Web-based distribution of geo-scientific models

Abstract

Scientific model developers have learned that the time required for the science and research phases of software development is relatively short when compared with the time needed to develop GUIs, writing documentation, developing support programs (e.g. pre-processors, visualization tools, and reports), debugging source code, and modifying the software for various computer operating systems. Another component of model development that requires a great deal of time and effort is the distribution and maintenance of model software. Consider the example of the US Geological Survey’s (USGS) Modular Modeling System (MMS). MMS allows a user to build a hydrologic model by selecting a set of modules that simulate a number of hydrologic processes. MMS is currently being used on various computer systems (e.g. Windows, Solaris, Linux, HP-UX, and AIX). Because each of these operating systems is slightly different, several versions of the software have been developed and maintained. When updates occur, they need to be added and tested for each version of the model. This process is time consuming. MMS is distributed via the internet from a web page. Users download MMS from the web page and then go through the task of installing the model on their system and then running it. Because so many different computer systems are used, the developers spend a considerable amount of time dealing with software bugs and trying to update various versions of the software. Each time the software is loaded onto a new system there are new problems to deal with, none of which have to do with the physics of the model; all are related to differences in computer operating systems. These problems are time consuming and take scientists away from further development of the physics included in the models. To overcome these problems, a method is needed whereby model developers can distribute an executable version of a model that will operate on all computer systems. The advent of the Internet and Java programming language makes this type of model distribution possible. This method of model distribution allows the delivery of (1) executable programs; (2) model documentation and (3) a robust GUI for model operation, all in a single Java archive file. Additionally, there is the issue of security related to the distribution of a model from the internet. For a model to be useful to a user, the user must be able to both input their own data files to a model and write output to his/her own computer. Sitraka Software (2001) proposes several guidelines for choosing an effective deployment strategy. Based on the anticipated end user and the nature of the application, Java Web Start (JWS) provides a way to address the security issues. JWS is a platform independent way to launch a wide variety of Java applications from a computer desktop or a web browser. The following sections describe the procedures necessary to implement and distribute a model with this method.