Legacy ISAM Access Methods for Java?

GamerGeek asks: "I work for a small company in the Midwest. We have some old products written in Databus / PL/B. In my spare time I have been investigating the idea of rewriting these programs in Java. My main problem is that the programs store data in ISAM (Indexed Sequential Access Method) files. Rewriting everything all at once is not feasible so the data needs to stay in the ISAM files. I am looking for a 100% java solution for reading and updating ISAM files. A Google search does not turn up anything. Is there one out there? Does anyone know the file format / process for reading an ISAM file? I would be willing to write a package myself if I had that information and open source it too."

Comments

ISAM is not a format

[PD]

ISAM is Indexed Sequential Access Method. It's not a format. Lots of people sell ISAM libraries, but the formats are all different and non-compatible. Your best bet is to dump your data from your old ISAM files. Then reengineer the database. Write your Java apps to use the new database.

Not trivial, but not rocket science either.

it depends...

[Spudley]

It really does depend on the files themselves.

ISAM is a method of storing data, but it isn't a standard file format any more than "relational database"; it's just a name for a type of file, and there are many different ISAM files.

I'm not familiar with Databus / PL/B, so I can't speak with absolute authority, but I do have experience with a near-identical situation involving a different type of ISAM file, so with luck I might be able to at least offer some clues.

A couple of years ago, I was asked to look into the possibility of accessing our existing ISAM files in a web page.

These files were the database for a fairly old application that we sold on various flavours of Unix, and some of our clients wanted to give their customers a web front-end for ordering.

I offered three approaches:
1) Write a web interface using the same language and tools as the existing application. This would mean that the data would be easily available, as would our existing business logic.
2) Write a VB-Script web site, and use the ODBC driver that we knew was available for the ISAM files.
3) Write a Java-based web site, and try to find a JDBC driver to do the same job.

Option 1 was ruled out quite quickly for various reasons.

We eventually went with the VB route, primarily because the technology was already in place. There was a beta-test JDBC driver available, but we couldn't get it to work.

However, the important point was that we did find a company that specialises in supplying drivers for all sorts of obscure file formats.

I recommend you have a look at Trifox inc. Their Vortex and Genesis database drivers support just about every database I've ever heard of, and plenty I haven't, are available for practically every platform, and for a wide variety of languages and interfaces.

I have to confess that they weren't particularly helpful when I contacted them; it was their JDBC driver that didn't work (their ODBC driver did work, but we already had one of those), but don't let that put you off - they do seem to have a lot of expertise in the area.