Refactoring HUBzero for Linked Data

The HUBzero cyberinfrastructure provides a virtual research environment that includes a set of tools for web-based, scientific collaboration and a platform for publishing and using resources such as executable software, source code, images, learning modules, videos, documents, and datasets. Released as open source software in 2010, HUBzero has been implemented on a typical LAMP stack (Linux, Apache, MySQL, and PHP) and utilizes the Joomla! content management system. This paper describes the subsequent refactoring of HUBzero to produce and expose Linked Data from its backend, relational database, altering the external expression of the data without changing its internal structure. The Open Archives Initiative Object Reuse and Exchange (OAI-ORE) specification is applied to model the basic structural semantics of HUBzero resources as Nested Aggregations, and data and metadata are mapped to vocabularies such as Dublin Core and published within the web representations of the resources using RDFa. Resource Maps can be harvested using an RDF crawler or an Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) data provider that were bundled for demonstration purposes. A visualization was produced to browse and navigate the relations among data and metadata from an example hub