in my current project which is EPS (Electronic Procedure Systems) I need to visualize all the possible paths that any procedure may pass throw, beside visualizing the actual path the application (procedure instance ) pass throw.

 I have two options either building it from scratch, or using any existing visualization toolkit, the later option sounds good but you have to invest a good period of time before reaching the correct / best visualization toolkit that will satisfy your needs.

thanks Good I found prefuse, so lets know what is prefuse? copied from prefuse official site

Prefuse is a set of software tools for creating rich interactive data visualizations. The original prefuse toolkit provides a visualization framework for the Java programming language. The prefuse flare toolkit provides visualization and animation tools for ActionScript and the Adobe Flash Player.

Prefuse supports a rich set of features for data modeling, visualization, and interaction. It provides optimized data structures for tables, graphs, and trees, a host of layout and visual encoding techniques, and support for animation, dynamic queries, integrated search, and database connectivity.
Prefuse is written in Java, using the Java 2D graphics library, and is
easily integrated into Java Swing applications or web applets. Prefuse is licensed under the terms of a BSD license,
and can be freely used for both commercial and non-commercial purposes.

The visualization gallery and
demonstration video
provide numerous examples
of the types of applications that can be built with the prefuse toolkit.

To learn more about prefuse, take a look at the user's
manual or the frequently asked questions. For
users of the alpha version of the toolkit, there is also a
porting guide for migrating to the beta version.

so I have decided to use prefuse in our application to do the job for us,

and it was a magic as all you need to do is generating xml fill describing the nodes and edgesand pass this xml file to the prefuse and it will do the layouting and the job for you. prefuse support search, multiple/different layouts, zoom-in, zoom-out, and layout adjustment by hand/mouse.

and here is a screen shoot for the prefuse output

Mouse Effects:

Zoom-IN

Zoom-Out

Layout Adjustment:

References:

prefuse website: http://prefuse.org/