oscar sensor web enablement prototype

OSCARSensor Web Enablement Prototype

Presentation to WGISS-24October 2007

Paul MartinComSine Limited

[email protected]

© ComSine Limited, 2007

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


OSCAR OSCAR Concept


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


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


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


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


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)



Sensor Observation Service (SOS)• XML Encoding compliant with OGC

Implementation Specification 06-009r1• A web service for describing Sensors and

obtaining their Observations



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



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


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


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


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


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


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)


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


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


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


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


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


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

oscar sensor web enablement prototype

Documents

sensor web architectureprovide

following sensor

sensor observationsregister

009r1a web service

build2 sensor nodes

role satellite communications

highlevel access

inmarsat d serviceuk