2.3 Data flow systems - application builders

Data flow systems - or application builders as they are also called - are powerful visualization systems which allow the investigator to control the flow of data through a network of processing modules. In general a number of characteristics are shared by this class of visualization software.

• Modular approach - modules can be selected and combined by the investigator for a particular visualization task.
• Network - a network of modules may be composed by using a visual interface.
• Extensible - a large number of modules are provided by the system and others can be added by the investigator.

The investigator can begin by using already provided visual networks and can then proceed to modify these by selecting other modules from the provided pallette. When experience is gained, modules can be gathered from elsewhere or written oneself and then included in the system.

The result is a powerful capability to proceed by example in easy stages.

The systems summarised here are:

• Application Visualization System (AVS) version 5, from AVS Inc which is now available on most workstation ranges
• Khoros version 1, from University of New Mexico (version 2 will be available soon)
• Visualization Data Explorer (VDE) version 1.2, from IBM Inc (version 2 is becoming available)
• Iris Explorer version 2, from Silicon Graphics Inc (with versions for other workstations being ported by Nag Ltd)

An evaluation of AVS, Khoros and another system apE took place in 1991/92 and is described in a report on behalf of the UK academic community [AGOCG 9]

AVS is the most technically mature of the systems, being now in its release 5 and is available on a wide range of workstations. There is a CHEST deal for AVS.

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