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The 21th century Repairman Agenda Introduction J2EE J2ME Demonstration.

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Presentation on theme: "The 21th century Repairman Agenda Introduction J2EE J2ME Demonstration."— Presentation transcript:

1 The 21th century Repairman Agenda Introduction J2EE J2ME Demonstration

2 Goal of the project The purpose of this project is: To get some experience with J2EE Investigate some of the possibilities with J2ME Build a semi-large distributed system

3 Pervasive Repairer We ended up with a system intended to support situated and distributed work of a repairer, who is working with large technological systems.

4 System overview Administrative clerk Company Server (J2EE) The repair company The situated repairer Customers place Subcontractor companies DB Http Vendor Subcontractor Manager XMLSOAPXML Interactive web services

5 Model

6 Server side architecture J2MEWebSessionEntity Presentation Layer (Servlet/JSP) Business Layer (Session Beans) Model Layer (Entity Beans) J2ME FLAF / HTTP Web HTML / HTTP DB Container Managed Persistence Value Objects

7 Session beans

8 CLDC, MIDP 1.0, KVM MIDlets. Life cycle. MIDP/CLDC API. No interface, high-level GUI. –Core packages:, java.lang, java.util, –Packages:,.midlet,.rms, lcdui Application development. –J2ME Wireless Toolkit: Network monitor, Output window, Debugger, Memory monitor, Profiler. –IBM J9 CLDC- and MIDP-compliant Java Virtual Machine J2ME CLDCCDC J2SE java.* javax.*

9 J2ME platform Profiles: software application issues Configurations: hardware issues

10 J2ME Client Application BaseFunction BaseFormBaseList Screen CommandListener MIDlet RepairmanClient MainMenu ServerConnection HttpConnection RequestPart BrowseOrders CreateOrder EditOrder CancelOrder RecordStore Store

11 Client(J2ME)-server interaction Client: a wireless, handheld device (cell phone, PDA): Limited resources (memory, CPU), limited connection bandwidth, reduced facilities for user interaction, etc. etc Challenges: –Minimize number of request-responses –Minimal amount of data sent per response –On the server side: minimize number of requests to session beans –Do as much data processing as possible server-side

12 Client-server interaction II A collection of Java Servlets translate value objects, supplied by session beans, to flat strings of data Data transmitted to J2ME client in HTTP headers – eases parsing on the client side This defines a protocol for sending data to J2ME client

13 Client-server interaction III Lists of objects (e.g. product types, orders) - the client requests a specific part of the list; detailed data only sent upon request Session tracking implemented (unable to use javax.servlet.http.HttpSession with J2ME client) Thread-safety

14 Deployment – what’s in it? IBM WebSphere, Device Developer –Create MIDlet suite –Install and run application: Run on handheld target device iPAQ –Install VM: copy files from workstation to iPAQ –Install Wireless communication card driver from workstation.

15 Evaluation: J2EE Advantages –A lot is granted: Transaction, Scalability Disadvantages –Hard to understand errors (combination of deployment description and Code) –Immature tools. Bugs, User Interfaces not always intuitive.

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