1. Introduction

The sustained and continuous efforts put by DST/NRDMS resulted in development of National Spatial Data Infrastructure (NSDI) for the country. Recently, Cabinet Secretary has cleared the NSDI proposal and constituted high powered Committees for its implementation. NSDI aims at bringing various National geo-spatial data generators on to a single platform and adoption of common International standards like ISO and Open Geospatial Consortium (OGC) for seamless data interoperability. NSDI will facilitate users to discover, query and access the geo-spatial data available with various organisations and are distributed across the country. It also aims at building a single point, a source of meta data repository called electronic clearinghouse.

Once in place, the NSDI will enable and drive various applications like

• Environmental monitoring
  

• Transportation management
  

• Public safety & facility security
  

• Utilities supervisory control and data acquisition control operations
  

• Industrial controls, facilities management
  

• Intelligent Transport System (ITS)
  

• Preparation of disaster mitigation, management and damage assessment plans
  

• Environmental impact assessment
  

• automatic data capturing methodologies
  

• Other Location Based Services (LBS).
  

However, some of these high end applications require on-line data, automatic data capturing in terms of audio, video and text facilities, digital image processing, recognition, analysis and integration with the spatial data for efficient decision making/ alert generation. Therefore, there requires a deep integration of observational networks with the spatial data. The observational networks could be cameras, satellites, sensors and other devices. A telescopic view and 360 degrees analysis, provides an impression that there will be gap emerging between spatial data and applications that require on-line observations i.e., integration of sensor data with spatial datasets. The present proposed programme aims at bridging this gap so that the NSDI and its full benefits could be realized in coming days. Primarily, it is with this objective, the international organizations and various governments have realized the requirement of Senor Networks, standardised protocols, unified sensor communication methodologies and procedures that enable Sensors communicate through the WWW. Combined together it forms basis for SENSOR WEB ENABLEMENT (SWE).

2. Sensor Web Enablement

A sensor network is a computer accessible network of many, spatially distributed devices using sensors to monitor conditions at different locations, such as weather parameters, pollution parameters and implementation estimation. A sensor web refers to web accessible sensor networks and archived sensor data that can be discovered and accessed using standard protocols and Application Programme Interfaces (APIs). International communities are working hard for building a unique framework of open standards for exploiting Web-connected sensors and sensor systems of all types: rain gauges, air pollution monitors, stress gauges on bridges, mobile heart monitors, Webcams, satellite-borne earth imaging devices and numerous other sensor systems. Sensor Web Enablement presents many opportunities for adding a real-time sensor dimension to the Internet and the web. This has extraordinary significance for science, environmental monitoring, transportation management, public safety, facility security, disaster management, utilities supervisory control and data acquisition control operations, industrial controls, facilities management and many other domains of activity. Definitely India should become part of this international movement and get benefited by the technological advancement.

3. Science & Technology of SWE

In much the same way that HTML and HTTP standards enabled the exchange of any type of information on the Web, the Open Geospatial Consortium's (OGC) Sensor Web Enablement (SWE) initiative is focused on developing standards to enable the discovery, exchange, and processing of sensor observations, as well as the tasking of sensor systems. The functionality that OCG has targeted within a sensor web includes: Discovery of sensor systems, observations, and observation processes that meet our immediate needs, Determination of a sensor's capabilities and quality of measurements, Access to sensor parameters that automatically allow software to process and geolocate observations, Retrieval of real-time or time-series observations and coverages in standard encodings, Tasking of sensors to acquire observations of interest, Subscription to and publishing of alerts to be issued by sensors or sensor services based upon certain criteria Within the SWE initiative, the enablement of such sensor webs is being pursued through the establishment of several encodings for describing sensors and sensor observations, and through several standard interface definitions for web services. Sensor Web Enablement standards that have been built and prototyped by members of the OGC include the following :

3.1 Sensor Model Language (SensorML) - standard models and XML Schema for describing the processes within sensor and observation processing systems; provides information needed for discovery, georeferencing, and processing of observations, as well as tasking sensors and simulations.

3.2 Observations & Measurements (O&M) - The general models and XML encodings for observations and measurements made using sensors.

3.3 Transducer Model Language (TML) - Conceptual approach and XML encoding for supporting real-time streaming observations and tasking commands from and to sensor systems.

3.4 Sensor Observation Service (SOS) - An open interface for a service by which a client can obtain observations from a sensor and platform descriptions from one or more sensors.

3.5 Sensor Planning Service (SPS) - An open interface for a service by which a client can, Determine the feasibility of collecting data from one or more sensors or models and Submit collection requests to these sensors and configurable processes.

3.6 Sensor Alert Service (SAS)- An open interface for a web service for publishing of and subscribing to deliverable alerts from sensor or simulation systems.

3.7 Web Notification Service (WNS) - An open interface for a service by which a client may conduct asynchronous dialogues, message interchanges, with one or more other services.
The sensor web standards infrastructure defined by these specifications constitutes a revolution in the discovery, assessment and control of live data sources and archived sensor data. The goal of this programme is to understand, design and operational concepts for the SWE Architecture for common good.

4. Sensor Web Enablement Architecture overview

The SWE architecture was designed to enable the creation of web-accessible sensor assets through common interfaces and encodings. Sensor assets may include the sensors themselves, observation archives, simulations, and observation processing algorithms. The role of SWE is depicted in the figure below. SWE not only enables interoperability among disparate networks of sensors and among disparate models and simulations, but it also enables increased interoperability between sensors and models, and between these and the decision support tools where the final application of observations occurs.

The role of the OGC Sensor Web Enablement framework is to provide interoperability among disparate sensors and models, as well as to serve as an interoperable bridge between sensors, model and simulations, and decision support tools.
As described, the SWE framework has been designed by the International communities, to enable solutions that meet the following desires:

4.1 Discovery of sensors, observations, and processes - It enables one to easily discover all sensor assets (sensor systems, simulations, and data processes) that are available for meeting that individuals needs in a timely fashion; this is particularly important, for example, during rescue or mitigation operations following an unexpected disaster or attack

4.2 Determination of a sensor's capabilities and an observation's reliability - To provide the ability to readily assess the capabilities of a sensor or simulation system, as well as provide sufficient lineage of an observation to determine its reliability for decision support

4.3 Access to parameters and processes that allow on-demand processing of observations - To provide the means to sufficiently be able to support on-demand geolocation and processing of sensor observations by generic software, without the need for a priori knowledge of the sensor system

4.4 Retrieval of real-time or time-series observations in standard encodings - To be able to access and immediately utilize observations from newly discovered sensors within decision support tools, models, and simulations without needing to develop sensor-specific readers

4.5 Tasking of sensors and simulators to acquire observations of interest - To be able to task a sensor or simulation system, and to provide my collection requirements, using a common interface; this interface needs to be able to support tasking as simple as controlling a web cam, as well as something as sophisticated as a military surveillance operation

4.6 Subscription to and publishing of alerts based on sensor or simulation observations - To provide a means by which a sensor system or simulation can publish possible alerts to be issued by sensors or sensor services based upon certain criteria, and allow one to subscribe to and receive these alerts when criteria are met; such criteria could be a simple as a measured value exceeding a certain threshold or as complex as pattern recognition within a single or multiple observations.

5. SWE Implementation components

The SWE components listed above are defined in detail by the OGC. The following are some of the core components that provides an informative description and status of each component within the SWE Architecture.

5.1 SWE Common - There are several common core definitions used throughout the SWE framework that have been pulled from other SWE specifications, such as O&M and SensorML, and have been placed within the SWE Common namespace. These are currently not defined within a separate document, but rather are defined within SensorML or O&M specification documents. Future releases may separate SWE Common definitions into a separate document. Earlier O&M and SensorML specification documents defined four fundamental data types derived from ScalarValue, including: Quantity, Count, Boolean, and Category. These were extended within the SensorML specification where they serve as fundamental data types for all input, output, and parameter definitions, as well as property values within characteristics and capabilities. Also defined within SensorML are data encoding types, supporting efficient ASCII and Binary data blocks, as well as simple MIME types. The SWE Common data definitions are used throughout the SWE framework to provide a "common" means to specify expected or observed data components.

6. International Scenario

Considering the importance and requirements of the current times Open Geo-spatial Consortium (OGC) along with International Standards Organisation (ISO) initiated a major programme and development of interoperable framework for SWE. Following are the some of the major groups and activities that are being carried out. A Joint Advisory Group which facilitates and manages the relationship between ISO Technical Committee 211 and OGC. This agree relationship with TC-211 ties OGC to advance ISO standard consistent with OGC document. There are a number of OGC abstract specification topic volumes that are actually ISO documents, such as metadata services, spatial referencing and feature geometry. This important arrangement also allows OGC to submit New Works Item Proposals (NWIPs) to ISO. NWIPs tend to be either suggested changes to an existing ISO TC 211 document or OGC adopted implementation specifications submitted for consideration as ISO standards. The work on Cordinated Reference Systems (CRS) is an example of the former case and the work on simple features, web map service, and geography markup language are examples of the latter. Thus, ISO and OGC are working in tandem for development of common standards for spatial data infrastructure benefits in general and SWE in particular.

Organisation for the Advancement of Structured Information Standards (OASIS) is a not-for-profit, international consortium that drives the development, convergence, and adoption of e-business standards. OGC work intersects OASIS work at several levels. OASIS is organized into many Technical Committees, and several OGC members and staff are actively involved in OASIS groups covering topics such as the electronic business resource information model (ebRIM), E-Government, and Emergency Services. The OASIS Common Alert Protocol (CAP) standard as elements that are being harmonized with OGC work. Future change proposals to CAP will integrate components of existing OGC specifications as normative.

6.1 World Wide Web Consortium: OGC also works closely with World Wide Web Consortium (W3C) to discuss items of mutual interest for enabling common protocols. OGC work with W3C on SVG, XML, XSLT, SOAP, WSDL and RDF ( resource, description, framework and also on web ontology in OWL). Internet Engineering Task Force (IETF) is large open, international community of network designers, operators, service providers and researchers concerned with the evolution of the Internet architectures and smooth operation of the Internet. OGC represent in the geo-PRIB working group whose primary task is to assess the authorization, integrity and privacy requirements e.g. meeting in order to transfer geo-information or authorized to release or representation of such information through on an agent.

7.National Scenario

Though much work being carried out by reputed institutes like IIT's, IISc, other academic institutions and R&D laboratories. However, the efforts are in a stand alone and isolated. There is no co-ordinated efforts to bring them to a common framework and to address a specific requirements of stakeholders in general and to provide solutions to industry/people centric common issues. There is an every need to consolidate the distributed efforts being carried out in SWE and work towards a common goal by combining strengths. Here, the international communities particularly OGC brings a rich expertise and reach of global standards evolution. DST is a member of OGC for a long and at present actively involved with data interoperability test bed initiatives. Recently, DST has conducted a interoperability experiment which is a first in Asia - Pacific region and 7th in world. Moreover, the recent nomination of Dr R Siva Kumar, Head, NRDMS, DST as one of the members to Board of Directors of OGC will enhance and strengthen the already established ties with OGC. Initiation of R&D in the country in a framework and participation in the global efforts in SWE is the requirement of hour. Though, it is late, nevertheless , we need to take steps to walk along with the global initiatives.

8. Broad objectives of the proposed SWE programme:

• To identify SWE R&D priorities, assessment of inherent strengths, development in participative mode and interlinking with National developmental goals and Vision-2020
  

• To create R&D opportunities and to promote R&D in SWE in a framework
  

• To demonstrate sensor-based Web-enabled interoperable technology in support of geospatial information
  

• To implement, test, and refine the current SWE framework of web services and encodings within real working environments that is beneficial to the country
  

• To extend SWE to support simulation and modeling
  

• To participate in International R&D collaborations and in participation in standards development.

9.DST, NRDMS Division identified the SWE as one of the thrust areas for research. R&D projects are invited from the researchers working in this area or related fields.