Handling Web Services with Apache AXIS

1
Handling Web Services with Apache AXIS
2
Web-Service Review

• By Examples ...

3
POST /wsprimegenerator.exe/soap/IPrimeGenerator
HTTP/1.0 Content-Type text/xml
charsetutf-8 Host www.jusufdarmawan.com SOAPActi
on "urnUnitIPrimeGenerator-IPrimeGeneratorprime
generator" Content-Length 527 lt?xml
version"1.0" encoding"UTF-8"?gt ltsoapenvEnvelope
xmlnssoapenv"http//schemas.xmlsoap.org/s
oap/envelope/" xmlnsxsd"http//www.w3.org/2
001/XMLSchema" xmlnsxsi"http//www.w3.org/2
001/XMLSchema-instance"gt ltsoapenvBodygt
ltns1primegenerator soapenvencodingStyle
"http//schemas.xmlsoap.org/soap/encoding/"
xmlnsns1"urnUnitIPrimeGenerator-IPrim
eGenerator"gt ltvalstart
xsitype"xsdstring"gt12lt/valstartgt
ltvalend xsitype"xsdstring"gt120lt/valendgt
lt/ns1primegeneratorgt lt/soapenvBodygt lt/soape
nvEnvelopegt
A request to www.jusufdarmawan.com
4
HTTP/1.0 200 OK Date Mon, 09 May 2005 205835
GMT Content-Length 619 Content-Type
text/xml Server Microsoft-IIS/5.0 X-Powered-By
ASP.NET lt?xml version"1.0" encoding'UTF-8'?gt
ltSOAP-ENVEnvelope xmlnsSOAP-
ENV"http//schemas.xmlsoap.org/soap/envelope/"
xmlnsxsd"http//www.w3.org/2001/XMLSchema
" xmlnsxsi"http//www.w3.org/2001/XMLSche
ma-instance" xmlnsSOAP-ENC"http//schemas
.xmlsoap.org/soap/encoding/"gt
ltSOAP-ENVBodygt ltNS1primegeneratorRespons
e xmlnsNS1"urnUnitIPrimeGenerator
-IPrimeGenerator"
SOAP-ENVencodingStyle"http//schemas.xmlsoap.org
/soap/encoding/"gt ltreturn
xsitype"xsdstring"gt13,17,19,23,29,31, 37,
41,43, 47, 53,59,61,67,71,73,7
9,83,89,97,101,103,107,109,113lt/returngt
lt/NS1primegeneratorResponsegt
lt/SOAP-ENVBodygt lt/SOAP-ENVEnvelopegt
The Response
5
POST /soap HTTP/1.0 SOAPAction
"" Content-Length 520 lt?xml version"1.0"
encoding"UTF-8"?gt ltsoapenvEnvelope
xmlnssoapenv"http//schemas.xmlsoap.org/soap/e
nvelope/" xmlnsxsd"http//www.w3.o
rg/2001/XMLSchema"
xmlnsxsi"http//www.w3.org/2001/XMLSchema-instan
ce"gt ltsoapenvBodygt ltns1getRate
soapenvencodingStyle"http//schemas.xmlsoap.o
rg/soap/encoding/" xmlnsns1"urnxmethod
s-CurrencyExchange"gt ltcountry1
xsitype"xsdstring"gtEurolt/country1gt
ltcountry2 xsitype"xsdstring"gtIsraellt/country2gt
lt/ns1getRategt lt/soapenvBodygt lt/soapenvEnvel
opegt
A request to services.xmethods.net
6
HTTP/1.0 200 OK Date Sat, 07 May 2005 232621
GMT Content-Length 492 Content-Type
text/xml lt?xml version'1.0' encoding'UTF-8'?gt lt
soapEnvelope xmlnssoap'http//schemas.xml
soap.org/soap/envelope/'
xmlnsxsi'http//www.w3.org/2001/XMLSchema-instan
ce' xmlnsxsd'http//www.w3.org/2001/XMLS
chema' xmlnssoapenc'http//schemas.xmlsoap
.org/soap/encoding/' soapencodingStyle'htt
p//schemas.xmlsoap.org/soap/encoding/'gt
ltsoapBodygt ltngetRateResponse
xmlnsn'urnxmethods-CurrencyExchange'gt
ltResult xsitype'xsdfloat'gt5.5825lt/Res
ultgt lt/ngetRateResponsegt
lt/soapBodygt lt/soapEnvelopegt
The Response
7
A WSDL Example
lt?xml version"1.0"?gt ltdefinitions
name"CurrencyExchangeService"
targetNamespace"http//www.xmethods.net/sd/Curren
cyExchangeService.wsdl" xmlnstns"http//www.x
methods.net/sd/CurrencyExchangeService.wsdl"
xmlnsxsd"http//www.w3.org/2001/XMLSchema"
xmlnssoap"http//schemas.xmlsoap.org/wsdl/soap/"
xmlns"http//schemas.xmlsoap.org/wsdl/"gt
ltmessage name"getRateRequest"gt ltpart
name"country1" type"xsdstring"/gt ltpart
name"country2" type"xsdstring"/gt
lt/messagegt ltmessage name"getRateResponse"gt
ltpart name"Result" type"xsdfloat"/gt
lt/messagegt ltportType name"CurrencyExchangePort
Type"gt ltoperation name"getRate"gt
ltinput message"tnsgetRateRequest"
name"getRate"/gt ltoutput
message"tnsgetRateResponse" name"getRateRespo
nse"/gt lt/operationgtlt/portTypegt
8
ltbinding name"CurrencyExchangeBinding"
type"tnsCurrencyExchangePortType"gt
ltsoapbinding style"rpc" transport"http//schema
s.xmlsoap.org/soap/http"/gt ltoperation
name"getRate"gt ltsoapoperation
soapAction""/gt ltinput name"getRate"gt
ltsoapbody use"encoded" namespace"urnxmethods-
CurrencyExchange"
encodingStyle"http//schemas.xmlsoap.org/soap/enc
oding/"/gt lt/inputgt ltoutput
name"getRateResponse"gt ltsoapbody
use"encoded" namespace"urnxmethods-CurrencyExch
ange" encodingStyle"http//schemas.
xmlsoap.org/soap/encoding/"/gt lt/outputgt
lt/operationgt lt/bindinggt ltservice
name"CurrencyExchangeService"gt
ltdocumentationgtReturns the exchange rate between
the two currencieslt/documentationgt ltport
name"CurrencyExchangePort" binding"tnsCurrencyE
xchangeBinding"gt ltsoapaddress
location"http//services.xmethods.net80/soap"/gt
lt/portgt lt/servicegt lt/definitionsgt
9
WSDL Elements
Service
Port

Binding
Input
Output
Port Type
Operation

10
Apache EXtensible Interaction System(Axis)
11
What is AXIS

• Axis is essentially a SOAP engine a framework
  for constructing SOAP processors
• clients side
• server side
• Axis implements the interfaces of JAX-RPC
  (XML-based remote procedure calls in Java)
• AXIS Apache Extensible Interaction System

12
Remote Method Invocation is not a New Idea

• java.rmi has been in Java since Javas early
  versions
• In Java RMI, objects can invoke methods of
  objects that reside on a remote computer
• (RMI Remote Method Invocation)
• So, what has been changed?
• Using HTTP for communication
• Using agreed protocols, Java can invoke methods
  that were not written in Java (e.g., .NET
  methods) and vice versa
• A complex registry procedure has been required in
  RMI

13
AXIS Includes

• Axis package includes
• a simple stand-alone server
• a server which plugs into servlet engines such as
  Tomcat
• tools for Web service invocation
• extensive support for the Web Service Description
  Language (WSDL)
• emitter tooling that generates Java classes from
  WSDL
• and more

14
What We Would Like to Create

• Client applications applications that can call a
  remote Web service
• Services methods that can be called by remote
  applications
• Service descriptions WSDL files that describe
  our methods

15
Client Applications
16
Calling Web Services

• By now, we already know how to invoke a remote
  Web service in Java
• Open a socket to the remote server
• Through the socket, send a SOAP request wrapped
  by a HTTP request
• Parse the response (e.g., using SAX/DOM)
• However, this approach is cumbersome, and most of
  it can be automated

17
Invoking Services with Apache

• Axis includes comfortable tools for managing
  calls to Web services
• The programmer configures the request for the Web
  service using a friendly API
• with, or without considering the WSDL
• According to the configuration, a method
  invocation is transformed into a SOAP request
  that is sent to the remote server

18
Invoking Services with Axis

• To invoke an operation of a Web service, do the
  following
• Construct a Service instance
• Using the Service instance, generate a Call
  instance
• Configure the Call instance
• Invoke the call

19
Example Currency Exchange
import org.apache.axis.client. import
javax.xml.namespace.QName import
javax.xml.rpc.ParameterMode import
javax.xml.rpc.encoding.XMLType public class
CurrencyExchange1 public static void
main(String args) throws Exception
System.setProperty("http.proxyHost","wwwproxy.huji
.ac.il") System.setProperty("http.proxyPort","
8080") String endpointUrl
"http//services.xmethods.net80/soap" String
nsuri "urnxmethods-CurrencyExchange"
Service service new Service() Call call
(Call) service.createCall()
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Example Currency Exchange (cont)
call.setTargetEndpointAddress(endpointUrl)
call.setOperationName(new QName(nsuri,"getRate
")) call.addParameter("country1",
XMLType.SOAP_STRING,
ParameterMode.IN)
call.addParameter("country2", XMLType.SOAP_STRING,

ParameterMode.IN) call.setReturnType(XMLTyp
e.SOAP_FLOAT) Object ret
call.invoke(new Object "Euro","Israel")
System.out.println(ret)
21
Using the WSDL

• Axis can read a given WSDL and configure the
  service as much as possible from that WSDL
• Instead of using the default constructor,
  construct the service using the following
  constructor
• Service(String wsdlLocation, QName serviceName)
• Also, supply the port to get a prefilled Call
  object
• In this approach, you usually need to know the
  following about the service
• the WSDL URL, the service name, the namespace
  uri, the operation name and port and the expected
  arguments

22
public class CurrencyExchange2 public static
void main(String args) throws Exception
System.setProperty("http.proxyHost","wwwproxy.huji
.ac.il") System.setProperty("http.proxyPort",
"8080") String wsdl "http//www.xmethods.n
et/sd/2001/CurrencyExchangeService.wsdl"
String nsuri "http//www.xmethods.net/sd/Currenc
yExchangeService.wsdl" String sName
"CurrencyExchangeService", String oName
"getRate" Service service new
Service(wsdl, new QName(nsuri,sName))
String port service.getPorts().next().toString()
Call call (Call)service.createCall
(new QName(nsuri,port), new QName(nsuri,oName))
System.out.println(call.invoke(new Object
"UK","Israel"))
23
The WSDL2Java Application

• Axis provides a mechanism for communicating with
  a Web service using stubs
• That is, generation of regular Java classes that
  have an interface similar to that of the Web
  service and implementation that wraps Web service
  management
• Invoke class WSDL2Java in order to create the
  required Java classes

24
An Example
25
Using The Generated Classes
import net.xmethods.www.sd.CurrencyExchangeService
_wsdl. public class CurrencyExchange3
public static void main(String args) throws
Exception CurrencyExchangeService ce new
CurrencyExchangeServiceLocator()
CurrencyExchangePortType cep
ce.getCurrencyExchangePort() float rate
cep.getRate("USA","Israel")
System.out.println("Rate " rate)
26
Generated Classes

• WSDL2Java generates the following
• A service interface and a service implementation
  (locator) for each service
• A stub class for each binding
• An interface for each port type
• This interface contains methods that correspond
  to the operations of the port type
• A class for each complex type

27
Server Applications
28
AXIS Installation

• Axis works inside a Servlet container (e.g.,
  Tomcat)
• You should add to your Tomcat libs some jar
  files axis.jar, saaj.jar, wsdl4j.jar,
• You need to include several jar files in your
  CLASSPATH
• This has already been done for you!
• The needed CLASSPATH definitions where added to
  dbi.cshrc
• The needed jar files are in CATALINA_BASE/shared/
  lib/

29
AXIS Installation (cont)

• You need to copy the Axis application to your
  Tomcat's application directory
• cp -r dbi/tomcat/axis/ CATALINA_BASE/webapps

CATALINA_BASE
webapps
shared
myapplication
axis
lib
classes
30
Creating a Web Service

• Next, we will see how we can create and publish a
  Web service using the Axis plugin in Tomcat

31
1. Generate the Implementing Class
package myws public class Power
public int power(int a, int n)
return (int)Math.pow(a,n)
CATALINA_BASE/webapps/axis/classes/myws/Power.cla
ss
32
2. Deploy the Service using Web Service
Deployment Descriptor
ltdeployment xmlns"http//xml.apache.org/axis/wsdd
/" xmlnsjava"http//xml.apache.org/a
xis/wsdd/providers/java"gt ltservice
name"mypower" provider"javaRPC"gt
ltparameter name"className" value"myws.Power"/gt
ltparameter name"scope" value"application"
/gt ltparameter name"allowedMethods"
value""/gt lt/servicegt lt/deploymentgt
services.wsdd
java org.apache.axis.client.AdminClient
-hlocalhost -p8090 services.wsdd
33
That's it. Call the Service.
import org.apache.axis.client. public class
PowerClient public static void
main(String argv)throws Exception
String endpoint
"http//mangal8090/axis/services/mypower"
Call call (Call) new Service().createCall(
) call.setTargetEndpointAddress(endpo
int) call.setOperationName("power")
Object value call.invoke(new
Object new Integer(2), new
Integer(5))
System.out.println(2""5 "" value)
34
How Does it Work?

• The AXIS plugin is simply a Web application that
  resides in Tomcat (under webapps/)
• The Servlet AxisServlet of this application is
  responsible for invoking services
• All URLs of the form /services/ are mapped to
  the AxisServlet
• Where is that written?

35
How Does it Work? (cont)

• The wsdd file defines mappings between a Web
  service elements to a Java class elements
• I.e., names, methods, etc.
• The class AdminClient sends a request to the
  application to register the service based on the
  wsdd content
• When a SOAP request arrives, the AxisServlet
  object parses the request and invokes the
  corresponding method of the class associated with
  the service URL

36
The Deployment Descriptor
ltdeployment xmlns"http//xml.apache.org/axis/wsdd
/" xmlnsjava"http//xml.apache.org/a
xis/wsdd/providers/java"gt ltservice
name"mypower" provider"javaRPC"gt
ltparameter name"className" value"myws.Power"/gt
ltparameter name"scope" value"application"
/gt ltparameter name"allowedMethods"
value""/gt lt/servicegt lt/deploymentgt
services.wsdd
37
The Scope of the Object

• Request (the default) a new object is created
  for each request, the service instance is
  available for the duration of the request,
  regardless of forwarding
• Session a new object is created for each new
  session and the service instance is available for
  the entire session
• Application a singleton shared service instance
  is used to serve all invocations

38
Undeploying a Service
ltundeployment xmlns"http//xml.apache.org/axis/ws
dd/"gt ltservice name"mypower"/gt lt/undeploymen
tgt
undeploy.wsdd
java org.apache.axis.client.AdminClient
-hlocalhost -p8090 undeploy.wsdd
39
Implementing Classes

• The class that implements the Web service must be
  accessible to the Axis Servlet
• Hence, this class should reside in a package in
  one of the directories
• CATALINA_BASE/webapps/axis/WEB-INF/classes
• CATALINA_BASE/shared/classes (classes that are
  required for other applications besides Axis)
• Of course, all helper classes should be
  accessible to the Axis application too

40
The Service WSDL

• Axis automatically provides a WSDL for each
  deployed service
• To get the WSDL, use the service URL with the
  empty argument wsdl
• http//localhost8090/axis/services/mypower?wsdl

41
Power-Service WSDL
lt?xml version"1.0" encoding"UTF-8"?gt ltwsdldefin
itions targetNamespace"http//localhost/axis/serv
ices/mypower" xmlns"http//schemas.xmlsoap.or
g/wsdl/" xmlnsapachesoap"http//xml.apache.org
/xml-soap" xmlnsimpl"http//localhost/axis/ser
vices/mypower" xmlnsintf"http//localhost/axis
/services/mypower" xmlnssoapenc"http//schemas
.xmlsoap.org/soap/encoding/" xmlnswsdl"http//
schemas.xmlsoap.org/wsdl/" xmlnswsdlsoap"http
//schemas.xmlsoap.org/wsdl/soap/"
xmlnsxsd"http//www.w3.org/2001/XMLSchema"gt
ltwsdlmessage name"powerResponse"gt
ltwsdlpart name"powerReturn" type"xsdint"/gt
lt/wsdlmessagegt ltwsdlmessage
name"powerRequest"gt ltwsdlpart name"a"
type"xsdint"/gt ltwsdlpart name"n"
type"xsdint"/gt lt/wsdlmessagegt
42
ltwsdlportType name"Power"gt ltwsdloperation
name"power" parameterOrder"a n"gt
ltwsdlinput message"implpowerRequest"
name"powerRequest"/gt ltwsdloutput
message"implpowerResponse" name"powerResponse"
/gt lt/wsdloperationgt lt/wsdlportTypegt
43
ltwsdlbinding name"mypowerSoapBinding"
type"implPower"gt ltwsdlsoapbinding
style"rpc" transport"http//schemas.x
mlsoap.org/soap/http"/gt ltwsdloperation
name"power"gt ltwsdlsoapoperation
soapAction""/gt ltwsdlinput
name"powerRequest"gt ltwsdlsoapbody
encodingStyle"http//schemas.xmlsoap.org/
soap/encoding/" namespace"http//myws"
use"encoded"/gt lt/wsdlinputgt
ltwsdloutput name"powerResponse"gt
ltwsdlsoapbody
encodingStyle"http//schemas.xmlsoap.org/soap/enc
oding/" namespace"http//loc
alhost/axis/services/mypower" use"encoded"/gt
lt/wsdloutputgt lt/wsdloperationgt lt/wsdl
bindinggt
44
ltwsdlservice name"PowerService"gt
ltwsdlport binding"implmypowerSoapBinding"
name"mypower"gt ltwsdlsoapaddress
location"http//localhost/axis/s
ervices/mypower"/gt lt/wsdlportgt
lt/wsdlservicegt lt/wsdldefinitionsgt
45
jws Files

• There is a fast and easy way of crating a
  service
• Create a Java class myClass.java
• Rename your class to end with jws myClass.jws
• Put the jws file directly under the directory
  CATALINA_BASE/webapps/axis/
• That is all. Now you can call the service!

46
Example a Calculator Service
public class SimpleCalculator public int
add(int i1, int i2) return i1 i2
public int subtract(int i1, int i2) return
i1 - i2
CATALINA_BASE/webapps/axis/SimpleCalculator.jws
Service URL http//serverport/axis/SimpleCalcula
tor.jws
47
Example a Calculator Service
public class CalculatorClient public static
void main(String argv)throws Exception
String endpoint
"http//localhost80/axis/SimpleCalculator.jws"
Call call (Call) new Service().createCal
l() call.setTargetEndpointAddress(endpoi
nt) call.setOperationName("add")
Object value call.invoke(new Object new
Integer(4), new
Integer(6)) System.out.println(v
alue)
48
How does it Work?

• On the first time the jws file is being called,
  it is compiled into a class
• WEB-INF/jwsClasses/SimpleCalculator.class
• Axis then considers the URL of the jws as one of
  a regular web service
• Default configurations are assumed
• Sounds like any other technology we know?

49
When not to Use jws Files

• When you do not have the Java source code
• When you dont want to expose your code
• When you want to use custom type mappings
• When you want to use other configuration options

50
Axis Type Mappings
51
Axis Type Mappings

• Axis uses mappings between SOAP types and Java
  classes and primitive types
• In client side SOAP ? Java
• In server side Java ? SOAP
• Serialization and deserialization are executed by
  objects of the interfaces Serializer and
  Deserializer (provided by Axis), respectively
• For example, SimpleSerializer,
  SimpleDeserializer, DateDeserializer,
  ArraySerializer

Axis Type Mapping
52
Complex Type Example - Service Side
package myws import java.util. public class
VectorService public Vector
getAsVector(int array) Vector result
new Vector() for(int i0 iltarray.length
i) result.add("Number "
arrayi) return result
VectorService.java
53
Input in The WSDL
ltcomplexType name"ArrayOf_xsd_int"gt
ltcomplexContentgt ltrestriction
base"soapencArray"gt ltattribute
ref"soapencarrayType" wsdlarrayType"xsdint"
/gt lt/restrictiongt lt/complexContentgt lt/com
plexTypegt
ltwsdlmessage name"getAsVectorRequest"gt
ltwsdlpart name"array" type"implArrayOf_xsd_int
"/gt lt/wsdlmessagegt
54
Output in The WSDL
ltcomplexType name"Vector"gt ltsequencegt
ltelement maxOccurs"unbounded" minOccurs"0"
name"item" type"xsdanyType"/gt
lt/sequencegt lt/complexTypegt
ltwsdlmessage name"getAsVectorResponse"
ltwsdlpart name"getAsVectorReturn"
type"apachesoapVector"/gt lt/wsdlmes
sagegt
55
Complex Type Example - Client Side
import java.util. import org.apache.axis.client.
public class VectorClient public static
void main(String argv)throws Exception
String endpoint
"http//localhost/axis/services/tovector"
Call call (Call) new Service().createCall()
call.setTargetEndpointAddress(endpoi
nt) call.setOperationName("getAsVecto
r") int array 3,7
Vector value (Vector)call.invoke(new
Object array) printVector(value)

VectorClient.java
56
A Snapshot from the Request
ltgetAsVector soapenvencodingStyle"http//s
chemas.xmlsoap.org/soap/encoding/"gt ltarg0
xsitype"soapencArray"
soapencarrayType"xsdint2"
xmlnssoapenc"http//schemas.xmlsoap.org/soap/enc
oding/"gt ltitemgt3lt/itemgt
ltitemgt7lt/itemgt lt/arg0gt lt/getAsVectorgt
57
A Snapshot from the Response
ltgetAsVectorResponse soapenvencodingStyle"h
ttp//schemas.xmlsoap.org/soap/encoding/"gt
ltgetAsVectorReturn href"id0"/gt lt/getAsVectorResp
onsegt ltmultiRef id"id0" soapencroot"0"
soapenvencodingStyle"http//schemas.xmlsoap.org
/soap/encoding/" xsitype"ns1Vector"
xmlnssoapenc"http//schemas.xmlsoap.org/soap/en
coding/" xmlnsns1"http//xml.apache.org/x
ml-soap"gt ltitem xsitype"soapencstring"gtN
umber 3lt/itemgt ltitem xsitype"soapencstri
ng"gtNumber7lt/itemgt lt/multiRefgt
58
Java Beans

• Java Beans are simply objects of classes that
  follow some (natural) coding conventions
• An empty constructor
• A readable property has a matching getter
• A writable property has a matching setter
• A property has name and a type
• The getter of property prop type getProp()
• The setter of property prop void setProp()

59
An Example
package myws public class Person private
String firstName, lastName private int
personID public String getFirstName()
return firstName public void
setFirstName(String firstName)
this.firstName firstName public String
getLastName() return lastName public void
setLastName(String lastName)
this.lastName lastName public void
setId(int id) personID id public int
getId(int id) return personID
60
Using Beans in Web Services

• A Web service can use beans in its definition
• either in its input or output
• For that, you need to tell the Axis engine that
  the corresponding object needs to be serialized
  as a bean
• In this serialization, every readable property
  (i.e., one that has a getter) is specified
• Where, in the file system, should the bean class
  reside?

61
A Service Example
package myws public class PersonService
public Person createPerson() Person
person new Person() person.setFirstName("
f") person.setLastName("l")
person.setId(2) return person
62
The WSDL
ltdeployment xmlns"http//xml.apache.org/axis/wsdd
/" xmlnsjava"http//xml.apache.org
/axis/wsdd/providers/java"gt ltservice
name"person" provider"javaRPC"gt
ltparameter name"className"
value"myws.PersonService"/gt
ltparameter name"scope" value"application"/gt
ltparameter name"allowedMethods" value""/gt
ltbeanMapping qname"nsperson"
xmlnsns"http//www.cs.huji.ac.il/dbi/xsd"
languageSpecificType"javamyws.Person"/gt
lt/servicegt lt/deploymentgt
63
Using Beans in Clients

• To use a bean on the client side, you need to
  configure service to deserialize the SOAP type
  into a Java bean
• For that, we use the class BeanSerializer
  provided by Axis
• Note that client and server beans need not be the
  class
• What should they have in common?

64
public class PersonClient public static void
main(String argv) throws Exception String
endpoint "http//localhost/axis/services/person"
Call call (Call) new Service().createCall()
call.setTargetEndpointAddress(endpoint)
call.setOperationName("createPerson") QName
qn new QName("http//www.cs.huji.ac.il/
dbi/xsd", "person") BeanDeserializerFactory
bdf new BeanDeserializerFactory(MyP
erson.class,qn) call.registerTypeMapping(MyPer
son.class, qn, null, bdf) MyPerson value
(MyPerson)call.invoke(new Object )
System.out.println(value)
Identical to Person
65
Exception Handling
66
Exception in Service Calls

• Several problems can cause exception to be thrown
  when a service is being invoked
• For example
• the server cannot be connected
• the server does not find the requested URL
• the request is inappropriate (no such operation,
  invalid arguments, etc.)
• the implementing service method has thrown an
  exception

67
Service Exception

• When the implementing service throws an
  exception, a SOAP fault response is returned by
  the server
• The client invocation method translates this
  response to a java.rmi.RemoteException after
  parsing the response

68
An Example
package myws public class ExceptionService
public void throwException() throws
IllegalStateException throw new
IllegalStateException ("I
only throw an exception!")
ltservice name"exception" provider"javaRPC"gt
ltparameter name"className"
value"myws.ExceptionService"/gt
ltparameter name"allowedMethods"
value""/gt lt/servicegt
services.wsdd
69
public class ExceptionClient public static
void main(String argv) String endpoint
"http//localhost80/axis/services/exception"
try Call call (Call) new
Service().createCall() call.setTargetEndpoin
tAddress(endpoint) call.setOperationName("th
rowException") Object value
call.invoke(new Object )
System.out.println(value)
catch(RemoteException exp)
System.err.println("WS invocation error "

exp.getMessage()) catch(Exception exp)
System.err.println("Error "
exp.getMessage())
70
A Snapshot from the Response
ltsoapenvBodygt ltsoapenvFaultgt
ltfaultcodegtsoapenvServer.userExceptionlt/faultcode
gt ltfaultstringgtjava.lang.IllegalStateExcept
ion I only throw an
exception!lt/faultstringgt ltdetailgt...lt/detail
gt lt/soapenvFaultgt lt/soapenvBodygt
71
Sharing Information with Web Applications
72
The Scenario

• In your project, you will have two Web
  applications under Tomcat 5.0
• Your Web site
• Axis application for publishing Web services
• The above two applications need to share
  information
• e.g., the database connection parameters
• How will your Web application pass that
  information to the service method?

73
A Possible Solution

• Tomcat uses one class loader for all classes
  under CATALINA_BASE/share/
• Hence, a static variable in one of those classes
  will be accessible to every class running under
  Tomcat

74
A Possible Solution
CATALINA_BASE
webapps
shared
myapplication
axis
lib
classes
SharedClass

• Put the the shared class under shared
• Use a static field of the shared class to hold
  the shared object
• The first time a you discover the parameter,
  store it the shared class