If you have a Java web application implemented with Java 5 and Spring Framework, it is really easy to expose your POJOs as web services. In this example I use XFire and JSR 181 annotations for that. I’ll also make a small web service client example with PHP . The goal is to add web services to the existing Java code with absolute minimal code addition. I was about to add web service authentication with Acegi Security, but instead for now, there is no authentication in this example.

XFire has a quite versatile but scarce user’s guide . But it is a good start, so start with overview and quick start. Add XFire libraries and the depencies with the help of a Depency quide . This example works at least with the following libraries:

  • xfire-all-1.2.2
  • activation-1.1
  • commons-codec-1.3
  • commons-httpclient-3.0
  • commons.logging-1.0.4
  • mail-1.4
  • jaxen-1.1-beta-9
  • jdom-1.0
  • junit-3.8.1
  • servlet-api-2.3
  • spring-2.0
  • stax-api-1.0.1
  • wsdl4j-1.5.2
  • xbean-spring-2.5
  • wstx-3.0.1
  • XmlSchema-1.1
  • xfire-jsr181-api-1.0-M1
  • jaxb-xjc-2.0.1
  • jaxb-impl-2.0.1
  • jaxb-api-2.0
  • aopalliance-1.0
  • commons-beanutils-1.7.0

XFire 1.2.2 package comes with xbean-spring-2.6. There can be some problems with that version but at least version 2.5 is working with Spring 2.0.

First, add xfire-servlet.xml into WEB-INF directory. Here are the default settings from the user’s manual:

<?xml
 version
="1.0"
 encoding
="UTF-8"
?>


<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
   "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>



  <import
 resource
="classpath:org/codehaus/xfire/spring/xfire.xml"
/>


  <bean
 id
="jaxbTypeMappingRegistry" 

class
="org.codehaus.xfire.jaxb2.JaxbTypeRegistry" 

 init-method

="createDefaultMappings"
 singleton
="true"
/>


  
<bean
 id
="webAnnotations" 

 class
="org.codehaus.xfire.annotations.jsr181.Jsr181WebAnnotations"

/>
   

<bean
 id
="handlerMapping" 

class
="org.codehaus.xfire.spring.remoting.Jsr181HandlerMapping"
>


      <property
 name
="typeMappingRegistry"
>

<ref
 bean
="jaxbTypeMappingRegistry"
/>

</property>



      <property
 name
="xfire"
>

<ref
 bean
="xfire"
/>

/property>



      <property
 name
="webAnnotations"
>

<ref
 bean
="webAnnotations"
/>

</property>



    </bean>



    <bean
 class
="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping"
>


      <property
 name
="urlMap"
>
        

<map>



          <entry
 
key
="/"
>


            <ref
 bean
="handlerMapping"
/>


          </entry>



        </map>



      </property>



    </bean>



</beans>

Add xfire-servlet.xml into the Spring’s contextConfigLocation and XFireServlet in web.xml file:

<context-param>
  


<param-name>


contextConfigLocation</param-name>



  <param-value>
    


/WEB-INF/applicationContext.xml
    /WEB-INF/xfire-servlet.xml
  </param-value>



</context-param>


 
<servlet>



  <servlet-name>


XFireServlet</servlet-name>



  <display-name>


XFire Servlet</display-name>



  <servlet-class>


org.codehaus.xfire.spring.XFireSpringServlet</servlet-class>



</servlet>



<servlet-mapping>



  <servlet-name>


XFireServlet</servlet-name>



  <url-pattern>


/servlet/XFireServlet/*</url-pattern>



</servlet-mapping>



<servlet-mapping>
 


 <servlet-name>


XFireServlet</servlet-name>



  <url-pattern>


/services/v1/*</url-pattern>



</servlet-mapping>

Let’s have a simply MinimizrFacade.java Java interface:

package
 com.minimizr.service
;
 
import
 java.util.List
;
import
 com.minimizr.service.domain.ExampleObject
;
 
public
 interface
 MinimizrFacade {

  String
 getString(
)
;
  String
 echoString(
String
 string)
;
  ExampleObject echoObject(
ExampleObject exampleObject)
;
  List<
ExampleObject>
 loadExampleObjectList(
)
;
}

And let’s have another MinimizrService.java Java interface for web services:

package
 com.minimizr.service
;
 
import
 java.util.List
;
import
 javax.jws.WebService
;
import
 com.minimizr.service.domain.ExampleObject
;
 
@WebService
public
 interface
 MinimizrService {

  String
 getString(
)
;
  String
 echoString(
String
 string)
;
  ExampleObject echoObject(
ExampleObject exampleObject)
;
  List<
ExampleObject>
 loadExampleObjectList(
)
;
}

And for this example a ExampleObject.java Java object:

package
 com.minimizr.service
;
 
public
 class
 ExampleObject {

   private
 String
 name;
   private
 Integer
 age;
   public
 Integer
 getAge(
)
 {

    return
 age;
  }


  public
 void
 setAge(
Integer
 age)
 {

    this
.age
 =
 age;
  }


  public
 String
 getName(
)
 {

    return
 name;
  }


  public
 void
 setName(
String
 name)
 {

    this
.name
 =
 name;
  }


}

And finally a MinimizrImpl.java Java implementation for the interfaces:

package
 com.minimizr.domain.logic
;
 
import
 java.util.List
;
import
 javax.jws.WebService
;
import
 com.minimizr.service.ExampleObject
;
import
 com.minimizr.service.MinimizrService
;
 
@WebService(
serviceName =
 "MinimizrService"
, endpointInterface =
 "com.minimizr.service.MinimizrService"

)


public
 class
 MinimizrImpl implements
 MinimizrFacade, MinimizrService {


  public
 String
 getString(
)
 {

    return
 "Example string"
;
  }


  public
 String
 echoString(
String
 string)
 {

    return
 string;
  }


  public
 ExampleObject echoObject(
ExampleObject exampleObject)
 {


    return
 exampleObject;
  }


  public
 List
 loadExampleObjectList(
)
 {


    /* Here you would get list of ExampleObjects for example from database
    and return it instead of null */

   return
 null
;
  }


}

XFire does not support RPC-encoding but you can use XFire web services with PHP with document/literal style of SOAP.

Here is a really simple example to use all the exposed java web services in this example with NuSOAP PHP SOAP library. There are no checks for errors in the code:

<?php

require
(
"../lib/nusoap.php"
)
;
$soapClient
 =
 new
 soapclient(
 "http://www.minimizr.com/ws/services/v1/MinimizrService?wsdl"
,
 "wsdl"

)
;
$proxyClass
 =
 $soapClient
->
getProxy
(
)
;
 
// getString


$string
 =
 $proxyClass
->
getString
(
)
;
print
(
"<b>String:</b> "
 .
 $string
[
"out"
]
 .
 "<hr/>"

)
; 
// echoString


$string
 =
 $proxyClass
->
echoString
(
array
(
"in0"
 =>
 "ABC"
)
)
;
print
(
"<b>String:</b> "
 .
 $string
[
"out"
]
 .
 "<hr/>"
)
;
 
// echoObject


$requestObject
 =
 array
(
"name"
 =>
 "John"
,
 "age"
 =>
 50
)
;
$result
 =
 $proxyClass
->
echoObject
(
array
(
"in0"
 =>
 $requestObject)
)
;
$resultObject
 =
 $result
[
"out"
]
;
print
(
"<b>Object:</b> name: "
 .
 $resultObject
[
"name"
]
)
;
print
(
", age: "
 .
 $resultObject
[
"age"
]
 .
 "<hr/>"
)
;
 
// loadExampleObjectList


$exampleObjectList
 =
 $proxyClass
->
loadExampleObjectList
(
)
;
foreach
 (
$exampleObjectList
[
"out"
]
[
"ExampleObject"
]
 as
 $key
 =>
 $value
)
 {

  print
(
$value
[
"name"
 .
 " "
 .
 $value
[
"age"
]
 .
 "<br/>"
)
;
}


?>

Authentication

Added November 14, 2006 : Well, easiest and most straightforward way to secure web service is to use HTTP Authentication. It doesn’t need any additional code in the server side. While still looking for solution to use easily Acegi Security, I’ll add HTTP Authentication to this example. On the server side you’ll have to add security constraint into web.xml :

<security-constraint>



  <web-resource-collection>



    <web-resource-name>


Protected Minimizr Web Services</web-resource-name>



    <url-pattern>


/services/v1/*</url-pattern>



  </web-resource-collection>




  <auth-constraint>



    <role-name>


minimizr.webservices.client</role-name>



  </auth-constraint>




</security-constraint>


 
<login-config>






  <auth-method>





BASIC</auth-method>






  <realm-name>





Minimizr Realm</realm-name>






</login-config>






 
<security-role>






  <description>





Required roles to use the Web Services</description>






  <role-name>





minimizr.webservices.client</role-name>






</security-role>

And couple more lines into the PHP file. Credentials must be added into the wsdl url and proxy class. Notice that it is quite necessary to use SSL connection (https) with basic authentication since username and password are in clear text. You can use useHTTPPersistentConnection method to use persistent connection, if possible:

<?php


require

(

"../lib/nusoap.php"

)

;
 
$username

 =

 "username"

;
$password

 =

 "password"

;
$method

 =

 "basic"

;
 
$soapClient

 =

 new

 soapclient(


  "https://$username:$password@www.minimizr.com/ws/services/v1/MinimizrService?wsdl"

,


  "wsdl"

)

;
$proxyClass

 =

 $soapClient

->

getProxy

(

)

;
$proxyClass

->

setCredentials

(

$username

,

 $password

,

 $method

)

;
$proxyClass

->

useHTTPPersistentConnection

(

)

;
...

Conclusion

It is no brainer to expose Java POJOs as web services with Spring, XFire and JSR-181 annotations. And it is as easy use those web services with Java or PHP or other platforms. I guess integrating Acegi Security with XFire web services needs a little bit more work. Any suggestions for the easiest way to implement it?

Additional recourses