Esperio-tsdb is a project mainly written in Java, it's free.
Esperio Input Adapter for OpenTSDB time series database
h3. Project Description
Esperio-OpenTSDB is an EpesrIO adapter for OpenTSDB time series database. It enables connecting "Esper":http://esper.codehaus.org/ complex event processing engine to the open source "OpenTSDB":http://opentsdb.net/ time series database. The following capabilities are supported/planned:
h3. Sample Code
h3. Getting Started
h3. Development Status
h4. TODO
h3. Related Work