Deploying Web Services with AXIS

1
Deploying Web Services with AXIS

• Representation and Management of Data on the Web

2
Web Services

• Web services are methods that a remote
  application can call
• The methods are invoked through usual Web
  protocols (e.g., HTTP)
• Calling a method
• Discovery (UDDI)
• Description (WSDL)
• Invocation (SOAP)

3
What is AXIS

• Axis is essentially a SOAP engine a framework
  for constructing SOAP processors such as clients,
  servers, gateways
• AXIS implements the interfaces of JAX-RPC
  (remote procedure calls in Java, using XML)
• AXIS Apache EXtensible Interaction System

4
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 Invokation)
• So, what has been changed
• Using HTTP and port 80 we can bypass the firewall
• 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

5
AXIS Includes

• Axis isn't just a SOAP engine it also includes
  
• a simple stand-alone server
• a server which plugs into servlet engines such as
  Tomcat
• extensive support for the Web Service Description
  Language (WSDL)
• emitter tooling that generates Java classes from
  WSDL
• a tool for monitoring TCP/IP packets

6
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 were added to
  CATALINA_BASE/shared/lib/

7
Working With AXIS

• AXIS uses Servlets that Tomcat apply
• You should copy the axis directory from dbi to
  your webapps directory
• cp r dbi/tomcat/axis CATALINA_BASE/webapps/

CATALINA_BASE
webapps
shared
friendsnet
axis
lib
classes
8
(No Transcript)
9
What We Would Like to Create

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

10
Will We Do a Lot of XML Parsing?

• You will not directly read or write SOAP messages
• Instead, use Java methods that create request and
  analyze result
• Use the AxisServlet that actually includes a SOAP
  processor
• Code the Client Application and the Service
  Application

11
A Client in a Web Service
Web Server
12
A Client in a Web Service
Web Server
13
Creating a Client

• Create a Service object
• Create a Call object
• Set the endpoint URL, i.e., the destination for
  the SOAP message
• Define the operation (method) name of the Web
  Service
• Invoke the desired service, passing in an array
  of parameters

14
A Simple Client Example

• import org.apache.axis.client.Call
• import org.apache.axis.client.Service
• import javax.xml.namespace.QName
• public class TestClient
• public static void main(String args)
• try
• String endpoint "http//nagoya.apac
  he.org5049/axis/services/echo"
• Service service new Service()
• Call call (Call)
  service.createCall()

15
A Simple Client Example

• call.setTargetEndpointAddress( new
  java.net.URL(endpoint) )
• call.setOperationName(new
  QName("http//soapinterop.org/",
  "echoString"))
• String ret (String) call.invoke( new
  Object "Hello!" )
• System.out.println("Sent 'Hello!',
  got '" ret "'")
• catch (Exception e)
• System.err.println(e.toString())

16

• POST http//nagoya.apache.org5049/axis/services/e
  cho HTTP/1.0
• Content-Type text/xml charsetutf-8
• Accept application/soapxml, application/dime,
  multipart/related, text/
• User-Agent Axis/1.1
• Host nagoya.apache.org5049
• Cache-Control no-cache
• Pragma no-cache
• SOAPAction ""
• Content-Length 461
• lt?xml version"1.0" encoding"UTF-8"?gt
• ltsoapenvEnvelope xmlnssoapenv"http//schemas.xm
  lsoap.org/soap/envelope/" xmlnsxsd"http//www.w3
  .org/2001/XMLSchema" xmlnsxsi"http//www.w3.org/
  2001/XMLSchema-instance"gt
• ltsoapenvBodygt
• ltns1echoString soapenvencodingStyle"http//sc
  hemas.xmlsoap.org/soap/encoding/"
  xmlnsns1"http//soapinterop.org/"gt
• ltns1arg0 xsitype"xsdstring"gtHello!lt/ns1arg
  0gt
• lt/ns1echoStringgt
• lt/soapenvBodygt

The HTTP Request
17
Example A Client that Uses WSDL

• We create an application that calls a remote Web
  service
• In our example the remote Web service produces
  prime numbers in a given range
• The service is in URL http//www.jusufdarmawan.com
  /wsprimegenerator.exe/wsdl/IPrimeGenerator

18
The WSDL of the Service
lt?xml version"1.0" ?gt ltdefinitions
xmlns"http//schemas.xmlsoap.org/wsdl/"
xmlnsxs"http//www.w3.org/2001/XMLSchema"
name"IPrimeGeneratorservice"
targetNamespace"http//www.borland.com/soapServic
es/" xmlnstns"http//www.borland.com/soapServ
ices/" xmlnssoap"http//schemas.xmlsoap.org/
wsdl/soap/" xmlnssoapenc"http//schemas.xmlso
ap.org/soap/encoding/"gt ltmessage
name"primegeneratorRequest"gt  ltpart
name"valstart" type"xsstring" /gt  
ltpart name"valend" type"xsstring" /gt  
lt/messagegt ltmessage name"primegeneratorResponse
"gt  ltpart name"return" type"xsstring"
/gt   lt/messagegt
19
ltportType name"IPrimeGenerator"gt
ltoperation name"primegenerator"gt 
ltinput message"tnsprimegeneratorRequest" /gt  
ltoutput message"tnsprimegeneratorRespon
se" /gt   lt/operationgt  lt/portTypegt
String primegenerator(String valstart, String
valend)
Defining the function
20
ltbinding name"IPrimeGeneratorbinding"
type"tnsIPrimeGenerator"gt  ltsoapbinding
style"rpc"
transport"http//schemas.xmlsoap.org/soap/http"
/gt ltoperation name"primegenerator"gt 
ltsoapoperation soapAction"urnUnitIPrimeGe
nerator-IPrimeGeneratorprimegenerator" /gt
ltinputgt  ltsoapbody use"encoded"
encodingStyle"http//schemas.xm
lsoap.org/soap/encoding/"
namespace"urnUnitIPrimeGenerator-IPrimeGenerator
" /gt   lt/inputgt ltoutputgt 
ltsoapbody use"encoded"
encodingStyle"http//schemas.xmlsoap.org/soap/en
coding/" namespace"urnUnitIPr
imeGenerator-IPrimeGenerator" /gt  
lt/outputgt  lt/operationgt  lt/bindinggt
Binding the method as an RPC
21
ltservice name"IPrimeGeneratorservice"gt
ltport name"IPrimeGeneratorPort"
binding"tnsIPrimeGeneratorbinding"gt 
ltsoapaddress location"http//www.jusufdarmawan
.com/wsprimegenerator.
exe/soap/IPrimeGenerator" /gt   lt/portgt 
lt/servicegt  lt/definitionsgt
The Service URL
22
The Client Source Code

• import org.apache.axis.client.Call
• import org.apache.axis.client.Service
• import javax.xml.namespace.QName
• import java.net.URL
• public class PrimeGenerator
• public static void main(String argv)
• try
• / Set the porxy parameters /
• System.setProperty("http.proxyHost",
  "wwwproxy.huji.ac.il")
• System.setProperty("http.proxyPort",
  "8080")

23

• / Set the service parameters /
• String defaultNS null
• String endpoint null
• URL wsdl new URL("http//www.jusufda
  rmawan.com/
• wsprimegenerator.exe/wsdl/IPri
  meGenerator")
• QName serviceName new
• QName("http//www.borland.com/soapServices/",
  
• "IPrimeGeneratorservice")
• String method "primegenerator"
• String port "IPrimeGeneratorPort"
• / Set the service arguments /
• String start "200"
• String end "300"

24

• / Invoke the service /
• Service service new Service(wsdl,
  serviceName)
• Call call (Call) service.createCall(
  new
• QName(port),
• new QName(method))
• String value (String)call.invoke(new
  Object start, end )
• System.out.println("Primes between "
  start " and "
• end
  " " value)
• catch (Exception exp)
• exp.printStackTrace(System.err)

25
(No Transcript)
26
The HTTP Request
POST /wsprimegenerator.exe/soap/IPrimeGenerator
HTTP/1.0 content-typetext/xml
charsetutf-8 acceptapplication/soapxml,
application/dime, multipart/related,
text/ user-agentAxis/1.1 hostwww.jusufdarmawan.
com cache-controlno-cache pragmano-cache soapact
ion"urnUnitIPrimeGenerator-IPrimeGeneratorprime
generator" content-length540 -- empty line --
27
lt?xml version"1.0" encoding"UTF-8"?gt ltsoapenvE
nvelope xmlnssoapenv"http//schemas.xmlsoap.org/
soap/envelope/" xmlnsxsd"http//www.w3.org/2001/
XMLSchema" xmlnsxsi"http//www.w3.org/2001/XMLSc
hema-instance"gt ltsoapenvBodygt
ltns1primegenerator soapenvencodingStyle"http/
/schemas.xmlsoap.org/soap/encoding/"
xmlnsns1"urnUnitIPrimeGenerator-IPrimeGenerat
or"gt ltvalstart xsitype"xsdstring"gt200lt/valst
artgt ltvalend xsitype"xsdstring"gt300lt/valendgt
lt/ns1primegeneratorgt lt/soapenvBodygt lt/soapen
vEnvelopegt
28
The HTTP Response
HTTP/1.0 200 OK Date Tue, 08 Jun 2004 201016
GMT Content-Length 603 Content-Type
text/xml Server Microsoft-IIS/5.0 X-Powered-By
ASP.NET Content Via 1.1 proxy7 (NetCache
NetApp/5.5R4)
29
lt?xml version"1.0" encoding'UTF-8'?gt ltSOAP-ENVE
nvelope xmlnsSOAP-ENV"http//schemas.xmlsoap.o
rg/soap/envelope/" xmlnsxsd"http//www.w3.org/2
001/XMLSchema" xmlnsxsi"http//www.w3.org/2001/
XMLSchema-instance" xmlnsSOAP-ENC"http//schema
s.xmlsoap.org/soap/encoding/"gt ltSOAP-ENVBodygt
ltNS1primegeneratorResponse
xmlnsNS1"urnUnitIPrimeGenerator-IPrimeGenerator
" SOAP-ENVencodingStyle"http//schemas.
xmlsoap.org/soap/encoding/"gt ltreturn
xsitype"xsdstring"gt 211, 223, 227,
229, 233, 239, 241, 251, 257, 263, 269, 271, 277,
281, 283, 293lt/returngt
lt/NS1primegeneratorResponsegt
lt/SOAP-ENVBodygt lt/SOAP-ENVEnvelopegt
30
Service

• Service()
• the constructor assumes that the caller will set
  the appropriate fields by hand rather than
  getting them from the WSDL
• Service(java.io.InputStream wsdlInputStream,
• QName serviceName)
• Constructs a new Service object for the service
  in the WSDL document in the wsdlInputStream and
  serviceName parameters

31
Creating a Call

•  Call createCall()
• Creates a new Call object with no prefilled data
•  Call createCall(QName portName,
  QName operationName)      
• Creates a new Call object - will prefill as much
  info from the WSDL as it can

32
Call

• Used to actually invoke the Web service
• You can invoke the operation associated with the
  call using invoke()
• invoke(Object params)
• Invokes the operation associated with the call
  using the passed in parameters as the arguments
  to the method

33
Setting Types

• You can set parameters using the method
  addParamether()
• You can set the returned type using
  setReturnedType()

call.addParameter("testParam", org.apache.axis.Co
nstants.XSD_STRING, javax.xml.rpc.ParameterMode
.IN) call.setReturnType(org.apache.axis.Constant
s.XSD_STRING)
34
Creating a Service

• 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 under the directory
  CATALINA_BASE/webapps/axis/
• That is all. Now you can call the service!

35
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

We rename the file SimpleCalculator.jws We put
the file under webapps/axis
36
http//computer-that-runs-tomcatport/axis/SimpleC
alculator.jws
37
The Client For the Calculator

• import org.apache.axis.client.Call
• import org.apache.axis.client.Service
• import org.apache.axis.encoding.XMLType
• import org.apache.axis.utils.Options
• import javax.xml.rpc.ParameterMode
• public class SimpleCalcClient
• public static void main(String args) throws
  Exception
• String endpoint "http//mangal.cs.huji.ac
  .il8999/axis/SimpleCalculator.jws"
• if (args null args.length ! 3)
• System.err.println("Usage
  SimpleCalcClient ltaddsubtractgt arg1 arg2")
• return
• String method args0
• if (!(method.equals("add")
  method.equals("subtract")))
• System.err.println("Usage CalcClient
  ltaddsubtractgt arg1 arg2")
• return

38

• Integer i1 new Integer(args1)
• Integer i2 new Integer(args2)
• Service service new Service()
• Call call (Call)
  service.createCall()
• call.setTargetEndpointAddress( new
  java.net.URL(endpoint) )
• call.setOperationName( method )
• call.addParameter( "op1", XMLType.XSD_INT,
  ParameterMode.IN )
• call.addParameter( "op2", XMLType.XSD_INT,
  ParameterMode.IN )
• call.setReturnType( XMLType.XSD_INT )
• Integer ret (Integer) call.invoke( new
  Object i1, i2 )
• System.out.println("Got result " ret)

39
Tomcat
CATALINA_BASE
webapps
shared
friendsnet
axis
lib
classes
WEB-INF
jwsClasses
classes
AxisServlet.class
40
Tomcat
CATALINA_BASE
webapps
shared
friendsnet
axis
lib
classes
WEB-INF
jwsClasses
classes
AxisServlet.class
41
Tomcat
CATALINA_BASE
webapps
shared
friendsnet
axis
lib
classes
WEB-INF
jwsClasses
classes
AxisServlet.class

• The class SimpleCalculator is compiled and
  dynamically loaded
• The SOAP request is parsed and analyzed
• A response is created by the SimpleCalculator
• The result is wrapped as a SOAP response an
  returned to the caller

5
HTTP Response
42
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

43
AxisServlet

• Dealing with service calls is done by AxisServlet
• The following files are mapped to AxisServlet (in
  web.xml of the axis application directory)
• servlet/AxisServlet
• .jws
• services/

44
Deploying Services

• When a service is called, the AxisServlet must
  know where to look for the application
• Telling where the application can be found is
  called "deploying"
• Deploying is a two-step process
• Create a deployment descriptor file
• Call the java command that deploys the web
  application

java org.apache.axis.client.AdminClient -p port
deploy-file.wsdd
45
Creating a Service

• Create a Java class
• Compile the class
• Put the class under
  axis/WEB-INF/classes/the-package-name/
• Create a deployment descriptor file mydeploy.wsdd
• Call the AdminClient Service with the deployment
  file as a parameter (in the computer where Tomcat
  runs AXIS)
• You are done and can call the service!

46
Example A Power Function

• We create a service that computes the power of
  two numbers
• We show how to deploy the service
• We demonstrate the service with a client that
  calls the service

47
The Service Code

• package dbi
• public class PowerService
• public int power(int a, int n)
• return (int)Math.pow(a,n)

48
Deployment File

• ltdeployment xmlns"http//xml.apache.org/axis/wsdd
  /" xmlnsjava"http//xml.apache.org/ax
  is/wsdd/providers/java"gt
• ltservice name"dbiPowerService"
  provider"javaRPC"gt
• ltparameter name"className"
  value"dbi.PowerService"/gt
• ltparameter name"scope"
  value"application"/gt
• ltparameter name"allowedMethods"
  value""/gt
• lt/servicegt
• lt/deploymentgt

We call the file dbideploy.wsdd
java org.apache.axis.client.AdminClient -p8090
dbideploy.wsdd
After deployment you can call the service
49
A Client that Calls the Power Service

• import org.apache.axis.client.Call
• import org.apache.axis.client.Service
• import javax.xml.namespace.QName
• public class PowerClient
• private static final String host
  "mangal.cs.huji.ac.il"
• private static final int port 8090
• public static void main(String argv)
• try
• int x2, n5
• String endpoint "http//" host
  "" port
• 
  "/axis/services/dbiPowerService"

50

• call call (Call) new Service().createCal
  l()
• call.setTargetEndpointAddress(new
  java.net.URL(endpoint))
• call.setOperationName("power")
• Integer value (Integer)call.invoke(n
  ew Object
• new Integer(x), new Integer(n)
• )
• System.out.println(x""n ""
  value)
• catch (Exception exp)
• exp.printStackTrace(System.err)

Is it important from which directory I call the
client? Is it important from which computer I
call the client?
51
The HTTP Request

• POST /axis/services/dbiPowerService HTTP/1.0
• content-typetext/xml charsetutf-8
• acceptapplication/soapxml, application/dime,
  multipart/related, text/
• user-agentAxis/1.1
• hostmangal.cs.huji.ac.il8090
• cache-controlno-cache
• pragmano-cache
• soapaction""
• content-length499

52

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltsoapenvEnvelope
• xmlnssoapenv"http//schemas.xmlsoap.org/soap/en
  velope/" xmlnsxsd"http//www.w3.org/2001/XMLSche
  ma"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-insta
  nce"gt
• ltsoapenvBodygt
• ltns1power
• soapenvencodingStyle"http//schemas.xm
  lsoap.org/soap/encoding/"
• xmlnsns1"http//dbi/"gt
• ltns1arg0 xsitype"xsdint"gt2lt
  /ns1arg0gt
• ltns1arg1 xsitype"xsdint"gt5lt
  /ns1arg1gt
• lt/ns1powergt
• lt/soapenvBodygt
• lt/soapenvEnvelopegt

53
The HTTP Response

• HTTP/1.1 200 OK
• Content-Type text/xmlcharsetutf-8
• Date Sat, 05 Jun 2004 180002 GMT
• Server Apache-Coyote/1.1
• Connection close
• lt?xml version"1.0" encoding"UTF-8"?gt
• ltsoapenvEnvelope
• xmlnssoapenv"http//schemas.xmlsoap.org/soap/en
  velope/"
• xmlnsxsd"http//www.w3.org/2001/XMLSchema"
  xmlnsxsi"http//www.w3.org/2001/XMLSchema-instan
  ce"gt
• ltsoapenvBodygt
• ltns1powerResponse soapenvencodingStyle"http/
  /schemas.xmlsoap.org/soap/encoding/"
• xmlnsns1"http//dbi/"gt
• ltns1powerReturn xsitype"xsdint"gt32lt/ns1pow
  erReturngt
• lt/ns1powerResponsegt
• lt/soapenvBodygt
• lt/soapenvEnvelopegt

54
The WSDL (1)

• ltwsdldefinitions targetNamespace"http//mangal.c
  s.huji.ac.il8090/axis/services/dbiPowerService"gt
• ltwsdlmessage name"powerResponse"gt
• ltwsdlpart name"powerReturn" type"xsdint"/gt
• lt/wsdlmessagegt
• ltwsdlmessage name"powerRequest"gt
• ltwsdlpart name"in0" type"xsdint"/gt
• ltwsdlpart name"in1" type"xsdint"/gt
• lt/wsdlmessagegt
• ltwsdlportType name"PowerService"gt
• ltwsdloperation name"power" parameterOrder"in0
  in1"gt
• ltwsdlinput message"implpowerRequest"
  name"powerRequest"/gt
• ltwsdloutput message"implpowerResponse"
  name"powerResponse"/gt
• lt/wsdloperationgt
• lt/wsdlportTypegt

55
The WSDL (2)

• ltwsdlbinding name"dbiPowerServiceSoapBinding"
  type"implPowerService"gt
• ltwsdlsoapbinding style"rpc"
  transport"http//schemas.xmlsoap.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//dbi" use"encoded"/gt
• lt/wsdlinputgt
• ltwsdloutput name"powerResponse"gt
• ltwsdlsoapbody encodingStyle"http
  //schemas.xmlsoap.org/soap/encoding/"
  
• namespace"http//mangal.cs.huji.ac.il8090/axis
  /services/dbiPowerService" use"encoded"/gt
• lt/wsdloutputgt
• lt/wsdloperationgt
• lt/wsdlbindinggt

56
The WSDL (3)

• ltwsdlservice name"PowerServiceService"gt
• ltwsdlport binding"impldbiPowerServiceSoapB
  inding" name"dbiPowerService"gt
• ltwsdlsoapaddress location"http//mangal.cs.hu
  ji.ac.il8999/axis/services/dbiPowerService"/gt
• lt/wsdlportgt
• lt/wsdlservicegt
• lt/wsdldefinitionsgt

57
Deployment File

• ltdeployment xmlns"http//xml.apache.org/axis/wsdd
  /" xmlnsjava"http//xml.apache.org/ax
  is/wsdd/providers/java"gt
• ltservice name"dbiPowerService"
  provider"javaRPC"gt
• ltparameter name"className"
  value"dbi.PowerService"/gt
• ltparameter name"scope"
  value"application"/gt
• ltparameter name"allowedMethods"
  value""/gt
• lt/servicegt
• lt/deploymentgt

Required namespaces Saying that this is a
deployment file of axis
58
Deployment File

• ltdeployment xmlns"http//xml.apache.org/axis/wsdd
  /" xmlnsjava"http//xml.apache.org/ax
  is/wsdd/providers/java"gt
• ltservice name"dbiPowerService"
  provider"javaRPC"gt
• ltparameter name"className"
  value"dbi.PowerService"/gt
• ltparameter name"scope"
  value"application"/gt
• ltparameter name"allowedMethods"
  value""/gt
• lt/servicegt
• lt/deploymentgt

The name of the service
The service is an RPC (not document)
59
Deployment File

• ltdeployment xmlns"http//xml.apache.org/axis/wsdd
  /" xmlnsjava"http//xml.apache.org/ax
  is/wsdd/providers/java"gt
• ltservice name"dbiPowerService"
  provider"javaRPC"gt
• ltparameter name"className"
  value"dbi.PowerService"/gt
• ltparameter name"scope"
  value"application"/gt
• ltparameter name"allowedMethods"
  value""/gt
• lt/servicegt
• lt/deploymentgt

60
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

61
Undeployment of Services

• ltundeployment xmlns"http//xml.apache.org/axis/ws
  dd/"gt
• ltservice namedbiPowerService"/gt
• lt/undeploymentgt

We call this file dbiundeploy.wsdd
java org.apache.axis.client.AdminClient -p8090
dbiundeploy.wsdd
After undeployment you cannot call the service
anymore
62
Service Styles

• RPC a call according to SOAP RPC conventions
• Document do not use encoding but maps XML to
  Java types
• Wrapped similar to document, except that they
  unwrap the body to individual parameters
• Message the services and returns raw XML in the
  SOAP envelop, I.e., no type mappings or data
  bindings

63
Standard mappings from WSDL to Java

• xsdbase64Binary byte
• xsdboolean boolean
• xsdbyte byte
• xsddateTime
  java.util.Calendar
• xsddecimal
  java.math.BigDecimal
• xsddouble double
• xsdfloat float
• xsdhexBinary byte
• xsdint int
• xsdinteger
  java.math.BigInteger
• xsdlong long
• xsdQname javax.xml.namespace
  .QName
• xsdshort short
• xsdstring java.lang.String

64
Note on Parameters

• It must be possible to "serialize" the parameters
  that the method invoked receives and returns.
  Why?
• The following have default serialization/deseriali
  zation
• primitive types int, long, double, etc.
• primitive Objects Integer, Long, Double, String,
  etc.
• complex Objects Vector, Enumeration, Hashtable,
  arrays
• easy to use JavaBeans (not discussed here)

65
Remote Exceptions

• When you call a Java method an exception can be
  thrown
• Consider a case where a client supplies a bad
  argument and an exception occurs in the server
  (while handling the service call)
• What should happen?

66
AXIS Support of WSDL

• When you deploy a service in Axis, users may then
  access your service's URL with a standard web
  browser and by appending "?WSDL" to the end of
  the URL
• AXIS provides a "WSDL2Java" tool which builds
  Java proxies and skeletons for services with WSDL
  descriptions
• AXIS provides a "Java2WSDL" tool which builds
  WSDL from Java classes

67
WSDL2Java Mappings

• WSDL clause Java class(es)
  generated
• For each entry in the A java class
• type section
• A holder
  if this type is
• used as an inout/out parameter
• For each portType A java interface
• For each binding A stub class
• For each service A service interface
• A service
  implementation
• (the
  locator)

68
Using Reflection for Implementing Web Services
69
How Could a SOAP Processor be Implemented?

• No, we won't be implementing a SOAP Processor in
  this course ?
• However, it could be implemented using reflection
  
• Reflection is a Java mechanism for discovering
  the class/methods/fields of an object
• Reflection allows you to load classes and invoke
  methods

70
Simple SOAP Implementation

• In SOAP, the details about the RPC are in an XML
  message
• In our Simple SOAP Implementation example,
  details will be in parameters of HTTP request
• We will allow user to invoke any method of any
  class, provided that the method only has String
  arguments
• All this is to give us an idea of how a SOAP
  processor works

71
Getting Invocation Details from Client (HTML Form)

• ltform name"info" method"get" action"servlet/SOA
  PImitation"gt
• Class Name ltinput type"text" name"class"gtltbrgt
• Method Name ltinput type"text"
  name"method"gtltbrgt
• ltinput type"button" value"Set Number of
  Arguments" onClick"setArguments()"gt
• ltinput type"hidden" name"paramNum" value"0"gt
• ltp id "argumentP"gtlt/pgt
• ltinput type"submit"gt
• lt/formgt

72
Getting Invocation Details from Client (HTML Form)

• function setArguments()
• num prompt("Enter the number of arguments to
  the method", 0)
• p document.getElementById("argumentP")
• str ""
• for (i 0 i lt num i)
• str "Argument " i " "
• "ltinput type'text' name'param"
  i "'gtltbrgt"
• p.innerHTMLstr
• info.paramNum.valuenum

73
Our Simple SOAP Processor

• import java.io. import javax.servlet. import
  javax.servlet.http.
• import java.lang.reflect.
• public class SoapImitation extends HttpServlet
• public void doGet(HttpServletRequest req,
• HttpServletResponse res)
• throws ServletException, IOException
• res.setContentType("text/html")
• PrintWriter out res.getWriter()
• try
• Class objClass Class.forName(req.getParamet
  er("class"))
• int numParams Integer.parseInt(req.getParame
  ter("paramNum"))

74

• Class paramClasses new ClassnumParams
• Object paramObjs new ObjectnumParams
• for (int i 0 i lt numParams i)
• paramClassesi Class.forName("java.lang.Strin
  g")
• paramObjsi req.getParameter("param" i)
• Method method
• objClass.getMethod(req.getParameter("method"),
• paramClasses)
• Object result method.invoke(objClass.newIns
  tance(), paramObjs)
• out.println("ltHTMLgtltBODYgtlth1gtMethod
  Resultlt/h1gt"
• result "lt/BODYgtlt/HTMLgt")
• catch (Exception e)
• out.println("ltHTMLgtltBODYgtError!lt/BODYgtlt/HTMLgt
  ")

75
A Class and a Method
package hello public class HelloServer
public String sayHelloTo(String name)
Return(new String(Hello name , How are
you doing?)
76
(No Transcript)
77
(No Transcript)
78
Scoping

• What did the scoping of the Web Service
  correspond to (request?, session?, application?)
• How would the implementation differ if the
  scoping was different?

79
When Web Application Need to Share Information

• In your implementation of the friendsnet Web
  application you will create instances of the
  class FriendsDatabase
• Where is the login for accessing the database is
  taken from?
• If you will have a service under axis, will the
  service be able to create a FriendsDatabase
  instance that includes the login parameter?

80
A Possible Solution
CATALINA_BASE
webapps
shared
friendsnet
axis
lib
classes

• Put the FriendsDatabase class under shared
• Use a static field of FriendsDatabase to hold the
  login argument
• The first time a Servlet in friendsnet creates an
  instance of FriendsDatabase, this servlet sets
  the login
• Now, what about servlets of axis?

FriendsDatabase