This is just a really simple stub XTDB instance that starts an HTTP server on port 3030.
You can use this to try out the XTDB REST API, such as by using tekacs/xtdb-ts.
For production use, you should update and customize the configuration in src/http.clj.
To get started, just run ./run.sh with a recent Clojure distribution installed.
It might be interesting to package this as a JAR to make it easily runnable for anyone with a JVM. It's not hard, but... eventually -- PRs to that end welcome.