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20040428 Wednesday April 28, 2004

Why Hibernate Rocks - easy database switching The app I've been developing over the last 6 months is going live next week. As part of that process, my client decided they wanted to put the production database on their AS400, rather than their JDE/WebSphere/DB2 Server. Hibernate and AppFuse made this super-easy. Add the JDBC Driver, specify a new dialect/jdbc url/driver name, and voila - we're talking to DB2400! After creating the initial tables using Ant we noticed that the table names were too long since the 400 has a limit of 10 characters. To fix this, I simply modified my XDoclet @hibernate.class table="..." to have shorter table names. After that, I simply had to re-arrange a few tables in my sample-data.xml file (for DBUnit) to avoid referential integrity issues. All-in-all, we migrated from MySQL to DB2 on an AS400 in a little under an hour this morning. Hibernate makes my development life soooo much easier. Posted in Java at Apr 28 2004, 11:53:43 AM MDT 7 Comments

Comments:

I like the benefits of database abstraction too (for example, I maintain a Hibernate-based app that different clients run with MySQL, MS SQL Server, and Oracle). But when I move something for the first time I always still have small hassles. Hassles such as limitations on field length, reserved words (e.g. can't use "User" as a table name in Oracle) and referential integrity issues when deleting data. Admittedly, the referential problems could be called bugs that MySQL never complained about. My point is don't trust the system works 100% on a new database until it's had a bit of a shakedown. Good dbunit (or similar) tests help, of course.

Posted by Will on April 28, 2004 at 02:01 PM MDT #

This has been my experience (minus the XDoclet stuff since I don't use that) with both of the other ORM tools that I've used in the past (OJB and JRF).

Posted by inignokt on April 28, 2004 at 02:32 PM MDT #

On an AS/400 or iSeries which is what IBM calls it now, table names can be 128 characters. If the client used DDS, the old way, the table names are limited to 10. A table can have 2 names, System name and DB2 name. The system name is limited to 10. Same table just 2 different views of the "Catalog". In SQL (JDBC or ODBC), you will see the 128 length names. In RPG or Cobol you will see only the 10 characters.

Posted by Raymond Phillips on April 28, 2004 at 04:57 PM MDT #

Good to know it works with DB2400. I have a new client who has all his data on an iSeries, so interfacing with DB2400 is a must. But my iSeries knowledge is not as good as I would like it to be. Anyone know of good resources (besides developerWorks) or books on developing Java web apps interfacing with iSeries?

Posted by dsuspense on April 28, 2004 at 05:02 PM MDT #

Matt, Another too which does as good a job as Hibernate, however without the HQL to deal with, is OJB. That said, OR tools are just absolutely fabulous for making our lives easier. R

Posted by Robert S. Sfeir on April 29, 2004 at 05:57 AM MDT #

A good place to find iSeries books are redbooks from IBM. www.redbooks.ibm.com is the URL. When you get to the web page , on the left pane, select the iSeries redbook domain.

Posted by Raymond Phillips on April 29, 2004 at 08:22 AM MDT #

I also found this article over at MidrangeServer.com.

Posted by dsuspense on April 29, 2004 at 01:01 PM MDT #

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