SHARE - Glossary

This page provides running definitions for those terms that may be specific to virtual machine technology or the SHARE system in particular. Whenever possible, we try to use standard terminology but sometimes there are several possible interpretations of one term. Moreover, people often use different terms to denote the same thing. If you think we abuse a particular term or if we should include more terms in this glossary, please don't hesitate to contact us

  • Bundle: a container for demo environments (VDIs). Each environment belongs to exactly one bundle. A bundle is administered by an Organizer.
  • Mutable VDI (mutable environment, mutable demo image): A SHARE environment that preserves state across usage sessions. To avoid conflicts, a mutable VDI is locked for use by at most one user. More specifically, when preparing a new demo image, a demonstrator has exclusive access to a mutable VDI. Once the demo is complete, the demonstrator will release the exclusive access and SHARE the demo to all users in the bundle of that VDI (see SHARE - Publishing the new environment).
  • Session: a virtual machine that runs a demo environment for one user specifically, for an agreed duration. Users can connect to an active session using an RDP client. In most cases, we are referring to stateless sessions but sessions can also be stateful. Note that users can reconnect to the same SHARE session even when their RDP client or complete computer has crashed. However, when shutting down the operating system underlying a SHARE environment, the session will be terminated. Users can also terminate sessions by clicking Abort this VM in their list of active sessions.
  • Stateless session: a session for which all side-effects will be discarded after its use. Sessions are stateless by default, since in most cases, users want to evaluate a tool without worries about damaging the demo environment. SHARE users can safely change a complete tool configuration since they will start from the original state again when starting over.
  • Stateful session: a session for which all side-effects are persisted to the demo environment. All sessions on mutable environments are stateful.
  • VDI (Virtual Disk Image, SHARE environment, SHARE demo image): A format for storing virtual machines. A virtual disk is a persistent container of an operating system (XP, Ubuntu, ...), programs (AGG, PROM, ...) and data (solutions to case studies, ...). This term comes originally from the underlying VirtualBox technology but in SHARE, one VDI corresponds directly with one demo image. In fact, a demonstrator can send us a link to download a VirtualBox VDI file that contains a complete demo environment. After moderation, a SHARE administrator may upload it to our VM servers and make it available for scheduled/protected/secure access by SHARE users (see SHARE - Registering a new environment to a Bundle). In most cases, users may want to create demos as extensions to existing SHARE environments. When a demo is an update of another SHARE demo (e.g. the GraBaTs08 AGG demo), the upcoming demonstrator will request a mutable clone of that AGG demo. Even when a SHARE user wants to create a new demo image from scratch, he does need a basic operating system to start from. Therefore, there are special SHARE bundles (e.g. the Operating Systems bundle) available with emptly operating system environments (XP, Ubuntu, ...). These environment do not contain other tool demos.