nyaraka will collect the data in an Omeka instance using its API and persist it to the file system. nyaraka was used as a name because it is Swahili for archive, and omeka is also a Swahili word that means "to display or layout goods or wares; to speak out; to spread out; to unpack".1
pip install nyaraka
nyaraka.py http://omeka.example.org
If you want to collect private items and user information you'll need an API key:
nyaraka.py --key sldkjslkjflkjdflkjsdfkljs http://omeka.example.org
nyaraka is single threaded, so there will only be one request issued at a time. But if you want to be extra polite and sleep a little bit between requests you can use the --sleep option:
nyaraka.py --sleep .5 http://omeka.example.org
Since Omeka's database schema requires one-to-many relationships between collections and items, and items and files, the metadata and media files are written to disk using the following naming scheme:
{archive-dir}/collections/{collection-id}/items/{item-id}/files/{file-id}/original.jpg
For example:
omeka.example.org
omeka.example.org/site.json
omeka.example.org/collections
omeka.example.org/collections/1
omeka.example.org/collections/1/collection.json
omeka.example.org/collections/1/items
omeka.example.org/collections/1/items/1
omeka.example.org/collections/1/items/1/item.json
omeka.example.org/collections/1/items/1/files
omeka.example.org/collections/1/items/1/files/1
omeka.example.org/collections/1/items/1/files/1/fullsize.jpg
omeka.example.org/collections/1/items/1/files/1/original.jpg
omeka.example.org/collections/1/items/1/files/1/file.json
omeka.example.org/collections/1/items/1/files/1/thumbnail.jpg
omeka.example.org/collections/1/items/1/files/1/square_thumbnail.jpg
If collections are not used by the Omeka instance then the collections portion of the path will be omitted.