostgreSQL, DODS didn't seem to take foreign keys or sequences into account, both of which would have made for more solid table designs.

DODS works well when coupled with the rest of Enhydra, though. As with XMLC and super servlets, I found DODS to be somewhat overwhelming and clunky at first, and then useful and clever. As a first stab at things, DODS in Enhydra is a good attempt to bridge the gap between the object and relational worlds. I look forward to the final version of Enhydra Enterprise, which will undoubtedly push things ahead even further.

Next month, we'll look at an increasingly standard way to not only bridge the relational and object worlds, but also to add transactional capabilities to our server-side Java applications. Enterprise JavaBeans represent services and data for web applications and have become increasingly popular among web developers who want to be able to find objects, work with them and store them to a database, without having to think too hard.



Reuven M. Lerner ( owns a small consulting firm specializing in web and internet technologies. He lives with his wife Shira and daughter Atara Margalit in Modi'in, Israel. You also can reach him on the ATF home page,