Introduction
This README describes how to develop and test a Brown Dog extractor tool, based on the template project in this repository. It also explains how you can contribute your new tool to the Brown Dog Tools Catalogue. Brown Dog Extractor Tools are used to analyse files and produce data points as a result. For example, one existing extractor uses the OpenCV software to process photographs, finding any human faces that are in a picture. You can find these and other extractor examples in the Brown Dog code repository. This repository contains a template project only. You can clone this repository to your local system and build it right away. However, until you add your custom extraction code the extractor will only report a tag of "Hello, World" for any given file.
Brown Dog Runtime Environment
The Brown Dog environment includes several services that work together to deliver the Brown Dog API. These include the Brown Dog web application, hosting the API, a RabbitMQ message broker and extractor tools running on separate hosts. Brown Dog extractors are message-based network services that process data files in response to RabbitMQ messages. The client-facing Brown Dog API receives data from a client and passes messages to the extractor message topic. Any extractors that are subscribed to the topic will receive the message and decide for themselves if they can process the data, usually by looking at the MIME type. When an extractor starts or finishes working on a file it posts status and results back onto a message queue. All communication between the Brown Dog servers and the extractor tools is handled by messaging, except for ??? ANY EXCEPTIONS ???
Docker
In general the Brown Dog extractors are developed to run within Docker containers, allowing them to be lightweight yet well described in a Dockerfile and well encapsulated along with their dependencies. This project contains a template Dockerfile that is ready to build and run within the Brown Dog environment. It can be customized to include any dependencies your extractor will need. The project also includes a docker-compose.yml file. This file can be used with the docker-compose command to create a fully functional Brown Dog runtime environment on your local machine. You can use docker-compose to deploy your extractor tool locally during development and testing.
Step-by-Step Instructions