Development of Communication Software for Mobile Computing 246 Development of Communication Software for Mobile Computing Susumu Matsui Yasuhiro Takahashi Takeshi Kondo OVERVIEW: The mobile computing market is expected to take off soon as a number of factors come into play. These factors include the rapid growth in the cellular subscriber base, standardization of a next-generation mobile communications network (IMT-2000) capable of high-speed multimedia communications, and escalated use of notebook and handheld personal computers and personal digital assistants. One objective of mobile computing is to provide the mobile environment with a means of information processing on a par with that of the office environment. Compared with the latter, however, the former suffers from low data speeds, poor communications quality, high connection costs, and low security. These problems must be addressed to make mobile computing successful, and to this end, Hitachi has developed four key technologies: Secure Socket, which compresses and encrypts data; Mobile Message Queue; DB Partner Mobile; and Web Access Agent, which accesses s on behalf of a portable terminal. This paper overviews these technologies and describes their role in mobile computing. INTRODUCTION THE explosive growth of the Internet and the expanding use of groupware like e-mail parallel an increasing need for rapid communications and access to various types of information in business activities. What this means is that mobile computing, which professes to provide communications anytime and anywhere, is fast becoming an indispensable information platform for business. To achieve viable mobile computing, however, a variety of technical issues must be dealt with. These include means for achieving compact and light terminals, high-speed and high-reliability wireless communications networks, and mobile middle software to deal with the low speed and low reliability inherent in mobile communications. Among these issues, we focus here on mobile middle software, and how Hitachi is solving the problems in this area. RECENT TRENDS IN MOBILE COMPUTING To examine the current environment surrounding mobile computing, we first look at the number of portable terminals shipped domestically. In 1998, this came out to 3,400,000 notebook PCs, 1) 1,300,000 portable information terminals, 2) and 200,000 smartphones. 2) Next, while the communication environment for mobile computing consists of both the fixed-wire communication network and the wireless communication network, recent years have seen a remarkable growth in the subscriber base for the wireless network. As of the end of February 1999, the numbers of cellular subscribers and personal handy phone system (PHS) subscribers were 40,500,000 and 5,780,000, respectively, giving a total of 46,280,000 subscribers. 3) These numbers reflect an annual growth of at least 30%, which means that the number of subscribers to the wireless network should surpass that of the fixed network (60,000,000 subscribers) in the year 2000. Table 1 lists typical data speeds of wireless and fixed communication networks. At present ISDN features the highest data speed, 128 kbit/s, but this is about two orders of magnitude slower than the 10-Mbit/s standard speed of an office TABLE 1. Data Speeds of Wireless and Fixed Networks Network type PDC Cellular cdmaone PHS PSTN (modem) ISDN Transmission scheme Packet switching PDC: personal digital cellular PSTN: public switched telephone network ISDN: integrated services digital network Data speed 9.6 kbit/s 28.8 kbit/s 14.4 kbit/s 32-64 kbit/s 56 kbit/s 64-128 kbit/s
Hitachi Review Vol. 48 (1999), No. 4 247 environment. In the future, however, communications speeds from 384 kbit/s to 2 Mbit/s can be expected in conjunction with the IMT-2000 (International Mobile Telecommunications-2000) standard under which services are scheduled to begin in 2001 in Japan. is driving the demand for mobile computing. At the same time, handsets with built-in browsers are beginning to appear, and the number of mobile computing users may exceed 20,000,000 in 2001. 2) Meanwhile, a survey targeting the corporate world has revealed that about one-fourth of the surveyed companies have already introduced mobile computing in one form or another; and of those companies that have not yet done so, about one-half intend to. This survey also predicted large growth in the mobile computing market. EXISTING PROBLEMS WITH MOBILE COMPUTING As mentioned in the previous section, the demand for mobile computing is high. However, a number of issues concerned with providing the mobile environment with means of information processing on a par with that of the office environment still remain. These issues include hardware ones like how to produce compact and light terminals, but here we focus on the following issues related to mobile software. Low data speeds Communication speeds in the mobile environment are about two orders of magnitude slower than that in the office environment. Most existing applications are prepared with the office environment in mind, and they are extremely cumbersome to use as such in the mobile environment. Poor communications quality Stable communications can generally be achieved in the office environment. On the other hand, communications quality may significantly deteriorate according to the location in the mobile environment, especially in the wireless communication environment. High connections costs Communication in the office environment is generally free. In the mobile environment using circuit switching, however, communication cost depends on connection time. In contrast, in the case of packet switching, communication cost depends on the volume of data transferred, but even here the cost is high at present. PPP: point-to-point protocol Browser Mobile computing Web access proxy DB partner mobile client Web access agent DB partner mobile base platform Mobile message queue client base platform Mobile message queue client DB Web Enterprise TCP/IP / PPP TCP/IP Mobile phone Network Remote access Fig. 1 Configuration of a Mobile Computing System. Using mobile computing, it is possible to access efficiently to the enterprise from the terminal.
Development of Communication Software for Mobile Computing 248 Low Security The office environment uses firewalls to block out the outside wired world. In the mobile environment, however, one enters the office environment from the outside. Extra security, such as authentication, must therefore be considered. Encrypting of transferred data is also necessary. RAS Server Environment changes according to location It is common in the office environment to work at one location and on one terminal. In the mobile environment, however, it is not rare for the user to move from one location to another and to even use a variety of terminals. This makes it necessary to change various terminal settings. HITACHI S CURRENT MOBILE COMPUTING SOFTWARE As already mentioned, a number of problems must be solved to make mobile computing a reality. Hitachi has developed several approaches for solving these problems; that is Secure Socket, Mobile Message Queue, and DB Partner Mobile, which have already reached the product stage, and Web Access Agent, which is currently under development. Fig. 1 shows the mobile computing system that contains these technologies. Secure Socket Secure Socket can be installed in terminals and s. It consists of software that authenticates a terminal at the and compresses and encrypts data transferred between the terminal and the. Secure Socket may also be installed on a firewall instead of on s. In this case, it becomes possible to authenticate a terminal at the firewall and compress/ encrypt data transferred between the firewall and the terminal. Fig. 2 shows the configuration of a system using Secure Socket, which has the following features and functions: (1) Applicable to existing communication applications Existing communication applications often use TCP/IP as a communication protocol and many of them have been developed on a socket application program interface (API). Secure Socket is logically placed between the application and the socket library. Secure Socket itself supports socket API (Fig. 3) and provides authentication and data compression/ encryption without having to modify the existing communication application. (2) Authentication conforming to international Internet FW Server : : client RAS: remote access FW: firewall Fig. 2 Configuration of a System Using Secure Socket. Using Secure Socket, it is possible to perform compression/ encryption of data transferred between the terminal and / firewall. standards Secure Socket adopts a mutual authentication scheme in which a certificate issued from the side is used as a basis for challenge and response actions. This scheme is specified by ISO/IEC9798. It provides a level of authentication that is safer and more powerful than the general scheme based on user IDs and passwords. (3) Data compression and encryption Communication devices like modems normally support data-compression functions. However, as redundancy is lost if data is encrypted, the efficiency of data compression is poor if performed at a communication device for encrypted data. For this reason, a function for compressing transfer data is also supported by Secure Socket. Moreover, by focusing on similar points between data compression processing and encryption processing, Secure Socket can both compress and encrypt data by linked processing. Hitachi s data compression function compresses text data by 50% and its MULTI2 encryption technology provides strong encryption. Mobile Message Queue Mobile Message Queue (MMQ) operates on a terminal and a mobile computing installed in offices and is progressing with the aim of compensating for the low speed and high connection cost of the mobile environment. A client software that
Hitachi Review Vol. 48 (1999), No. 4 249 matches the MMQ is installed in a terminal, and an agent software that matches the MMQ is installed in the mobile computing corresponding to an application. The client software in the terminal issues processing instructions to the agent software in the mobile computing, and on the basis of these instructions, the agent software accesses the and returns only results to the client software. In short, the process for accessing the becomes asynchronous. The traffic generated by issuing process instructions and returning results is smaller than that would normally be required to access the sever directly. Adopting asynchronous processing in this way makes it possible to decrease the volume of transferred data in the mobile environment. In addition, as the terminal and the mobile computing need only communicate in order to issue process instructions and return results, the connection can be released while the is being accessed by the agent software; therefore, connection costs are lowered. DB Partner Mobile DB Partner Mobile is a database access application software and processes on top of the MMQ. It consists of DB Partner Mobile Client (the client software described in the previous section Mobile Message Queue and DB Partner Mobile Server (the agent software described in the previous section). In DB Partner Mobile Server, processing scripts that describe the DB access conditions, access time, etc. are registered in advance. DB Partner Mobile Server receives processing instructions, accesses DB according to the instructions and returns the results to DB Partner Mobile Client. The registration tool of procession scripts and operation interfaces are prepared, so it is possible to be customized for fitting to business. Web Access Agent When using MMQ, we must develop terminal-side software as well as agent software for each application. Moreover, although a message communication by MMQ is highly reliable and functional communication that have message tracking or canceling function, it is necessary to develop MMQ software for each kind of terminals. Enterprise systems are becoming increasingly linked to Web s, thus allowing users to access company s via Web pages. We are therefore developing Web access agent technology that does not constrain this function. Linking the enterprise systems and the Web is accomplished by a common gateway interface (CGI). Through this interface, a terminal can access various s through a CGI program within the Web. A Web Access Agent makes use of this mechanism in asynchronously initiating a CGI program. The following two points give a more detailed description of this process. (1) The terminal possesses a replica of the Web page used for accessing the, and with this replica, the terminal can set parameters for running a CGI program via offline processing. (2) Communications between the terminal and the mobile computing (issuing process instructions including the CGI parameters and receiving results from the mobile computing ) take place through MMQ and e-mail. This means that even if the MMQ software is not installed in the user's terminal, and even if the user is in an environment in which communications between the terminal and the mobile HTML & browser FTP HTTP News HTML: hypertext markup language HTTP: hypertext transfer protocol FTP: file transfer protocol TCP: transmission control protocol IP: Internet Protocol PPP: point-to-point protocol Socket I/F Socket I/F TCP IP PPP Fig. 3 Software Configuration of Secure Socket System. Secure Socket itself supports socket I/F and provides authentication and data compression/encryption without having to modify the existing communication application.
Development of Communication Software for Mobile Computing 250 Request Mobile agent access CGI Via e-mail Mobile agent Web Replica of Web page (change initiate CGI) Condition Search Product original CGI initiation information Original CGI initiation information Access to Web and initiate original CGI Condition Search CGI Result Access Save result to Web page Via e-mail Receive result Web page Result Web page <Search result> Enterprise Fig. 4 Flow of Asynchronous CGI Access. Mobile agents make use of the mechanism in a function that asynchronouly initiates CGI program. computing cannot take place, instructions for asynchronous processing can still be delivered as long as the environment allows e-mail to be used. The process flow of CGI asynchronous access is shown in Fig. 4. CONCLUSIONS This report has described Hitachi's current work on mobile middle software for mobile computing. The use of mobile computing is expected to become widespread in the coming years, and to support this growth, more technologies than just the ones described here will be required. Research and development work in this area will therefore continue with the goal of achieving a thorough product system. REFERENCES (1) Japan Electronic Industry Development Association (http:// www.jeida.or.jp/). (2) Mobile Computing Promotion Consortium (http:// club.pep.ne.jp/mcpchp/). (3) Statistical Data of the Ministry of Posts and Telecommunications (http://www.zaimu.mpt.go.jp/tokei/ index.html). ABOUT THE AUTHORS Susumu Matsui Joined Hitachi, Ltd. in 1980, and now works at the communication and computing system. Mr. Matsui is a member of the IEEE, the Information Processing Society of Japan, and the Institute of Electronics, Information and Communication Engineers of Japan, and can be reached by e-mail at matsui@sdl.hitachi.co.jp Yasuhiro Takahashi Joined Hitachi, Ltd. in 1981, and now works at the computing system. Mr. Takahashi is a member of the Information Processing Society of Japan and the Institute of Electronics, Information and Communication Engineers of Japan, and can be reached by e-mail at y-takaha@sdl.hitachi.co.jp Takeshi Kondo Joined Hitachi, Ltd. in 1988, and now works at the computing system. Mr. Kondo is a member of the Information Processing Society of Japan, and can be reached by e-mail at t-kondo@sdl.hitachi.co.jp