Semantic Web-based Intelligent Geospatial Web Services

verfasst von: Peng Yue

Verlag: Springer New York

Buchreihe : SpringerBriefs in Computer Science

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

By introducing Semantic Web technologies into geospatial Web services, this book addresses the semantic description of geospatial data and standards-based Web services, discovery of geospatial data and services, and generation of composite services. Semantic descriptions for geospatial data, services, and geoprocessing service chains are structured, organized, and registered in geospatial catalogue services. The ontology-based approach helps to improve the recall and precision of data and services discovery. Semantics-enabled metadata tracking and satisfaction allows analysts to focus on the generation of a geospatial process model rather than spending large amounts of time in data preparation. “DataType”-driven service composition and path planning can help to automate a range of knowledge discovery processes in a limited geospatial domain. Process planning facilitates the construction of complex services and models for geocomputation. A three-phase procedure to cover the lifecycle of service chaining and to identify the roles of the methods involved is proposed. It includes process modeling, process model instantiation, and workflow execution. The approach is implemented in a prototype system with use cases to demonstrate applicability.

The objective of the research is to develop the key technologies for an intelligent geospatial knowledge system based on Web services to automate the data discovery and data preprocessing steps in the distributed Web service environment, to automate a range of knowledge discovery processes in a limited geospatial domain, using the automated construction and execution of service chains, and to facilitate the construction of complex services and models for geocomputation.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

More than 150 Earth observation satellites are currently in orbit measuring the state of the Earth system (Tatem et al. 2008). These satellites, together with countless air-, land-, and water-based monitoring systems, are generating large volumes of geospatial data. For example, the National Aeronautics and Space Administration (NASA)’s Earth Observing System (EOS) alone collect 1000 terabytes annually (Clery and Voss 2005). This unprecedented data-collecting capability brings considerable challenges to geospatial research and applications, one of which is how to derive high-level information and knowledge from the oceans of data in an effective and timely way. The traditional methods of analyzing data by expert analysts fall far short of today’s increased demands for geospatial knowledge. As a result, much data may never been analyzed even once after collection. Geospatial users are experiencing a data-rich yet analysis-poor period. Therefore, technologies for semi-automated or automated geospatial knowledge discovery and dissemination are urgently needed for geospatial applications.

Peng Yue

Chapter 2. Geospatial Web Service

Abstract

Interoperability is the capability to exchange information, execute programs, or transfer data among various functional units in a manner that requires the user to have little or no knowledge of the unique characteristics of those units (Percivall 2002). There are two levels of interoperability: syntactical interoperability and semantic interoperability (Percivall 2002). The former requires that there is a technical connection, i.e., that the data can be transferred between Web services. It does not provide an interpretation for the content transferred in the connection. The latter assures that the contents of data and services are correctly understood when data/services are connected.

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Chapter 3. Geospatial Semantic Web

Abstract

Inspired by Tim Berners-Lee (Berners-Lee 1998), inventor of the Web, a growing number of individuals and groups from academia and industry have been evolving the Web into another level—the Semantic Web. By representing not only words, but their definitions and contexts, the Semantic Web provides a common interoperable framework in which information is given a well-defined meaning such that data and applications can be used by machines (reasoning) for more effective discovery, automation, integration and reuse across various application, enterprise and community boundaries. Compared to the conventional Web, the Semantic Web excels in two aspects (W3C 2001): (1) common formats for data interchange (the original Web only had interchange of documents) and (2) a language for recording how the data relates to real world objects. With such advancements, reasoning engines and Web-crawling agents can go one step further—and inductively respond to questions such as “which airfields within 500 miles of Kandahar support C5A aircraft?” rather than simply returning Web pages that contain the text “airfield” and “Kandahar”, which most engines do today.

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Chapter 4. Automatic Service Composition

Abstract

Broadly speaking, service composition, the process of creating a service chain, can address many aspects of Web service provision and use, including discovery, selection, composition, negotiation, invocation. However, following the main efforts published in the literature, the automatic service composition issue addressed here focuses on the methods for dynamic service discovery and composition in automatic generation of composite service. This chapter briefly sketches the methods from the business perspective and AI research area. In particular, some basic concepts of workflow and AI planning are introduced. Finally, related work in geospatial domain is introduced.

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Chapter 5. Semantics for Geospatial Data and Services

Abstract

Ontologies have been used in the geospatial domain for information integration and semantic interoperability. By mapping concepts in a geospatial Web resource (e.g. geospatial data, service, or geoprocessing service chain) to ontological concepts in the geospatial domain, the semantics of that geospatial resource can be explicitly defined. To provide the semantic concepts, the research uses ontologies represented using Semantic Web technologies. OWL is used as the basic technology. The foundation of knowledge representation formalism for OWL is the description logic (DL) (Baader and Nutt, 2003). DL is more like an object-oriented approach to knowledge representation. The basic elements of description logics are concepts, roles, and constants. In the Web ontology context, they are also commonly named classes, properties, and individuals respectively. Concepts group individuals into categories, roles stand for binary relations of those individuals and constants stand for individuals.

Peng Yue

Chapter 6. Semantics-Enabled Geospatial Data and Services Discovery

Abstract

In the geospatial domain, a geospatial catalogue service provides a network-based meta-information repository and interface for advertising and discovering shared geospatial data and services. OGC technology is the widely used choice for the standards-based interoperability and sharing technology in the geospatial domain. The most widely used interface specification for geospatial catalogue services is the OGC CSW. It is an open industry consensus on a standard interface to online catalogs for geospatial data, services, and related resource information. Descriptive information (i.e., metadata) for geospatial information resources is structured and organized in catalogue services. The metadata can be queried and returned for evaluation, processing, and further binding or invocation of the cited resource. However, current standards mainly focus on syntactic interoperability and do not address semantic interoperability (ISO/TC211 2005). This work uses OGC standards to address the semantic interoperability of geospatial catalogue services.

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Chapter 7. Automatic Composition of Geospatial Web Service

Abstract

The geoprocessing algorithm provided by geospatial services may handle only a tiny part of the overall geoprocessing or may be a large aggregated processing. In both situations, the service should be well defined, have clear input and output requirements, and be independently executable. Such services can be chained to construct different geoprocessing workflows (or service chains) for geospatial knowledge discovery. In a distributed data and information environment such as the World Wide Web, there are many independent data and service providers. A complex geoprocessing workflow may be scattered among multiple service providers. Therefore, standards for publishing, finding, binding, and execution of services are needed. By following the standards for interfaces, interoperability of different software systems is achieved. Web services developed by different organizations can then be combined to fulfill users’ requests. Through the OWS testbeds, OGC has been developing a series of interface specifications under the OGC Abstract Service Architecture.

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Chapter 8. Prototype Implementation and Result Analysis

Abstract

A prototype is implemented as part of the work in this book. The OWL-S Application Programming Interface (API) (MINDSWAP, 2004) is used for OWL-S parsing and execution. The approach has been implemented in a common data and service environment enabled by the OGC and W3C standards. Section 8.1 introduces the extensions to OWL-S and OWL-S API. Section 8.2 presents the prototype architecture and its implementation. Finally, Section 8.3 provides analysis of results.

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Chapter 9. Conclusions

Abstract

This book addresses the key technologies for developing an intelligent geospatial knowledge system based on Web services. In particular, Semantic Web technologies are introduced into the area of geospatial Web services. The ontology-based approach helps to improve the recall and precision of data and services discovery provided by the catalogue service. Semantics-enabled metadata tracking and satisfaction allows analysts to focus on the generation of a geospatial process model rather than spending large amounts of time in data preparation. “DataType”-driven service composition and path planning can help to automate a range of knowledge discovery processes in a limited geospatial domain. Process planning facilitates the construction of complex services and models for geocomputation. The process models and service chains can be archived, catalogued, and advertised as new geospatial services in CSW and thus be discovered and used for future geospatial modeling.

Peng Yue

Backmatter

Titel: Semantic Web-based Intelligent Geospatial Web Services
verfasst von: Peng Yue
Verlag: Springer New York
Electronic ISBN: 978-1-4614-6809-7
Print ISBN: 978-1-4614-6808-0
DOI: https://doi.org/10.1007/978-1-4614-6809-7