University of Twente Student Theses


Design and orchestration of web processing services as service chains

Alemu, Meazanesh Asres (2012) Design and orchestration of web processing services as service chains.

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Abstract:Currently, several OGC WPS processing-functionalities have been implemented and exposed as service over the web. These WPS processing-functionalities are already providing a useful application to generate geospatail information out of geospatail data on-the-fly in a distributed environment. However, individual processing-functionalities are not sufficient to solve a complex geoprocessing task, as the complex nature of geospatail data often requires multiple geoprocessing-steps. Therefore, chaining of individual WPS processing-functionalities to buildup larger application that can solve complex geoprocessing task is necessary. The current popular standard, BPEL, to orchestrate services into service chain, which is dependent on WSDL, is not suitable for geoservices. The WPS processing-functionalities are not described by WSDL mandatorily, instead using DescribeProcess in detail, and using Getcapabilities briefly. Consequently, it is mandatory to generate WSDL for each processing-functionalities to be orchestrated in BPEL, taking up much time and effort. This requirement limits their application to be utilized through chaining. Therefore, it is necessary to devise a method to chain without extra description requirements per processing-functionalities. This research was an attempt to provide a method for chaining of disparate processing- functionalities to be utilized as single application through chaining without the need to generate WSDL per each processing- functionaries to support expert users in GI application domain. For this we designed a generic chaining schema using XSD language. The chaining schema is generic by defining all possible contents required for chaining conceptually, serving as template, to chain any two or more number of processing-functionalities in any GI application domain. This chaining schema basis on selected parameters of DescribeProcess response content. In addition, architecture for chaining of processing-functionalities using the designed chaining schema is provided. A proof-of-concept was demonstrated with implementation of the designed chaining schema using a real-world application scenario. Keywords web services, geoservices, web processing service, processing-functionalities, orchestration, chaining engine, service chain, chaining schema
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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