aiSee

aiSee is a graph-visualization tool that automatically computes a customizable layout for a graph described textually and then lets the user explore, print, and export it. It was developed by AbsInt GmbH (Saarbrücken, Germany) and grew directly out of VCG (Visualization of Compiler Graphs), a tool built by students in Reinhard Wilhelm's group at Saarland University in the 1990s; several of those students founded AbsInt around 1998 and continued VCG's development commercially as aiSee. Its origins in compiler research shaped its central design goal: rendering the large, machine-generated graphs (call graphs, control-flow graphs, dependency and data-structure diagrams) that compilers and program-analysis tools emit.

Input is supplied in GDL (Graph Description Language), a human-readable ASCII format that describes a graph as nested declarations of nodes, edges, and subgraphs, each carrying key-value attributes. Every node has an obligatory title used as its identifier; edges reference source and target titles; and defaults can be declared and redefined per node, edge, or subgraph class. GDL adds layout-directing constructs such as special edge kinds (for example nearedge) and recursive subgraph nesting, so a hierarchy can be folded and unfolded interactively. Because GDL is plain text emittable from any programming language, aiSee is designed to be scripted into tool-chains rather than authored by hand—indeed the GUI cannot construct a graph from scratch, only display one loaded from a GDL file. This makes GDL (catalogued here as GDL) a peer of other declarative graph-drawing languages such as DOT and GML.

aiSee offers around 15 layout methods, including hierarchical (layered) layouts, force-directed placement, depth-first-search and tree layouts, plus fish-eye views and a panner for navigating large graphs. It was engineered for scale, handling graphs up to roughly a million nodes, and exports to numerous bitmap and vector formats (with PDF, anti-aliasing, and UTF-8 added in the 3.x line). A bundled dot2gdl converter imports Graphviz DOT files, positioning it against Graphviz and layout libraries like OGDF and Tulip in the automatic-layout space.

Its main limitation today is availability: as of 1 November 2014 aiSee was withdrawn as a stand-alone product and is now shipped only embedded inside AbsInt's static-analysis tools (aiT, StackAnalyzer, TimingProfiler). GDL layout for very large graphs can also become prohibitively slow, and the GDL dialect is proprietary and not widely interchanged outside the VCG/aiSee lineage.