ZVEI-Elektronik - Wireless Congress 2004, München, November 2004
Monitoring & Control Integrating Wireless Agents and Mobile Users Prof. Dr.-Ing. Diederich Wermser, University of Applied Sciences Braunschweig/Wolfenbüttel Salzdahlumerstr . 46/48, D-38302 Wolfenbüttel; Fon: 05331/939-3115; e-mail:
[email protected] Dipl.-Ing. Sven-Ove Wähling, Netzlink GmbH Heinrich-Büssing-Ring 42, 38102 Braunschweig; Fon: 0531/7073430; e-mail:
[email protected] Frank Hauptmann, Netzlink GmbH Heinrich-Büssing-Ring 42, 38102 Braunschweig; Fon: 0531/7073430; e-mail:
[email protected]
Abstract Embedded wireless agents supporting various kinds of sensors and actuators increasingly become available as commercial products "off-the-shelf". But the end user needs integrated solutions meeting his particular needs, like for instance remote monitoring and control of complex machinery, e.g. huge arrays of IT-servers and routers or wind turbines. In order to ease working conditions for operators and maintenance personnel as well as reduce staffing costs for 24h surveillance, user interfaces have to be provided on compact smart-phone like equipment through mobile communication networks moreover. This paper identifies problems and technical alternatives for development of such wireless integrated remote monitoring and control solutions. Demand and constraints for a specific software -platform enabling efficient development of individualized, reliable and maintainable wireless monitoring and control solutions, including adaptors for various kinds of wireless devices, are outlined in detail. Examples taken from the "Mobile Secure Interaction System Platform" (MoSIS) developed by a team headed by the authors will provide concrete illustrations.
Keywords: Mobile Data Services, Remote Control & Monitoring, Wireless Sensors & Actuators, Mobile Application Development, MoSIS
1.
Introduction
Wireless communication networks and standards have developed dramatically during the last years. For short-range communications standards like Bluetooth and W-LAN in all its variants are standardized and have reached low price levels due to economies of scale in this fast growing market. For long -range communication GSM/GPRS networks have achieved almost full coverage in central Europe. UMTS, offering by far high bit rates as a third generation network, gains more and more coverage. At least the metropolitan areas are completely covered today. Roaming between different network standards enables seamless communication for distributed applications based on mobile communication.
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The need for distributed applications including wireless devices, agents, sensors, actuators etc. significantly increases on the other hand. Driving forces are cost pressure, increased demand for reliability and availability, 24 h control of remote equipment and the trend towards lifelong control as well as continuous updating of products by manufacturers. Thus two major preconditions for a rapid development of the market of mobile communication based applications are given. However: costs, project duration and risks for development of respective software solutions, which actually provide the intended benefits to users, are serious obstacles for this progress. The rules of best practice for development of application software in general apply for integrated wireless solutions as well, e.g.: o o
well defined, structured software engineering process reusable solution concepts, design and code modules
Beyond this, a number of specific constraints for wireless solutions have to be considered: o o o o o o o o o
lower bit rates of communication links higher average delay times, strong delay time jitter frequent and unexpected link interruptions small terminal devices with low computing power and little storage capacity small displays and keypads for user interaction more strict requirements with respect to security and authentication remote maintenance and upgrade of software on wireless devices becomes inevitable, when large numbers of wireless and mobile devices are involved rapidly changing standards for signalling& control mechanisms due to further evolution of mobile and wireless communication standards [1],[2],[3] continuing evolution of APIs and software development environments for small and medium wireless devices, in particular J2ME (Java 2 Micro-Edition)
The failure of numerous attempts to port software applications developed for fixed network communication to a wireless environment have shown the impact of these specific constraints as mentioned above. Integrated wireless monitoring and control systems, as discussed here, are a first step towards the vision of Ambient Intelligence, describing a world of pervasive smart wireless devices, easing life and optimising any kind of processes and remote interaction [4]. The subsequent chapters will elaborate on architecture and engineering of distributed applications based on wireless and mobile communication infrastructure. A description of the MoSIS platform (Mobile Secure Interaction System) developed by the authors will demonstrate, how the requirements for robust applications based on wireless communication can be met.
2.
General Architecture of Wireless Integrated Monitoring & Control Solutions
Figure 1 outlines the general architecture of wireless monitoring and control solutions. Towards the mobile terminals of the users (left side) a number of mobile communication networks ranging from GPRS and UMTS to Wireless-LAN have to be supported. In order to be future-proof, communication interfaces
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of the applications need to be prepared for next generation protocols such as SIP (Session Initiation Protocol), which will be used by UMTS Release 5 and later [2],[3]. Today mobile terminals are used as thin clients, i.e. simply display information provided by the central Integrating Wireless Application. The more computing power and storage capacity the mobile terminals will offer in the near future, truly distributed mobile applications can be implemented, where parts of the overall functionality beyond display functions are provided by the mobile terminal (rich clients). This will help to better cope with the specific deficiencies of mobile communications like link interruptions, limited bit rates, delay times etc.
Figure 1: Basic architecture of Wireless Integrated Monitoring& Control Solutions Sensors and actuators involved in the specific monitoring and control process may either directly be connected to the integrating wireless application or indirectly through domain specific units, providing specific data evaluation and actuator control capabilities. For some application domains specific data sensor data evaluation and actuator control units or respective software applications already exist. Exploiting these capabilities by connecting the integrating wireless application to these units will be advantageous in many cases. In case of remote monitoring and control of a combine harvester, e.g., there may be local on-board controller units pre-evaluating and combining the measuring results of tens of sensors, which can be connected through an on-board Wireless-LAN to it. This local controller is connected through mobile networks (in remote territories even satellite based) to the integrating wireless application run by the manufacturer and/or the operator of the combine harvester. Sensors monitoring most critical parts of the machinery will rather be directly connected to the central integrating wireless application. For controlling of extended IT-infrastructure , including servers, routers etc., network management tools like HP open-view or IBM-director are used frequently. An integrated wireless monitoring and control solution, enabling 24h remote operation by mobile staff members, can be connected to such tools, if they provide sufficient alarm classification, thresholding and parameterization possibilities. The integrating wireless application will anyway in parallel be directly connected to housebreaking sensors, fire sensors, remote controllable cameras etc. through wireless or wired connections.
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3.
Mobility: Who and What is Mobile?
3.1 Mobile Users Two types of users of mobile applications can be identified: Consumers and Business Users. Consumers use mobile applications mainly for entertainment purposes. Typical Applications are Micro payment (e.g. in Transportation) or download of ring tones. The consumer uses his cell phone to access mobile applications. With inexpensive smart phones and MDAs available today, mobile applications become more and more widespread for business users. Companies realize that linking the mobile workforce with the enterprise and its data resources is key to enhancing productivity, accuracy, profitability and, ultimately, customer satisfaction. Mobility is seen by a growing number of users as an extension of existing email and telephony services already being provided, particularly with the blurring of work and home boundaries in an information-driven society. Different business needs lead to two basic approaches for realizing mobile applications. These approaches differ in how data is distributed to the mobile users. Asynchronous applications distribute data to the handhelds data cache. Mobile users can access that data without the need to establish a connection to the server. This approach is used for applications where the mobile user does not need to have access to the enterprise data. The user mainly collects data and sends it to the enterprise. A typical use case would be a sales application where the user selects products from a list, builds an order and submits this order to the enterprise server. The asynchronous approach does not work for every type of business need. There are several use cases where synchronous access to real time data is necessary. An application providing system management functionality needs to refresh its state any time the user accesses. The user wants to know, what the systems he is monitoring are doing right now. This synchronous approach to data distribution can be achieved by applications using thin clients (e.g. built-in browser) or rich clients (client application installed on the handheld). This synchronous approach was chosen by the authors for the development of the MoSIS platform, as explained subsequently. 3.2 Mobile Sensors and Actuators Apart from the user even the monitored systems can be mobile. The mobile sensor is collecting data and submits it to the application server. Based on the data the server can submit commands to the mobile actuators. There are many types of business cases where mobile sensors and actuators have to be monitored or controlled. One example for applications of wireless sensors is an offshore windmill, which is monitored from a centralized control station und shut down in case of damage. A special case is the combination of mobile user and mobile sensor. Location based services allow the collection of position data. These position data can be processed by the application server and decisions can be made based on the data. One example application is the management of vehicle fleets, where orders can be sent to the drivers in dependence of their current geographical position.
4.
Engineering of Mobile Monitoring & Control Solutions
Expenses and project risks of application development, i.e. mainly software development, are the main obstacles for a broader success of mobile monitoring and control solutions so far, as mentioned in the introduction.
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As for the development process of any other software-system, most relevant criteria are: o o o o o o o
efficiency of development process adherence to agreed delivery dates reliability of resulting software security maintainability and extensibility portability scalability
However, development of distributed applications for mobile monitoring and control solutions significantly differs from the development of conventional applications: reliability means to cope with instable communication links and delay times, which put conventional synchronisation mechanisms out of operation; security means to consider radio links and mobile specific authentication procedures; maintainability and extensibility means to keep in mind heterogeneous devices with different display sizes, computing power and product renewal cycles as well as the need for remote software updating and maintenance; portability means to consider heterogeneous systems with diverging operating systems (Symbian, Linux, Microsoft CE,...), APIs, browser capabilities etc., as well as different network operators and lower layer protocols.
Figure 2: Software development process utilizing reusable elements for all phases
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The best way to meet all these intentions is to develop reusable concepts, architecture elements and code modules for all phases of the specific wireless oriented software development process. Projects developing new mobile applications will reuse existing concepts, models and code modules and at the same time generate new reusable concepts and modules. Figure 2 illustrates the software development process as defined by the Rational Unified Process [8]. Requirements analysis, mainly taking place during inception and first part of the elaboration phase, will be significantly more focussed and efficient, if predefined solution concepts and models exist for similar application areas. System analysis and design, primarily carried out in the elaboration phase, enormously profit from predefined architectures and design specifications. Implementation and test, mainly belonging to the construction phase, benefit from reusable code modules as are usually provided by workbenches supporting development of software systems for specific application areas.
5.
MoSIS (Mobile Secure Interaction System)
Netzlink GmbH as a provider of integrated wireless systems has recognized the need for prefabricated solutions and reusable building blocks as a means to deliver reliable and cost effective solutions to its customers. Consequently Netzlink has developed the Mobile Secure Interaction System (MoSIS). MoSIS has been designed to serve as a basis for a broad range of mobile solutions ranging e.g. from customer relationship management (MoSIS CRM) over timekeeping for technical workforce to remote monitoring and control of large machinery. Subsequent elaborations focus on application of MoSIS for remote monitoring and control of technical systems. Paragraph 5.1 will explain the architecture of MoSIS, paragraph 5.2 will illustrate as an example the utilization of MoSIS for remote control and monitoring of the IT-infrastructure of a large clinical centre. 5.1 MoSIS Architecture The MoSIS architecture, as shown in Figure 3, provides all functions necessary to monitor and control wireless or wired sensors as well as actuators and to allow for mobile user interaction. Besides polling, handling, distribution and presentation of relevant data, MoSIS comprises modules to provide user and device authentication, offers logging and statistic features, allows for scheduling of different tasks, i.e. functions, which enable utilization under fully commercial constraints. Extended alarm handling features support 24 h monitoring of operational infrastructure, without the need to have expensive staff on location all time.
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Figure 3: MoSIS Architecture: Functional Modules (Mobile Secure Interaction System) The software architecture of MoSIS is based on Java-Technology, which means availability of efficient software development environments and best conditions for portability (Figure 4) [5],[6],[7].
Figure 4: MoSIS Basic Software Architecture (Mobile Secure Interaction System) Relevant parameters and control mechanisms of MoSIS Applications can be adapted using the operations, administrations and maintenance terminal. Figure 5b illustrates the structure of tables for entering and changing parameters in a monitoring & control application based on MoSIS. More complex control structures can be edited by a graphical editor, when setting up a new MoSIS application (Figure 5a).
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Figure 5: Alternatives for parameterization/ customization of control logic in MoSIS a) Graphical manipulation of control logic / workflow b) Tables for specification of monitoring parameters The user interaction modules are prepared to adapt to simple terminal devices, operating as thin clients, or complex powerful mobile devices operating as rich clients. Mobile security for enterprise applications can be supported by IP-Sec based mobile VPNs (illustrated in Figure 6) or proprietary solutions as the popular RIM infrastructure [9]. The respective protocol stacks are illustrated in Figure 7. The sound separation of control logic from mobile terminal oriented modules makes MoSIS future-proof with respect to frequently changing terminal devices and expected new application oriented signalling protocols for the next generation of UMTS [2],[3]. As soon as smart phones supporting stable and emulator-compliant versions of MIDP 2.0 become available, portability of rich clients will improve significantly.
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Figure 6: Mobile VPN enabling end-to-end encryption and secure operation in closed user groups [1]
Figure 7: Protocol stacks involved, when using RIM´s solution for secure communication with mobile devices 5.2 MoSIS IT-CaSe: Remote Monitoring and Control of Complex IT-Infrastructure A typical example for a pre-fabricated MoSIS solution is MoSIS IT-CaSe (MoSIS Information Technology Calling Service). MoSIS IT-CaSe enables remote monitoring and control of any kind of ITinfrastructure, including servers, routers, operating systems, operation of application software etc. It offers all necessary mechanisms like polling of devices and applications, handling and priorization o f IT-
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specific alarm classes, offering of remote diagnosis choices or remote initiation of broadcast information for user groups affected in case of failures. Remote sensors for break-in control, temperature monitoring etc. can be connected through W-LAN or other radio communication standards. A recent application of MoSIS IT-CaSe is MoSIS-HITCaSe (Hospital Information Technology Calling Service). All critical elements of the IT-infrastructure of a large clinical centre are monitored 24h. Critical states or events generate alarms on the mobile terminals, which are carried along by staff members assigned to on-call-service at the respective time. Figure 8 illustrates usage of MoSIS HITCaSe.
6.
Future Development
Technical development of mobile and embedded wireless equipment will continue and lead to more powerful and inexpensive devices. Mobile data communication services provided by network operators will become even more IP-centric and will be available with increasing bit rates for lower prices. Reusable integrated wireless solutions and adaptable off-the-shelf products for frequent application areas, as offered by the MoSIS system introduced here, will penetrate the market. Applications achieving high commercial gains, like mobile monitoring and control of complex machinery, will dominate at the beginning, but within medium term even quite cheap products of everyday life will be under lifelong maintenance of their manufacturers by means of wireless communications.
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Figure 8: Example screenshots of MoSIS IT-CaSe application: MoSIS HITCaSe (Hospital Information Calling Service) a) Entrance: Selection of inspection function b) Alarming of user, caused by fault of a monitored process c) Overview of servers with remote monitoring d) Remote diagnosis: Delay time measurement for test messages e) Remote diagnosis: Information on files monitored
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7.
References
[1]
Golding, P.: Next Generation Wireless Applications. Wiley&Sons, London 2004.
[2]
Wermser, D. et al.: Adaptive Mobile Multimedia Dienste für das zukünftige All-IP UMTS. VDE / ITG Kongress "Ambient Intelligence", Oktober 2004. VDE Verlag, Berlin 2004.
[3]
Poikselkä, M., Mayer, G., Khartabil, H. and Niemi, A.: "The IMS- IP Multimedia Concepts and Services in the Mobile Domain". John Wiley & Sons, Ltd, 2004.
[4]
Mattern, F.: Ambient Intelligence. In: Trendbarometer Technik, Hrsg.Bullinger, H.J. . Hanser Verlag, München 2004.
[5]
Schäffer, S.; Schilder, W.: Enterprise Java mit IBM Websphere, Addison Wesley, München 2002.
[6]
Gamma, E. et al.: Design Patterns. Adisson Wesley, 1995.
[7]
Yuan, Michael Juntao: Enterprise J2ME - Developing Mobile Java Applications, Prentice Hall PTR, Upper Saddle River 2004.
[8]
Versteeegen, G: Projektmanagement mit dem Rational Unified Process, Springer-Verlag, Berlin Heidelberg 2000.
[9]
Neubauer, J: Brombeere auf Reisen, Windows 2000 Magazin 2004, Ausgabe 1, Seite50.
8.
Abbreviations
CASE
Computer Aided Software Engineering
J2ME
Java 2 Micro-Edition
J2EE
Java 2 Enterprise Edition
GGSN
Gateway GPRS Support Node
GPRS
Generalized Package Radio System
MDA
Mobile Digital Assistant
MIDP
Mobile Independent Device Profile
MoSIS
Mobile Secure Interaction System (Mobile Solution Platform of Netzlink GmbH)
MoSIS IT-CaSe
MoSIS Information Technology Calling Service
PDA
Personal Digital Assistant
RIM
Research In Motion Limited
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SIP
Session Initiation Protocol
UML
Unified Modeling Language
UMTS
Universal Mobile Communication System
W-LAN
Wireless Local Area Network
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Authors Diederich Wermser: Professor for Communication Systems, head of the Telecommunications R&D Group of the Faculty of Electrical Engineering at the University of Applied Sciences, Braunschweig/ Wolfenbüttel. His current research focus is development of applications for wireless communication systems and devices. Diploma in electrical engineering/communication systems 1980 and PhD in digital image analysis 1984 at the University of Hannover; long term of cellular industry experience with international operators; co-founder and CTO of two Munich based network operators from 1997 to 1999 and 1999 to 2002 respectively.
Sven-Ove Wähling: Founder of Netzlink Informationstechnik GmbH (1997); Founder of Grouplink (2004) Diploma in electrical engineering 1988 at the Technical University of Brunswick; in the 90s industrial experience in international IT development projects; nowadays concentration on application integration and mobile IT solutions in the industry.
Frank Hauptmann is studying industrial engineering and management at the Technical University of Brunswick. Simultaneously he concentrates on the development of distributed business applications since the late 90s; since 2002 cooperation with Netzlink Informationstechnik and development of mobile applications.
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