Geospatial Sensor Web Conference – Tutorials
Sensor Web Introduction
Simon Jirka ([email protected]) - 52°North GmbH
28th August 2017 – Münster (Germany) Motivation
• More and more sensors are deployed • Human observations • Lots of different phenomena – Weather – Pollution – Biodiversity – Hydrological Data – Traffic – ...
2 3 Motivation
• Different structures and elements of observations • Sensor interfaces are very heterogeneous • Need for harmonisation interoperability • Provide a layer on top of observation databases and low level sensor network technology integration into web applications
4 Motivation
• Traditional services allow to – request maps (images) • Web Mapping Service – request (binary) raster data • Web Coverage Service – request vector data • Web Feature Service • Lack of a generic framework for integration observation data into spatial data infrastructures
5 Motivation
6 Motivation
7 SWE Building Blocks
8 Observations & Measurements
• Conceptual model for – Representing observations – Exchanging observations • Implementation as application schema – XML schemata extending the Geography Markup Language (GML) • Primary use: Encode SOS GetObservation response documents • O&M 2.0 is now available (OGC and ISO standard)
9 O&M Basic Observation Model
• Observation – Act of observing a phenomenon – Producing an estimate for a property of a feature of interest – Specialized event with result • Inherits temporal attributes – Observation properties support result interpretation (e.g. quality)
10 O&M Observation Model
Source: OGC
11 O&M Basic Observation Model
• Procedure – Determines the value of a phenomenon – A procedure can be an instrument, a sensor, a human observer, a computation, a simulation … – O&M contains only a short description of the process – More detailed information is provided via SensorML / TML
12 O&M Basic Observation Model
• FeatureOfInterest – A Feature represents the observed real-world object – The feature of interest is the target of the observation – Examples: River, road, person, scene, specimen, …
13 O&M Basic Observation Model
• ObservedProperty – Identifies or describes the observed phenomenon – Examples: Air temperature, water level, wind speed, air pollution concentration – Description of the observed properties are often accessible through dictionaries
14 O&M Observation Example (XML)
15 O&M Observation Example (JSON)
16 SensorML
• General sensor information discovery • Facilitate processing and analysis of sensor measurements • Geolocation of observed values • Description of the process by which an observation was obtained • Current version: SensorML 2.0
17 SensorML Overview
18 Process
• Base for all processes in SensorML physical and non-physical processes • Elements – Inputs & Outputs – Parameter – Processing method – Reference systems – Any further metadata
19 Aggregate process
• Process chains are modelled as aggregate processes • An aggregate process describes – Processes of the chain – Data sources – Connections between processes
20 (Physical) System
• Extension of process chain • Defines relative positions of all components (processes and data sources) within the system • Spatial and temporal position • Describes interfaces of the system to the external world
21 Process Metadata
• Allows discovery and interpretation of results • Possible content – Common metadata (ID, classification, textual Description, Contact information) – Constraints (e.g. temporal validity of document) – Capabilities and characteristics of the sensor – References – History
22 SensorML – Example (i)
23 SensorML – Example (ii)
24 SWE - Interfaces
25 SMS Email Fax Phone Call
Response Request (O&M, SensorML) Subscribe Request Response Alerts SOS Event Notification SPS Processing Service
Observations Observations
Commands
26 Sensor Observation Service (SOS)
• Pull-based access to observations • Mediator between: – client data archive / simulation / real- time sensor system • Hides the heterogeneous structure of proprietary sensor data formats and protocols • Data formats: O&M and SensorML • Versions: 1.0 and 2.0
27 Sensor Observation Service (SOS)
Response Request (O&M, SensorML) SOS
Observations NetCDF NetCDF NetCDF
28 SOS – Requirements Classes
Core: -GetCapabilities -DescribeSensor -GetObservation
Transactional ResultHandling -InsertSensor -InsertResultTemplate -DeleteSensor -InsertResult -InsertObservation Enhanced -GetResultTemplate -GetFeatureOfInterest -GetResult -GetObservationById
29 SWE Eventing
• Sensor Alert Service • Sensor Event Service • Web Notification Service • Pub-Sub Extension recently adopted as OGC standard
30 OGC Publish/Subscribe Standard
31 Sensor Planning Service (SPS)
• Standardized interface for tasking sensors and sensor systems • Task management – Defining tasks – Checking tasks – Updating/modifying tasks – Cancelling tasks • Does not archive the data itself points to access points for the data
32 Introduction
• Usage: – Parameterization of: • Sensors, Simulations – Planning and executing of: • UAVs, Robots, Satellites, … • Asynchronous communication with clients that submit tasks via WNS (e.g. notification if a task is completed)
33 Operations
• Mandatory in SPS 1.0 and 2.0 – GetCapabilities: Request a self description of a SPS instance – DescribeTasking: Request which information is needed for submitting a task – Submit: Submitting tasks – DescribeResultAccess: Request information where the data resulting of a task can be retrieved
34 SPS workflow
35 Summary
• Data Models/Encodings: – Sensor Descriptions: SensorML – Observation Data: Observations & Measurements • Web Services: – Pull-based access: Sensor Observation Service – Eventing – Tasking sensors: Sensor Planning Service
36 Further Information: https://52north.github.io/sensor-web-tutorial/
Questions?
Simon Jirka ([email protected])
37 Geospatial Sensor Web Conference – Tutorials
Practical Exercise: Helgoland - A Sensor Web Viewer
Simon Jirka ([email protected]) - 52°North GmbH
28th August 2017 – Münster (Germany) Helgoland
• Based on JavaScript • Web application to – Discovery data offered by SOS servers – Explore sensor networks – Visualise observation data • Diagrams • Tables • Tracks (in development) • Uses 52°North Sensor Web REST-API to connect to SOS servers
39 Helgoland
40 Helgoland
41 Helgoland
• Open source: https://github.com/52North/helgoland • Test it: http://sensorweb.demo.52north.org/client/ – Select a data provider – Use the map view to discover a sensor/station – Visualise the data as a diagram – Open the table view • Advanced version: http://sensorweb.demo.52north.org/client/
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Questions?
Simon Jirka ([email protected])
43 Geospatial Sensor Web Conference – Tutorials
Deployment Strategies for the 52°North SOS
Simon Jirka ([email protected]) - 52°North GmbH
28th August 2017 – Münster (Germany) Agenda
1. How to integrate the 52°North SOS into your existing IT infrastructure?
45 Existing DB via new SOS Data Access Layer
SOS Client
GetObservation O&M
SOS Server
Database (e.g. PostgreSQL, MySQL, Oracle)
46 Existing DB via Hibernate
SOS Client
GetObservation O&M
SOS Server Hibernate
Database (e.g. PostgreSQL, MySQL, Oracle)
47 Existing DB via Views
SOS Client
GetObservation O&M
SOS Server
Database Views
Database (e.g. PostgreSQL, MySQL, Oracle)
48 Default SOS DB with Transactional Feeding
SOS Client Data Feeder
GetObservation O&M InsertObserva- tion (O&M)
SOS Server
Default DB
49 Default SPS DB with SQL Feeding
SOS Client
GetObservation O&M
SOS Server
SQL Data Feeder Default DB
50 SOS as Proxy
SOS Client
GetObservation O&M
SOS Server (Translator)
Proprietary Service
51
Questions?
Simon Jirka ([email protected])
52