Pedro R. Muro-Medrano

Metadata standard interoperability: application in the geographic information domain

Abstract The use of metadata expands on the opportunities for interoperability. Interoperability involves making multiple information sources access, manipulate and share data across their boundaries. Metadata descriptions from different domains are not semantically distinct but overlap and relate to each other in complex ways. As the number, size and complexity of the metadata standards grow, the task of facilitating metadata in different standards becomes more difficult and tedious. A possible solution for this problem is the creation of mechanisms that enable the translation of this information in order to make it conform to the different standards. These mechanisms are denominated “crosswalks” and the objective of this work is to present the process of “crosswalk-creation”, which has been used by a research team at the University of Zaragoza in order to translate information among some of the most extended standards for geographic information metadata.

A Web Ontology Service to facilitate interoperability within a Spatial Data Infrastructure: Applicability to discovery

Ontologies are used within the context of Spatial Data Infrastructures to denote a formally represented knowledge that is used to improve data sharing and information retrieval. Given the increasing relevance of semantic interoperability in this context, this work presents the specification and development of a Web Ontology Service (WOS), based on the OGC Web Service Architecture specification, whose purpose is to facilitate the management and use of lexical ontologies. Additionally, this work shows how to integrate this service with Spatial Data Infrastructure discovery components in order to obtain a better classification of resources and an improvement in information retrieval performance.

An architectural style for spatial data infrastructures

This work proposes an architectural style, a pattern, for spatial data infrastructures (SDIs). This style provides a tool and a shared vocabulary to help system architects to design these infrastructures, and facilitates the exchange of knowledge about them. This style is defined under the component‐and‐connector architectural viewtype, extending the client–server and shared‐data styles. The style has been created after analyzing six of the most relevant SDIs and geo‐service architectural proposals. Several architectural elements that these proposals have not properly addressed are considered. Three real projects, with published architectural views or models, have been examined to verify the applicability of the style. The proposed style offers a systematization and refinement of knowledge about SDIs, grounded in well‐known concepts in software architecture.

Availability of the OGC geoprocessing standard: March 2011 reality check

This paper presents an investigation about the servers available in March 2011 conforming to the Web Processing Service interface specification published by the geospatial standards organization Open Geospatial Consortium (OGC) in 2007. This interface specification gives support to standard Web-based geoprocessing. The data used in this research were collected using a focused crawler configured for finding OGC Web services. The research goals are (i) to provide a reality check of the availability of Web Processing Service servers, (ii) to provide quantitative data about the use of different features defined in the standard that are relevant for a scalable Geoprocessing Web (e.g. long-running processes, Web-accessible data outputs), and (iii) to test if the advances in the use of search engines and focused crawlers for finding Web services can be applied for finding geoscience processing systems. Research results show the feasibility of the discovery approach and provide data about the implementation of the Web Processing Service specification. These results also show extensive use of features related to scalability, except for those related to technical and semantic interoperability.

Geo linked data

Semantic Web applications that include map visualization clients are becoming common. When the description of an entity contains coordinate pairs, semantic applications often lay them as pins on maps provided by Web mapping service applications, such as Google Maps. Nowadays, semantic applications cannot guarantee that those maps provide spatial information related to the entities pinned to them. To address this issue, this paper proposes a refinement of Linked Data practices, named Geo Linked Data, which defines a lightweight semantic infrastructure to relate URIs that identify real world entities with geospatial Web resources, such as maps.

A CORBA infrastructure to provide distributed GPS data in real time to GIS applications

This paper shows a distributed object-oriented architecture to provide global positioning system (GPS) data for geographical information system (GIS) applications. Data captured in real time by GPS units are sent via radio to the computer. Several sources of this real data, in addition to simulated GPS data, are distributed in a computer network. These servers of GPS data can be accessed by distributed client applications. A Common Object Request Broker Architecture (CORBA)-based infrastructure provides the integration and distribution mechanisms. Client applications range from simple graphical user interfaces (GUIs) for GPS remote control to GIS applications used for automatic vehicle monitoring. The basic components which provide the radio communication and GPS data servers are presented in detail.

A Method to Derivate SOAP Interfaces and WSDL Metadata from the OGC Web Processing Service Mandatory Interfaces

Web Processing Services (WPS) expose processing functionality using Web Service technology. The WPS specification describes the interfaces to publish geospatial processes on the Web. It includes a platform-neutral and several platform-specific versions of its interfaces. Some of the platform-specific interfaces are mandatory and others are optional. In this paper, we present a method to support the automatic derivation of the optional SOAP interfaces and WSDL metadata from the mandatory ones in any WPS. These interfaces can then be used to facilitate the chaining of the WPS with other Web Services, using for example BPEL, and to improve the interoperability of these services. In addition to that, we have created a tool to validate the proposed method.

Discovering geographic web services in search engines

Purpose – There is an open discussion in the geographic information community about the use of digital libraries or search engines for the discovery of resources. Some researchers suggest that search engines are a feasible alternative for searching geographic web services based on anecdotal evidence. The purpose of this study is to measure the performance of Bing (formerly Microsoft Live Search), Google and Yahoo! in searching standardised XML documents that describe, identify and locate geographic web services.Design/methodology/approach – The study performed an automated evaluation of three search engines using their application programming interfaces. The queries asked for XML documents describing geographic web services, and documents containing links to those documents. Relevant XML documents linked from the documents found in the search results were also included in the evaluation.Findings – The study reveals that the discovery of geographic web services in search engines does not require the use of...

Knowledge representation-oriented nets for discrete event system applications

This paper presents knowledge representation-oriented nets (KRON), a knowledge representation schema for discrete event systems (DES). KRON enables the representation and use of a variety of knowledge about a DES static structure and its dynamic states and behavior. It is based on the integration of high-level Petri nets with frame-based representation techniques and follows the object-oriented paradigm. The main objective considered in its definition is to obtain a comprehensive and powerful representation model for data and control of DES. The use of the DES behavioral knowledge is governed by a control mechanism stored in a separate inference engine. KRON provides an efficient execution mechanism to make the models evolve. This is an adaptation of the RETE matching algorithm in order to deal with the features provided by high-level Petri nets and it takes advantage of its integration with a frame/object-oriented representation schema, Moreover, KRON facilitates dealing with decision points in the execution of nondeterministic models. A prototype of a simulation tool with graphical display and animation facilities has been implemented for KRON and it has been used in several case studies in the manufacturing systems domain.

On the problem of identifying the quality of geographic metadata

Geographic metadata quality is one of the most important aspects on the performance of Geographic Digital Libraries. After reviewing previous attempts outside the geographic domain, this paper presents early results from a series of experiments for the development of a quantitative method for quality assessment. The methodology is developed through two phases. Firstly, a list of geographic quality criteria is compiled from several experts of the area. Secondly, a statistical analysis (by developing a Principal Component Analysis) of a selection of geographic metadata record sets is performed in order to discover the features which correlate with good geographic metadata.