Structure and terminology
The essence of Research Cloud is that users can run compute Resources (like Virtual Machines) on a cloud system. The compute resources are turn-key configured according to Applications that are offered in Research Cloud's catalog. An Application that is selected and started, results in a Workspace - an actual Resource that can be logged into and that can be used. Technically, the Research Cloud catalog consists of four main components:
Plugins
Applications
Subscriptions
Application Offerings
Plugin
A plugin is one script (typically an Ansible Playbook) that realizes a particular feature in a workspace. This feature might be OS-related, like an alternative login method. Or a plugin might, for instance, install a particular software package.
Application
An application is a sequence of plugins that are run in a given order when a workspace is created.
ApplicationOffering
Application offerings are the user-facing component of Research Cloud. An application offering is a "ready to use" application that specifies which application is deployed on which cloud with a particular size (flavour) to form a usable workspace for the user.
Subscription
Subscriptions embody the right to deploy resources/workspaces on a particular cloud through particular (but undisclosed) credentials. Like with all other catalog items, the access to a subscription can be controlled in great detail through collaborations.