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Aleksandar Kovačević & Mina Mićanović1 Introduction to Mobile Computing Aleksandar Kovačević, Mina Mićanović, Veljko.

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Presentation on theme: "Aleksandar Kovačević & Mina Mićanović1 Introduction to Mobile Computing Aleksandar Kovačević, Mina Mićanović, Veljko."— Presentation transcript:

1 Aleksandar Kovačević & Mina Mićanović1 Introduction to Mobile Computing Aleksandar Kovačević, Mina Mićanović, Veljko Milutinović,

2 2 / 95 Wireless Mobile or Mobile Wireless? Wireless communication systems are type of communication system Dimensions of mobility: The set of properties that distinguishes the mobile computing system from stationary computing system

3 Aleksandar Kovačević & Mina Mićanović 3 / 95 Dimensions of Mobile Computing Location awareness Network connectivity quality of service (QOS) Limited device capabilities Limited power supply Support for a wide variety of user interfaces Platform proliferation Active transactions

4 Aleksandar Kovačević & Mina Mićanović4 Mobile Development Frameworks and Tools

5 Aleksandar Kovačević & Mina Mićanović 5 / 95 Mobile Development Frameworks and Tools Fully Centralized Frameworks and Tools N-Tier Client-Server Frameworks and Tools

6 Aleksandar Kovačević & Mina Mićanović 6 / 95 Fully Centralized Frameworks and Tools Have custom-designed clients Embedded in nature Designed to do only one thing

7 Aleksandar Kovačević & Mina Mićanović 7 / 95 Fully Centralized Frameworks and Tools Applies: QOS Limiter power supply Active transactions Location awareness Do not apply: Platform proliferation Limited device capabilities Support for variety of user interfaces

8 Aleksandar Kovačević & Mina Mićanović 8 / 95 Examples Call centers Battlefield systems Grocery store

9 Aleksandar Kovačević & Mina Mićanović 9 / 95 N-Tier Client-Server Framework and Tools N-Tier -Any Number of Tiers – No Limits 3-Tier –Client (User Agent) –Application Server –Database

10 Aleksandar Kovačević & Mina Mićanović 10 / 95 Basic problems Code portability Mobility

11 Aleksandar Kovačević & Mina Mićanović 11 / 95 Needs Layer of Software Performance and system requirements

12 Aleksandar Kovačević & Mina Mićanović 12 / 95 Selection of the Frameworks and Tools Thin-Client Wireless Client-Server Thick-Client Wireless Client-Server Stand-alone Applications

13 Aleksandar Kovačević & Mina Mićanović 13 / 95 Thin-Client Wireless Client-Server Browser that loads markup code (Web-model) No concern about environment Server-side structure Example: WAP with his WML

14 Aleksandar Kovačević & Mina Mićanović 14 / 95 Thick-Client Wireless Client-Server Client application-custom application Using the client as a means of storing data for the offline business logic performs Does not need to be centralized Having thick clients is more difficult

15 Aleksandar Kovačević & Mina Mićanović 15 / 95 Difficulties??? Restricted resources Deployment and provision problem –Operating system or virtual machine –Programming environment

16 Aleksandar Kovačević & Mina Mićanović 16 / 95 Examples Operating system –Windows CE –Symbian Virtual Machine –J2ME

17 Aleksandar Kovačević & Mina Mićanović 17 / 95 Stand-alone Applications They do not need networking components Needs of synchronization with some external system periodically

18 Aleksandar Kovačević & Mina Mićanović 18 / 95 Some products Connectivity Platform Stand-alone Networked WiredWireless Mobile Platforms WAP Symbian BREW Java.NET

19 Aleksandar Kovačević & Mina Mićanović 19 / 95 JAVA - features Object oriented language Complete code mobility Weak mobile agent ability It is a platform

20 Aleksandar Kovačević & Mina Mićanović 20 / 95 J2ME Addresses the needs of two categories of devices: –Personal, mobile, connected information devices (CLDC) –Shared, fixed, connected information devices (CDC)

21 Aleksandar Kovačević & Mina Mićanović 21 / 95 CLDC/MIDP Features(1) Providing: a virtual machine for providing language features a security framework for tasks such as downloading MIDlets (J2ME CLDC/MIDP applications) *MIDP - Mobile Information Device Profile

22 Aleksandar Kovačević & Mina Mićanović 22 / 95 CLDC/MIDP Features(2) Providing: a reasonable amount of functionality for input and output some internationalization capabilities a reasonable amount of networking capabilities

23 Aleksandar Kovačević & Mina Mićanović 23 / 95 KVM Does not provide: –Floating point arithmetic –Support for JNI –Thread grouping –Full-blown exception –Automatic garbage collection of unused objects –Weak references

24 Aleksandar Kovačević & Mina Mićanović 24 / 95 CLDC/MIDP features Providing a security framework for tasks such as downloading MIDlets (J2ME CLDC/MIDP applications)

25 Aleksandar Kovačević & Mina Mićanović 25 / 95 CLDC/MIDP features Providing a reasonable amount of functionality for input and output

26 Aleksandar Kovačević & Mina Mićanović 26 / 95 Internationalization capabilities Provides I/O stream readers that can handle different character encoding schemes Two ways of internationalization: Dynamic Static

27 Aleksandar Kovačević & Mina Mićanović 27 / 95 Profiles The areas addressed by profiles are the following: –Download and installation of application –Life-cycle management of application –User interface feature –Database functionality –Event handling

28 Aleksandar Kovačević & Mina Mićanović 28 / 95 CLDC profiles MIDP (Mobile Information Device Profile) –Widely known and accepted Personal Digital Assistant Profile (PDAP) etc.

29 Aleksandar Kovačević & Mina Mićanović 29 / 95 MIDP Designed for devices with assumed characteristics Small displays ( 96x24,1:1 shaped pixels, depth 1bit ) Min 128kB of nonvolatile memory ( for storing application itself ) Wireless connection to the internet Min of 8kB of nonvolatile memory (for use by the application) ITU-T phone keypad

30 Aleksandar Kovačević & Mina Mićanović 30 / 95 Overview of the CLDC and MIDP Java APIs J2SE-like APIs – inherited from the J2SE environment –java.lang.* –* –java.util.* CLDC-specific APIs – (connector class)

31 Aleksandar Kovačević & Mina Mićanović 31 / 95 Networking Capabilities J2SE assumes the availability of a TCP/IP connection CLDC defines a connection framework in its Java API example – WAP-style connections (WDP/UDP)

32 Aleksandar Kovačević & Mina Mićanović 32 / 95 Review of MIDP APIs Timers –java.util.Timer –java.util.TimerTask Networking –HTTP implementation –* holds HttpConnection

33 Aleksandar Kovačević & Mina Mićanović 33 / 95 Review of MIDP APIs Storage –javax.microedition.rms.* (RMS-Record Management System) – for storing and retrieving data User Interface –javax.microedition.lcdui.* user interface APIs to build interfaces for MIDlets

34 Aleksandar Kovačević & Mina Mićanović 34 / 95 Hello MIDP example For a J2ME class to qualify as a MIDlet, it has to do the following: 1.Extend the MIDlet class 2.Implement the following methods: a)startApp() b)pauseApp() c)destroyApp(boolean b)

35 Aleksandar Kovačević & Mina Mićanović 35 / 95 import javax.microedition.midlet.*; import javax.microedition.lcdui.*; public class HelloMIDP extends MIDlet implements CommandListener { public static final String HELLO = “Hello MIDP”; private DIsplay mDIsplay; private Command mExit; public HelloMIDP() { mDisplay = Display.getDIsplay(this); mExit = new Command(“Exit”, Command.SCREEN, 1); } Hello MIDP example

36 Aleksandar Kovačević & Mina Mićanović 36 / 95 public void startApp() { TextBox myMessage = new TextBox(HELLO, HELLO, 256, 0); myMessage.addCommand(mExit); myMessage.addCommand((CommandListener) this); mDisplay.setCurrent(mDIsplay); } public void pauseApp() {} public void commandAction(Command aCommand, Displayable aDisplayHandle) { if (aCommand == mExit) { destroyApp(false); } public void destroyApp(boolean b) { notifyDestroyed(); } Hello MIDP example

37 Aleksandar Kovačević & Mina Mićanović 37 / 95 Sun’s Development Kit Offers following components: KToolbar (GUI) Preverifier Compiler Emulators Emulation of Performance

38 Aleksandar Kovačević & Mina Mićanović 38 / 95 Dimensions of Mobility by CLDC and Profiles Location awareness –no treatment –javax.microedition.location Network QOS Limited Device Capabilities Limited Power Supply Management Support for a Large Variety of User Interfaces Platform proliferation Active Transactions

39 Aleksandar Kovačević & Mina Mićanović 39 / 95 XML & J2ME Types of parsers: Model Parsers Push Parsers Pull Parsers

40 Aleksandar Kovačević & Mina Mićanović 40 / 95 Using UML to Model J2ME Applications Class Diagrams State Diagrams Component Diagrams Sequence Diagrams

41 Aleksandar Kovačević & Mina Mićanović 41 / 95 CDC Targeted at environments where more than 512kB (usually about 2MB) of memory is available for the Java environment CDC Profiles are built on top of the Foundation Profile CDC has his own virtual machine (CVM-C Virtual Machine) CVM supports all of the features that the J2SE VM does

42 Aleksandar Kovačević & Mina Mićanović 42 / 95 Java Card Smart cards – embedded processor or electronic memory device Java Card API – allows interoperability between different card readers/writes and cards regardless of the manufacturer and Java Card API implementer

43 Aleksandar Kovačević & Mina Mićanović 43 / 95 Java Card

44 Aleksandar Kovačević & Mina Mićanović 44 / 95 Three Types of Smart Cards IC (Integrated Circuit) Memory Cards IC Microprocessor Cards Optical Memory Cards

45 Aleksandar Kovačević & Mina Mićanović 45 / 95 JINI Java Intelligence Network Infrastructure – a base technology for ad-hoc networking Basic transaction that JINI provides: Lookup Discovery Events Leasing Joining Transaction Management

46 Aleksandar Kovačević & Mina Mićanović 46 / 95 JINI Specification Most today’s implementations are not designed for mobile devices There are some that offer “mobilized JINI” –PSINaptic

47 Aleksandar Kovačević & Mina Mićanović 47 / 95 Java-based Peer-to-Peer Protocol JXTA – peer-to-peer protocol Implementation on J2ME –Direct Implementation (JXTA APIs - provided on J2ME device) –Indirect Implementation (JXTA through proxies)

48 Aleksandar Kovačević & Mina Mićanović 48 / 95 BREW BREW (Binary Run-time Environment for Wireless) It is built directly on hardware Software Development Kit (SDK)

49 Aleksandar Kovačević & Mina Mićanović 49 / 95 BREW SDK Overview –register as a developer –download BREW SDK –offered only as a integrate set of components with MS Visual C You get this applications –BREW MIF Editor –BREW Device Configurator –BREW Emulator –BREW Image Authoring Tool –BREW ARM Compiler –Image Converter –BREW Resource Editor –BREW Pure Voice Converter –BREW AppLoader –BREW Grinder –BREW TestSig Generator and AppSigner

50 Aleksandar Kovačević & Mina Mićanović 50 / 95 Building and Deploying a BREW Application Download the SDK and get started Obtain a Verisign Class 3 certificate Get a BREW phone Register as a BREW developer Obtain a Class ID for your application Perform a unit test and send it to a testing lab Perform a pricing and carrier evaluation

51 Aleksandar Kovačević & Mina Mićanović 51 / 95 Download SDK and Start Unit Test Obtain Class 3 Certificate from Verisign Get a BREW Phone Pricing and Carrier Evaluation True BREW Test Get a Class ID Develop Done No Yes

52 Aleksandar Kovačević & Mina Mićanović 52 / 95 Hello BREW AEEClsCreateInstance –BREW Run-time environment HelloBREW_HandleEvent –EventHandler

53 Aleksandar Kovačević & Mina Mićanović 53 / 95 Architectural Concerns About BREW Application Everything in BREW is event driven (tight coupling to the hardware platform) Two groups of APIs you can use: –t–those provided by qualcomm –t–those provided by third-party vendors BREW API is still developing in C

54 Aleksandar Kovačević & Mina Mićanović 54 / 95 Windows CE Different flavors of the Windows CE OS, depending on hardware platform. Pocket PC Windows CE.NET Pocket PC 2002

55 Aleksandar Kovačević & Mina Mićanović 55 / 95 Tools to build Applications Embedded Visual C++ –separate from Visual Studio –Emulators and a debugger is provided –exception handling, run-time debugging Embedded Visual Basic –can be developed faster –no ability to be tuned and optimized for resource-starved mobile devices Smart Device Extensions for.NET Microsoft Mobile Internet Toolkit

56 Aleksandar Kovačević & Mina Mićanović 56 / 95 eMbedded Visual C++ Compilers available for: ARM MIPS Intel’s x86 PowerPC Hitachi processors

57 Aleksandar Kovačević & Mina Mićanović 57 / 95 eMbedded Visual C++ Provides: a subset of the Win32 APIs for building Windows CE applications a subset of the MFC (Microsoft Foundation Classes) libraries a set of classes specific to the Windows CE platform

58 Aleksandar Kovačević & Mina Mićanović 58 / 95 Things You Should keep in mind Graphics are expensive Use events instead of polling when possible Economize with your memory (saving power) Provided functionality of getting the status of the Power Consumption –useful for testing application –useful to change behavior of application Clean up memory resources whenever you get WM_HIBERNATE event

59 Aleksandar Kovačević & Mina Mićanović 59 / 95 Databases on Windows CE Three ways to store data: MS SQL Server Windows CE Edition –most functionality –takes the most resources –offers only subset of its desktop/server version views stored procedure CEDB –small and simple database –it’s not relational database File System –fewer resources –increases the application

60 Aleksandar Kovačević & Mina Mićanović 60 / 95 Windows CE and Web Services Importance of XML-based Web Service.NET has Web Service-based functionality based on two key technologies: –WSDL (Web Service Definition Language) –SOAP (Simple Object Access Protocol)

61 Aleksandar Kovačević & Mina Mićanović 61 / 95 Microsoft Smart Phone Microsoft Smart Phone 2002, Microsoft's attempt to enter the mobile technology market It can host custom applications written using smart phone SDK. SDK is provided as a plug-in for eVC

62 Aleksandar Kovačević & Mina Mićanović 62 / 95 WAP WAP – Wireless Application Protocol Installed on almost every mobile phone Basics about WAP: WAP is intended for thin clients –all logic calculated on the server –simple display instructions in some markup language are done by the client WAP is built on its own lower level communication protocol Typical deployment of WAP includes a proxy or a gateway WAP is a complete framework for a mobile applications

63 Aleksandar Kovačević & Mina Mićanović 63 / 95 WAP Architecture It’s a client-server Architecture Implementation standards –for client to interpret content –communication mechanisms between the clients and the servers –additional required features in the server (particulary proxy servers) Communication functionality between clients and server: –Handling of Telephony on the Device –Push

64 Aleksandar Kovačević & Mina Mićanović 64 / 95 Application Server WAP Proxy / Gateway Basic Communication Architecture in WAP WAP Client WSP,WTP,WTLS,WDP HTTP/ HTTPS

65 Aleksandar Kovačević & Mina Mićanović 65 / 95 WAP UI Developing WML pages WML – Mark-up language rendered by the WAP micro browsers Advantages over HTML WML tag is smaller WML is XML compliant WML is designed for small monochrome screens –allows breaking a page into a deck of cards –allows client-side navigation between the cards WML has mark-up tags that allow interacting with the telephony Disadvantages Most content on Internet is in HTML Conversion of HTML to WML is not easy process –WAP 2.0 fixes that using XHTML that is well-formed and using XML techniques like XSLs to convert XHTML to WML

66 Aleksandar Kovačević & Mina Mićanović 66 / 95 WAP Proxies and Gateways A server that supports WAP and HTTP Difference between the proxy and the gateway: user can determine will he use proxy

67 Aleksandar Kovačević & Mina Mićanović 67 / 95 WAP Gateways (1) Features of WAP Gateways: Security –Handoff point between WTLS (Wireless Transport Layer Security) to external security mechanisms (SSL) Network Access –Access point –Controlled access by Network Provider Protocol Conversions –Converting WSP (Wireless Session Protocol) to HTTP

68 Aleksandar Kovačević & Mina Mićanović 68 / 95 WAP Gateways (2) Caching –Extremely aggressive caching –cache expire must be set manually –reduces the pervasiveness of content Preparation of Content and Scripts –Gateway encodes WML into Compiled WML (WMLC) –WMLScript must be compiled before being sent to client Functionality offered through WAP 2.x –offering model of connectivity that puts increasingly less functionality into the proxy

69 Aleksandar Kovačević & Mina Mićanović 69 / 95 MMS - Multimedia Messaging Services WAP MMS is a standard Overview: –Presentation handled through SMIL (Synchronized Multimedia Integration Language) –Addressing two addresses: –address of the MMS Proxy-relay –address of the recipient user and terminal –Delivery is possible through variety of interfaces. These include the following: a.MMS proxy-relay b.Standard interface (supports any protocol) c.Legacy wireless messaging systems

70 Aleksandar Kovačević & Mina Mićanović 70 / 95 WAP Push Based on Push Access Protocol (PAP) Push operation WAP push event do the following: The mobile device connects and registers to Master Pull Proxy Application Server establishes a connection to PPG through PAP protocol The content being pushed can be a multipart document following the MIME format The user agent profile is accessed. The message is then sent to PPG The devices receives the message

71 Aleksandar Kovačević & Mina Mićanović 71 / 95 Security WAP does not have application authorization Offers guaranteed authentication of user devices Offers guaranteed integrity of transactions

72 Aleksandar Kovačević & Mina Mićanović 72 / 95 Symbian EPOC Symbian OS 7.0 supports: MMS, HTTP, SyncML, SMS, Mobile IP, IrDA, and Bluetooth It has free SDK (supported languages: C++ and Java) Designed more as a PDA OS

73 Aleksandar Kovačević & Mina Mićanović 73 / 95 Publishing Frameworks Presenting content in several different formats Matching the type of document requested with the type of document available (or one that may need to be generated at run time) Modularized infrastructure that separates the various components of the framework, the processing components, and the content

74 Aleksandar Kovačević & Mina Mićanović 74 / 95 Publishing Frameworks Examples: Apache’s Cocoon –best known publishing framework today –written in Java, supports ASP, Java and XSL (and many other) IBM’s Wireless Transcoding Publisher They treat the user interface problems presented by the following: Proliferation of mobile devices Localized and Internationalized user interfaces Selection of segments of multichannel content Selection and composition of content based on device information

75 Aleksandar Kovačević & Mina Mićanović 75 / 95 Cocoon Open-source – widely accepted Got his name from the movie Cocoon’s Architecture aim to separate: –content –style (the formatting of content) –logic (how content is generated or chosen) –management of content (creating content)

76 Aleksandar Kovačević & Mina Mićanović 76 / 95 Cocoon’s Architecture XHTML PDF VXML WML XML Binary Java Transformers GeneratorsSerializers

77 Aleksandar Kovačević & Mina Mićanović 77 / 95 Generators Take static/dynamic content Generate XML in the form of SAX events There are series of generators: File generator Server pages generator JSP generator Request generator

78 Aleksandar Kovačević & Mina Mićanović 78 / 95 Transformers Xalan – XSL transformation engine XSLs are not platform dependent or language dependent

79 Aleksandar Kovačević & Mina Mićanović 79 / 95 Serializer Responsible for publishing to the client through HTTP response FOPSerializer (Converts HTML to PDF) SVG Serializer

80 Aleksandar Kovačević & Mina Mićanović 80 / 95 IBM Wireless Transcoding Publisher Focusing on product, IBM Wireless Everyplace Suite Integrated environment with IBM’s Websphere Application Server Our focus is on pervasive and mobile aspects of this suite and comparison with Cocoon

81 Aleksandar Kovačević & Mina Mićanović 81 / 95 Overview of IBM Everyplace Suite Addresses issues like: wireless connectivity content management for wireless clients wireless security provisioning and device management

82 Aleksandar Kovačević & Mina Mićanović 82 / 95 Comparison of the WTP and Cocoon WTP offers better functionality in converting HTML to any other markup language than Cocoon WTP offers custom transformers that convert variety of image formats WTP offers a set of WAP devices that allow very simple publishing of HTML and XML content to WML-enabled devices Very rich set of tools for developers

83 Aleksandar Kovačević & Mina Mićanović 83 / 95 Other Tools Asynchronous Messaging Systems UML Tools

84 Aleksandar Kovačević & Mina Mićanović84 XML for Mobile Computing

85 Aleksandar Kovačević & Mina Mićanović 85 / 95 XML and Mobile Applications Mobile applications should understand and be able to manipulate XML content Mobile applications use XML to facilitate their implementations

86 Aleksandar Kovačević & Mina Mićanović 86 / 95 Key XML Technologies for Mobile Computing XHTML VXML –designed for voice user interfaces –allows specification of a command-based voice dialog through a markup language WML XForms CCXML XML Pipeline WBXML SSML RDF

87 Aleksandar Kovačević & Mina Mićanović 87 / 95 CCXML Call Control Extensible Markup Language –Application of XML for managing voice calls –It focuses on routing the calls and connecting calls (in contrast to VXML) –It is based on Java Telephony APIs (JTAPI)

88 Aleksandar Kovačević & Mina Mićanović 88 / 95 XML Pipeline It specifies how to process various XML resources It can be thought in two different contexts: It specifies the flow of processing instructions that are applied to one or more given documents residing on the host It specifies the flow of processing instructions that are applied to a variety of XML documents, residing at a variety of hosts

89 Aleksandar Kovačević & Mina Mićanović 89 / 95 Sample XML Pipeline Document

90 Aleksandar Kovačević & Mina Mićanović 90 / 95 Sample XML Pipeline Document

91 Aleksandar Kovačević & Mina Mićanović 91 / 95 XML Pipeline Recognize type of processes: Constructive processes produce new information Augmenting processes add new types (definitions) of information Inspection processes look at the content of a document Extraction processes copy a part of the document that they look into Packaging processes are distributed processes that address the processing of distributed resources

92 Aleksandar Kovačević & Mina Mićanović 92 / 95 WBXML WAP Binary Extensible Markup Language Defines a way to represent XML in 0’s and 1’s instead of text KXML (parse WBXML)

93 Aleksandar Kovačević & Mina Mićanović 93 / 95 SSML Synthetic Speech Markup Language It is used for the infrastructure of the voice user interface

94 Aleksandar Kovačević & Mina Mićanović 94 / 95 RDF Resource Description Framework Created specifically: –to allow discovery of various resources –indexing them –creation of resources that are made up of other RDF resources by simply nesting the RDF descriptions RDF is part of Semantic Web.

95 Aleksandar Kovačević & Mina Mićanović95 Thank You for Your Attention

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