3194 Web Services Access from MIDP Devices

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3194Web Services Access from MIDP Devices

• Ken Sipe
• Chief Instructor / TO
• Code Mentor

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Overall Presentation Goal
Learn details necessary in order to consume a web
service from a wireless MIDP device. Understand
the current issues with the technology.
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Speakers Qualifications

• Sun Certified Java 2 Architect.
• Instructor for Visibroker for Java
• Rational OOAD Rose
• Frequently speaks on the subject of distributed
  computing programming, including CORBA and EJB
  architecture.

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WARNING!!!

• Letter of the Law
• Presentation has greatly change from what was
  advertised in the brochure
• Spirit of the Law
• Presentation provides the new and future
  approach to accomplish the goals of the session.

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Presentation Agenda

• MIDP
• MIDP Connectivity
• MIDP XML
• Web Services
• WSA
• Demo

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Whats not Covered

• MIDP GUI Development
• Security
• Communication Topology
• kSOAP
• http//webservices.xml.com/pub/a/ws/2003/08/19/kso
  ap.html

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MIDP
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What is MIDP

• MIDP Mobile Information Device Profile
• A specification of a set of APIs for the Java
  platform used for writing portable applications
  on mobile devices.
• Cell Phones
• Pagers
• PDAs

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MIDP Architecture
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Wireless Device Characteristics

• Small displays
• Limited keyboard
• Limited memory
• Slow processors
• Limited battery life
• Low bandwidth connectivity

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Benefits of J2ME

• Rich GUI
• Multiple target support

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J2ME Limitations

• No RMI
• No finalization
• No reflection
• Lacking XML parsers
• Issue with size of parsers
• Intermittent Communication

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MIDP Connectivity
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Connection Framework
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HttpConnection

• HttpConnection defines the necessary methods and
  constants for HTTP connection.
• Connector.open("http//borland.com/webapp")

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HTTP Get

• Where c is a HTTPConection
• c.setRequestMethod(HttpConnection.GET)

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HTTP Post

• Where c is a HTTPConection
• c.setRequestMethod(HttpConnection.POST)

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MIDP 2.0

• HTTPS
• The only addition to MIDP 2.0 for connectivity
  was the requirement to support HTTPS.

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MIDP XML
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J2ME XML Options

• KXML
• Kxml.org
• SAX / DOM
• NanoXML
• Nanoxml.sourceforge.net/kvm.html
• DOM

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J2ME Web Service options of the past

• HTTP Connectivity using kXML or nanoXML
• Connectivity to Web Proxy for Web Service
  Consumption
• kSOAP
• - connectivity to SOAP proxy
• - direct connectivity to the service

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Web Services / SOAP
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What are Web Services?

• XML - Extensible Markup Language
• SOAP - Simple Object Access Protocol
• WSDL - Web Services Definition Language
• UDDI - Universal Description, Discovery and
  Integration

Alphabet Soap
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Governing Bodies

• W3C World Wide Web Consortium
• OASIS Organization for the Advancement of
  Structured Information Standards
• WS-I Web Services Interoperability Organization

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Web Services
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SOAP Payload Structure

• The body can be formatted either
• RPC or
• Document
• Its parameters are formatted either
• Encoded or
• Literal

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RPC Centric

• Web services transmit objects as XML
• Typically used with Encoded body.

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Document Centric

• Web services transmit XML documents. Applications
  on either end create and parse XML documents
• Typically used with literal body.

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Java / RPC vs. Doc

• JAX-RPC is an RPC centric approach
• JAXM is document centric
• SAAJ is low-level document centric by default
• Document centric is best when you are really
  dealing with documents newsfeeds for example
• Doesnt make sense to change XML to objects back
  to XML again
• Usually, you want to deal with objects, not XML
• However
• Business tends to think in documents (P.O.,
  Invoice)
• Documents are more naturally coarse grained

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WS Challenges

• The building blocks are their, however almost
  immediately several camps chose different
  directions.
• The Java / Axiss approach RPC
• MS / .Nets Approach Document

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WS-I Basic Profile

• Provides Compatibility
• Requires
• HTTP binding for SOAP
• HTTP posts
• WSDL 1.1
• Requires rpc/literal or document/literal

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J2ME meets Web Services
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The new TLA -- WSA

• JSR 172 J2ME Web Services API (WSA)
• Extends the J2ME platform to support web services
  through two features
• Remote Service Invocation
• XML parsing

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WSA

• Requires Conformance to WS-I Basic Profile.
• Supports SOAP 1.1

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WSA Doesnt Support

• No SOAP Message Attachments
• No Message Handlers
• No libraries for service end points
• No UDDI

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WSA Architecture
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WSA Libraries

• Subset of JAXP
• The JAXP is limited to SAX 2.0.  It supports
  UTF-8 and UTF-16, DTD and XML namespaces.  It
  doesnt support DOM, or XLST
• Subset of JAX-RPC
• Subset of RMI
• There are 3 remote Exceptions necessary to
  satisfy the JAX-RPC dependencies.

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J2ME WSA Demo
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Questions?
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Thank You

• 3194
• Web Services Access from MIDP Devices
• Please fill out the speaker evaluation
• You can contact me further at kensipe_at_codementor
  .net