An Object-oriented Design and Push Web Server based Framework for Physical Object Interactions and Services Runhe Huang, Kei Nakanishi, Jianhua Ma Faculty of Computer and Information Sciences, Hosei University, Tokyo, Japan Email: {rhuang, jianhua}@hosei.ac.jp nakanishi@gs-cis.hosei.ac.jp Bernady O. Apduhan Faculty of Information Science, Kyushu Sangyo University, Fukuoka, Japan Email: bob@is.kyusan-u.ac.jp Abstract— One of the substantial issues in ubiquitous computing is the automatic processing of information from real world objects and enabling their interactions in the background. This scenario requires a framework on which such information processing and object interaction can be supported. This article presents our research progress in developing a framework based on the object-oriented design approach and the use of a push web server. With the concept of object abstraction, an object can hide its internal structure from the outside world, which can make the object secure. Moreover, object interaction can be conducted via message exchanges, which makes the interface simple and standardized and the heterogeneous objects can be easily handled as well. Instead of using the traditional pull web server, a push web server, i.e., Comet, which runs on top of HTTP protocol is used to exchange messages. To this, object interactions can be operated smoothly and seamlessly in real time with shorter delay. Index Terms— ubiquitous computing, pushing web service, object-oriented design, robot motion control, RFID, Comet I. INTRODUCTION Different from cyber computing, ubiquitous computing emphasizes on adding computing ability to real world physical things such that they are able to process acquired information, communicate and interact with each other. In order to differentiate real world physical things with computing ability from those software entities known as e-things/e-objects, real world physical things with computing ability are called u- things/u-objects [1]. With the continuing miniaturization of electronic chips and electro-mechanical devices, there are more and more u-objects being developed ranging from handheld devices such as cell phones and PDAs, home appliances such as TVs and refrigerator, to ordinary goods. For example, a book can be attached with a RFID tag to store the book’s related information such as the book’s title, author’s name, year of publication, ISBN number, etc. As a result, u-objects can be regarded as a special kind of physical entities that are able to store some data electronically and interact with each other via wired or wireless communications. In contrast, software entity such as digital services, known as e-things/e-objects, which resides in either a local or a remote system, can be used to process u- objects related information by providing various specific service functions. A service performs some operations upon request and replies the request with the result. For example, an online bookstore may have a book information service which provides catalog searching, online purchasing, latest news, and so on. In fact, there are already many digital services, such as map service, navigation service, online banking service, and other services that are available via the Internet or other networks. A ubiquitous system [2] generally involves many physical u-objects and digital services. They need to communicate and interact with each other in order to accomplish some assigned task(s). Therefore, both communication and interaction are important and necessary functions which a ubiquitous system has to support. To enable their efficient communications and interactions, it requires a middleware or framework. Due to the heterogeneity of u-objects and digital services, developing such framework is not an easy thing to do and there are many challenging problems to be solved. There have been quite a number of developments [3][4][5][6] in this area based on the service-oriented architecture [7] in which everything is viewed as a service. This approach seems unnatural since some physical devices can hardly be regarded as services. In contrast, it is natural to regard everything as an object, and so it is appropriate to adopt the object-oriented design in which everything is viewed as an object [8]. This article proposes a framework based on the object- oriented design and Comet, also known as a push web server, which runs on top of HTTP protocol for message exchanges. 34 JOURNAL OF SOFTWARE, VOL. 3, NO. 8, NOVEMBER 2008 © 2008 ACADEMY PUBLISHER