Figure 1: Basic J2ME structure

INFORMATION SYSTEMS SUPPORT ON MOBILE DEVICE

PLATFORM

Java SCADA Client/Server model and .NET localization enhancement

Ondřej Krejcar, Jindřich Černohorský

VSB Technical University of Ostrava, Faculty of Electrical Engineering and Computer Science, Department of

Measurement and Control, Centre for Applied Cybernetics, 17.listopadu 15, 708 33 Ostrava-Poruba, CZECH REPUBLIC

eywords: Mobile device, PDA, WM2003, Linux, Java, J2ME, .NET CF, OpenNetCF, Location-aware services.

Abstract: The paper deals with programming possibilities of mobile devices. It discusses the relationships with control

systems and problems with solutions of possible situations arising from their design or their operation. It is

focused mainly on Java language and use of created SCADA based application on wide scale of mobile

devices without any changes of source code. The proliferation of mobile computing devices and local-area

wireless networks has fostered a growing interest in location-aware systems and services. Another area of

interest is in model of radio-frequency (RF) based system enhancement for locating and tracking users of

our information system inside buildings. User location is used to data pre-buffering and pushing information

from server to user’s PDA.

1 INTRODUCTION

Programming of personal digital assistant (PDA) is

possible in two ways. The first and the best known

way is based on MS Windows CE, now renamed to

Windows Mobile for Pocket PC. Contemporary

version of Windows Mobile is 2003 SE (WM2003).

The second way is based on Linux distribution. OS

Win CE is used not only in pocket computers, but it

can be found it in other devices. There are two

usable and supported programming platforms. The

first one, .NET framework, is otherwise younger, but

more preferred by Microsoft. It can be installed on

Win CE on PDA. The .NET platform hasn't however

portation to Linux. The second way is based on Java

language. Java can run on both OS. Program written

in Java is possible to start on every processor on

which virtual machine of Java called Java Virtual

Machine (JVM) is running. JVM is virtual (software

or hardware) processor on which is possible to start

the program or applet written in Java (java applet).

JVM is implemented in a number of embedded

devices, servers, mobile phones and PDA’s. Next

benefits are in uniform language platform for

development of company systems and a reuse of

code.

2 JAVA 2 MICRO EDITION -

J2ME

Java language is currently distributed in three

different packages various in their sets. One of them

is known as Java microedition platform. This

distribution started up with the aim to consolidate

various offshoots of Java language for small devices,

which aren’t contained in the standard edition. This

establishment encompasses devices with various

properties. Microedition isn't one specification like

standard edition, but it is a set of various

configurations and profiles. These configurations

designate basic set of libraries and properties of

devices, which refine profile.

MIDP

PD AP

CLDC

KVM

CDC

CVM

Founda tion Profile

RM I

profile

Game

profile

Conected Device Configuration

Kilobyte Virtual Machine

Compact Virtual Machine

205

Krejcar O. and

Cernohorský J. (2005).

INFORMATION SYSTEMS SUPPORT ON MOBILE DEVICE PLATFORM - Java SCADA Client/Server model and .NET localization enhancement.

In Proceedings of the Second International Conference on Informatics in Control, Automation and Robotics - Signal Processing, Systems Modeling and

Control, pages 205-210

DOI: 10.5220/0001179202050210

 SciTePress

2.1 Mobile Information Device

Profile

MIDP profile specifies Connection Limited Device

Configuration (CLDC) for use in smallest devices,

like usual mobile phones. Just this platform pleases

largest focus, because it is concerned in a body of

extensive devices. The MIDP profile adds to

hardware specifications a minimum requirement on

display size (96 x 54 pixels) and the possibility to

control device by character keyboard or by screen

touching. It also requires at least 8 kB stable

memory for saving data application. In version

MIDP 2.0, whose specification is already available,

important functionality is improved, like interface by

sockets or sound control. Practically each of mobile

phones belongs to MIDP category. Application for

this category is called midlet according to basic class

of MIDP profile.

3 JAVA AND LINUX ON PDA

IPAQ

The most common variant is using Linux on

classical Pocket PC. Since Pocket PC’s are in most

cases on purchase already equipped with Windows

CE system, it is necessary to replace it with desired

Linux distribution. This is user's exacting operation

requiring higher knowledge level in the area of

installation and system repair. There are now

multiple projects focussed on development of Linux

implementations for the iPAQ, including one from

the Hewlett-Packard sponsoring handhelds.org site.

In particular, this Familiar Project provides

comprehensive free and open support for the iPAQ.

3.1 HP iPAQ platform

HP iPAQ 5450

The iPAQ 5450 model has a 240 x 320 pixel backlit

colour LCD screen and is powered by a 400MHz

Intel Strong-Arm processor with 64MB of RAM and

64MB of flash memory. This device has integrated

support for wireless solutions as Wi-Fi, Bluetooth

and infra red.

On this model of iPAQ we have installed a

Familiar Linux distribution on which is running

JVM needed for SCADA application. We use HP

iPAQ H4150 on which is running WM2003

operating system to tests created applications.

HP iPAQ 4150

HP iPAQ 4150 is classical PDA from Hewlett-

Packard too. It has the same parameters as 5450

model. Only flash memory (NAND flash) is smaller

in compare with.

This system is equipped by WM2003, and a

special virtual machine J9 from IBM Company.

3.2 WebSphere Everyplace - J9 VM

If we want to work with an application written in

Java, we have to install Java runtime Environment

(JRE). JRE includes JVM, which is typed and

compiled for existent platform, respective concrete

processor of given Pocket PC, how it was already

described above.

The J9 VM is the core of WebSphere Everyplace

Micro Environment (WEME), the IBM

implementation of the JVM Specification, Version

1.3.

The J9 VM and Java Class Libraries (JCL)

comprise the J9 runtime environment. The J9

runtime environment is J2ME compliant and

contains CLDC and CDC based technologies. In

addition, the WebSphere Everyplace Custom

Environment (WECE) is a combination of the J9

VM and IBM custom libraries.

The WEME product is supported on a variety of:

• Operating systems (including Microsoft

Windows, Linux, PalmOS, OSE, Rex,

VxWorks, PocketPC, Symbian, QNX and

Nucleus)

• Hardware architectures (including Intel x86,

xScale. ARM, MIPS, SH4, and PowerPC)

On J9 VM we can run application created for mobile

phone under MIDP specification without any change

of source code. Developer must create only one

product in one specification and it is runnable on

PDA, mobile phone or on other embedded device

with running J9 VM.

Space required to install J9 VM is:

• J2ME Mobile Information Device Next

Generation (JSR-118) MIDP 2.0 – 3MB

• J2ME Personal Profile 1.0 (JSR-62) – 8MB

4 SCADA

SCADA stands for Supervisory Control And Data

Acquisition. As the name indicates, it is not a full

control system, but it rather focuses on the

supervisory level. As such, it is a purely software

package that is positioned on top of hardware to

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206

Figure 2: J2ME mobile phone & PDA client

which it is interfaced, in general via Programmable

Logic Controllers (PLCs), or other commercial

hardware modules.

4.1 SCADA model

We have created new SCADA client – server

application based on SCADA systems principals.

This model is very useful and scalable for many tests

of embedded devices (SCADA clients). Model of

SCADA server’s doesn’t contain some standards of

SCADA based systems like real-time database and

historical trends. We plan to extend our SCADA

application by these features in the future.

SCADA J2SE server

Model of SCADA server was created using Java

application base in standard IDE environment of

Borland JBuilder X. Application is based on J2SE

functionality and library. Some options of user

interface like graph are developed for better

visualization of measured values. The needed values

like temperature are generated by special created

algorithms, or are set by user. User can set value by

adjustable scrollbars, and their value is visualized

online by other graphical element.

SCADA J2ME client

Model of SCADA client was developed in the same

IDE JBuilder X as server above. As development

platform the Java 2 Mobile Environment

specification (J2ME) was used. This specification

allows running applications on mobile phone and on

PDA with installed JVM. In our case it is IBM J9

VM. This is very important for code reuse and safety

of our application. Application is created by high

level MIDP components interface and other MIDP

component usable for SCADA systems. This

guaranties trouble free portability between mobile

devices.

High level components of SCADA system

The first component which is used in SCADA client

is text field. This can be used to setting request for

sending value from SCADA server. Gauge is the

second component and it is used for visualization of

actual temperature value. The gauge is in enabled

state, what means, that we can change the value of

this component. Example of these two components

is shown on figure 2 (mobile and PDA).

Other high level component is the image item

component, which is useful for graphical

representation of some problem. Notice that there is

a different presentation of application between

mobile phone and PDA. In mobile phone the buttons

are on tool list, meanwhile in PDA they are visible

as self button.

Alarms in J2ME SCADA applications

Alarms are well known and used in SCADA

systems. J2ME platform has this support too. Alarms

are in Alert class, which is subclass of Screen class.

Alert’s behaviour is the same as known dialogs, but

it has reduced functionality. There are many types of

alerts:

• ALARM - alarm

• CONFIRMATION - confirmation

• ERROR - error

• INFO - information

• WARNING - notification

Alerts are characterised by many parameters like

their name, message for user, image and timeout.

5 LOCALIZATION

ENHANCEMENT

The proliferation of mobile computing devices and

local-area wireless networks has fostered a growing

interest in location-aware systems and services. A

key distinguishing feature of such systems is that the

application information and/or interface presented to

the user is, in general, a function of his physical

location. The granularity of location information

needed could vary from one application to another.

For example, locating a nearby printer requires fairly

coarse-grained location information whereas

locating a book in a library would require fine-

grained information.

While much research has been focussed on

development of services architectures for location-

aware systems, less attention has been paid to the

fundamental and challenging problem of locating

and tracking mobile users, especially in in-building

INFORMATION SYSTEMS SUPPORT ON MOBILE DEVICE PLATFORM - Java SCADA Client/Server model and

.NET localization enhancement

207

Figure 3: Locator

–

AP intensity

Positioning

environments. We focus mainly on RF wireless

networks in our research. Our goal is to complement

the data networking capabilities of RF wireless

LANs with accurate user location and tracking

capabilities for user needed data pre-buffering. This

property we will use as information ground for our

information system.

5.1 Data Collection

A key step in proposed research methodology is the

data collection phase. We record information about

the radio signal as a function of the user’s location.

The signal information is used to construct and

validate models for signal propagation.

Among other information, the WaveLAN NIC

makes available the signal strength (SS) and the

signal-to-noise ratio (SNR). SS is reported in units

of dBm and SNR is expressed in dB. A signal

strength of s Watts is equivalent to

10*log10(s/0.001) dBm. A signal strength of s Watts

and a noise power of n Watts yields an SNR of

10*log10(s/n) dB. For example, a signal strength of

1 Watt is equivalent to 30 dBm. Furthermore, if the

noise power is 0.1 Watt, the SNR would be 10 dB.

The WaveLAN driver extracts the SS and the SNR

information from the WaveLAN firmware each time

a broadcast packet is received. It then makes the

information available to user-level applications via

system calls. It uses the wlconfig utility, which

provides a wrapper around the calls, to extract the

signal information.

6 PDPT FRAMEWORK

Predictive data push technology (PDPT) framework

is name of our project. Basic idea is in connection

between location information and data push

technology. When we know user position and user

track, the data which could be needed by the user in

the future is pushed to his mobile device. This part

of project is being developed under .NET CF and

OpenNETCF on mobile device (client) side. .NET

language is basic for server side application. It is

supposed that in the future will be possible to make

an interconnection to existing Java SCADA

application discussed before.

6.1 Pushing in Intranets

Intranets are simply local 'internets' close inside

various organisations. They allow transfer of

information between users. Important company

news and information can be pushed straight to the

Screen of the employees. This could be done in form

of screen savers, tickers (scrolling bars of text) or by

some client application. A good example of a useful

application of push within companies is automatic

notification of events. For example, by linking a

push system to a database of stocks and components

in a manufacturing company a manager could be

alerted if the number of a particular component

drops below a certain level.

When some intelligence is added to push system,

the very useful system may be created. This is what

we do. Location information about users is added to

server as intelligence for push technology.

6.2 Predictive data push technology

This part of project is based on model of location-

aware enhancement, which will be used in created

information system for adding user location

informations. These information about will be useful

for next generation of framework to increase real

dataflow from wireless access point (server side) to

PDA (client side). Primary dataflow is enlarged by

data pre-buffering. These techniques form the basis

for predictive data push technology (PDPT). PDPT

copies data from information server to clients PDA

to be on hand when user comes at desired location.

The benefit of PDPT consists in reduction of

time needed to display desired information requested

by user command on PDA. Time delay may be from

a few seconds to number of minutes. It depends on

two aspects. First aspect is the quality of wireless

Wi-Fi connection used by client PDA. A theoretic

speed of Wi-Fi connection is max 825 kB/s.

However, the test of transfer rate from server to

client’s PDA, which we have carried out within our

Wi-Fi infrastructure provided the result speed only

160 KB/s. Second aspect is the size of copied data.

The application (locator)

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Figure 4: WLA for building

Figure 5: System architecture – UML design

based on .NET language is now created for testing.

Current application records just one set of signal

strength measurements. By this set of value the

actual user position is determined.

6.3 Wireless location architecture

Another very important part of project is design of

Wireless Location Architecture (WLA). WLA

define structure for data store in database. Structure

is defined as data levels in building plan for

example.

Example of function: User location is

determined and analyzed. Server activates the PDPT

and pushes data to PDA. As first the data about

Building Block will be copied. As next the Block

Floor data and finally the data about user occurred

cell will be copied.

6.4 Framework design

PDPT framework design is based on most

commonly used server-client architecture. To

process data the server has online connection to

Control System. Data from technology are

continually saved to SQL Server database (WLA

architecture). The part of this database (desired by

user location or his demand) is replicated online to

client’s PDA where it is visualized on the screen.

User PDA has location sensor component which

continuously sends to framework kernel information

about nearby AP’s intensity. The kernel processes

this information and makes a decision if and how a

part of WLA SQL Server database will be replicated

to client’s SQL Server CE database.

These kernel decisions constitute the most important

part of whole framework because the kernel must

continually compute the user position and track and

make a prediction of his future movement. After

doing this prediction the appropriate data (part of

WLA SQL Server database) are pre-buffered to

client’s database for future possible requirements.

7 CONCLUSION

The paper deals with programming possibilities of

control systems and problems with solutions of

possible situations. The main objective is to show

how to use information systems on concrete mobile

device (mobile phone and PDA iPAQ) in context of

use Java language. The main advantage is in

possibility to use created java based SCADA

application on wide scale of mobile devices without

any changes of source code.

Other in this paper presented feature is the

enhancement of information system for locating and

tracking of users inside a building. It is possible to

locate and track the users with high degree of

accuracy. The median resolution of the system is in

the range of 2 to 3 meters, about the size of a typical

office room. Our practice and experiments indicate

that it is possible to build an interesting class of

location-aware services, such as printing to the

nearest printer, users navigating through a building,

etc., on an RF wireless LAN. User location is used

to data pre-buffering and pushing information from

server to user’s PDA. Data pre-buffering is most

important technique to reduce time from user request

to system response. This, we believe, is a significant

contribution of our research.

ACKNOWLEDGEMENT

This work was supported by the Ministry of

Education of the Czech Republic under Project

1M6840770004

PDA

Clients application

SQL server CE

Server

SQL server

Framework

Framework kernel

Control System

Location sensor

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.NET localization enhancement

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