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Web Services

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A Web Service is a software component that could be described via WSDL (Web Service Description Language) and is capable of being accessed via standard network protocols, such as SOAP, over HTTPWeb Services define a platform and language-independent standard based on XML to communicate within distributed systems. SOAP is a lightweight protocol defined by the World Wide Web Consortium (W3C), which defines how to exchange information in a decentralized, distributed systems based on XML.

Ref: http://www.hta-bi.bfh.ch/Projects/wssec/generated/html/glossary.htmlhttp://www.oasis-open.org/committees/wsia/glossary/wsia-draft-glossary-03.htm

Web Services - 1

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Web Services - 2

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Use of web service:– RPC-based: Java API for XML-based remote

procedure calls (JAX-RPC) defines mappings between Java types and XML types

– Message-based (SOA): SOAP messages– REpresentational State Transfer (REST): “a network

of web pages (a virtual state-machine), where the user progresses through an application by selecting links (state transitions), resulting in the next page (representing the next state of the application) being transferred to the user and rendered for their use.” -- Dr. Roy T. Fielding

Web Services - 3

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Web service protocol stack

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s e rv ice dis co v e ry

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s e rv ice de s cript io n

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a pplica t io n a pplica t io n

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Web service protocols

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a pplica t io n

UD D I (Un iv e rs a l D e s cript io n , D is co v e ry , a n d I n te g ra t io n )

W S D L (W e b S e rv ice D e s cript io n L a n g u a g e )

X M L , S O A P (S im ple O bje ct A cce s s Pro to co l)

TC P, H TTP, S M TP, J a bbe r

I P

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SOAPSOAP is a protocol, which applies XML for message exchange in support of remote method calls over the Internet.Compared to Remote Method Invocation (RMI) or CORBA-based facilities: – SOAP is web-based or “wired” and hence is not subject

to firewall restrictions– is Language-independent– provides just-in-time service integration--as requesters

use a service broker (e.g., UDDI--Universal Description, Discovery, and Integration ) to find services, the discovery will take place dynamically.

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Remote Procedure Call using HTTP

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SOAP Messages

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< s o a p:En v e lo pe x m ln s : s o a p= 'h t tp: //www.w3 .o rg /2 0 0 1 /1 0 /s o a p-e n v e lo pe '> < s o a p:H e a de r>

< - - H e a de rs g o h e re - ->

< /s o a p:H e a de r> < s o a p:B o dy >

< - - R e qu e s t g o e s h e re - ->

< /s o a p:B o dy >< /s o a p:En v e lo pe >

S o u rce : h t tp: // www.x m l.co m /

SOAP Messages

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Example of a SOAP message< s o a p:En v e lo pe x m ln s : s o a p= 'h t tp: //www.w3 .o rg /2 0 0 1 /1 0 /s o a p-e n v e lo pe '>

< s o a p:H e a de r> < h :L o g x m ln s :h = 'h t tp: //e x a m ple .o rg /cv s /lo g g in g '> < tra ce > 4 < /t ra ce > < /h :L o g > < h : PS e rv e r x m ln s :h = 'h t tp: //e x a m ple .o rg /cv s /ps e rv e r' s o a p: m u s tUn de rs ta n d= 't ru e ' > < u s e rn a m e > a n o n cv s @ e x a m ple .o rg < /u s e rn a m e > < pa s s wo rd> a n o n cv s < /pa s s wo rd> < /h : PS e rv e r> < /s o a p:H e a de r>

< s o a p:B o dy > < m :C h e ck o u t x m ln s :m = 'h t tp: //e x a m ple .o rg /cv s '> < s o u rce > /x m l/s o a p/we bs e rv ice s /cv s < /s o u rce > < re v is io n > 1 .1 < /re v is io n > < de s t in a t io n > /e tc/u s r/m a rt in g /s o u rce /x m l< /de s t in a t io n > < /m :C h e ck o u t> < /s o a p:B o dy >< /s o a p:En v e lo pe >

s o u rce : h t tp: //www.x m l.co m

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A SOAP Message with a RPCsource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

<SOAP-ENV:Envelope SOAP-ENV:encodingStyle= "http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance">

<SOAP-ENV:Body>       <m:getStateName xmlns:m="http://www.soapware.org/">         <statenum xsi:type="xsd:int">41</statenum>         </m:getStateName> </SOAP-ENV:Body>

</SOAP-ENV:Envelope>

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An Example SOAP Requestsource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

< ? x m l v e rs io n = " 1 .0 " ? >< S O A P- ENV :En v e lo pe S O A P- ENV :e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENC = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < m :g e tS ta te Na m e x m ln s :m = " h t tp: //www.s o a pwa re .o rg /" > < s ta te n u m x s i: ty pe = " x s d: in t" > 4 1 < /s ta te n u m > < /m :g e tS ta te Na m e > < /S O A P- ENV :B o dy > < /S O A P- ENV :En v e lo pe >

pa ra m e te r o f ty pe in t a n d v a lu e 4 1

pro ce du ren a m e

n a m e o f s e rv e r

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Response example source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

< ? x m l v e rs io n = " 1 .0 " ? >< S O A P- ENV :En v e lo pe S O A P- ENV :

e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENC = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < m :g e tS ta te Na m e R e s po n s e x m ln s :m = " h t tp: //www.s o a pwa re .o rg /" > < R e s u lt x s i: ty pe = " x s d:s trin g " > S o u th D a k o ta < /R e s u lt> < /m :g e tS ta te Na m e R e s po n s e > < /S O A P- ENV :B o dy >< /S O A P- ENV :En v e lo pe >

n a m e o f s e rv e r

r e tu r n ed v a lu e

pro ce du re n a m e

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Example of a SOAP message for an Error RPC response

http://www.soapware.org/bdg

< ? x m l v e rs io n = " 1 .0 " ? >< S O A P- ENV :En v e lo pe S O A P- ENV :

e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < S O A P- ENV :Fa u lt> < fa u lt co de > S O A P- ENV :C lie n t< /fa u lt co de > < fa u lt s t r in g > C a n 't ca ll g e tS ta te Na m e be ca u s e th e re a re t o o m a n y pa ra m e te rs . < /fa u lt s t r in g > < /S O A P- ENV :Fa u lt> < /S O A P- ENV :B o dy >< /S O A P- ENV :En v e lo pe >

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HTTP and SOAP RPC Requestsource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

A SOAP message can be used to transport a SOAP remote procedure request/response, as follows: POST /examples HTTP/1.1

User-Agent: Radio UserLand/7.0 (WinNT)Host: localhost:81Content-Type: text/xml; charset=utf-8Content-length: 474SOAPAction: "/examples"<blank line>

<text for SOAP message>

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An HTTP request that carries a SOAP RPC request source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

POST /examples HTTP/1.1User-Agent: Radio UserLand/7.0 (WinNT)Host: localhost:81Content-Type: text/xml; charset=utf-8Content-length: 474SOAPAction: "/examples"

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle=

"http://schemas.xmlsoap.org/soap/encoding/" xmlns: SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns: SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"><SOAP-ENV:Body>       <m:getStateName xmlns:m="http://www.soapware.org/">         <statenum xsi:type="xsd:int">41</statenum>         </m:getStateName> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

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An HTTP request that carries a SOAP RPC responsesource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To

Soap1.1 HTTP/1.1 200 OK

Connection: closeContent-Length: 499Content-Type: text/xml; charset=utf-8Date: Wed, 28 Mar 2001 05:05:04 GMTServer: UserLand Frontier/7.0-WinNT

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance">   <SOAP-ENV:Body>      <m:getStateNameResponse xmlns:m="http://www.soapware.org/">         <Result xsi:type="xsd:string">South Dakota</Result>         </m:getStateNameResponse>      </SOAP-ENV:Body>   </SOAP-ENV:Envelope>

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An HTTP request that carries a SOAP Error messagesource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

HTTP/1.1 500 Server ErrorConnection: closeContent-Length: 511Content-Type: text/xml; charset=utf-8Date: Wed, 28 Mar 2001 05:06:32 GMTServer: UserLand Frontier/7.0-WinNT

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance">   <SOAP-ENV:Body>      <SOAP-ENV:Fault>         <faultcode> SOAP-ENV:Client </faultcode>         <faultstring> Can't call getStateName because there are too many parameters.</faultstring>         </SOAP-ENV:Fault>      </SOAP-ENV:Body>   </SOAP-ENV:Envelope>

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Advantages of web serviceshttp://en.wikipedia.org/wiki/Web_service#Advantages_of_web_services

Web services provide interoperability between various software applications running on disparate platforms. Web services use open standards and protocols. Protocols and data formats are text-based where possible, making it easy for developers to comprehend. By utilizing HTTP, web services can work through many common firewall security measures without requiring changes to the firewall filtering rules. Other forms of RPC may more often be blocked. Web services allow software and services from different companies and locations to be combined easily to provide an integrated service.

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Disadvantages of Web Serviceshttp://en.wikipedia.org/wiki/Web_service

Lacks of standard features, such as transactions, while comparing to other open standards, such as CORBA.

Poor performance due to using of XML text-formats.

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Example of Web Service Request

<?xml version="1.0" encoding="UTF-8" ?> <SOAP-ENV:Envelope

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:q0="http://wsv.mci.com/ETECapability" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<SOAP-ENV:Body> <q0:BuildingID>rvc</q0:BuildingID> </SOAP-ENV:Body></SOAP-ENV:Envelope>

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<?xml version="1.0" encoding="utf-8" ?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">  <soapenv:Header />

<soapenv:Body><ETESitesForBuilding xmlns="http://wsv.mci.com/ETECapability">  <BuildingID>rvc</BuildingID>   <OnNet>1</OnNet>   <BuildingStatus>active</BuildingStatus>   <BuildingServiceType>fiber</BuildingServiceType>

<Sites>  <SiteCode>80</SiteCode>   <SiteCLLI>CHCGILTOH44</SiteCLLI>

<PortTypes> <EquipmentType>ee4000</EquipmentType> <PortType>10/100</PortType> <PortType>GigE</PortType>   </PortTypes>  <Dedicated>0</Dedicated>

<CSiteID xsi:nil="true" /> <ColloRestrictedFlag>0</ColloRestrictedFlag> <SiteStatus>active</SiteStatus> <SiteType>node</SiteType>

</Sites></ETESitesForBuilding></soapenv:Body></soapenv:Envelope>

Example of Web Service Response

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SOAP Packagessource: http://www.soapuser.com

Apache SOAP for JavaApache Axis for JavaIdoox WASP for C++Microsoft SOAP Toolkit (part of the .net framework)SOAP::Lite for Perl

Demo: http://cs1.cs.gmu.edu:8081/admin/index.html

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Apache SOAP

Allows clients and services to be written in Java

Part of the Apache-XML project (http://xml.apache.org/)

SOAP package downloadable: http://xml.apache.org/dist/soap/

Installation instruction:

http://www.xmethods.com/gettingstarted/apache.html

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Apache SOAP installation

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Classpath setting

set CLASSPATH=C:\soap\soap-2_2\lib\xerces.jar;

C:\jdk1.3\bin;

C:\jdk1.3\lib\tools.jar;

C:\soap\soap-2_2\lib\mail.jar;

C:\soap\soap-2_2\lib\soap.jar;

C:\soap\soap-2_2\lib\activation.jar;

C:\tomcat\lib\servlet.jar;

.;

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Writing a Client Application using Apache SOAPsource: http://www.xmethods.com/gettingstarted/apache.html

Classpath The CLASSPATH environment variable should have both the "soap.jar" and "xerces.jar" JAR files included. Importing packages For basic SOAP method invocation:// Required due to use of URL class , required by Call class import java.net.*;

// Required due to use of Vector class import java.util.*;

// Apache SOAP classes used by client import org.apache.soap.util.xml.*; import org.apache.soap.*; import org.apache.soap.rpc.*;

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Ready-made SOAP Services

A number of SOAP ready-made services are available at http://www.xmethods.com/

XMethods Service Weather Temperature ID8 Service Owner:xmethods.net Contact Email:support@xmethods.net Service Description:Current temperature in a

given U.S. zipcode region. SOAP Implementation:Apache SOAP

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Sample SOAP service

An aly ze W S D L | View R P C P r o f ile | h t tp :/ /w w w .x m eth o d s .n e t /s d /2 0 0 1 /T em p era tu r eS erv ic e .w s d lX M eth o d s I D 8S er v ic e O w n er : x m eth o d s .n e tC o n tac t Em ail: s u p p o r t@ x m eth o d s .n e tS er v ic e Ho m e P ag e:D es c r ip tio n : C u r r en t tem p era tu r e in a g iv en U.S . z ip c o d e r eg io n .S O AP Im p lem en ta tio n : Ap ac h e S O AP

W e a the r - T e m p e ra tu re

Found at http://www.xmethods.com

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RPC Profile for Service

R PC Pro f ile fo r S e rv ice " W e a th e r - Te m pe ra tu re "

M e th o d Na m e g e tTe m pEn dpo in t UR L h t tp: //s e rv ice s .x m e th o ds .n e t :8 0 /s o a p/s e rv le t /rpcro u te rS O A PA ct io nM e th o d Na m e s pa ce UR I u rn :x m e th o ds -Te m pe ra tu reI n pu t Pa ra m e te rs z ip c o d e s t rin g

O u tpu t Pa ra m e te rs r e tu r n f lo a t

See sample: TempClient.java

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Client program samples

See samples in client folder:– TempClient.java– StockQuoteClient.java– CurrencyClient.java

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SOAP data types

SOAP Data Types http://www.sdc.iup.edu/outreach/spring2002/webservices/datatypes.html

Uses XML Schema data types

Primitive Types

string, boolean, decimal, float, double, duration, dateTime, time, date, gYearMonth, gYear, gMonthDay, gDay, gMonth, hexBinary, base64Binary, anyURI, QName, NOTATION

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SOAP data types

Derived Types

Simple types (derived from a single primitive type)* integer is derived from decimal* int (-2147483648 <= int <= 2147483647) is derived from long which is derived from integer * 5-digit zip code can be derived from int* may use regular expressions to specify derived types, such as ([A-Z]){2,3}-\d{5}

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Complex Type

Complex types (struct or array)Struct example<instructor> <firstname xsi:type="xsd:string">Ed</firstname>

<lastname xsi:type="xsd:string">Donley</lastname> </instructor>

Array example <mathcourses xsi:type=

"SOAP-ENC:Array" SOAP ENC:arrayType="se:string[3]"> <se:string>10452C</se:string> <se:string>10454C</se:string> <se:string>11123T</se:string>

</mathcourses>

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Creating Web Services (server-side SOAP)

O'Reilly Network: Using SOAP with Tomcat http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.htm

Apache SOAP allows you to create and deploy a SOAP web service.Some jar files must be installed, and must be accessible by the CLASSPATH.

Algorithm:1. Develop a class for providing the service.2. Create a deployment descriptor in XML.3. Deploy the service with the service manager.

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The Apache SOAP service manager

The service manager is itself implemented as a SOAP service.

To see what services are deployed on your system:

java org.apache.soap.server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter list

To deploy a service:

java org.apache.soap.server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter deploy foo.xml

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Creating a SOAP ServiceO'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002]http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.html

A SOAP service can be just about any Java class that exposes public methods for invocation.

The class does not need to know anything about SOAP, or even that it is being executed as a SOAP service.

The method parameters of a SOAP service must be serializable. The available types that can be used as SOAP service parameters are shown in the next slide

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SOAP Service Parameter TypesAll Java primitive types and their corresponding wrapper classes

Java arrays

java.lang.String

java.util.Date

java.util.GregorianCalendar

java.util.Vector

java.util.Hashtable

java.util.Map

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SOAP Service Parameter Typesjava.math.BigDecimal javax.mail.internet.MimeBodyPart

java.io.InputStream

javax.activation.DataSource

javax.activation.DataHandler

org.apache.soap.util.xml.QName

org.apache.soap.rpc.Parameter

java.lang.Object (must be a JavaBean)

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Sample SOAP Service Implementations

TempService: A temperature service

Exchange: currency exchange service and client

Ref: http://ise.gmu.edu/~yhwang1/SWE622/Sample_Codes/chapter11/SOAP/

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Sample SOAP Service Class// A sample SOAP service class// ref: http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.html

package onjava;public class CalcService { public int add (int p1, int p2) { return p1 + p2; }

public int subtract (int p1, int p2) { return p1 - p2; }}

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Deployment Descriptor

<isd:service xmlns:isd="http://xml.apache.org/xml-soap/deployment"

id="urn:onjavaserver"> <isd:provider type="java" scope="Application" methods="add subtract"> <isd:java class="onjava.CalcService"/> </isd:provider>

<isd:faultListener>org.apache.soap.server.DOMFaultListener </isd:faultListener></isd:service>

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Sources of Information

Programming Web Services with SOAP, by Snell et al, O’ReillySOAP Tutorial, http://www.w3schools.com/soap/default.aspSoapRPC.com: Tutorials, http://www.soaprpc.com/tutorials/--Developer’s Guide To Soap1.1DaveNet : XML-RPC for Newbies, http://davenet.userland.com/1998/07/14/xmlRpcForNewbiesSoapRPC.com: Other resources, http://www.soaprpc.com/resources/

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Summary

SOAP is a protocol that makes use of HTTP requests and responses to effect remote method calls to web services.

A SOAP method call is encoded in XML and is embedded in an HTTP request

The return value of a method call is likewise embedded and encoded in an HTTP response

A number of SOAP APIs are available for programming web services and client method calls. The Apache API was introduced.