Location
Tracker
Provides visual representation of
real time location data of assets.
SUMMARY
To
develop a Swing based applet application, which provides a real-time and
historical locations of an asset (eg: hospital equipments, patients, employees
etc) in a visual form.
TECHNOLOGIES
1.
Eclipse 3.2 IDE for
development, debugging.
2.
JBoss-4.0.4.GA as the
web server.
3.
SVN version control for
versioning and code delivery.
4.
Ant for our build and
remote deploy.
5.
Programming Language:
Java (jdk 1.5)
6.
PostgreSQL8.1 as the
database
7.
Hibernate is used as
the object/relational persistence
8.
Java\Swings for Visual
Mapper.
9.
JMS for feeding the location data.
PROJECTS IMPLEMENTATION DETAILS
This applet pulls a stream of location co-ordinates data from a web
server and plots the location on X-Y graph. It provides the following options
to the user. It draws a particular location as a map. It represents different
zones in a location as circles. It shows the location of the assets.
Based on the co-ordinate and
map information obtained from an RTLS engine, the map will be populated with
asset information. If an asset’s location changes, the asset’s position on the
map will be redrawn. This project also supports
Active and Passive RFID technology. Unlike RTLS where the co-ordinate
information will be provided by an external engine, for active and passive RFID
technology, Web Application will need to have logic to identify where to show
the assets in the map. This involves two steps – a design-time step of
understanding how the site is made up of (what constitutes a room, where are
readers located, etc), and a run-time step of displaying asset information on a
visual map.
Design-Time:
In order to support displaying visual location information
of passive assets, we need to get information of what constitutes an area (such
as a room). In order to deduce the current location of an item based on where
it was seen, we need to get information about where readers are positioned on
the map.
Run-Time:
In order to display the location of the asset, the system
shall launch an applet using JNLP technology. Applet shall provide various
options for the user to select. Based on the selection the applet shall fetch
the data from the Web application to draw the position of the asset on the map.
The position of the asset drawn on the applet shall continuously be updated
based on the data rendered by an external engine.
Following shall be the features provided by the applet:
Ř
User shall be able to
select an area (such as a room). Applet shall draw the location of all the
assets in the area selected.
Ř
User shall be able to
select an asset. Applet shall draw the location of the selected asset.
Ř
User shall be able to
select a date (with time) and an area or asset. Applet shall display the
location of the assets based on the date selected.
Ř
Upon rendering the
response based on the user selected option(s), applet shall start to record the
drawing to provide fast forward and re-wind functionalities.
Ř
Applet shall be able to
display the details of an asset when the user moves the mouse over the asset.
As shown in Figure 1, the Applet communicates to the Web
Application through Http connection. Web Application fetches the location
information from a JMS Queue and supplies to the Applet for displaying.
Figure 1
Following are the challenges that we had
while developing this project:
1. Develop the Applet as a client application to display
the real time view of the equipments using the data received from the web
application.
2.
Communication between the Applet and the web Application is established through
an Http Connection using a servlet.
3. Develop a JMS client Application to generate the test
data. We developed a JMS client that feeds data continuously to the JMS Queue
and another JMS client that fetches the data from the JMS Queue and stores into
the database.
4. Applet shall be launched through JNLP technology. On
launch, it shall start 2 threads. One shall be responsible for co-coordinating
the effort to display the data and other to collect the data over the network
from web application. We shall call the former thread as “Data Displayer” and
the later as “Data Collector”. These two
threads share a common object called “Data Repository”.
DataRepository:
DataRepository object is a HashMap. Its key shall represent
the asset and the value shall be an ArrayList of Location objects. Location
object encapsulates assetID, mapID, timestamp, x and y positions. MapID is a
unique representation of the area an asset belongs to. DataRepository is updated
by Data Collector and the information in it is retrieved by Data Displayer.
For instance, we have 5 assets (say Asset1, Asset2, Asset3,
Asset4 and Asset5) in MapID = MapID1 then the data in DataRepository object
would like
|
Key |
Value |
||||||||||||||||||||
|
Asset1 |
ArrayList
<Location>
|
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|
Asset2 |
|
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|
Asset3 |
|
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|
Asset4 |
|
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|
Asset5 |
|
Figure 2
Data Displayer:
This thread shall fetch the data from DataRepository
object. It shall draw the location of an asset at the speed set by the user. Figure
2 shows life cycle representation of this thread.
Figure 3
This thread shall wait for a predefined amount of time till
enough of data is accumulated in the DataRepository object. Data shall be
retrieved in batch mode from DataRepository object. Every time data is retrieved, this thread
shall maintain a marker on the DataRepository object for an asset. This marker
shall help this thread to identify the next index from where it has to start to
read the data. Once a set of data is gathered, the locations of the assets are
drawn on the area selected. Upon completion of the current data set, this
thread shall check with DataRepository object (based on the marker set earlier)
if there are enough data to draw the locations during the next cycle. If there
is enough data then this thread shall fetch the next pre-defined amount of data
starting from the marker that was set earlier otherwise this thread shall not
update the location until there is new data for an asset in DataRepository
object.
For
example,
Ř
At the beginning, this
thread waits until it is notified by Data Collector thread.
Ř
Upon receiving
notification, this thread shall read pre-defined set of data from
DataRepository (let’s say 2 amount of the pre-defined data set). The marker
shall be
|
Key |
Value |
||||||||||||||||||||
|
Marker Position |
ArrayList
<Location>
|
||||||||||||||||||||
|
|
ArrayList
<Location>
|
||||||||||||||||||||
|
|
ArrayList
<Location>
|
Ř
Next cycle
Ř
|
Key |
Value |
||||||||||||||||||
|
|
ArrayList
<Location>
|
||||||||||||||||||
|
Asset2 |
ArrayList
<Location>
|
||||||||||||||||||
|
|
ArrayList
<Location>
|
Ř
In the next cycle,
since the marker is at 5 for Asset2 and does not have enough of data the
location of the asset will not be updated.
|
Key |
Value |
||||||||||||||||||
|
|
ArrayList
<Location>
|
||||||||||||||||||
|
|
ArrayList
<Location>
|
||||||||||||||||||
|
|
ArrayList
<Location>
|
||||||||||||||||||
|
New
Asset Added |
ArrayList
<Location>
|
Figure 4
Data Collector:
This thread will start before the Data
display thread. It connects to the SAM web server to collect the location
points of the all equipments based on the search options selected by the user.
Before it notifies the Data display thread it collects data for a predefined
amount of time. Every time data is appended to DataRepository. Data is received
in terms of predefined fixed number of rows.
Following are the features of Location
Tracker:
User can select:
Ř
The mode as current
Location or History Location.
Ř
The starting date from
which the user is interested to view the location of equipments.
Ř
Depending on the
category selected, the available data for the selected category will be
populated in the dropdown Box.
Ř
User can vary the speed
of movement.
Figure 7 shows couple of equipments location changing over
different zones on a map.
Figure 7
When the user selects Category ‘Map’, the dropdown Box will
be populated with the available location maps. When User selects any map from
the list, the map and the different zones on that map will be displayed. The
configuration data for the zones comes from the properties file. The location
data of the equipments for the selected map will be fetched from the database
and drawn continuously on the map.
When Category ‘Asset’ is selected all the available assets will be listed in the dropdown box. When user selects a particular asset, its location data will be fetched from the database and drawn continuously on the map. When the asset’s location changes from one map to other, map will be redrawn.