Earth observation scientific workflows in a distributed computing environment

Abstract

Geospatially Enabled Scientific Workflows offer a promising paradigm to facilitate researchers, in the earth observation domain, with many aspects of the scientific process. One such aspect is that of access to distributed earth observation data and computing resources. Earth observation research often utilises large datasets requiring extensive CPU and memory resources in their processing. These resource intensive processes can be chained; the sequence of processes (and their provenance) makes up a scientific workflow. Despite the exponential growth in capacity of desktop computing, resources available on such devices are often insufficient for the scientific workflow processing tasks at hand. By integrating distributed computing capabilities into a geospatially enabled scientific workflow environment, it is possible to provide researchers with a mechanism to overcome the limitations of the desktop computer. The majority of effort in regard to extending scientific workflows with distributed computing capabilities has focused on the web services approach as exemplified by the OGC's Web Processing Service and by GRID computing. The approach to leveraging distributed computing resources described in this paper uses instead remote objects via RPyC and the dynamic properties of the Python programming language. The Vistrails (http://www.vistrails.org) environment has been extended to allow for geospatial processing through the EO4Vistrails package (http://code.google.com/p/eo4vistrails/). In order to allow these geospatial processes to be seamlessly executed on distributed resources such as cloud computing nodes, the Vistrails environment has been extended with both multi-tasking capabilities and distributed processing capabilities.