Transcript Niš, September 2007

DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Web-based measurement of temperature
and humidity from distributed objects
Mitko Shopov, Nikolay Kakanakov, and Grisha Spasov
Virtual Laboratory of Computer Networks and Distributed Systems
http://net-lab.tu-plovdiv.bg
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Motivation
Recent years, with the progress in computer networks, more and more people and organizations have access to
the global network - Internet and the services it offers. Besides, the advances in information systems have emerged
new technologies like e-learning, e-business, e-government in different areas of society (medicine, industry, education,
etc.). These new technologies are now being transferred toward the field of distributed measurement and automation.
A trend from the recent years is to migrate away from proprietary hardware and software platforms for distributed
measurement and control (DMC) in favor of open and standardized approaches. High-level programming languages,
object-oriented platforms, Internet technology, and standardized communication interfaces, all influence the
development of today’s DMC.
Additionally, rapidly advancing hardware, provides the market with a plenty of new embedded devices with
integrated TCP/IP stack, embedded web server and continuously increasing processing power. This gives the
designers of distributed measurement systems the ability to put into practice some of the well-proven architecture
models from distributed desktop systems.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Multi-tier Architectures
After a research made on the distributed measurement systems the following three major models are identified.
These models are derived from some of the well-proven architecture models from the business systems. However, they
have some specific characteristics that reflect the limited resources available and the increased demand for data
actuality. These models are:
• Client/Server systems, based on custom communication protocol. Although cheap for manufacturing, these
systems are based on proprietary technologies. This limits their freely distribution and makes them hard to extend and
difficult to integrate in complex systems. An improvement of such systems is to use Applets or Active-X controls at the
client side, thus unifying the user interface.
•
CGI based distributed embedded systems. Such systems have additional requirement to microcontrollers –
Network interface, TCP/IP stack and embedded Web server. This is no more of such a problem, since embedded
devices that fulfill these requirements are becoming widely available on the market today.
• Three-tier Client/Server architecture. Such systems are derived from the popular three-tier client server
architecture – user interface on the front-end tier, business logic on the middle tier, and database on the back-end tier.
Here, the back-end tier is replaced with network of controllers with sensors and actuators.
Starting from that point we suggests a further separation of functionality of the systems for distributed
measurements and automation because of the number of benefits that the multi-tiered architectures provide over
traditional client/server ones:
• Installing and deploying the user interface is virtually instantaneous - only the Web interface on middle tier needs to
be updated.
• Without a "thick" client interface, it is easier to deploy, maintain, and modify applications - no matter the clients
location.
• Because the application itself is server-based, users always access the most up-to-date version.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Three-tier Web-based system for distributed measurements
The design of a modern distributed measurement systems have to be carried out in accordance with well-proven
architecture models, allowing the system to benefit from the various available technologies, thus giving it added
flexibility and scalability. It has to be highly abstract, easily extendable and user-friendly. These characteristics have
motivated the design of a system for distributed measurement, based on three-tier architecture, Java programming
language and Web technologies.
Below the architecture of the system is shown. It uses the popular Model-View-Controller architecture (MVC). From
the view point of the three-tier architecture, it consists of standard client – Web browsers, located at the client tier that
provides an interface to other applications or operators; Web/Application server located in the application tier that
provide presentation and application functions; and data producer components – networks of controllers and database
servers – located in data tier.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Three-tier Web-based system for distributed measurements (Cont.)
The system uses the MVC architecture. Controller functions are handled by a servlet. It processes all HTTP requests
and determines the appropriate object from the model and appropriate view. The servlet also offers authentication and
validation services. The model consists of two components – Measurement Bean and DB Access Bean.
The view represents the display of the model in the user interface. In our case, the view is an HTML/WML page
rendered with information from the model. It is only responsible for displaying of information; any changes to the
information are handled by the controller. The controller takes user input, manipulates the model, and causes the view
to update appropriately. In this way user interface is a combination of the view and the controller.
The view consists of various JSP pages – for observing of measurement values and for statistical data, for HTML
and WML clients and etc. The formation of a HTTP response with temperature and humidity data from the
Measurement Java Bean component is shown below together with the view of the measured values in client browser.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
N-tier Model for Distributed Automation
The presented model generally consists of four tiers. It is
called N-tier because some of the tiers can be skipped/merged
while other can be further separated. The tiered architecture is
chosen for flexibility and separation of presentation and business
roles with the real automation. The additive benefit is the security
– every tier can communicate only with its direct neighbor. So the
data and the business rules cannot be directly accessed from the
Internet, and thus cannot be harmed.
The model is applicable for enterprise systems, allowing
integration of business information technologies and automation.
It provides inherited separation of presentation and application
logic, security, and reliability. The component approach used,
allows interoperability and code reuse.
On the Services tier different functionality can be combined
and presented by a single Web portal. The services on this tier
can be physically distributed on large distances, which allow
centralized control of different plants or factories. Failure of a
single server on this tier will affect only the corresponding service,
keeping other services available.
Client and Presentation tiers of the model are based on
component-of-the-shelf solutions. On the Client tier every web
browser can be used. The Presentation tier implementation is
based on Java enterprise technology. It can use every Web server
supporting Servlets/JSPs and standard web development tools.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
N-tier Model for Distributed Automation (Cont.)
Niš, September 2007
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Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
N-tier System for Distributed Automation (Implementation)
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Four-tier integration model
The four-tier model shown on the right is aimed to
provide provisions for seamless integration of enterprise
business models and simple automation models (SAM). The
interoperability should focus on the overlapping parts of the
Multi-tier business model and the Expanded Automation
Model (EAM). The middleware technology used is Serviceoriented architecture (SOA) implemented with Web services.
This assures interoperability while distributing functionality
over Internet.
The SAM represents the existing automation
environments with its vendor specific standards and
technologies (fieldbus, modbus, EtherNet/IP and etc.). The
only requirement is that the Automation controller has Ethernet
and TCP/IP capabilities that is not unusual for recently
manufactured controllers.
The key component is the Application Unit. It plays the
role of a gateway for the automation plant to the enterprise
network. Here the functions of the network of controllers,
sensors, and actuators is exposed as services described with
the standardized interface of Web services technology.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Use-case scenario
Application of the model for
effective management of a HVAC
(heating,
ventilating,
and
air
conditioning) system in residential
buildings.
Networks of controllers, with
sensors and actuators, are built up on
every floor of the building. These
controllers
use
preconfigured
behavior logic to control the
environment parameters. They are
accessed through optimized, TCP/IP
based
standard
communication
protocols.
On the upper tier a floor
application
unit
analyzes
and
manages the work of each controller.
Since it has a view over the whole
floor it can make decisions based on
that knowledge and to use predictive
adjustment of behavior logic of
individual controllers. However, no
information about the neighbor floors
is available and so cannot be taken
into consideration here.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Use-case scenario (Cont.)
On the next tier, one central
computer
called
Web
Portal
summarizes the information from all
floors in the building, together with
some external information like
whether forecast, information for
prices (if more than one energy
source is available), disruption in
energy supplying (if planned) and
inhabitant’s preferences. These can
be accessed as Web services offered
by suppliers or third parties.
Such a system is supposed to
improve the energy efficiency of a
building for several reasons. First, a
zoned heating can be introduced.
This will allow a more granular
application of heat similar to noncentral heating systems. Second, a
predictive logic based on information
for condition in neighbor rooms,
neighbor floors, weather information,
inhabitant’s preferences, prices and
disruption information can be used on
different tiers of the system.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Hardware components involved in experiments
Several hardware components are used in the test-bed architectures and experiments:
•
SHT71 Sensor – Intelligent digital sensor for temperature and humidity measurements from Sensirion.
[http://www.sensirion.com/en/02_sensors/00_overview.htm]
•
VIA EPIA Mini-ITX - Industrial fanless PC used is some of the test-beds as application unit.
[http://www.via.com.tw/en/products/mainboards/motherboards.jsp?motherboard_id=301]
•
IPC@Chip – Controller with Ethernet, TCP/IP stack, and RTOS from Beck.
[http://www.beck-ipc.com/en/products/sc1x/index.asp]
•
DS Tini – Networked controller from Dallas-Maxim with Tini OS, 10/100 Mbps Ethernet, TCP/IP stack, and JVM
[http://www.maxim-ic.com/products/microcontrollers/tini/]
•
CS-E9302 – Development board from Olimex with 10/100Mbps Ethernet port and Linux/Unix ported OS.
[http://www.olimex.com/dev]
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
SHT71 Sensor
Niš, September 2007
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Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
VIA EPIA Mini-ITX
Niš, September 2007
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Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
IPC@Chip
Niš, September 2007
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Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
DS Tini
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Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
CS-E9302
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Papers referenced
• M. Shopov and G. Spasov, "Distributed measurement systems based on java and web technologies," Proc. Fourth
National Youth Science and Practical Session, 2006, pp. 200-205.
• Kakanakov, N., M. Shopov, I. Stankov, and G. Spasov, “Web Services and Data Integration in Distributed Automation
Systems in Internet Environment”, Journal International Review on Computer and Software (IRECOS), Vol.1, N. 3,
November 2006, ISSN: 1828-6003.
• N. Kakanakov, "Web based models for distributed automation," Journal of Automatics and Informatics, N. 3, 2006,
ISSN: 0861-7562.
• N. Kakanakov, M. Shopov, and G. Spasov, "A new web based multi-tier model for distributed automation systems,"
Journal Information Technology and Control, N. 2, 2006, ISSN: 1312-2622.
• N. Kakanakov, M. Shopov, and G. Spasov, "Distributed automation systems based on java and web services,"
Proceeding of CompSysTech’06 , V. Tarnovo, 15-16 June 2006, pp.III-A.24-1-6.
Niš, September 2007
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DAAD
Deutscher Akademischer Austausch Dienst
German Academic Exchange Service
Projekt „ISSNB“
Author’s information
Mitko P. Shopov was born in Plovdiv, Bulgaria on June 17,
1982. He received the BSc degree in computer engineering
from Technical University of Sofia, branch Plovdiv, Bulgaria in
2005. Currently, he is an MSc student in dept. of Computer
Systems and Technologies in Technical University of Sofia,
branch Plovdiv.
From June to September 2005, he was a Visiting Researcher
at Nottingham Trent University, UK. Since October 2005, he
has been with Virtual Laboratory of Computer Networks and
Distributed Systems, where he currently serves as a research
assistant. His research interests include parallel and
distributed computing, distributed embedded systems and
networking.
Contact Info:
e-mail: [email protected],
www: http://net-lab.tu-plovdiv.bg/~mshopov/
Nikolay Kakanakov is born 1980 in Plovdiv, Bulgaria. He has a BSc degree
in “Computer Systems and Technologies” from Technical University – branch
Plovdiv. Now, he is a PhD student in dept. of Computer Systems in Technical
University – branch Plovdiv. The topic of his dissertation is “Methods for
developing distributed embedded systems based on the TCP/IP environment”.
His interests include: Computer Networks Hardware; Network Programming;
Embedded Systems; Distributed and Parallel Computing; Distributed
Automation.
Contact Info:
e-mail: [email protected],
www: http://net-lab.tu-plovdiv.bg/~kakanakov/
Grisha Spasov received an MSc degree in computer engineering from
Technical University of Sofia, Bulgaria in 1983. He received a PhD degree in
computer systems and networks from Technical University of Sofia, branch
Plovdiv, Bulgaria in 2000. Currently, he is an associate professor in
Department of Computer Systems and Technologies, and vice dean of Faculty
of Electronics and automatics in Technical University Sofia, branch Plovdiv.
His professional interests include Computer networks, Distributed systems,
Distributed Embedded System and Distributed Automation, Design and
modeling of Wireless LAN, Application of Information technologies in medicine.
Contact Info:
e-mail: [email protected],
www: http://net-lab.tu-plovdiv.bg/~gvs/
Niš, September 2007
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