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Figure 1. Sequence showing the Authentication Procedure for a Client interface to Chemical Object Store. (a) Request to grant security permission requested by applet using Netscape Navigator or (b) Using Internet Explorer, (c) The digital certificate, (d) the COS application in action, (e) File Dialogs enabled by the granted permission.

Example 2: MoldaNet. Molda was initially developed as a pilot project in creating a molecular modelling and visualisation environment, and evolved into an implementation using the Java language with the intent of creating a tool for distance learning in chemistry.⁸In its initial form it was created as a conventional application with local file access, and in this form it had to be installed on each local computer as required. As a Java-based application, the user had to also pre-install the appropriate Java run-time environment for their operating system, a relatively non-trivial procedure that might be unduly inhibiting for less expert users wishing to benefit from a distance learning course. By signing the Molda applet as described above, we have been able to create a genuinely distributed chemical application which is acquired by the user as and when needed, and has no local pre-installation requirements other than that of the Browser itself. We also note that MoldaNet, as we term the signed network version, also implements the new Java3D class libraries to allow direct access to graphic device drivers to enhance the 3D rendering speeds, and some CML (Chemical Markup Language)¹⁴classes. Together, and also permit the user to filter their model into 3D model descriptors such a VRML97¹⁵or CML for saving on the local disk, and illustrates the utility of such a component-based object oriented approach for building application solutions.¹⁶A demonstration for use with Windows and Netscape 4.05 or higher is available at http://origin.ch.ic.ac.uk/molda/(Figure 2).