Mark Jepsen

1
(No Transcript)
2
Web Services for Mobile Computing
Mark Jepsen Software Engineer Intermec
Technologies
3
Agenda

• What is a Web Service?
• Why Web Services?
• Calling Web Service.
• Connected Web Services.
• Disconnected Web Services.
• Questions.

4
Web Services for Mobile Computing

• What is a Web Service?
• http//msdn.microsoft.com/webservices/webservices/
  
• XML eXtensible Markup Language
• Data markup language
• WSDL Web Services Description Language
• XML dialect describing service parameters
• SOAP Simple Object Access Protocol
• XML dialect for encoding calls to services
• Usual transport is HTTP
• HTTP HyperText Transport Protocol
• Universal Discovery, Description, Integration
  (UDDI)
• Registry standard for advertising services
• Searchable repository

5
Web Services for Mobile Computing

• Why Web Services?
• Leverage existing standards and tools
• Provide modular application components
• Lower cost and shorten timeframe required to
  deliver mobile applications
• Cross Language/Environment
• Not tied to a single language
• One codebase suffices for all languages

6
Web Services for Mobile Computing

• An XML Web service is a software service exposed
  on the Web through SOAP, described with a WSDL
  file and registered in UDDI.
• Web services does not equal service-oriented
  architecture. Web services is a collection of
  technologies, including XML, SOAP, WSDL, and
  UDDI, which let you build programming solutions
  for specific messaging and application
  integration problems.
• A Web service is a software system designed to
  support interoperable machine-to-machine
  interaction over a network. It has an interface
  described in a machine-processable format
  (specifically WSDL). Other systems interact with
  the Web service in a manner prescribed by its
  description using SOAP messages, typically
  conveyed using HTTP with an XML interface in
  conjunction with other Web-related standards.

7
Web Services for Mobile Computing

• Calling a Web Service
• What is UDDI?
• Where in the world is WSDL?
• What does WSDL tell us?
• Why do I care?

8
Web Services for Mobile Computing

• Web Service Client on Windows CE
• C/VB.NET (Compact Framework)
• Built-in support for WS calls
• HTTP-based transport by default
• Other transports are pluggable
• No transport selection logic
• C
• 3rd-party libraries available
• HTTP-based transport by default
• Other transports are pluggable
• No transport selection logic

9
Web Services for Mobile Computing

• Browser Support
• The Windows CE Browser doesnt support Web
  Services!
• The browser supports HTML, XML and scripting via
  JScript. JScript allows hosting of ActiveX
  controls which can be used to call Web Services.
• The JScript script loads the ActiveX SOAP
  control and dynamically builds a SOAP request.
  This request is posted to the local WS Host and
  the appropriate COM object is instantiated to
  handle the request. This will work, but it is a
  good example of the overhead required to
  accomplish the feat.

10
Web Services for Mobile Computing

• Connected Web Services
• Demo of calling an actual Web Service
• Temperature
• http//www.xmethods.net/sd/2001/TemperatureServic
  e.wsdl
• Stock Quote
• http//services.xmethods.net/soap/urnxmethods-de
  layed-quotes.wsdl

11
Web Services for Mobile Computing

• Disconnected Web Services
• Local Web Server
• An example gSOAP
• http//www.cs.fsu.edu/engelen/soap.html
• The gSOAP Web Services development toolkit offers
  an XML to C/C language binding to ease the
  development of SOAP/XML Web services in C and
  C/C.

12
Web Services for Mobile Computing

• Questions?