# Reductionist

Reductionist is a web service that provides an API to perform reductions on numerical data stored in an S3-compatible object store.
By implementing these reductions in the storage system the volume of data that needs to be transferred to the end user is vastly reduced, leading to faster computations.

The work is funded by the [ExCALIBUR project](https://www.metoffice.gov.uk/research/approach/collaboration/spf/excalibur) and is done in collaboration with the [University of Reading](http://www.reading.ac.uk/).

This site provides documentation for the Reductionist application.
Documentation for the source code is available on [docs.rs](https://docs.rs/reductionist/latest/reductionist/).

This is a performant implementation of the Active Object Storage server.
The original Python functional prototype is available [here](https://github.com/stackhpc/s3-active-storage-prototype).

Note: The original S3 Active Storage project was renamed to Reductionist, to avoid confusion due to overuse of the term Active Storage.

## Features

Reductionist provides the following features:

* HTTP(S) API with JSON request data
* Access to data stored in S3-compatible storage
* Basic numerical operations on multi-dimensional arrays (count, min, max, select, sum)
* Perform calculations on a selection/slice of an array
* Perform calculations allowing for missing data
* Compressed data (GZip, Zlib)
* Filtered data (byte shuffle)
* Data with non-native byte order (endianness)
* Server resource (CPU, memory, files) management
* [Prometheus](https://prometheus.io/) metrics
* Tracing with an option to send data to [Jaeger](https://www.jaegertracing.io/)
* Ansible-based containerised deployment

## Related projects

* [PyActiveStorage](https://github.com/valeriupredoi/PyActiveStorage) is a Python library which performs reductions on numerical data in data sources such as netCDF4. It has support for delegating computation to Reductionist when the data is stored in an S3-compatible object store.