Sensor Observation Service Client for Android Mobile Phones

Sensor Observation Service Client for Android Mobile Phones

Alain Tamayo, Pablo Viciano, Carlos Granell, Joaquín Huerta Geospatial Technologies Research Group, Universitat Jaume I, Spain

SWE 2011, Oct 6-‐7

Sensor Observation Service Client for Android Mobile Phones 2

1 . Motivation

The number of sensors deployed worldwide and the amount of data captured by them is growing at a fast pace.

Hardware and software of mobile phones have had a rapid evolution making possible to users to access Web content anytime and anywhere.


2 . Motivation

The Sensor Observation Service (SOS) specification provides a web service interface to retrieve sensor and observation data.

Several clients for this specification have been developed mostly for web and desktop environments, but not for mobile phones.


3 . Goal

Linux-‐based OS developed by Google Android had 22.7% of the smartphones' market share (February 22.7% Source: Gartner Inc.)

It provides a Java API Plug-‐in for Eclipse IDE available

Our goal is to develop a SOS client for the Android platform


4 . Application Requirements

•  SOS client for Android versions 2.2 and above

•  Support for the core profile of SOS 1.0.0 (GetCapabilities, DescribeSensor, GetObservation)

•  Visualisation of sensor locations and information

•  Support for temporal and spatial filters

•  Visualisation of observations in tables and charts

•  Easy management of server information

•  Connection to existing servers without the use of mediator components


5 . Application Architecture


6 . Data Access Layer

•  Network communication Library

•  Support for operations in the Core Profile using HTTP Bindings

•  XML Processing Code (Adapters)

•  An adapter exists for every type of response

•  Adapters are generated from the SOS schemas using an Instance-‐based approach from a corpus gathered from 56 SOS servers


7 . Instance-‐based Code Generation

9 Type Definition Hierarchy GML 3.1.1

Dependencies of types in GML 3.1.1


8 . Business Logic Layer

Google Maps Library is used for map visualisation: http://code.google.com/intl/es-‐ES/android/add-‐ons/google-‐apis/maps-‐overview.html


9 – UI Layer


10 – UI Layer (2)


11 – UI Layer (3)

aChartEngine is used to display charts: http://code.google.com/p/achartengine/


12 . Limitations

•  Support only for observations encoded using ObservationType

•  Observations must be encoded as swe:DataArray (52 North SOS, Deegree)

om:result defined as xsd:anyType

•  Limited support for filtering observations (TM_During, TM_Equals, BBOX)

•  Only one table at a time can be displayed


11 – Challenges and Open Issues

•  Large size and complexity of the schemas difficult development: XML data binding tools produces large binaries, producing this code manually is an error-‐prone and time-‐consuming task.

•  Constraints related to display size limit the amount of information that can be shown to the user.

•  SOS specification is generic and open to extension

•  Potentially large volume of data returned by SOS servers


11 -‐ Conclusions

•  We have implemented an Android client for the SOS specification that allows the visualisation of sensor locations and information, to visualise of observations in tables and charts, to filter observations according to temporal and spatial criteria and to easily manage the information about server end-‐points

•  During the development of the application a group of challenges and open issues were found. We were able to partially tackle some of these problems, but their definitive solution remains open.


12 – Licensed Content

Some of the images included in this presentation has been obtained from Flickr. Details below:

•  Slide 2: Cell phone evolution by sean dreilinger,

•  Slide 2: Train Sensor "mass detector” by Frosted Peppercorn,

•  Slide 2: Precipitation Sensor by ARM Climate Research Facility,

•  Slide 2: NASA's Upper Atmosphere Research Satellite by NASA Goddard Photo and Video,

•  Slides 2 and 4: android pixelpipe by osde8info,

•  Slides 2 and 4: Samsung Galaxy S by yum9me,

•  Slide 4: Android -‐ White Background by Saad Irfan,

•  Slide 4: Samsung Galaxy Tab by 3 Sverige

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Sensor Observation Service Client for Android Mobile Phones

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