Powerful molecular rendering hardware and software would be useless without molecular data to crunch. The IUMSC supplies the need for data by backing the Rendering Cluster with the extensive web-based library of crystallographic data maintained on the IUMSC data server. IUMSC staff and collaborators use the data server to examine and distribute structural data determined by X-ray crystallographic techniques. The web is an ideal medium for exchange of crystallographic data because the final results for even complex structures can be expressed compactly as coordinate data and easily transmitted. Data for structures determined in the IUMSC are added to the server as soon as they are available, and there is an ongoing project to add structural data of general insterest. The server currently contains data for more than 2,500 compounds.

The IUMSC provides specialized Java applets for many visualization tasks. The applets allow the user to interactively examine the crystallographic model by rotating and scaling it, and by representing it in any of a variety of drawing modes including simple stick figures, ball-and-stick figures, and space-filling representations. In any mode the user can also select red/green or split-pair stereographic images. If the user wants more detail then he can use the applets to examine interatomic distances and angles in the molecule.

Visualization is only part of the problem, however. Applets cannot be embedded in print publications or posters, so the user is still sometimes faced with the daunting task of preparing high-quality static illustrations. Through the applets, the user can generate "ORTEP" figures such as have been standard in most scientific journals for the past several decades,and ray-tracing facilities allow the generation of very high quality images. The data server has provided ray-tracing for some time, but before the Molecular Rendering Cluster was introduced ray tracing operations were time-consuming and put a significant load on the data server. Now the server offloads its rendering jobs to the Cluster, which is faster and improves server performance as well.

The original server-based programs were run on a Silicon Graphics Challenge-S, which was adequate for several years.As the usage of the server increased (currently over 20,000 hits per day), the responsiveness of the server-based software became a critical issue. As a result, the server is currently being migrated to a dual-processor Compaq Proliant ML370 running the Apache web server on Linux. ORTEP images are generated on the web server itself, but ray-tracing jobs are now run on the Molecular rendering Cluster.