oscar sensor web enablement prototype
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OSCAR Sensor Web Enablement Prototype. Presentation to WGISS-24 October 2007. Paul Martin ComSine Limited [email protected]. Introduction. OSCAR – “On-Line Sensor Control & Access Resource” - PowerPoint PPT PresentationTRANSCRIPT
OSCARSensor Web Enablement Prototype
Presentation to WGISS-24October 2007
Paul MartinComSine Limited
© ComSine Limited, 2007
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OSCAR Introduction
OSCAR – “On-Line Sensor Control & Access Resource”
Project under the BNSC Internal Co-operation Program that funds a number of small “Exploitation Projects”
• Aimed at allowing UK companies to exploit and contribute to international activities
Completed in October 2007
© ComSine Limited, 2007
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OSCAR OSCAR Concept
© ComSine Limited, 2007
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OSCAR Project Objectives
Work with real-world user partners to understand their requirements and determine focus of the project
Build a UK software resource that supports the major aspects of the OGC Sensor Web Enablement specifications
Look at the role satellite communications can play in a Sensor Web architecture
Provide a live demonstration of the OSCAR framework
© ComSine Limited, 2007
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OSCAR User Partners
Critical Software• Portuguese software development company• Sensor Web interests: Operational services for fire hazards
Hidromod• Portuguese technical consulting company• Sensor Web interests: Monitoring coastal waters
UK Environment Agency• Already operating and extensive network of in-situ sensors• Sensor Web interests: A need to promote high-level access to
their sensors Satamatics
• UK Satellite Communications Company• Suppliers of terminal operating under Inmarsat D+• Sensor Web interests: Oil pipeline monitoring
© ComSine Limited, 2007
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OSCAR Partner Requirements Feedback
Each sees a need for deploying sensors in remote areas with limited or no terrestrial communications coverage.
Open standards are an important aspect for their business in both “sharing information and reducing the time-to-market” for their products.
They identified the need to gain high-level access to their sensors as critical.
The ability of remotely monitor and control their sensors would enable their business to run more efficiently
In support of efforts such as GMES (Global Monitoring for Environment and Security), adopting standards to provide alerts on environmental conditions is critical
© ComSine Limited, 2007
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OSCAR What We Planned to Build
2 Sensor Nodes (one in UK, one in Australia) Each node will host a representative set of weather
station sensors Australia Node will use Satellite Communications over
the Inmarsat D+ service UK Node will be directly connected to the Internet via
WAN/LAN Implement a subset of the O&M and SensorML XML
encodings• Describe both sensors and their observations
Implement the major elements of the SOS, SAS and WNS web services
• Obtain sensor descriptions and sensor observations• Register to receive alerts for “alarming conditions” from a
sensor
© ComSine Limited, 2007
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OSCAR OGC SWE Components
Observations & Measurements (O&M)• XML Encoding compliant with OGC Best
Practices Document 05-087r4• Subset of the encoding to handle the following
observations: Temperature, Rainfall, Wind Speed/Direction, Humidity,
Air Pressure Sensor Modelling Language (SensorML)
• XML Encoding compliant with OGC Implementation Specification 05-086r2
• Subset of the encoding to describe the following sensor: Weather Station (TechnoLine WS-2300)
© ComSine Limited, 2007
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OSCAR OGC SWE Components
Sensor Observation Service (SOS)• XML Encoding compliant with OGC
Implementation Specification 06-009r1• A web service for describing Sensors and
obtaining their Observations
© ComSine Limited, 2007
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OSCAR OGC SWE Components
Sensor Alert Service (SAS)• XML Encoding compliant with OGC Discussion Paper 06-028• A web service that allows a sensor to be monitored for an
“alarming condition”, e.g. temperature exceeds a given value• A user may subscribe to receive alerts
© ComSine Limited, 2007
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OSCAR OGC SWE Components
Web Notification Service (WNS)• XML Encoding compliant with OGC Best Practices Document
06-095• Web Service for mediating asynchronously between web
services, e.g. Confirmation of a SPS tasking request issuing an alert from an SAS when an “alarming condition” occurs
© ComSine Limited, 2007
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OSCAR System Context
Sensor Node• Laptop PC with Weather
Station and WebCam sensors attached via RS-232 or USB
• A Data Logger will record observations from sensors at a pre-defined interval
• Periodically the Sensor Node will send observations via some communications protocol to the OSCAR Server Data Repository
• Communications via SATCOM and Internet will be demonstrated
© ComSine Limited, 2007
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OSCAR System Context contd
OSCAR Server• The OSCAR Server will
periodically scan the Data Repository for new observations
• The Data Loader will load new observations into Data Storage
• Data Storage will store observations using SWE O&M
• Data Storage will also store description of the sensor using SWE SensorML
© ComSine Limited, 2007
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OSCAR System Context contd
OSCAR SWE and Client
• A set of OGC SWE compliant web services accessible over the internet
• Sensor Observation Service - obtain O&M and SensorML
• Sensor Alert Service - Monitor sensors for “alarming conditions”
• Web Notification Service - alert user of “alarming condition” & mediate with user for planning requests
© ComSine Limited, 2007
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OSCAR Satellite Communications
Australian Demo Site• Satamatics SAT-201
terminal via Inmarsat D+• Sensor Node will load
SAT-201 with latest observations
• Observations are sent via satellite to the LES
• The MHS (gateway) will retrieve messages from the LES
• Message Client on the OSCAR Server will use ASPI-XML to look for new observations
• New Observations are written to the Data Repository
© ComSine Limited, 2007
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OSCAR WAN/LAN Communication
UK Demo Site• Sensor Node
connected to the internet via a wired Ethernet connection
• New observations will be sent directly over the internet to the Data Repository (e.g. FTP)
© ComSine Limited, 2007
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OSCAR Web Services Architecture
O&M and SensorML are stored in a PostGres/PostGIS relational database
Data exposed to upper layers using Java Data Objects (Object Persistence)
Web Service is implemented as Java objects
OGC SWE XML requests and responses are marshalled and un-marshalled into objects using Apache XML Beans (Data Binding)
Client passes XML requests and responses using SOAP over HTTP
Non XML messages handled via Java Servlet, e.g. GetCapabilities
© ComSine Limited, 2007
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OSCAR Equipment Setup
Sensor Node (SATCOM)• Weather Station in Torquay, Australia• Observations collected on demand by issuing a Forward
Message to the Sensor Node via a SAT-201 terminal over D+• Observations packaged into OSCAR Data File (ComSine
format) to compress data for transmission via a SAT-201 terminal over D+ to the OSCAR Server
Sensor Node (WAN/LAN)• Weather Station in South Warnborough, UK• Observations collected every 10 minute (stored as an
OSCAR Data File)• OSCAR Server retrieves observations using an FTP pull
© ComSine Limited, 2007
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OSCAR Issues We Experienced
Complete OGC schemas not available at time of development
• All schemas were extracted from OGC documentation• There were conflicts in namespaces between the different
services• There were conflicts in the use of GML (v3.1 vs 3.2) and other
supporting libraries Sharing of objects between SWE components
• In some cases similar object definitions were implemented across server namespaces
• E.g. A different FeatureOfInterest object exists for the SOS and the SAS
Standards not yet mature• Each implementation of the standard is at a different stage in
the OGC lifecycle• All (except SensorML) are yet to be release as an
Implementation Specification at version 1.0
© ComSine Limited, 2007
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OSCAR Issues We Experienced
There are some missing links in the process chain• E.g. When you register a new sensor, there is no reference to
adding it to an ‘Observation Offering’ via an OGC request
InsertObservation only allows for a single observation to be added per request
• This could be a performance bottleneck when a single sensor node wished to communicate several observations
• There may be an argument for a batch insert option
© ComSine Limited, 2007
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OSCAR On-Line Demonstrator Plans
Weather observations from our UK test site will continue to be uploaded into OSCAR
We plan to modify the Australian test site to the WAN/LAN setup which will also load weather observations into OSCAR
Access to the OSCAR-SWE services will be made available at the following URL
• http://81.29.75.200/oscar Demonstrator will offer access our implementations of
the SOS, SAS and WNS services Very keen to continue work on OSCAR/Sensor
Web and would welcome collaboration with others
© ComSine Limited, 2007
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OSCAR Who We Are
ComSine is a UK SME with a wholly owned subsidiary in Australia, ComSine Australia PTY Ltd
• We specialise software and hardware development in the domains of satellite communications, geographical information, navigation and Earth observation. Particular expertise in application of OGC standards and
development of web services/SOAs• Customers include: ESA, BNSC, the EC, the GSA,
Inmarsat, QinetiQ, SEEDA, LogicaCMG, etc..• Operating from premises in NE Hampshire, UK and
Torquay, near Melbourne, Victoria, Australia.• Website - http://www.comsine.co.uk