Last night I released the first draft specification of a new, simple, open API for Java-based OLAP. This specification is called olap4j.

Who’s behind olap4j? Well, I initiated it, because strongly feel that a standard API will benefit mondrian. But other people agree that it will be good for BI in general. Various companies and projects are represented on the specification committee, and we’re open to more.

What does olap4j mean for mondrian? At first glance, it would seem that an open standard would make it easier for people to migrate away from mondrian, and would reduce mondrian’s market share.

But that’s not how it works. It’s well known that open source projects thrive when a standard API allows them to compete with each other and with commercial products. We expect olap4j to have the same effect on mondrian. Using olap4j, it will be possible to write an OLAP application on one server, say mondrian, and run it on another, say Microsoft Analysis Services via olap4j’s XML/A driver. I would also like to see drivers for other open-source OLAP servers such as PALO and OpenOLAP. And olap4j should spur development of new OLAP client tools. Users will be free to choose whichever OLAP server and OLAP client fits their needs best - which should increase adoption of mondrian.

Transitioning to a new API won’t be painless for existing mondrian users. I made a post to mondrian’s Open Discussion forum to discuss how olap4j will affect them.

To find out more, visit Download the specification, and subscribe to the olap4j forum and mailing list at SourceForge. Most important, get involved in the review process, and let us know what you’d like to see in an OLAP API.

And watch this space. As the specification evolves over the next few months, I’ll be writing more about it at this blog.