How scalable is J2EE technology?

ECperf, the widely recognized industry standard J2EE benchmark, has attracted a large number of results submissions and their subsequent publication. However, ECperf places little restriction on the hardware platform, operating systems and databases utilized in the benchmarking process. This, combined with the existence of only two primary metrics, makes it difficult to answer critical questions such as "Is there a limit to J2EE scalability?" and "Is scale-up or scale-out more effective?". By mining the full-disclosure archives for trends and correlations we have discovered that J2EE technology is very scalable, both in a scale-up and scale-out manner. Other observed trends include, a linear correlation between middle-tier total processing power and throughput, as well as between J2EE Application Server license costs and throughput. However, the results clearly indicate that there is an increasing cost per user with increasing capacity systems, and scale-up is proportionately more expensive than scale-out.