The state of the art of visual languages for visualization

Data flow visual language systems are now being used to provide sophisticated environments for the visualization of scientific data. These systems are evolving rapidly and are beginning to encompass related technologies such as distributed computing and user interface development systems. This paper presents a hierarchical classification of the components and issues involved, giving the reader an understanding of the design decisions and trade-offs that the developers of these systems are making. The component categories can be used as a framework for discussing where interoperability of competing visual programming environments might occur and what the future holds for these systems.