1. Sensor Web Enablement (SWE) and Sensor Modeling Language (SensorML)
Öner Balçıklı
Middle East Technical University
May 2011 1

2. Presentation Outline Motivation Open Geospatial Consortium (OGC)
Sensor Web Enablement (SWE)
Sensor Model Language (SensorML)
Examples

3. Motivation An application area of process modeling concepts in design
Sensors are devices for the measurement of physical quantities.
There are a great variety of sensor types from simple visual thermometers to complex electron microscopes and earth orbiting satellites.
Sensors play vital roles within the environmental, intelligence, emergency management, and defense.
These sensors are not easily discoverable and accessible.
Processing of observations from these sensors are often confined to its own systems.
Often one is unaware of private or public sensor systems that are available for a particular application.
An application area of process modeling concepts in design

4. Why is this a Challenge?
There is a lack of uniform operations and standard representation for sensor data.
There exists no means for resource reallocation and resource sharing.
Deployment and usage of resources is usually tightly coupled with the specific location, application, and devices employed.
Resulting in a lack of interoperability.
SensorML provides a common framework for describing virtually any sensor system, as well as the processing that might be associated with these sensor systems. 4

5. Interoperability
The ability of two or more autonomous, heterogeneous, distributed digital entities to communicate and cooperate among themselves despite differences in language, context, format or content.
These entities should be able to interact with one another in meaningful ways without special effort by the user – the data producer or consumer – be it human or machine.

6. Open Geospatial Consortium-OGC
An international industry consortium of 334+ companies, government agencies and universities participating in a consensus process to develop publicly available interface specifications and encodings.
Open Standards development by consensus process
Interoperability Programs provide end-to-end implementation and testing before spec approval
Develop standard encodings and Web service interfaces
Sensor Web Enablement Framework 6

7. Open Geospatial Consortium-OGC
Standard encodings:
Geography Markup Language (GML)
Style Layer Description language (SLD)
SensorML
Observations and Measurement (O&M)
Standard Web Service interfaces:
Web Map Service (WMS)
Web Feature Service (WFS)
Web Coverage Service (WCS)
Catalog Service
Open Location Services – used by communications and navigation industry
Sensor Web Enablement Services (SOS, SAS, SPS)

8. What is Sensor Web Enablement?8 8

9. What is Sensor Web Enablement?
An interoperability framework for accessing and utilizing sensors and sensor systems via Internet and Web protocols
Enables a “Sensor Web” through which applications and services will be able to access sensors of all types over the Web
A set of web-based services can be used to maintain a registry of available sensors and observation queries
Web technology standard for describing the sensors’ outputs, platforms, locations, and control parameters should be used across applications
This standard encompasses specifications for interfaces, protocols, and encodings that enable the use of sensor data and services 9 9

10. Sensor Web Enablement Aims
Quickly discover sensors (secure or public) that can meet my needs – location, observables, quality, ability to task
Obtain sensor information in a standard encoding that is understandable by me and my software
Readily access sensor observations in a common manner, and in a form specific to my needs
Subscribe to and receive alerts when a sensor measures a particular phenomenon

11. OGC Sensor Web Enablement
Constellations of heterogeneous sensors
Vast set of users and applications
Satellite
Airborne
Sensor Web Enablement
Weather
Surveillance
Distributed self-describing sensors and related services
Link sensors to network and network-centric services
Common XML encodings, information models, and metadata for sensors and observations
Access observation data for value added processing and decision support applications
Network Services
Chemical
Detectors
Biological
Detectors
Sea State

12. SWE Components - Languages
Information Model for Observations and Sensing
Sensor and Processing Description Language
Observations & Measurements (O&M)
SensorML (SML)
TransducerML (TML)
GeographyML (GML)
Common Model for Geographical Information
Multiplexed, Real Time Streaming Protocol

13. SWE Components - Languages
Sensor Model Language (SensorML) – Standard models and XML Schema for describing sensors systems and processes; provides information needed for discovery of sensors, location of sensor observations, processing of low-level sensor observations, and listing of properties
Transducer Model Language (TransducerML) – The conceptual model and XML Schema for describing transducers and supporting real-time streaming of data to and from sensor systems
Observations and Measurements (O&M) – Standard models and XML Schema for encoding observations and measurements from a sensor, both archived and real-time

14. SWE Components – Web Services
Sensor Observation Service (SOS) – Standard Web service interface for requesting, filtering, and retrieving observations and sensor system information. This is the intermediary between a client and an observation repository or near real-time sensor channel
Sensor Alert Service (SAS) – Standard Web service interface for publishing and subscribing to alerts from sensors
Sensor Planning Service (SPS) – Standard Web service interface for requesting user-driven acquisitions and observations. This is the intermediary between a client and a sensor collection management environment
Web Notification Service (WNS) – Standard Web service interface for asynchronous delivery of messages or alerts from SAS and SPS web services and other elements of service workflows

15. SWE Components – Web Services
Access Sensor Description and Data
Command and Task Sensor Systems
SOS
SPS
Discover Services, Sensors, Providers, Data
Accessible from various types of clients from PDAs and Cell Phones to high end Workstations
SAS
Catalog Service
Dispatch Sensor Alerts to registered Users
Clients

16. Sensor Model Language (SensorML)16

17. SensorML Overview
SensorML is an XML schema for defining the geometric, dynamic, and observational characteristics of a sensor
SensorML provides the information needed for discovery of sensors, including the sensor’s capabilities, location, and task ability.
The purpose of the sensor description:
provide general sensor information in support of data discovery
support the processing and analysis of the sensor measurements
support the geo-location of the measured data.
provide performance characteristics (e.g. accuracy, threshold, etc.)
archive fundamental properties and assumptions regarding sensor
SensorML provides functional model for sensor, not detail description of hardware

18. Information provided by SensorML
Observation characteristics
Physical properties measured (radiometry, temperature, concentration, etc.)
Quality characteristics (accuracy, precision, etc.)
Response characteristics (spectral curve, temporal response, etc.)
Geometry Characteristics
Size, shape, spatial weight function of individual samples
Geometric and temporal characteristics of sample collections
Description and Documentation
Overall information about the sensor
History and reference information supporting the SensorML document 18

19. SensorML Properties
Within SensorML components (detectors, transmitters, actuators, and filters) are modeled as processes that can be connected and participated within a process chain or system.
SensorML provides a common framework for any process and process chain, but is particularly well-suited for the description of sensor and systems and the processing of sensor observations.
Processes are entities that take one or more inputs and through the application of well-defined methods using specific parameters, results in one or more outputs.
SensorML supports linking between processes and thus supports the concept of process chains, which are themselves defined as processes.

20. SensorML Properties
The models and schema within the core SensorML definition provide a “skeletal” framework for describing processes, process chains, and sensor systems
Within SensorML, all processes and components are encoded as application schema of the Feature model in the Geographic Markup Language (GML)

21. SensorML Properties
A sensor measurement can be modeled as a process by which an input phenomenon is observed by the sensor at some discrete moment in time.
Some measure of some property of that phenomenon is then output from the sensor.
through subsequent processing in software, raw observations are processed to higher-level knowledge.
The SensorML model does not try to define where observation measurement and observation processing begin or end. These are considered as part of the process.

22. Some Definitions in SensorML
Process: A process that takes one or more inputs, and based on parameters and methodologies, generates one or more outputs.
Process Method: Definition of the behavior and interface of a Process. It can be stored in a library so that it can be reused by different Process instances. It essentially describes the process interface and algorithm, and can point the user to existing implementations.
Process Chain: Processing block consisting of interconnected sub-processes, which can in turn be Process Models or Process Chains. A process chain also includes possible data sources as well as connections that explicitly link input and output signals of sub-processes together. It also precisely defines its own inputs, outputs and parameters.

23. SensorML Conceptual Models
In SensorML, all components are modeled as processes.
Components are transducers, actuators, processors (viewed as process components) and sensors and platforms (which are modeled as systems)
SensorML can be viewed as a specialized process description language with emphasis on application to sensor data
SensorML does not try to replace other existing technologies (such as BPEL or MATLAB Simulink)
SensorML-defined processes could be imported and executed within other execution environments, such as BPEL or MATLAB Simulink, as well as within SensorML-enabled process execution software.

24. SensorML Conceptual Models
Models for SensorML are represented using UML structure diagrams.
These UML diagrams represent conceptual models only and are not intended for automatic encoding within XML Schema.
SensorML models sensor systems as a collection of physical and non-physical processes.
A process in SensorML describes inputs and outputs expected, as well as the parameters and methodology required to create output values from input values.
All processes in SensorML are derived from Abstract Process which is itself derived from Abstract Feature. All features have as a minimum, name and description properties. In addition, all processes include inputs, outputs, and parameters.

25. Process Type

26. SensorML Processes

27. SML Concepts – Sensor

28. SML Concepts – Sensor Description
Mike Botts, "SensorML and Sensor Web Enablement," Earth System Science Center, UAB Huntsville

29. SML Concepts –Accuracy and Range

30. SML Concepts –Platform

31. SML Concepts – Process Model
In SensorML, everything is modeled as a Process
Process Model
defines atomic process modules (detector being one)
has five sections
metadata
inputs, outputs, parameters
method
Inputs, outputs, and parameters defined using SWE Common data definitions

32. SML Concepts – Process Process defines a process chain includes:
metadata
inputs, outputs, and parameters
processes (Process Model, Process)
data sources
connections between processes and between processes and data
System
defines a collection of related processes along with positional information

33. SML Concepts –Metadata Group
Metadata is primarily for discovery and assistance, and not typically used within process execution
Includes
Identification, classification, description
Security, legal, and time constraints
Capabilities and characteristics
Contacts and documentation
History

34. SML Concepts – Event

35. SensorML provides metadata suitable for discovery of sensors and processes

36. Tool Development and Support for SensorML
Open Source SensorML Process Execution Engine – Along with open-source process model library, provides execution environment for SensorML described algorithms
Open Source SensorML editor and process chain development client – on-going development of tools to allow human-friendly editors for SensorML descriptions
SensorML-enabled decision support client – Open source Space Time Toolkit is SensorML-enabled and will be available to discover, access, task, and process sensor observations; use as is or as template for COTS development

37. SensorML Process Editor: Ongoing Work by OGC

38. Example Applications
Northrop Grumman PulseNet Project

39. Application: NASA Sensor Web

40. Tsunami Early Warning & Mitigation Center
Systems
Seismic Monitoring
GPS
Tide Gauges
Ocean Bottom Units
Buoys
EO Data
Observations
Simulation
BMG 5in1 / 6in1
System
Risk- & Vulnerability Modelling
Geospatial Data Repository

41. NASA/NWS Forecast Model

42. THANK YOU