Web Server Development for Sensor Observation Service

Table of Contents

Scope

Sensor Observation Service (SOS) Overview:

1.Core Extension

ï‚·GetCapabilities

ï‚·GetObservation

ï‚·DescribeSensor

2.Enhanced Extension

ï‚·GetFeatureOfInterest

ï‚·GetObservaitonById

3.Transactional Extension

ï‚·InsertSensor

ï‚·UpdateSensorDescription

ï‚·DeleteSensor

ï‚·InsertObservation

4.Result Handling Extension

ï‚·InsertResultTemplate

ï‚·InsertResult

ï‚·GetResultTemplate

ï‚·GetResult

Installation:

Java runtime environment (JRE) 7.0 or higher:

Java Servlet-API 2.5 compatible application server:

Data Base Management System

Downloading the Sensor Observation Service API:

Installing the Web App:

Step.1:

Step.2:

Step.3:

Step.4:

Step.5:

Step.6:

Testing:

Resources & Reference:

Scope:

This document defines the installation and configuration process of the 52°North Sensor Observation Service (SOS) on a local Web server (Apache Tomcat 6.0).

Sensor Observation Service (SOS) Overview:

The Sensor Observation Service (SOS) is a well-known standard for the sensor web and is being approved by the organization called Open Geospatial Consortium. One of the most important feature of this standard is that it provide a web services based interface for the detection and access of real time and archived data, which is related to all the varieties of sensors such as mobile or stationary sensors. The sensor data can be in the form of observations being performed by the Sensor or the specifications of the sensors which are being used for the observation. The example of sensor data can be calibration information, positions, etc. The mechanism which is being followed for the retrieval of observations is by encoding them into the Observations & Measurements, while the sensor’s specification are retrieved by encoding them in SensorML (Sensor Modeling Language).The Open Geospatial Consortium SOS standard 2.0 (Which was adopted in 2012 )contains the following four extensions.

1. Core Extension

• GetCapabilities: Provides the self-description of the service.
• GetObservation: This service provides the sensor data which is encoded in the O&M model.
• DescribeSensor:Provides the information about a specific sensor in a language called Sensor ML.

2. Enhanced Extension

• GetFeatureOfInterest: Provides the information about the feature which is under observation.
• GetObservaitonById: Getting the observation on the basis of special identifier.

3. Transactional Extension

• InsertSensor: Introducing the new sensors.
• UpdateSensorDescription: Used to update the description of a specific sensor.
• DeleteSensor: Removal of sensor from the list.
• InsertObservation: Publishing the observations for recorded sensors.

4. Result Handling Extension

• InsertResultTemplate: Provides the facility to specify the Result Template into a SOS server for the representation of the values of GetResult request.
• InsertResult: Specifying the raw values according to the template defined in the InsertResultTemplate service.
• GetResultTemplate: Provides information regarding the result structure and encoding specification to help setting the parameter constellations.
• GetResult: Provides the raw data for specific parameter constellations.

Installation:

For the realization of above stated features of SOS, development of a web server is the fundamental part of this project. And a temp database will be used for the storage of observations and the sensor related information. This server will behave like a central entity such as an interface in between the sensor and the client.

Pre-Requisites:

This tutorial demands that the following software packages must be in execution form for the successful deployment of Sensor Observation Service on the Apache Tomcat 6.0.

Java runtime environment (JRE) 7.0 or higher:

Required only if you are interested in building the SOS from source.

Link to download the Software Package:

http://www.oracle.com/technetwork/java/javase/downloads/index.html

Java Servlet-API 2.5 compatible application server:

Tomcat 6 or higher:

http://tomcat.apache.org/download-60.cgi

Data Base Management System

1. PostgreSQL 9 or higher
2. PostGIS 2.0 or higher
3. pgAdminIII

Important Note: During the Database Installation do not change the “User Name: postgres” and the Server Access Port “Port: 5432”. Set the desired password but keep in mind these settings because all these stuff will be required during the database configuration with the SOS instance.

All these packages are the part of PostgreSQL 9.0 installation and they provide a user friendly installation wizard.

Link to download the Software Package:

http://www.postgresql.org/download/

After the successful installation and configuration of theses software packages.

Downloading the Sensor Observation Service API:

This API software package contains a WAR file which is the pre compiled SOS source file and by using which we can deploy our SOS service on the local server.

Link to download the Software Package:

http://52north.org/downloads/sensor-web/sos

After downloading the package extract them by using Win-Rar or any software package at your desired location.

Installing the Web App:

Step.1:

First of all Make it sure that the Apache Tomcat 6.0 and the PostgreSQL are running. In order to confirm the execution of the local server just click to the following link:

http://localhost/manager/html

Step.2:

Then create a new PostgreSQL database by using the pgAdmin3 according to the PostGIS template that you have already created during the PostGIS installation.

Step.3:

For the sake of understanding let’s take a look at this short tutorial on how to create a new database using pgAdminIII.

1. Open the pgAdminIII GUI and select theDatabasestree where you can see all the available databases.
2. Right-click on theDatabasesitem and then selectNew Database. As clear from the Fig.1.

[Figure.1.]

3. Providing the required information such as the database name and the owner as below and clickOK. As clear from the Fig.2.and Fig.3.

[Figure.2.]

[Figure.3.]

4. Now Click the newSosDBdatabase instance and you’ll find in theSchemasapublicschema, but no tables or functions will be available. The database is created but it is not spatially enabled yet.

Select the SosDBdatabase .Then Click theSQL querybutton in the toolbar as shown in the Fig.4.

[Figure.4.]

5. The SQL query window will open. Type the following command “ CREATE EXTENSION postgis; “. Press F5 to execute the query. As clear from the Fig.5.

[Figure.5.]

6. And now all the tables and the function will be shown from the newly created database. As clear from Fig.6.

[Figure.6.]

Step.4:

After the creation of Database Go to the Server home page by following the Link below:

http://localhost/manager/html

Now Scroll down the main page of the server and find the “WAR file to deploy” section, after getting there, browse to the folder where we have extracted our 52 North SOS software package and finally browse to the directory that contains the WAR file. Click on “deploy” button. The new service instance will be appear in the list of Installed Applications.

Step.5:

Move to the SOS interface by clicking on the newly deployed service instance. 52N SOS home page will be opened with the following indication:

“You first have to complete the installation process! Click here to start it.”

Click Start and then select PostgrSQL9/PostGIS from the drop-down menu. A database configuration form will appear below. Fill it with your database settings such as, for the "sos" user created above, these will be the configuration values:

• User Name: postgres
• Password: admin(Your Defined Password During the Database Installation)
• Database: SosDB
• Host: localhost
• Database port: 5432
• Schema: sos

And set the remaining fields to their default values. As below

• Old observation concept:Unchecked
• Transactional profile:Checked
• Spatial Filtering Profile: Checked
• Minimum ConnectionPool size: 10
• Maximum ConnectionPool size: 30
• Create tables:Checked
• Delete existing tables:Unchecked
• Force updating existing tables:Unchecked

Step.6:

Click next and configure the further settings, and define a user name and password for the 52N SOS administrator panel and click Install. Now the SOS is successfully installed on the Apache Tomcat 6.0 local server.

Testing:

For the sake of testing we could use the Test Client which is the built in component of the SOS API and can test the functionality of Sensor Observation Service on the local server. Here is the list of SOS features that has been installed on the server and can be tested using the test client.

• GetCapabilities
• GetObservation
• DescribeSensor
• GetFeatureOfInterest
• GetObservationById
• InsertSensor
• UpdateSensorDescription
• DeleteSensor
• InsertObservation
• InsertResultTemplate
• InsertResult
• GetResultTemplate
• GetResult

Resources & Reference:

http://www.ogcnetwork.net/SOS_Intro

http://52north.org/communities/sensorweb/sos/

http://52north.org/downloads/sensor-web/sos

https://wiki.52north.org/bin/view/Main/WebHome

http://www.ogcnetwork.net/SOS

http://tomcat.apache.org/download-60.cgi

http://download.eclipse.org/jetty/

http://glassfish.java.net/public/downloadsindex.html#top

http://maven.apache.org/download.html

http://www.postgresql.org/download/

http://www.pgadmin.org/download/

http://www.postgis.org/download/

http://52north.org/downloads/sensor-web/sos

1 | SOS Configuration on Web Server