K2 is implemented in pure Java™, under JDK 1.2. It is provided as a .jar file, about 850 K, and requires ORO's Perl module for doing regular expression matching, and JGL for handling collections. Its OQL/ODL implementation is based on the ODMG 2.0 specification, with some additions, and a few portions that are not yet implemented.
The following technical documents are (or will be) available:
Connecting to a Data Source Using a DDD
Connecting to a JDBC Database
Connecting to a Website
Distributed Processing in K2
Writing a New K2 Function
If you're connecting to the K2 server intallation at GlaxoSmithKline, some additional technical documents are available.