Catalogue Service For The Web Research Articles

Developing an Open Data Portal for the ESA Climate Change Initiative

We introduce the rationale for, and architecture of, the European Space Agency Climate Change Initiative (CCI) Open Data Portal ( http://cci.esa.int/data/ ). The Open Data Portal hosts a set of richly diverse datasets – 13 “Essential Climate Variables” – from the CCI programme in a consistent and harmonised form and to provides a single point of access for the (>100 TB) data for broad dissemination to an international user community. These data have been produced by a range of different institutions and vary across both scientific and spatio-temporal characteristics. This heterogeneity of the data together with the range of services to be supported presented significant technical challenges. An iterative development methodology was key to tackling these challenges: the system developed exploits a workflow which takes data that conforms to the CCI data specification, ingests it into a managed archive and uses both manual and automatically generated metadata to support data discovery, browse, and delivery services. It utilises both Earth System Grid Federation (ESGF) data nodes and the Open Geospatial Consortium Catalogue Service for the Web (OGC-CSW) interface, serving data into both the ESGF and the Global Earth Observation System of Systems (GEOSS). A key part of the system is a new vocabulary server, populated with CCI specific terms and relationships which integrates OGC-CSW and ESGF search services together, developed as part of a dialogue between domain scientists and linked data specialists. These services have enabled the development of a unified user interface for graphical search and visualisation – the CCI Open Data Portal Web Presence.

Enhancing discovery in spatial data infrastructures using a search engine.

A spatial data infrastructure (SDI) is a framework of geospatial data, metadata, users and tools intended to provide an efficient and flexible way to use spatial information. One of the key software components of an SDI is the catalogue service which is needed to discover, query and manage the metadata. Catalogue services in an SDI are typically based on the Open Geospatial Consortium (OGC) Catalogue Service for the Web (CSW) standard which defines common interfaces for accessing the metadata information. A search engine is a software system capable of supporting fast and reliable search, which may use ‘any means necessary’ to get users to the resources they need quickly and efficiently. These techniques may include full text search, natural language processing, weighted results, fuzzy tolerance results, faceting, hit highlighting, recommendations and many others. In this paper we present an example of a search engine being added to an SDI to improve search against large collections of geospatial datasets. The Centre for Geographic Analysis (CGA) at Harvard University re-engineered the search component of its public domain SDI (Harvard WorldMap) which is based on the GeoNode platform. A search engine was added to the SDI stack to enhance the CSW catalogue discovery abilities. It is now possible to discover spatial datasets from metadata by using the standard search operations of the catalogue and to take advantage of the new abilities of the search engine, to return relevant and reliable content to SDI users.

Developing an OGC Standard-Based Platform for Integration of Radiation Monitoring Data from Fukushima Area, Japan

Geographical location of Japan is a reason that causes this country to become one of the most disaster-prone nation in the world. The Nuclear Emergency Response Headquarters of Japan Government has established a comprehensive plan for monitoring radiation due to the Tohoku earthquake on 11 March 2011 that caused the release of radioactive materials from Fukushima Daiichi Nuclear Power Station (NPS). The main purpose of this research is to develop a prototype platform based on Open Geospatial Consortium (OGC) international standards for integrating the radiation monitoring results from Fukushima Area, Japan. Because of the monitoring data was mainly stored in XML or CSV format, this platform provided a simple and standardized environment for converting original data into uniform format with three primary information including observation time, observation locations, and observation results. After stage of data standardization, all converted data was published as services utilizing OGC standards of Catalogue Service for the Web (CSW), Sensor Observation Service (SOS), Web Map Service (WMS) and JSON-based RESTful Application Program Interface (API). Finally, this platform visualizes the monitoring results and provides a client with the functionality of time series selection. The idea of this prototype platform in releasing the radioactive materials monitoring data using international standards has matured over time and does not exclude the possibility of making it open access. The result of this study has shown that the utilization of international standard is a necessary step for data integration and data sharing.

Near-Real-Time OGC Catalogue Service for Geoscience Big Data

Geoscience data are typically big data, and they are distributed in various agencies and individuals worldwide. Efficient data sharing and interoperability are important for managing and applying geoscience data. The OGC (Open Geospatial Consortium) Catalogue Service for the Web (CSW) is an open interoperability standard for supporting the discovery of geospatial data. In the past, regular OGC catalogue services have been studied, but few studies have discussed a near-real-time OGC catalogue service for geoscience big data. A near-real-time OGC catalogue service requires frequent updates of a metadata repository in a short time. When dealing with massive amounts of geoscience data, this comprises an extremely challenging issue. Discovering these data via an OGC catalogue service in near real-time is desirable. In this study, we focus on how the near-real-time OGC catalogue service is realized through several lightweight data structures, algorithms, and tools. We propose a framework of a near-real-time OGC catalogue service and discuss each element of the framework to which more attention should be paid when dealing with the massive amounts of real-time data, followed by a review of several methods that need to be considered in a near-real-time OGC CSW service. A case study on providing an OGC catalogue service to Unidata real-time data is presented to demonstrate how specific methods are utilized to deal with real-time data. The goal of this paper is to fill the gap in knowledge regarding an OGC catalogue service for geoscience big data, and it has realistic significance in facilitating a near-real-time OGC catalogue service.

Bolegweb Platform – Contribution to the Web Communities

The effective access to and reuse of geospatial information (GI) has come to be of critical value in modern knowledge based society. The standardized web services defined by Open Geospatial Consortium (OGC) are frequently used for the implementation of a spatial data infrastructure (SDI), to expose geospatial data, metadata and models on the Web. These GI are normally stored in an encoded geospatial layer, which is hidden from search engines. SDI uses a catalogue service for the web as a gateway to GI through the metadata defined by ISO standards, which are structurally diverse to OGC metadata. Therefore, a crosswalk needs to be implemented to bridge the OGC resources discovered on mainstream web with those documented by metadata in an SDI to enrich its information extent. We have to build mechanisms allowing entrepreneurs and developers access the information SDI is providing to build their apps. The paper reports a global wide and user friendly platform of OGC resources available on the web with the main goal to ensure and enhance the use of GI within a multidisciplinary context and to bridge the geospatial web from the end-user perspective, thus to open its borders to more web communities. The platform has been developed in the research project Borderless Geospatial Web (Bolegweb).

Normalized evaluation of the performance, capacity and availability of catalogue services: a pilot study based on INfrastruture for SPatial InfoRmation in Europe

Geographic information has a great potential to be re-used when supported by mechanisms for its discovery. Above all, the quality of a catalogue service is the key feature supporting users in the discovery process. So far, there have been in existence various methodologies dealing with the normalized evaluation of quality with respect to catalogue services. Their biggest weakness seems to be in the depth of quality testing, i.e. some influences are beyond the scope of evaluation of these methodologies with respect to quality in catalogue services. In this study, the quality of 45 catalogue services across Europe was verified with the proposed normalized evaluation methodology originating from documents within the INfrastruture for SPatial InfoRmation in Europe (INSPIRE) framework. This paper discusses the (statistical) influence of factors that may significantly change the results of catalogue service testing. The proposals for improving the existing INSPIRE normalized evaluation procedure are applicable for any spatial data infrastructure and/or Digital Earth component using the Open Geospatial Consortium Catalogue Service for the Web as a basis.

Restful Implementation of Catalogue Service for Geospatial Data Provenance

Abstract. Provenance, also known as lineage, is important in understanding the derivation history of data products. Geospatial data provenance helps data consumers to evaluate the quality and reliability of geospatial data. In a service-oriented environment, where data are often consumed or produced by distributed services, provenance could be managed by following the same service-oriented paradigm. The Open Geospatial Consortium (OGC) Catalogue Service for the Web (CSW) is used for the registration and query of geospatial data provenance by extending ebXML Registry Information Model (ebRIM). Recent advance of the REpresentational State Transfer (REST) paradigm has shown great promise for the easy integration of distributed resources. RESTful Web Service aims to provide a standard way for Web clients to communicate with servers based on REST principles. The existing approach for provenance catalogue service could be improved by adopting the RESTful design. This paper presents the design and implementation of a catalogue service for geospatial data provenance following RESTful architecture style. A middleware named REST Converter is added on the top of the legacy catalogue service to support a RESTful style interface. The REST Converter is composed of a resource request dispatcher and six resource handlers. A prototype service is developed to demonstrate the applicability of the approach.

Metadata Harvesting and Registration in a Geospatial Sensor Web Registry

AbstractA Sensor Web registry acts as a broker in a service‐oriented environment to publish and discover Sensor Web resources (e.g. sensors, sensor services, observations, and alerts). The Catalogue Service for the Web (CSW) developed by the Open Geospatial Consortium (OGC) defines a standard interface and protocol for publishing and discovering geospatial resources. This article adopts the CSW for the development of a Sensor Web registry. Metadata for Sensor Web resources are registered into the catalogue information model – the ebXML Registry Information Model (ebRIM). In the Sensor Web environment, sensor observations can be available in real‐time or near‐real‐time, and thus metadata registered in CSW need to be updated frequently. This article proposes an incremental harvesting approach, which can harvest the updated metadata efficiently. A prototypical implementation is provided to demonstrate the applicability of the approach.

Automatic On-Demand Data Feed Service for AutoChem Based on Reusable Geo-Processing Workflow

A new method for serving observational data, based on a reusable geo-processing workflow (GPW), is proposed in order to meet the requirements of the automatic AutoChem data feed service in the sensor web environment. A service-oriented architecture (SOA) is adopted. The system has three roles: the GPW provider, registry center, and portal. The system has GPW design, deployment, registration, search, and invocation functions. The AutoChem data discovery, processing, and integration GPW is implemented by chaining NASA EOS ClearingHOuse data service system, the George Mason University (GMU) Catalogue Service for the Web, the GMU Web Coverage Service, and a series of preprocessing services wrapped with the Web Processing Service. The reused data feed flows have been tested using data from the NASA Aura Ozone Monitoring Instrument. Test results show that the proposed data feed service can also be used by the NASA Aqua Atmospheric Infrared Sounder and the Aura Microwave Limb Sounder. Its architecture is more flexible, and it performs more automatically than the traditional method.

Geological applications using geospatial standards – an example from OneGeology-Europe and GeoSciML

The Geoscience Markup Language (GeoSciML) has been developed to enable the interchange of geoscience information, principally that portrayed on geological maps as well as boreholes. A GeoSciML testbed was developed both to test the implementation of the data model and its application in web services. The OneGeology-Europe project aims to use the GeoSciML data model, and build on the experience of the GeoSciML testbed, in implementing a geoportal for a harmonised geological map of Europe at 1:1 million scale. This involves the integration of web services from 20 participating organisations. An important objective of OneGeology-Europe is to contribute to Infrastructure for Spatial Information in the European Community (INSPIRE), both through the development of a geological data specification and the use of the INSPIRE technical architecture. GeoSciML and the OneGeology-Europe project are also steps towards incorporating geoscience data into a Digital Earth. Both the development of GeoSciML and the implementation of web services for GeoSciML and OneGeology-Europe, have followed a standards-based methodology. The technical architecture comprises a geoportal providing access to a Catalogue Service for the Web for metadata describing both the data and services available. OneGeology-Europe will provide both Web Map Services view and Web Feature Services download services, which aim to be compliant with the INSPIRE implementing rules.

A flexible geospatial sensor observation service for diverse sensor data based on Web service

Achieving a flexible and efficient geospatial Sensor Observation Service (SOS) is difficult, given the diversity of sensor networks, the heterogeneity of sensor data storage, and the differing requirements of users. This paper describes development of a service-oriented multi-purpose SOS framework. The goal is to create a single method of access to the data by integrating the sensor observation service with other Open Geospatial Consortium (OGC) services — Catalogue Service for the Web (CSW), Transactional Web Feature Service (WFS-T) and Transactional Web Coverage Service (WCS-T). The framework includes an extensible sensor data adapter, an OGC-compliant geospatial SOS, a geospatial catalogue service, a WFS-T, and a WCS-T for the SOS, and a geospatial sensor client. The extensible sensor data adapter finds, stores, and manages sensor data from live sensors, sensor models, and simulation systems. Abstract factory design patterns are used during design and implementation. A sensor observation service compatible with the SWE is designed, following the OGC “core” and “transaction” specifications. It is implemented using Java servlet technology. It can be easily deployed in any Java servlet container and automatically exposed for discovery using Web Service Description Language (WSDL). Interaction sequences between a Sensor Web data consumer and an SOS, between a producer and an SOS, and between an SOS and a CSW are described in detail. The framework has been successfully demonstrated in application scenarios for EO-1 observations, weather observations, and water height gauge observations.