Interfacing Hardware with Web Services

1
Interfacing Hardware with Web Services

• Jason Wambach
• 2006 Harpoon Technologies

2
XFire

• Free open-source Java SOAP framework
• StAX based (Streaming API for XML)
• Extremely simple
• Still very new (1.0-RC1)
• xfire.codehaus.org

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Exposing a Service

• POJO
• services.xml
• web.xml

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POJO Service

• TempService

public TempService() public String
readTemp() if (tempStr ! null)
return tempStr else return
"Error"
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services.xml

• META-INF Folder of Classpath!

ltbeans xmlns"http//xfire.codehaus.org/config/1.0
"gt ltservicegt ltnamegtTempServicelt/namegt
ltnamespacegthttp//vodkatonic.org/TempServicelt/name
spacegt ltserviceClassgtorg.vodkatonic.webservice
.TempServicelt/serviceClassgt lt/servicegt lt/beansgt
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web.xml
lt?xml version"1.0" encoding"UTF-8"?gt ltweb-app
version"2.4" xmlns"http//java.sun.com/xml/ns/j2
ee" xmlnsxsi"http//www.w3.org/2001/XMLSchema-
instance" xsischemaLocation"http//java.sun.co
m/xml/ns/j2ee http//java.sun.com/xml/ns/j2ee/we
b-app_2_4.xsd"gt ltservletgt
ltservlet-namegtXFireServletlt/servlet-namegt
ltdisplay-namegtXFire Servletlt/display-namegt
ltservlet-classgt org.codehaus.xfire.transpo
rt.http.XFireConfigurableServlet
lt/servlet-classgt lt/servletgt
ltservlet-mappinggt ltservlet-namegtXFireServletlt/
servlet-namegt lturl-patterngt/servlet/XFireServl
et/lt/url-patterngt lt/servlet-mappinggt
ltservlet-mappinggt ltservlet-namegtXFireServletlt/
servlet-namegt lturl-patterngt/services/lt/url-pa
tterngt lt/servlet-mappinggt lt/web-appgt
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Client
public interface TempService public String
readTemp()
XFire xfire XFireFactory.newInstance().getXFire(
) XFireProxyFactory factory new
XFireProxyFactory(xfire) Service serviceModel
new ObjectServiceFactory().create(TempService.cl
ass) TempService service (TempService)
factory.create(serviceModel,
http//192.168.1.708080/temp/services/TempServic
e") System.out.println(service.readTemp())
Thats all!
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Even easier client
Client client new Client(new URL("http//vodkato
nic.org/xfire/services/TempService?wsdl")) Object
response client.invoke(readTemp", new
Object ) String temp (String) response0

• No interface required
• Very much a WIP

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Glossed over details

• Fixed bug with HTTP Proxies
• Using RXTX libs for serial comm.
• rxtx.org
• Java Comm package no longer supported on Windows
  by Sun.
• Bug introduced, EOL windows port instead of
  fixing it.
• No longer needed
• Use USB (Java 1.6?)

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Glossed over (hardware)

• AVR Atmega8 microcontroller
• Hardware U(S)ART
• 10 bit ADC
• Firmware written in C (AVR-GCC)
• Power stolen from serial port

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Schematic
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Screenshot
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Resources

• xfire.codehaus.org
• rxtx.org
• atmel.com
• avrfreaks.net
• vps.harpoontech.com/blog