From the blog post:
As part of the Alveo project we’ve been using the Galaxy Workflow Engine to provide a web-based user-friendly interface to some language processing tools. ...
One of the recent updates to Galaxy is the ability to group data objects together into datasets. These datasets can then form the input to a workflow which can be run for each object in the dataset. This is something we’ve wanted for Alveo for a long time since applying the same process to all files in a collection is a common requirement for language processing. After a bit of exploration I’ve worked out how to write a tool that generates a dataset and since the documentation for this is somewhat sparse and confusing, I thought I’d write up my findings.