Dealing with large schema sets in mobile SOS-based applications

Although the adoption of OGC Web Services for server, desktop and web applications has been successful, its penetration in mobile devices has been slow. One of the main reasons is the performance problems associated with XML processing as it consumes a lot of memory and processing time, which are scarce resources in a mobile device. In this paper we propose an algorithm to generate efficient code for XML data binding for mobile SOS-based applications. The algorithm take advantage of the fact that individual implementations use only some portions of the standards' schemas, which allows the simplification of large XML schema sets in an application-specific manner by using a subset of XML instance files conforming to these schemas.Comment: 9 pages, 2 tables, 7 figure

Using SWE Standards for Ubiquitous Environmental Sensing: A Performance Analysis

Although smartphone applications represent the most typical data consumer tool from the citizen perspective in environmental applications, they can also be used for in-situ data collection and production in varied scenarios, such as geological sciences and biodiversity. The use of standard protocols, such as SWE, to exchange information between smartphones and sensor infrastructures brings benefits such as interoperability and scalability, but their reliance on XML is a potential problem when large volumes of data are transferred, due to limited bandwidth and processing capabilities on mobile phones. In this article we present a performance analysis about the use of SWE standards in smartphone applications to consume and produce environmental sensor data, analysing to what extent the performance problems related to XML can be alleviated by using alternative uncompressed and compressed formats

Measuring complexity in OGC web services XML schemas: pragmatic use and solutions

The use of standards in the geospatial domain, such as those defined by the Open Geospatial Consortium (OGC), for exchanging data has brought a great deal of interoperability upon which systems can be built in a reliable way. Unfortunately, these standards are becoming increasingly complex, making their implementation an arduous task. The use of appropriate software metrics can be very useful to quantify different properties of the standards that ultimately may suggest different solutions to deal with problems related to their complexity. In this regard, we present in this article an attempt to measure the complexity of the schemas associated with the OGC implementation specifications. We use a comprehensive set of metrics to provide a multidimensional view of this complexity. These metrics can be used to evaluate the impact of design decisions, study the evolution of schemas, and so on. We also present and evaluate different solutions that could be applied to overcome some of the problems associated with the complexity of the schemas

Empirical study of sensor observation services server instances

The number of Sensor Observation Service (SOS) instances available online has been increasing in the last few years. The SOS specification standardises interfaces and data formats for exchanging sensor-related in-formation between information providers and consumers. SOS in conjunction with other specifications in the Sensor Web Enablement initiative, at-tempts to realise the Sensor Web vision, a worldwide system where sensor networks of any kind are interconnected. In this paper we present an empirical study of actual instances of servers implementing SOS. The study focuses mostly in which parts of the specification are more frequently included in real implementations, and how exchanged messages follows the structure defined by XML Schema files. Our findings can be of practical use when implementing servers and clients based on the SOS specification, as they can be optimized for common scenarios.Comment: 25 pages, 11 tables, 6 figure

Building Standards-Based Geoprocessing Mobile Clients

Ponència presentada en AGILE’2012 International Conference on Geographic Information Science, "Multidisciplinary Research on Geographical Information in Europe and Beyond" celebrat a Avignon, els dies 24-27 d'abril de 2012The adoption of geoprocessing service clients in mobile devices seems to be still rare, even when the communication protocol provided by the Web Processing Service (WPS) seems to fit the philosophy of accessing computation-intensive processes from resourceconstrained devices such as mobile phones. One of the reasons to such a low use of WPS services is that input and output data used in geospatial processes are often encoded in some XML-based format, which demands large processing capabilities for mobile devices. In order to deal with this problem we present the WPS Mobile Framework. This framework provides light-weight libraries to communicate with WPS servers and it carries out automatic generation of XML data binding code for mobile devices tailored to specific application needs

Assessment of OGC Web Processing Services for REST principles

Recent distributed computing trends advocate the use of REpresentational State Transfer (REST) to alleviate the inherent complexity of the web services standards in building service-oriented web applications. In this paper we focus on the particular case of geospatial services interfaced by the OGC web processing service (WPS) specification in order to assess whether WPS-based geospatial services can be viewed from the architectural principles exposed in REST. Our concluding remarks suggest that the adoption of REST principles, to specially harness the built-in mechanisms of the HTTP application protocol, may be beneficial in scenarios where ad hoc composition of geoprocessing services are required, common for most non-expert users of geospatial information infrastructures

Visualization of Sensor Data in Virtual Globes

Ponència presentada en AGILE’2012 International Conference on Geographic Information Science, "Multidisciplinary Research on Geographical Information in Europe and Beyond" celebrat a Avignon, els dies 24-27 d'abril de 2012Virtual Globes have become a common platform for visualizing geographical data. The capability for customization, extensibility and the support of interaction with the visualized elements are some of the aspects to consider when selecting a Virtual Globe for visualization. For visualizing sensor data, aspects such as cardinality, the nature of the data and its temporal and spatial dimensions have to be considered. In this paper we present a prototype application to visualize sensor data retrieved from SOS servers over the NASA World Wind virtual Globe. For implementing the prototype application we relied on a categorization of the sensor data that provides possible visualization methods. The prototype has integrated the SEXTANTE library to enable data analysis over sensor data and include the results as part of the visualizations

gvSOS: a new client for the OGC® Sensor Obseration Service Interface standard

A key problem with sensor networks is achieving interoperability between different networks potentially built using different software and hardware platforms. Services interfaced by the Open Geospatial Consortium (OGC) specifications allow GIS clients to access geospatial data without knowing the details about how these data are gathered or stored. Currently, OGC is working on a set of interoperable interfaces and metadata encodings known as Sensor Web Enablement (SWE) that enables the integration of heterogeneous sensor systems and measurements into geospatial information infrastructures. In this article we present the implementation of gvSOS, a new module for gvSIG to connect to Sensor Observation Services (SOS). The gvSOS client module allows gvSIG users to interact with SOS servers, displaying the information gathered by sensors as a layer composed by features. We present the software engineering development process followed to build the module. For each step of the process we specify the main obstacles found during the development such as restrictions of the gvSIG architecture, inaccuracies in the OGC specifications, and a set of common problems found in current SOS server implementations available on the Internet. For most of the problems found we propose a solution, or at least we present a path that might lead to i