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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. Web-based measurement of temperature and humidity from distributed objects.

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Web-based measurement of temperature and humidity from distributed objects

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  1. Mitko Shopov, Nikolay Kakanakov, and Grisha Spasov Virtual Laboratory of Computer Networks and Distributed Systems http://net-lab.tu-plovdiv.bg Web-based measurement of temperature and humidity from distributed objects

  2. 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. Motivation

  3. 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. Multi-tier Architectures

  4. 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.

  5. 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. Three-tier Web-based system for distributed measurements (Cont.)

  6. 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. N-tier Model for Distributed Automation

  7. N-tier Model for Distributed Automation (Cont.)

  8. N-tier System for Distributed Automation (Implementation)

  9. 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 Service-oriented 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. Four-tier integration model

  10. 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. Use-case scenario

  11. 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 non-central 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.

  12. 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] Hardware components involved in experiments

  13. SHT71 Sensor

  14. VIA EPIA Mini-ITX

  15. IPC@Chip

  16. DS Tini

  17. CS-E9302

  18. 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. Papers referenced

  19. 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: mshopov@tu-plovdiv.bg, www: http://net-lab.tu-plovdiv.bg/~mshopov/ • Nikolay Kakanakovis 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: kakanak@tu-plovdiv.bg, • 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: gvs@tu-plovdiv.bg, • www: http://net-lab.tu-plovdiv.bg/~gvs/

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