Designing Wireless Enterprise Applications on Mobile Devices

Transcription

1 Designing Wireless Enterprise Applications on Mobile Devices Nadia Moertiyoso and Kin Choong Yow School of Computer Engineering Nanyang Technological University Nanyang Avenue, Singapore {d497019, phone: (65) / (65) fax: (65) Abstract-- Advancements in wireless technologies have made it possible to build wireless enterprise applications. These applications will give great impact in the workflow, work efficiency, and user convenience, which will result in increasing a company s revenue. Enterprise applications calls for challenging requirements such as two-way data transfer, complex business logic, multiple users, and the ability to integrate the wireless element with existing back-end systems. Java 2 Micro Edition (J2ME) allows applications to be executed locally using a mobile device s processing power and resources. This new language makes it possible to develop complex applications that were not possible before on mobile devices. With these technologies, it is now possible to develop wireless enterprise applications. This research examines and develops one enterprise scenario, Customer Support System. In this project, we developed a complete module for the system, including the wireless application, the back-end system, and a web site interface for other user to interact with the system. F I. INTRODUCTION or the last couple of years, the wireless industry has been experiencing tremendous growth. Wireless devices have become more intelligent and are providing a new notion of communication. These connected and intelligent devices are becoming increasingly important in the enterprise setting. Today, people enjoy the convenience of accessing real-time information such as news, stock quotes, and weather on the Internet from their cell phones or PDAs. As the wireless industry becomes more mature with the increasing bandwidth of wireless networks and processing power of wireless devices, we can expect more than just surfing the Internet from their cell phones. By adding more interactivity and intelligence on the application, it is possible to conduct business using the wireless network that will greatly improve the speed and quality of the business, giving rise to the mobile commerce (m-commerce). Mobile commerce (m-commerce) is any transaction with a monetary value that is conducted via mobile telecommunications network. II. WIRELESS TECHNOLOGIES Wireless voice and data transmission technologies are naturally of importance to the widespread availability and uptake of all wireless services. Without the appropriate network coverage, wireless data solution will not be viable. The technology is divided into a few generations, depending on their transfer rate, 2G (Second generation), 2.5G, and 3G (Third Generation). A. 2G (Second Generation) Global System for Mobile Communication (GSM) is the prevailing mobile standard in Europe and most of the Asia- Pacific region. GSM-enabled phones have a "smart card" inside called the Subscriber Identity Module (SIM). The SIM card is personalized to the user. It identifies the account to the network and provides authentication, which allows for appropriate billing. GSM networks presently operate in three different frequency ranges: GSM 900 (also called GSM) - operates in the 900 MHz frequency range and is the most common in Europe and the world. GSM 1800 (also called PCN (Personal Communication Network), and DCS 1800) - operates in the 1800 MHz frequency range and is found in a rapidly-increasing number of countries including France, Germany, Switzerland, the UK, and Russia. GSM 1900 (also called PCS (Personal Communication Services), PCS 1900, and DCS 1900) - the only frequency used in the United States and Canada for GSM. GSM is used by more than 215 million people, or more than 50%, of the world's mobile phone subscribers. However, North America had only 5 million GSM users as of late 1999 [6]. In Europe, the common GSM standard provides the ICITA2002 ISBN:

2 critical mass to make it economically feasible to develop a large variety of innovative applications and services. B. 2.5G (2.5 Generation) There are two prevailing technologies in the 2.5G wireless networks. They are GPRS (General Packet Radio Service) and Motorola s iden network. General Packet Radio Service, also known as GSM-IP (Internet Protocol), is a packet switched wireless protocol that offers instant access to data networks. This system allows bursts of transmission of up to 115 Kbps. The second main advantage of GPRS is the always-on connection between the mobile terminal and the network. GPRS is the first data transport mode to allow full instant mobile internet access. GPRS works by bundling GSM channels together, allocating the portion of bandwidth to its users. Therefore in practice, the actual transmission rate is about 30kbps or lower, and will decrease as the user base grows [7]. Motorola s iden, on the other hand, is an innovative digital technology that enables users to take full advantage of the benefits of the wireless world by integrating four communications services into one network, using one unit. iden's concept of integrated wireless business communications offers advanced capabilities that bring together the features of: dispatch radio full-duplex telephone interconnect short message service data transmission iden technology uses Spectrally Efficient Digital TDMA technology that is based on GSM Platform. iden technology allows cellular voice transmission as well as two-way-radio and voice messaging capability. The system allows transmission of packet data up to 22 kbps per user and is considered alternative to GPRS. iden is widely adopted in US, Canada, and South America and the first provider that provide J2ME-capable handset, which allows various application to be written on top of it [8]. C. 3G (Third Generation) With the support of international regulatory and standards bodies, the wireless industry is moving towards a new generation of wireless systems, so-called Third-Generation systems. 3G represents a significant upgrade from today's digital wireless networks and has the capability to deliver: Broadband data at rates up to 2 Mbps with always-on status Enhanced roaming capability by harmonizing existing standards Network efficiency due to a nearly doubling of the spectrum efficiency of existing cellular networks, thus increasing quality, efficiency and transmission speed of wireless services The formal standard for 3G is the IMT-2000 (International Mobile Telecommunications 2000) and two different developer communities have pushed this standard: 1. W-CDMA is backed by Ericsson, Nokia and Japanese handset manufacturers. 2. CDMA2000 is backed by Qualcomm and Lucent. The current state of the standard is that there exist three optional modes: W-CDMA for Europe and the Asian GSM countries, Multi carrier CDMA for North America, and TDD/CDMA for the Chinese. The first 3G network is expected to be in operation by NTTDoCoMo in Japan [4]. III. CASE STUDY - CUSTOMER SUPPORT SYSTEMS In this case study, we will look at the customer support group in a commercial company, Singapore Engineering Software (SES). The SES Software Support Group was formed in December 1999, and has the main functionality to monitor defects reported or incidents happening on the client site. The product that SES offers include important servers and database that serves critical service such as the Singapore Police department [9]. Currently the Support Group is divided into two groups, namely System Support and Helpdesk. Client reports defect or complaint via fax or phone to the Helpdesk, and the System Support group will respond by going to the user site to solve the problem. Fig. 1. Customer Support Scenario I: Describes the scenario of client, helpdesk and support engineer Due to the urgent nature of the problems, the group usually must be able to solve the problem within a few hours. Currently, the System Support Engineer carries a pager so that the Helpdesk group can contact them immediately when a case arrives. After being informed about the location of the client and the description of the case, the system support engineer must go down to the client site immediately. In order to be able to solve the case faster and easier, the support engineers need to have access to various databases that resides in the SES office, such as the historical info about the product and technical manual of the product. Without wireless access to the database, the support engineers need to carry this information in form of paper or record books. He or she also needs to know the product s warranty status. After each case, the support engineers need to do some paperwork to report the status of the case. The support

3 engineers need to update the level of severity of the problem, record the steps that have been taken, and forward this report to the appropriate person. to create new user, monitor database activity and update database. B. General System Architecture Fig. 3 shows the physical components in the system along with network between them: Fig. 2. Customer Support Scenario II: Describes the scenario of support engineer, manager, and back-end enterprise database. The Helpdesk group is responsible to schedule the system support engineer in the field effectively as well as dispatch the accurate case. The managers need to monitor the overall performance of the group such as average time of service, the engineer with fastest response, etc. In a complex system like this, a wireless enterprise application can help the Support Engineers to schedule new meeting with the Helpdesk group or to submit reports to the managers from anywhere in Singapore. If the Engineers handphones are further equipped with GPS (Global Positioning System), the Helpdesk will be able to monitor the whereabouts of the Support Engineer and dispatch the task more efficiently. A. General System View IV. SYSTEM DESIGN There are three main modules in the system that makes the complete Customer Support System. The conceptual modules are: J2ME module: This is the module that will run on the handphone and provide wireless access to the customer support system for Support Engineer. This module provides functions for Support Engineer to manage their tasks, submit report, query information, and store data locally. Back-end module (Application Server and Database Server): Besides the wireless application, a back-end system that sufficiently resembles the enterprise setting of the Customer Support System must be implemented. This module consists of a database server that stores the data and an application server that provides the business logic part of the application to leverage some processing from the J2ME module to the server. Web site module: This module provides an interface for the Helpdesk group and the Manager to interact with the system in the form of an internet web site. This web site allows the Helpdesk group to receive client request and to monitor the Support Engineer s task. The web site also allows the Manager to view the reports submitted by the Support Engineer and helps him to monitor the best performing engineers. The system administrator can also use this web site Support Engineer (Cellphone) iden data Carrier Network Helpdesk (Internet Browser) Internet Fig. 3. Physical System Architecture System Admin (Internet Browser) LAN RMI/IIOP JDBC Application Server (Weblogic 6.x) Web Server (Weblogic Web Server) Manager (Internet Browser) RDBMS (MS SQL Server) The J2ME module will run on a Motorola i85s mobile phone [3] on the iden data network. It accesses the back-end system using (Hypertext Transfer Protocol). The back-end system architecture follows the J2EE (Java 2 Enterprise Edition) solution [1]. The back-end system will be deployed in three machines: 1. Web Server: handles request from the internet and host the Customer Support Management web site. 2. Application Server: handles the request for the logic of the application. 3. RDBMS (Database Server): hosts and manage the database of the system. The communication between the Web Server and the Application Server was done using RMI/IIOP (Remote Method Invocation over Internet Inter-ORB Protocol). The communication protocol between the application server and the database server was using JDBC (Java Database Connectivity). This protocol allows connections to a database, create SQL statements, and run queries. The other users of the system, Helpdesk, Manager and System Admin, access the system through the web site from a LAN network. The web site is accessed in a PC or laptop using standard web/internet browser. The communication protocol in this case is. B. Considerations in Wireless Architecture Application Design In designing wireless applications, there are new considerations that have to be examined by the developer. Due to the requirements, the application needs to be able to communicate to the server to query and manipulate data. The wireless application presents new problems to database query management due to the mobility of users, power and resource restrictions, and the limited bandwidth of the wireless

4 connection. These challenges are summarized below and are the major issues in designing the architecture of the application. 1. Limited bandwidth: the wireless network operates at a much lower rate than a wired network. 2. Network disconnection: the wireless network is also more susceptible to network disconnection rather than wired network. Therefore, the framework must provide a way to ensure that data in the mobile device will not be lost because of this 3. Limited computing power and memory resources: mobile device has much lower computing power than a standalone PC. Therefore, the operation that requires a lot of computing power must be distributed to other node in the system. 4. Working online and offline: There are a lot of reasons that require the application to be able to work offline. Some of the reasons are; network interruption and weak signal. One of more economical reason is to save air-time charging. 5. Synchronization and data consistency problem: The framework must also provide a way to maintain the consistency of the data in the mobile device and server of resources. However, the client is no longer a simple data display. It can present an application-specific interface to the user, perform basic data validation, cache data, and so on. D. Local Device Database The application needs to be able to work offline to save network bandwidth. Therefore, the client device must have a local database in order to allow the user to work with the data without network connection. The information that is stored in the local device database has these characteristics: Information that needs to be accessed frequently: storing this type of information in the database will speed up interaction and save network bandwidth, because the application will not need to query the server s database repeatedly. Information that needs to persist upon program s termination: this type of information includes information about user, such as username, user preferences, etc. E. Architecture Diagram C. Client-Server Model: Thin, Fat, and Medium Clients Mobile device has a much more limited power and resources compared to the server. Therefore, the most obvious architecture choice for such application is client-server model. The mobile device, which acts as client, makes request of service to the server that has a larger power to perform the service. The next step is to define the degree of which the server performs the service. The term thin client refers to a software layer that only handles the user interface on the client side. Therefore all the other logic and processing are done in the server. On the other hand, a fat client system leverages some of the processing to client machine, thus requiring less powerful servers, and therefore resulting in cheaper cost. Client Tier (Midlet) User Interface Logic Network Logic H Data cache & synchronization logic Local Database Fig. 4: Device Application Diagram Back-end System Central Processing Central Database Fat client application also benefits by distributing task to various components in the network, therefore increasing the speed of computation. However, fat client is not suitable for mobile device application due to the limited power and resources in the client side. A thin client is also not suitable because the application requires more communication with the server, resulting in more network usage. Communication through wireless network is expensive and less reliable than wired network. To address the aforementioned issues, medium-client architecture [5] has evolved. It combines the advantage of leveraging most of the work in the server but exploit more of local computing power. Examples of this architecture are Java Applet on common desktop environment and MIDlet on hand phone environment. Most, if not all, the business logic still resides on the server, which has powerful processor and plenty The application that resides in the user s hand phone is called the Client Tier. The application, written using J2ME, is in the form of MIDlet that runs locally using the hand phone processor. Following our discussion about medium client, this tier has its own local database so that the information that is retrieved can be cached in the hand phone. The functions that the application must provide: 1. user interface logic 2. networking logic on 3. data cache in local database 4. synchronization between local database and central database

5 F. Mailbox Architecture The other issue that the architecture must solve is to provide two-way data communication. The communication protocol between the device and server is. is a stateless protocol, which means that each request and response pair is a complete interaction. When the communication is initiated from client device to the server, there will be no problems. The IP address of the server is static; therefore, the client can save this information and use it to open the connection. However, when the communication is initiated from the server to the client device, a few problems may arise. 1. The client device may be turned off 2. The client device may be out of reach or outside the network 3. The information about the mobile phone IP address is not available due to security concern imposed by the carrier provider. 3. agent checks for new message Server 1. new message is sent 2. message is stored in mailbox G. Using XML for Data Exchange format In recent years, the extensible Markup Language (XML) has been adopted as an industry standard for data exchange and sharing. XML provides a system-independent format for specifying the information to be exchanged over network and between applications. This means that XML makes the data portable among different applications. In enterprise setting, it is common that the back-end systems are implemented using various platforms. Using XML the J2ME application was able to talk to any back-end applications that support XML. It improves the interoperability of the J2ME program. Although the implementation of the project uses purely Java technology (with J2EE for the back-end system), it is possible to change the backend system with completely different technology (eg. Microsoft.NET). XML is used to wrap the information that needs to be transmitted. First, a set of Data Type Definition (DTD) that is public by the J2ME application and the back-end system is defined. Therefore, both application can agree upon what format of message that occurs and handle them accordingly. The XML parser parses the document according to the DTD and creates the objects that can be handled by each application. V. CONCLUSION AND FUTURE WORK In this project, we have successfully implemented a complete model for a Customer Support System and integrated the wireless element to the scenario. The wireless application runs on Motorola i85s on iden network. Screen shots of the J2ME module and the web site modules are shown in figures 6 and 7 respectively. 5. new message is forwarded Mailbox 4. new message is retrieved Fig. 5: Mailbox Architecture Diagram Therefore, in addition to the architecture discussed above, we introduce the idea of creating a mailbox for each mobile device. This is a store-and-forward architecture where the data from server is stored in the server database and persists until client device is ready to retrieve it. In this architecture, although the data originated from server, the client initiates the communication. The client device polls the server at certain interval to check for new message. When new message exist, the mobile client device will retrieve it and the data will be forwarded. In the client device, we add a piece of program that acts as an agent. The agent s task is to run at background and check the mailbox designated for the mobile device regularly. When a new message arrives in the mailbox, the agent retrieves it and notifies the user by displaying a flashing screen. The task of the agent is also extended to database synchronization, i.e., the agent also sends the status of local database that resides in the client device and checks it against database server to maintain data consistency. Fig. 6. Application Main Screen Future work will involve integrating a barcode reader to the handphone to allow faster, easier and more convenient use of the application. Products are normally shipped from the factory with barcode id for identification and it is therefore useful to utilize this to free the user from keying the id using keypad. Another future direction is to integrate a Global Positioning System (GPS) chip to the handphone so as to allow the Helpdesk to track the position of the handphone. This feature is especially important in the case of the Customer Support

6 System, so as to allow better management and monitoring of the Support Engineers in the field. Fig. 7. Helpdesk: Request Management Web Site REFERENCES [1] Girdley, M., Woollen, R., and Emerson, S.L., J2EE Applications and BEA WebLogic Server. New Jersey: Prentice Hall, [2] Yu Feng and Jun Zhu., Wireless Java Programming with J2ME. USA: SAMS Publishing, [3] Motorola Global Telecom Solution Sector. i85s and i50sx Multi Communication Device J2ME Developers Guide. Motorola, [4] The unofficial independent imode FAQ. Eurotechnology.com. January < [5] Nelson, C., and Pilone, D., A medium-client approach may be your best strategy for extending the information supply chain to mobile users. IntelligentEnterprise. January < htm> [6] GSM Technology. GSM World. September GSM Association. < [7] GPRS Platform GSM World. September GSM Association. < [8] iden Technology Motorola iden. Motorola iden Subscriber Group. < ew/tech_overview.html> [9] Tjahyadi, Agustinus George. Report on Industrial Seminar at Singapore Engineering Software, School of Computer Engineering, NTU, Singapore, April 2000.