Design and Implementation of SOAP-Based Residential Management for Smart Home Systems

Thinagaran Perumal, Member, IEEE, A.R.Ramli, Member, IEEE, and Chui Yew Leong, Member, IEEE

Abstract — This paper presents the design and

implementation of SOAP-based residential management for smart home system’s appliances control. An appliance control module based on SOAP and Web Services developed to solve the interoperation of various home appliances in smart home systems. 15 feedback based control channels implemented with residential management system through Web Services. If the residential management system experiences server downtime, the home appliances can still be controlled using alternate control mechanism with GSM network via SMS Module locally and remotely. This system offers a complete, bi-directional real-time control and monitoring of smart home systems.1.

Index Terms — Smart Home, Simple Object Access Protocol.

I. INTRODUCTION Smart home systems, the next gigantic leap in the field of

remote monitoring, has become an important emerging research field in recent times. In the past decade, research on smart homes has been gradually moving towards application of ubiquitous computing, tackling issues on device heterogeneity and interoperability. A smart home adjusts its function to the inhabitant’s need according to the information it collects from inhabitants, the computation system and the context [1]. Smart home systems and appliances increasingly contribute towards data-intensive environment, resulting in few problems of management and operation issues. The first problem is due to existence of multiple appliances and service in smart home systems, number of gateways grows up drastically with regard of protocols, standards and networks to be connected. The second problem is the differences in hardware, operating systems, programming language and resources accepted by smart home systems operation especially in home appliances control. The key factor is to solve the interface between external information networks and the smart home using a common gateway control which could cater for all type of home appliances. One potential solution is through Web Services technology which can provide vendor independence mechanism for smart home appliance control. Web Services are collected set of protocols and standards provides common method for programmatic interaction

1 Thinagaran Perumal is with the Institute of Advanced Technology,

Universiti Putra Malaysia (e-mail: thinagaran@hotmail.com). AR.Ramli is with the Institute of Advanced Technology, Universiti Putra

Malaysia (e-mail: arr@eng.upm.edu.my). Chui Yew Leong is with the Institute of Advanced Technology, Universiti

Putra Malaysia (e-mail:chuiyewleong@hotmail.com).

among applications, services and devices [2]. It revolutionized how software interacts regardless how the applications were built or the platform on which they run as well reduced lifetime cost for consumers or home dwellers. The use of Web Services technology provides a degree of flexibility and dynamic scalability of managing and adding home appliances of different genre in smart home systems for daily interoperation. In Web Services, instructions are based on the Simple Object Access Protocol or widely known as SOAP. SOAP is based on XML that provides standard network communications between software entities [3]. It functions as general-purpose protocol for sending messages from one application to another. Using SOAP technology, Web Services can be invoked by turning a service invocation into XML message format, exchange the message and finally turn the XML message format into actual service invocation.

Nunes and Delgado came up with an Internet application of remote monitoring in a home which adopts object oriented approach for each sub-systems configured [4]. However, their contribution was justified using a system conceptual model for the mentioned application and no real experiments were conducted. The solution developed by Al-Ali and Al-Rousan proposed a control software engine based on combination of Java and a stand-alone embedded board for home appliances control[5]. Despite the work showed how home appliances could be controlled remotely, home user may need to download Java Virtual Machine (JVM) into their external remote or client terminal to access the software engine in the server. Another similar approach using FPGA was proposed by Fernando Moraes et.al [6]. Their work discussed on the potential of using FPGA for home server which provides good outcome on web-based smart home automation, however lacks multi-protocol support whereas their system is dedicated using CAN protocol. Furthermore, using FPGA for smart homes means high investment in consumer perspectives and may results in complexities of operation for home dwellers. The works presented in [4-6] are some fundamental outcome on smart home appliances operation using Web technologies. However there is need for protocol glue that could incorporate an open solution, independent regardless of resources, operating systems and programming language. Therefore, in this paper, a SOAP-based residential management design and implementation is presented for smart home systems. Simple Object Access Protocol (SOAP) as a Web Services technology can be used to invoke remote procedures between smart home and its components that is platform independent. SOAP technology brings the benefits of Web Service-based connectivity to the consumer electronics industry in a logical extension progressively towards interoperability and scalability for smart home architecture. It is worth mentioning

Contributed PaperManuscript received January 14, 2008 0098 3063/08/$20.00 © 2008 IEEE

T. Perumal et al.: Design and Implementation of SOAP-Based Residential Management for Smart Home Systems 453

about Open Building Information Exchange Group (OBIX) that is working to create comprehensive standards using XML and Web Services to facilitate the home and building information exchanges between various entities [7]. Using SOAP as means of information exchange, assures smart homes effectively to transform into service hub itself and become distributed in nature to support multiple home appliances control and monitoring. A scalable smart home system also needs to protect the consumer’s initial investment by maintaining interoperability and accommodating future applications. In this paper, system architecture is discussed in Section II, followed by implementation in Section III. Experimental work and system operation are presented in Section IV, and finally concluded in Section V with justification and future work.

II. SYSTEM ARCHITECTURE The main components of SOAP-Based residential

management for smart home systems consists of residential application gateway configured using an embedded CPU, GSM Module, network interface, switching module and remote terminal. All the components are used and connected together in Ethernet configuration of smart home systems. Ethernet is chose due its performance oriented in real-time as well as taking into account the existence of Cat 5 cabling based structured wiring in smart home systems. A central theme in the implementation of this system architecture is that it should be lightweight and platform independent. This is an important consideration due to cost applicability of smart home systems application. Although penetration of desktop PC technology into the home market is increasing on a daily basis, it is expected that most homes will not rely on home PC for control and monitoring in smart home environment. Instead a set-top-box style solution with low cost embedded CPU will satisfy the need for most sub-systems or smart home components. In this work, an embedded CPU is used as residential application gateway for the entire system. There are two distinctly different approaches emerging in the field of smart home system: one approach is to incorporate TCP/IP networking even into the simplest consumer devices. Most available embedded processors used in consumer devices are not powerful enough to implement IP protocol. The second approach, which is more realistic, is to integrate existing established technologies, such as SMS and TCP/IP infrastructure. Following this approach, the residential management is designed such that only one IP number needed to be assigned per home. Therefore, other technologies such as X10[8] and Home Plug [9] can be integrated with the system to provide full control functionalities of home appliances. The whole system architecture is shown in Fig.1:

Fig. 1: System Architecture Layout

A. Residential Application Gateway The residential application gateway is configured using an embedded CPU, also act as a storage terminal for the entire system. The appliances control module using SOAP technology, written using C# language is stored in the residential application gateway. For this gateway design, the embedded CPU is installed with Windows Server 2003 and configured with Internet Information Service 6.0 environment. In addition, .NET Framework 2.0[10] is installed and configured. The embedded CPU supports 4 inputs and 4 outputs of Ethernet connectivity and system memory available up to 512MB. In smart home systems, control and monitoring means 24 / 7 nature and home dwellers are expected to access the appliances information all the time. Thus, an embedded CPU configured as residential application gateway will be an ideal platform for continuous operation, less system downtime, server consolidation and increased application availability. B. SMS Module The SMS module consists of GSM modem and a control program. The control program, GSM-dial up and communication protocol are stored in the residential application gateway and the GSM modem is connected to the embedded CPU via serial interface to the switching module. The SMS module acts as an interface between the embedded CPU and the GSM network, makes the system log on the network and ready to make any data transfer and communication. The module takes the AT command from remote terminal or mobile devices and send them to switching module via the GSM network. C. Network Interface Network interface between residential application gateway and switching module is significant to cater connectivity and acts as interface for switching control of home appliances. In this design, web server chip is used to configure interface of both entities. The functional protocol stack of the interface is

454 IEEE Transactions on Consumer Electronics, Vol. 54, No. 2, MAY 2008

installed on complete Real-Time Operating System (RTOS), integrated with all features needed for modern Ethernet and Internet applications. C language is selected for coding for the interface between TCP and RS-232 data. However, assembly language is also incorporated for protocol API within the entire coding process. The network interface will receive the network data from residential application gateway, converts it and initialize serial connection. The network interface will route data to the serial connection of switching module to perform control mechanism of home appliances. The entire process is also vice-versa whereas the network interface will convert the serial data, route into network through the residential application gateway and provides feedback to the remote terminal.

D. Switching Module Switching module is the expanded device that handles incoming signal for switching control of home appliances. The switching module is connected to the embedded CPU through the network interface and Ethernet connection. The functions of the switching module are listening to the incoming data, analyze the data and perform triggering action to home appliances. The switching module controlled by a microcontroller to enable data processing mechanism. The operation block of switching module is illustrated in Fig.2

Fig. 2: Operational Block of Switching Module

An 8-bit microcontroller is programmed to perform fetching mechanism to the incoming data from I/O interface connecting network interface and generate proper output switching signal. I/O interface is an operation block that is responsible to interface the switching module with microcontroller. This is a medium unit that resides between switching module and microcontroller to manage data exchange as well as signal routing through RS-232 connection. The switching signal will determine active channel in the switching unit for home appliances control. There are 15 switching channel for remote activation signal in switching module. Relay set is the final block of switching module that represents desired responds of

incoming signal. Home appliances are connected to the digital output of the relays which provide sufficient voltage compatibility. Fig. 3 shows the relay interface circuit. Darlington pair transistor is used to cater the 15 channels in switching circuit by providing high amplification of control current. Code selection for switching control is defined as trigger ON and trigger OFF. The codes for switching mechanism are shown in Table I below.

TABLE I

Switching Control Codes

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Fig. 3: Relay circuit using Darlington

connection

Code Trigger ON Trigger OFF Relay

Hex Binary Hex Binary 1 51 0101 0001 61 0110 0001 2 52 0101 0010 62 0110 0010 3 53 0101 0011 63 0110 0011 4 54 0101 0100 64 0110 0100 5 55 0101 0101 65 0110 0101 6 56 0101 0110 66 0110 0110 7 57 0101 0111 67 0110 0111 8 58 0101 1000 68 0110 1000 9 59 0101 1001 69 0110 1001

10 5A 0101 1010 6A 0110 1010 11 5B 0101 1011 6B 0110 1011 12 5C 0101 1100 6C 0110 1100 13 5D 0101 1101 6D 0110 1101 14 5E 0101 1110 6E 0110 1110 15 5F 0101 1111 6F 0110 1111 Micro

controller I/O

Interface Residential Application

Gateway

Relay triggering and switching

Switching Unit

Relay set

12V DC

5V DC

Module O/P

230V AC

Home Appliance Lamp

Relay

1k Ω

1k Ω

T. Perumal et al.: Design and Implementation of SOAP-Based Residential Management for Smart Home Systems 455

III. ALGORITHM FOR SOAP-BASED RESIDENTIAL MANAGEMENT IMPLEMENTATION

The proposed SOAP-Based residential management in this paper uses PC and mobile devices that supports web browser, as remote terminal to access the remote application home server. Fig. 4 shows a flowchart of the smart home systems operation using the residential management:

Fig. 4: Flowchart of SOAP-Based Residential Management

Prior connecting to home appliances, the residential application gateway needs to be activated. Once the network cable plugged into the RJ-45 socket of network switch, the pre-defined network configurations automatically launch the network service in the residential application gateway. Those configurations include IP address, subnet mask, gateway and DNS server. Network access connectivity is initialized by remote terminal or mobile devices to establish connection with residential application gateway. Once connected, home dwellers or the user will attempt to browse the SOAP application hosted in the server. Using a custom login information and password, the user will log into the application and configures the desired home appliances to be turned ON or OFF. Once the user selects the desired home appliances, code transfer started and data will be routed to network interface. Here, the received network data through TCP connection will be converted to serial data. Through the

RS-232 interface in switching module, relays for corresponding home appliances will be triggered either ON or OFF depending on the input given through XML-SOAP message. Fig.5 below shows the body of SOAP Message carrying the control description. Home appliances connected to the switching module might not guarantee successful operation of the appliances as there might be noise, defects or delay in receiving switching signals. To solve this, a feedback diagnostic unit has been included in the switching module to provide indication on appliances status after receiving the control command (ON/OFF).

Fig. 5: Body of SOAP Message carrying control description

During server downtime, the residential management system could still control and operate home appliances locally and remotely using an alternate control mechanism with SMS Module. Using the SMS Module, the user will send command in the form Short Message Service (SMS). The communication between residential application gateway and remote terminal is established by utilizing the GSM network. The GSM modem is attached to the residential application gateway and the communication between the server and GSM modem is carried out by the AT Commands. The message sent and received are in text mode, corresponding with SMS control program stored in the residential application gateway. The command will trigger the appropriate home appliances to either ON or OFF state based on the users command.

IV. EXPERIMENTAL WORK AND SYSTEM OPERATION

A. System Elements Taking into consideration of interoperability and scalability features of .NET Framework, C# language and ASP.NET with .NET Framework 2.0 are used to operate, manage and control the system operation of smart home system’s residential management. The software engine stored in the residential application gateway is written in C#. The software engine provides the functionality to control home appliances via the

Trigger the appropriate relay in switching module

Send Acknowledgement and Current Status of Home Appliances

END

Convert network data to serial data

Send XML-SOAP Message

Completed?

Initialize Residential Application Gateway

Initialize SMS Module

Completed?

Yes

Yes No

Send Command for Home Appliance

START

No

SOAP Message

SOAP Envelope

<..> <service <name>RELAY_1_ON</name <description> <…>

SOAP Header

s

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residential application gateway. .NET Framework provides mobility for smart home systems operation by enabling the use of multiple remote terminal or clients (i.e. mobile phones, desktop PC and PDA) to control home appliances by taking advantage of one single software engine stored in residential application gateway, accessible for home users all the time. Smart home systems control also requires simple and dynamic user interfaces for home dwellers, thus ASP.NET technology used to build the user execution environment for the smart home systems. The XML-SOAP web services is developed using C# language in managed code using Visual Studio 2005. The implementation of the XML-SOAP Web services resides in a code-behind file and associated with the .asmx page using the Codebehind attribute of .NET. Fig. 6 below shows the main page for home dwellers to authenticate their identity before operating smart home systems.

Fig. 6: Login page for residential management

The login.asmx page purpose is to authorize home dwellers as valid user to allow administration and control of the home appliances. This page defines a form tag for entering user name and password. Once successfully logged in, the login page will lead to session.asmx page of the user. Password protection is necessary in smart home environment to ensure security and safety of system operation. Fig. 7 below shows the session.asmx page. Information like previous login attempt as well as failed login will be displayed for user’s attention. The user will proceed to the home appliances control page by clicking PROCEED button which invokes the control.asmx page. In case of failed login, the login page will be displayed again for user to enter the username and password again.

Fig. 7: Session page for residential management The Fig. 8 below shows the control.asmx page which user can select which home appliances to be triggered ON or OFF.

Fig. 8: Control page for home appliances

A total 15 channel of appliances are configured with 15 relays. Once the residential application gateway received the code from the client, translation process is initialized to process the code before transferring to the switching module. In switching module, 15 programmed relays will perform appropriate operations to trigger corresponding appliances in the smart home systems. For instance, if the home user wants to turn on the LIGHT 1, he or she must check the radio button and followed by ACTIVATION button. Once validating the request, residential application gateway will passed the request to network interface and switching module to turn ON the LIGHT 1. Here, the control.asmx executes the control operation and proceeded to feedback.asmx page. The feedback.asmx page is meant for home user’s convenience on monitoring home appliances status via the web interface itself. Fig. 9 below shows the feedback.asmx page.

T. Perumal et al.: Design and Implementation of SOAP-Based Residential Management for Smart Home Systems 457

Fig. 9: Appliances status and feedback page In this page, the entire status of the home appliances will be visible to the home user. The mechanism behind this operation is the feedback signal status rendered by the switching module and XML-SOAP message to the remote client. The switching module is programmed to generate feedback signals respond to each successful appliances control event. These signals indicate the status of the home appliances for monitoring purpose on home users end. A total of 15 feedback signals corresponding to the relays status in the switching module are configured. The format of a feedback signal is Little-Endian; therefore the results are interpreted in binary. Table II below shows the feedback signals for relays status ON in switching module.

TABLE II Feedback Signals for Relay Status ON

Feedback Signals

Little Endian Adjusted Binary Relay ON

01 00 00 01 0000 0000 0000 0001 1 02 00 00 02 0000 0000 0000 0010 2 04 00 00 04 0000 0000 0000 0100 3 08 00 00 08 0000 0000 0000 1000 4 10 00 00 10 0000 0000 0001 0000 5 20 00 00 20 0000 0000 0010 0000 6 40 00 00 40 0000 0000 0100 0000 7 80 00 00 80 0000 0000 1000 0000 8 00 01 01 00 0000 0001 0000 0000 9 00 02 02 00 0000 0010 0000 0000 10 00 04 04 00 0000 0100 0000 0000 11 00 08 08 00 0000 1000 0000 0000 12 00 10 10 00 0001 0000 0000 0000 13 00 20 20 00 0010 0000 0000 0000 14 00 40 40 00 0100 0000 0000 0000 15

The generated feedback signal is sent through the residential application gateway for reverse transmission. Once the residential application gateway receives the feedback signal from switching module through the network interface, mechanism of data transformation is reversed through XML-SOAP messages to inform remote terminal or clients on home appliances status. Fig.10 below shows the prototype designed for the switching module.

Fig. 10: Switching Module Prototype with 15 channels Home appliances control and monitoring can be critical such that failure of turning ON or OFF due to unavailability of network connectivity or server downtime. To overcome this problem, an alternate control mechanism using SMS is deployed in this system. A set of 15 control commands configured using AT Command and GSM communication protocol residing in the residential application gateway. A feedback SMS message is sent back to client terminal or mobile device to indicate the status of the appliances. Table III below shows some of the control command used with SMS Module.

TABLE III SMS Control Commands

Command Function Location 0101 0001 Relay 1 ON Living

room 0110 0001 Relay 1 OFF Living

room 0101 0010 Relay 2 ON Kitchen

0110 0010 Relay 2 OFF Kitchen

0101 0011 Relay 3 ON Main Hall

0110 0011 Relay 4 OFF Fan

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B. Performance Evaluation The performance of residential management system was tested in a dedicated LAN and was measured in terms of response time. For effective control and monitoring purpose in smart home systems, response time is significant and crucial for real-time application. Response time in smart home systems indicates the maximum time of appliances control tasks would take by execution without any interrupts or loads, from remote terminal to appliances. Fig.11 below shows the comparison of response time of the residential application gateway during each control event mechanism using XML-SOAP messages. Total of 200 samples (testing) was performed.

Fig.11: Comparison of Response Time

From the Fig.11, the first response time peak (no load) obtained at 46ms. This is due to Just-In-Time Compiler (JIT) in .NET Framework compilation time for first launch of the software engine in the residential application gateway. The average time consumption for single operation of home appliance control is 25.87ms. This value is justified within the response time requirement for smart home systems control and monitoring. Standard deviation computed at 7.8ms. In comparison, the response time evaluation with load (312kbps) indicates 110ms for the first launch. The average response time with load is 33.94ms and with a standard deviation of 11.08ms.

V. CONCLUSION A SOAP-Based residential management for smart home systems is proposed in this paper. The SOAP technology with Web Services is an excellent choice for deploying interoperability and scalability approach for residential management and home appliances control. The residential management allows multi-protocol and proprietary based home appliances integrated together in a single platform. For future improvement, SOAP-Based residential management could be promising technology for multimedia based consumer electronic appliances towards seamless interoperation in smart home systems.

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[2] V. Miori, L. Tarrini, M. Manca, and G. A. T. G. Tolomei, "An open standard solution for domotic interoperability," IEEE Transactions on Consumer Electronics, vol. 52, pp. 97-103, 2006.

[3] P. Louridas, "SOAP and Web Services," IEEE Software, vol. 23, pp 62-67, 2006.

[4] R. J. C. Nunes and J. C. M. Delgado, "An Internet application for home automation," in Electrotechnical Conference, 2000. MELECON 2000. 10th Mediterranean, 2000, pp. 298-301 vol.1.

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[6] F. Moraes, A. Amory, N. Calazans, E. A. B. E. Bezerra, and J. A. P. J. Petrini, "Using the CAN protocol and reconfigurable computing technology for Web-based smart house automation," in Integrated Circuits and Systems Design, 2001, 14th Symposium on., 2001, pp. 38-43.

[7] oBIX (Open Building Information Xchange), http://www.obix.org/ [8] X10,http://www.x10.com [9] Home Plug, http://www.homeplug.org. [10] .NET Framework 2.0, http://msdn2.microsoft.com/en-

us/netframework/aa731542.aspx

Thinagaran Perumal received his B.Eng. in 2003 at Department of Computer and Communication Systems Engineering, Universiti Putra Malaysia. He completed his M.Sc. degree in Intelligent Systems and currently pursuing Ph.D. in Smart Technology and Robotics at Institute of Advanced Technology, Universiti Putra Malaysia. His main interests are smart home systems,

middleware technologies and embedded system design. He is a member of IEEE.

Abd Rahman Ramli received M.Sc. degree in Information Technology System from University of Strathclyde, United Kingdom in 1985 and Ph.D. in Image Processing from University of Bradford, United Kingdom in 1995. He is currently an Associate Professor and Head of Intelligent Systems and Robotics Laboratory in Institute of Advanced Technology,

Universiti Putra Malaysia. His main interests are imaging, image processing systems and intelligent systems. He is a member of IEEE.

Chui Yew Leong received his B.Eng. Electronics in 2000 from Universiti Malaysia Sabah and M.Sc. specializing in Computer Engineering in 2003 from Universiti Putra Malaysia He obtained his Ph.D. from same university. His main interests are embedded system design, network security and intelligent systems. Currently he is attached as postdoctoral fellow with Institute of Advanced Technology, Universiti Putra

Malaysia. He is a member of IEEE.

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