T. Perumal et al.: Design and Implementation of SOAP-Based Residential Management for Smart Home Systems
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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:
[email protected]). AR.Ramli is with the Institute of Advanced Technology, Universiti Putra Malaysia (e-mail:
[email protected]). Chui Yew Leong is with the Institute of Advanced Technology, Universiti Putra Malaysia (e-mail:
[email protected]).
Contributed Paper Manuscript received January 14, 2008
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
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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
T. Perumal et al.: Design and Implementation of SOAP-Based Residential Management for Smart Home Systems
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 Relay triggering and switching
Residential Application Gateway
I/O Interface
Micro controller
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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
Code Relay 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Trigger ON Hex Binary 51 0101 0001 52 0101 0010 53 0101 0011 54 0101 0100 55 0101 0101 56 0101 0110 57 0101 0111 58 0101 1000 59 0101 1001 5A 0101 1010 5B 0101 1011 5C 0101 1100 5D 0101 1101 5E 0101 1110 5F 0101 1111
Trigger OFF Hex Binary 61 0110 0001 62 0110 0010 63 0110 0011 64 0110 0100 65 0110 0101 66 0110 0110 67 0110 0111 68 0110 1000 69 0110 1001 6A 0110 1010 6B 0110 1011 6C 0110 1100 6D 0110 1101 6E 0110 1110 6F 0110 1111
12V DC Relay Relay set
Home Appliance Lamp
Switching Unit 1k Ω Module O/P
Fig. 2: Operational Block of Switching Module 5V DC
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
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Fig. 3: Relay circuit using Darlington connection
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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: START
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).
Initialize Residential Application Gateway
SOAP Message No Initialize SMS Module
Completed?
SOAP Envelope
Yes Send XML-SOAP Message
Send Command for Home Appliance
Convert network data to serial data
Trigger the appropriate relay in switching module
Send Acknowledgement and Current Status of Home Appliances
Yes No
SOAP Header
