Geoprocessing Workflow Interoperation Research For The Sensor Web Environment

As the development of Earth observation technology, the rising amount of satellites and many kinds of sensors in the space that can offer abundant of Earth observation data and information. These data and information provide important information resource to the human for the nature, society and economic research and then put forward the development of human beings. Since the rapidly development and fusion of IT technology, communication technology and micro electronic technology in the end of last century, there comes tremendous changing in the discovering, accessing and processing of spatial data and information. The Sensor Web is that kind of new technology that combines Sensor Network technology and Web technology. The Sensor Network technology is consisting of various sensors with capacity of sensing, computing and wireless network communicating.Under the Sensor Web environment, all kinds of sensor observation data and information are delivering to the Users in form of Web service content. The workflow technology can be widely used in all kinds of Web Service combination and integration process. The geospatial workflow from raw sensor observations to informational products connects sensors through serving planning and observations, data processing, and information managing. All activity partners (or Web services in the Web environment) need to be coordinated to collaboratively complete the mission. Under the Sensor Web environment, the geospatial workflow can be applied in online immediately integrating the distributed sensors, data, algorithm and computing resources and used for an emergency processing purpose. Usually, the geospatial integration under this kind of application scenarios often comes with the coupling of a series of heterogeneous geospatial workflows (also includes resource chain, processing chain and service chain) and geospatial Web Services. As there are diversity in the workflow architecture, information model and execution pattern, how to organize all kinds of heterogeneous geospatial workflow as collaborative services is the main challenge of Sensor Web in an emergency processing scenario. In this paper, we study the Sensor Web environment and put our research on the key technology of workflow collaboration and interoperation under Sensor Web environment. Our research can be briefly summarized as below:(1) Reviewing and summarizing of the current Web service, OGC Web service and Sensor Web Service technology and putting out the idea and technology of constructing workflow under sensor web environment.(2) We analyze the general asynchronous mechanism of Web service and Sensor Web Service under Service Oriented Architecture, and then we study the obstacle in constructing geospatial workflow under sensor web environment. Based on the Web service message transfer mechanism and asynchronous web service invoke mechanism, we proposed an internal message notification based on WNS service and external BPEL invoke method for an asynchronous geospatial workflow pattern.(3) We figure out the relation of "resource" and the abstract workflow, and then an ATOM protocol is applied in the workflow resource creation, publishing and operation process. Using the uniform resource description, the obstacle of difference in architecture and operation can be ignored between heterogeneous workflows interoperation.(4) We discuss the mainstream geospatial workflow build pattern (a SensorML workflow for the processing chain model, a BPEL workflow for service chain model and a XPDL workflow for resource chain model). Using a RESTFul method to achieve the heterogeneous concurrent coupling workflow interoperation under resource oriented architecture.(5) We Study the workflow interoperation method for an Earth observation using scenarios for science research. We use the proposed RESTFul heterogeneous workflow interoperation method to testify the feasibility in an emergency processing scenario of wild fire detecting and mapping. Based the methodologies in this paper, a concurrent collaboration issue in the asynchronous and heterogeneous geospatial workflow can be work out. And this kind of workflow interoperation method can be used to provide more intelligent workflow processing task for the geospatial information decision department. The main innovations of this paper can be summarized as below:(1) We proposed the internal message notification mechanism for the asynchronous OGC Web service and Sensor Web Service.(2) We achieved the complex asynchronous BPEL workflow based on asynchronous Web Service for Sensor Web scenario.(3) We figured out the RESTFul heterogeneous workflow interoperation framework and achieve the collaborative operation between all kinds of Web Services and workflow entities.In the future research steps, we will achieve the precise classifying and intelligent discovering of the geoprocessing workflow and build the ontology resource service system for a user-concentric geoprocessing workflow interoperation that relies on the ontology features of the sensors and workflows, the specific domain knowledge, temporal, theme and observation capabilities.