The Graph Description Language (GDL) of the VCG tool and its successor aiSee describes graphs in terms of nodes, edges, subgraphs and their attributes. The GDL syntax supports special kinds of edges (e.g., nearedge) that control the graph layout. Attributes are key-value pairs. Default attributes and redefinition of default attributes for edges, nodes, and subgraphs are supported as well. Nodes are identified with an obligatory title attribute. Edges must have source and target attributes that refer to the nodes' titles. GDL has a very rich set of predefined attributes. The core of GDL is compatible to GRL, the specification language of the Edge graph editor.

The following gives a code example that contains two nodes (called 'a' and 'b') that are connected with an edge. The edge is colored red.

 graph: {
  node: { title:  "a" }
  node: { title:  "b" }
  edge: { source: "a" target: "b" color: red }
        }

Resources:

• GDL in a Nutshell: http://www.absint.com/aisee/gdl/guide/index.htm
• VCG Graph Layout Tool: http://rw4.cs.uni-sb.de/users/sander/html/gsvcg1.html
• aiSee Graph Visualization Software: http://www.aisee.com
• Citations: http://citeseer.nj.nec.com/context/316931/0

-- TWikiGuest - 10 Oct 2001