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Mobile Web Services. Week II. Overview. Introduction Mobile Limitations Mobile Communication Types Device Platforms Design Considerations. http://cmer.cis.uoguelph.ca. 2. Introduction. Web services on mobile devices hold many opportunities and challenges. http://cmer.cis.uoguelph.ca.

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Presentation Transcript
overview
Overview

Introduction

Mobile Limitations

Mobile Communication Types

Device Platforms

Design Considerations

http://cmer.cis.uoguelph.ca

2

introduction
Introduction

Web services on mobile devices hold many opportunities and challenges

http://cmer.cis.uoguelph.ca

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introduction cont
Introduction (Cont.)
  • The sale of mobile devices has grown rapidly over recent years:
    • Laptops, notebooks, tablets, PDAs, Smart Phones, Cell Phones
  • Over 3.3 billion mobile subscribers as of November, 2007
  • People are becoming mobile offices

http://cmer.cis.uoguelph.ca

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introduction cont5
Introduction (Cont.)
  • Combining mobile devices and web services to offer wireless access to web services
  • Provides new services to consumers and enables employees to access Web service-based enterprise applications and data wherever and whenever

http://cmer.cis.uoguelph.ca

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mobile device limitations
Mobile Device Limitations
  • Mobile devices have different properties than PC’s, Laptops that need to be taken into account when implementing Web services:
    • Processing power
    • Memory
    • Screen size
    • Bandwidth
    • Connectivity
    • Security

http://cmer.cis.uoguelph.ca

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processing power
Processing Power
  • XML Parsing requires respectable processing power
  • Device Specifications:
    • PC’s/Laptops  ~ 2.0GHz
    • PDA’s  ~ 400MHz
    • Cell Phones  ~ 200MHz

http://cmer.cis.uoguelph.ca

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memory
Memory
  • Parsing large amounts of XML can be memory intensive
  • Device Specifications:
    • Desktops/Laptops  ~ 2GB
    • PDA’s  ~ 128MB
    • Cell Phones  ~ 32MB

http://cmer.cis.uoguelph.ca

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screen size
Screen Size
  • Device Specifications:
    • Desktops/Laptops  ~ 19”
    • PDA’s  ~ 2”
  • WAP made it possible to view the Web from a mobile device
    • Mostly strictly text
  • New methods for device interaction are making possible for full-on mobile Web browsing
    • Touch screens, advanced keypads

http://cmer.cis.uoguelph.ca

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bandwidth
Bandwidth
  • Internet-based applications require large amounts of bandwidth
  • XML traffic can be heavy and inefficient
  • Bandwidth Specifications:
    • DSL  ~ 256 Kbps to 24,000 Kbps
    • WiFi  ~ 54 Mbps
    • GPRS  ~ 170 Kbps
    • EDGE  ~ 384 Kbps
    • EVDO  ~ 2.4 Mbps
    • Bluetooth  ~ 2.1Mbps

http://cmer.cis.uoguelph.ca

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connectivity
Connectivity
  • Mobile devices typically rely on wireless mediums for connectivity
    • Cellular Network
    • WiFi
    • Bluetooth
  • Mobile devices move in and out of coverage areas
    • Synchronous connections are difficult
    • Moving towards a reliable “Always-on” network

http://cmer.cis.uoguelph.ca

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security
Security
  • Web service security is difficult to implement although specifications are in motion
    • WS-Security
    • WS-Encryption
  • Wireless connections are vulnerable to attacks

http://cmer.cis.uoguelph.ca

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mobile communication types
Mobile Communication Types
  • Voice
  • Text Messaging
    • SMS
    • EMS
    • MMS
  • Data
    • WAP
    • XHTML
    • SOAP

http://cmer.cis.uoguelph.ca

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voice
Voice
  • Digital cellular networks use various modulation schemes to encode voice data on to a carrier frequency
    • TDMA
    • FDMA
    • CDMA

http://cmer.cis.uoguelph.ca

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text messaging
Text Messaging
  • There are multiple forms of text messaging:
    • SMS (Short Messaging Service)
      • “texting”
      • 160 characters (140 bytes of 7 bit set)
    • EMS (Enhanced Messaging Service)
      • Standard text combined with:
      • Text, pictures, sounds
    • MMS (Multimedia Messaging Service)
      • a standard which is associated with 3G
      • text, pictures, sounds, video

http://cmer.cis.uoguelph.ca

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slide16
Data
  • There are various language protocols that can be used to send/receive information to/from mobile devices:
    • WML
    • HTML
    • SOAP

http://cmer.cis.uoguelph.ca

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slide17
WML

Wireless Markup Language

A markup language intended for devices that implement the WAP specification

Necessary for devices with little processing power (Micro Browsers)

WAP Forum created the WML 1.1 standard in 1998

http://cmer.cis.uoguelph.ca

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slide18
HTML

Hyper Text Markup Language

Gives structure to information

The predominant markup language of the Web

Standard HTML/XHTML pages can be accessed via PDA’s and Smart Phones

Not viably viewable from most cell phones due to screen size and processing power

http://cmer.cis.uoguelph.ca

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slide19
SOAP

XML-based messaging protocol

Used by Web services

Commonly operates over HTTP

Separates the presentation from the content

Like HTML, can be cumbersome on mobile devices

http://cmer.cis.uoguelph.ca

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device platforms
Device Platforms
  • Many familiar application platforms have mobile variations that support Web services.
    • Symbian
    • Java ME
    • .NET Compact Framework
    • Flash Lite
    • BlackBerry
    • Linux
    • Palm OS
    • iPhone OS (no WS support)

http://cmer.cis.uoguelph.ca

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symbian
Symbian
  • A proprietary OS
  • Owned by Nokia, Ericsson, Sony Ericsson, Panasonic, Siemens AG, and Samsung
  • Only runs on ARM processors
  • Can build Symbian C++ applications through favourite C++ IDE
  • Decent support of Web services
    • Various tools and SDKs

http://cmer.cis.uoguelph.ca

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java me
Java ME

Widely adopted and embedded into mobile devices

Development and tools are (for the most part) straight-forward and easy to use

Much Web service support from development community and third party

http://cmer.cis.uoguelph.ca

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java me ws architecture
Java ME WS Architecture

http://cmer.cis.uoguelph.ca

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java me wsa
Java ME WSA

Web Services APIs

Optional package that extends the Java Web services platform to include Java ME

Enable Java ME devices to be Web services clients

Provides a programming model that is consistent with the standard Web services platform

http://cmer.cis.uoguelph.ca

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java me wtk
Java ME WTK

Wireless Toolkit

Renamed to Sun Java Wireless Toolkit

Supports WSA 1.0

Allows application developers to easily emulate client Web services for MIDP, CDC, and CDLC devices

Includes emulation environments, performance optimization and tuning features, documentation, and examples

http://cmer.cis.uoguelph.ca

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blackberry
BlackBerry
  • Built on Java ME framework
  • Provides additional BlackBerry specific tools and API’s
  • Many available IDE’s
    • MDS Studio, JDE, Visual Studio
  • Web service support for both standard and enterprise environments
    • BlackBerry proprietary protocol for bandwidth efficiency on enterprise Web services

http://cmer.cis.uoguelph.ca

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linux
Linux
  • An open source kernel
  • Many successful distributions in the PC market
    • Fedora, SUSE, Ubuntu
  • Making headway in mobile OS market
    • Android by Open Handset Alliance
  • Huge developer community
  • Third party APIs

http://cmer.cis.uoguelph.ca

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palm os
Palm OS
  • Provides SDK and simulation tools for Palm OS applications
  • Not a large market share
  • Third party tools for Web services
    • WebServices Toolkit for Palm OS (CodeWarrior Platform) 1.51

http://cmer.cis.uoguelph.ca

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net compact framework
.NET Compact Framework
  • Robust environment for mobile applications
    • Visual Studio
  • Has no major share of the mobile phone market but…
  • Widely supported on many smart phones and PDAs
    • Windows Mobile
  • Support for Web services

http://cmer.cis.uoguelph.ca

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flash lite
Flash Lite
  • Is becoming broadly accepted by mobile device manufacturers
  • Extremely bandwidth efficient
    • Suitable for cellular networks
  • Highly interactive
  • Support for Web services

http://cmer.cis.uoguelph.ca

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iphone os
iPhone OS

A proprietary OS

Designed by Apple for iPhone and iPod Touch

Derived from Mac OS X

No support for Web services as of yet

http://cmer.cis.uoguelph.ca

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design considerations
Design Considerations

Proxies & Gateways

Device-Based vs. Web-Based

Mobile Web service support

Deep nested XML

Service Granularity

http://cmer.cis.uoguelph.ca

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proxies
Proxies

Cache server information

Can speed up requests by accessing cache instead of re-invoking Web service

If a device is out of service area the cache can complete request/response when service returns.

http://cmer.cis.uoguelph.ca

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gateways
Gateways

WAP Gateway

Mediates between the cell phone and a Web service.

Reformats Web service information to WML so that it is more mobile friendly (compact)

Does the reverse from cell phone to Web service

http://cmer.cis.uoguelph.ca

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gateways35
Gateways

http://cmer.cis.uoguelph.ca

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device based vs web based
Device-Based vs. Web-Based
  • Device Application
    • Put as little as possible of the client on the mobile unit to serve as a user interface and have all the functionality reside on a server
    • Improves performance
    • Java ME, .NET Compact, Flash Lite
  • Web Application
    • More accessible but may be bandwidth intensive
    • HTML, WML, SOAP

http://cmer.cis.uoguelph.ca

36

mobile web service support
Mobile Web Service Support

Older mobile devices likely will not have support for Web services

Older phones may not be Web enabled

Many phones may not have access to 3G services

http://cmer.cis.uoguelph.ca

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deep nested xml
Deep Nested XML
  • Avoid deeply nested XML elements that may prolong:
    • Parsing
    • Marshalling
    • Unmarshalling
  • A universal design consideration for Web services; more so for mobile Web services because of performance limitations

http://cmer.cis.uoguelph.ca

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service granularity
Service Granularity
  • Granularity  Level of detail at which information is viewed or described
  • Coarse-grained vs. fine-grained
    • Course-grained
    • Fine-grained

http://cmer.cis.uoguelph.ca

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fine grained
Fine-Grained

Fine-grained Web services will break operations down to their most basic components

Not effective in this case because of the overhead of XML on invocations

http://cmer.cis.uoguelph.ca

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course grained
Course-Grained

Course-grained Web services will combine the atomicity of the operations to reduce network latency

Could save up to 30% processing time

http://cmer.cis.uoguelph.ca

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conclusion
Conclusion

Mobile access to data is becoming more widespread as an essential service

Web services seem like a natural solution to Web integration

Web services have no guaranteed support from Web technologies

http://cmer.cis.uoguelph.ca

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references
References

http://java.sun.com/products/wsa/

http://java.sun.com/products/sjwtoolkit/

http://webservices.xml.com/pub/a/ws/2003/08/19/mobile.html

http://www.ibm.com/developerworks/wireless/library/wi-websvc/

http://cmer.cis.uoguelph.ca

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