Tuesday, June 2, 2009

Spring WebService with Castor


This tutorial is all about Spring based contract-first based web-services.
I am also demostrating how to use Castor as marshaller and unmashaller.
The client for web-service I am using as SOAP UI which will generate the
SOAP request for the web-service and offcourse it will also show the response
sent by the web-service.

For developing web services I will start with the XML Schema/WSDL because it is contract first web-service followed by the Java code second. Spring-WS focuses on this development style, and this tutorial will help you get started. Note that the first part of this tutorial contains almost no Spring-WS specific information: it is mostly about XML, XSD, and WSDL. The second part focusses on implementing this contract using Spring-WS .

The most important thing when doing contract-first Web service development is
to try and think in terms of XML. This means that Java-language concepts are
of lesser importance. It is the XML that is sent across the wire, and you
should focus on that. The fact that Java is used to implement the Web service
is an implementation detail. An important detail, but a detail nonetheless.

In this tutorial, we will define a Web service that is created by a Store
department. Clients can send order request to this service to add a order.

1.2. Messages
In this section, we will focus on the actual XML messages that are sent to
and from the Web service. We will start out by determining what these messages
look like.

1.2.1. Order
In the scenario, we have to deal with Order requests, so it makes sense
to determine what a Order looks like in XML:

<OrderRequest>
<item>
<id>13245</id>
<itemName>Keyboard</itemName>
<quantity>10</quantity>
<discount>0</discount>
<sellingprice>3000</sellingprice>
</item>
<item>
<id>13247</id>
<itemName>Monitor</itemName>
<quantity>10</quantity>
<discount>0</discount>
<sellingprice>90000</sellingprice>
</item>
<customerID>898798</customerID>
<orderID>8797</orderID>
</OrderRequest>

A OrderRequest consists of customer id ,order id and the list of items that are in order. We have also decided to use the "string" elements, because that will save a lot of parsing hassle.

1.3. Data Contract
Now that we have seen some examples of the XML data that we will use,
it makes sense to formalize this into a schema. This data contract
defines the message format we accept. There are four different ways
of defining such a contract for XML:
DTDsXML
Schema (XSD)
RELAX
NGSchematron

DTDs have limited namespace support, so they are not suitable for Web
services. Relax NG and Schematron certainly are easier than XML Schema.
Unfortunately, they are not so widely supported across platforms. We
will use XML Schema.

By far the easiest way to create an XSD is to infer it from sample
documents. Any good XML editor or Java IDE offers this functionality.
Basically, these tools use some sample XML documents, and generate a
schema from it that validates them all. The end result certainly needs
to be polished up, but it's a great starting point.

This is our final xsd:
orderService.xsd
---------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:ideeksha-spring-ws="http://ideeksha.gotdns.com/order" targetNamespace="http://ideeksha.gotdns.com/order" elementFormDefault="qualified">
<complexType name="item">
<sequence>
<element name="id" type="string" minOccurs="1"/>
<element name="itemName" type="string" minOccurs="1"/>
<element name="quantity" type="string" minOccurs="1"/>
<element name="discount" type="string" minOccurs="1"/>
<element name="sellingprice" type="string" minOccurs="1"/>
</sequence>
</complexType>

<complexType name="order-response">
<sequence>
<element name="code" type="string" minOccurs="1"/>
</sequence>
</complexType>

<complexType name="order-request">
<sequence>
<element name="item" type="ideeksha-spring-ws:item" minOccurs="1" maxOccurs="unbounded"/>
<element name="customerID" type="string" minOccurs="1"/>
<element name="orderID" type="string" minOccurs="1"/>
</sequence>
</complexType>

<element name="OrderRequest" type="ideeksha-spring-ws:order-request"/>
<element name="OrderResponse" type="ideeksha-spring-ws:order-response"/>
</schema>

1.4. Service contract
A service contract is generally expressed as a WSDL file.
Note that in Spring-WS, writing the WSDL by hand is not required. Based on the XSD and some conventions, Spring-WS can create the WSDL for you, as explained in the section entitled Section 3.6, “Implementing the Endpoint”.
This is our final wsdl file generated by Spring :

http://localhost:8080/SpringWebService/order-ws/orderWebService.wsdl
---------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?><wsdl:definitions xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:sch="http://ideeksha.gotdns.com/order" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:tns="http://ideeksha.gotdns.com/order" targetNamespace="http://ideeksha.gotdns.com/order">
<wsdl:types>
<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:ideeksha-spring-ws="http://ideeksha.gotdns.com/order" elementFormDefault="qualified" targetNamespace="http://ideeksha.gotdns.com/order">
<complexType name="item">
<sequence>
<element minOccurs="1" name="id" type="string"/>
<element minOccurs="1" name="itemName" type="string"/>
<element minOccurs="1" name="quantity" type="string"/>
<element minOccurs="1" name="discount" type="string"/>

<element minOccurs="1" name="sellingprice" type="string"/>
</sequence>
</complexType>

<complexType name="order-response">
<sequence>
<element minOccurs="1" name="code" type="string"/>
</sequence>
</complexType>

<complexType name="order-request">

<sequence>
<element maxOccurs="unbounded" minOccurs="1" name="item" type="ideeksha-spring-ws:item"/>
<element minOccurs="1" name="customerID" type="string"/>
<element minOccurs="1" name="orderID" type="string"/>
</sequence>
</complexType>

<element name="OrderRequest" type="ideeksha-spring-ws:order-request"/>
<element name="OrderResponse" type="ideeksha-spring-ws:order-response"/>
</schema>

</wsdl:types>
<wsdl:message name="OrderResponse">
<wsdl:part element="tns:OrderResponse" name="OrderResponse">
</wsdl:part>
</wsdl:message>
<wsdl:message name="OrderRequest">
<wsdl:part element="tns:OrderRequest" name="OrderRequest">
</wsdl:part>
</wsdl:message>

<wsdl:portType name="OrderResource">
<wsdl:operation name="Order">
<wsdl:input message="tns:OrderRequest" name="OrderRequest">
</wsdl:input>
<wsdl:output message="tns:OrderResponse" name="OrderResponse">
</wsdl:output>
</wsdl:operation>
</wsdl:portType>
<wsdl:binding name="OrderResourceSoap11" type="tns:OrderResource">

<soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>
<wsdl:operation name="Order">
<soap:operation soapAction=""/>
<wsdl:input name="OrderRequest">
<soap:body use="literal"/>
</wsdl:input>
<wsdl:output name="OrderResponse">
<soap:body use="literal"/>
</wsdl:output>

</wsdl:operation>
</wsdl:binding>
<wsdl:service name="OrderResourceService">
<wsdl:port binding="tns:OrderResourceSoap11" name="OrderResourceSoap11">
<soap:address location="http://localhost:8080/SpringWebService/order-ws/orderWebService"/>
</wsdl:port>
</wsdl:service>
</wsdl:definitions>

I define the OrderRequest message, which gets used in the
portType.

The OrderRequest type is defined in the schema.

I define the OrderResource port type, which gets used in the
binding.


I use a document/literal style.

The literal http://schemas.xmlsoap.org/soap/http signifies a
HTTP transport.

The soapAction attribute signifies the SOAPAction HTTP
header that will be sent with every request.

The http://localhost:8080/SpringWebService/order-ws/SpringWebService address is the URL where the web-service can be invoked.

This is the final WSDL. We will describe how to implement the resulting schema and WSDL in the next section.

1.5. Creating the project
In this section, we will be using Maven2 to create the
initial project structure for us. Doing so is not required, but greatly reduces the amount of code we have to write to setup our HolidayService.

The following command creates a Maven2 web application project for us, using the Spring-WS archetype (that is, project template)
mvn archetype:create -DarchetypeGroupId=org.springframework.ws \
-DarchetypeArtifactId=spring-ws-archetype \
-DarchetypeVersion=1.5.7 \
-DgroupId=com.ideeksha.spring.ws \
-DartifactId=SpringWebService

This command will create a new directory called SpringWebService. In this directory,
there is a 'src/main/webapp' directory, which will contain the root of the WAR file.
You will find the standard web application deployment descriptor 'WEB-INF/web.xml' here, which defines a Spring-WS MessageDispatcherServlet and maps all incoming requests to this servlet:

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<display-name>Store Department Order Service</display-name>
<servlet>
<servlet-name>order-ws</servlet-name>
<servlet-class>org.springframework.ws.transport.http.MessageDispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>order-ws</servlet-name>
<url-pattern>/order-ws/*</url-pattern>
</servlet-mapping>
</web-app>

In addition to the above 'WEB-INF/web.xml' file, you will also need another,
Spring-WS-specific configuration file, named 'WEB-INF/order-ws-servlet.xml'.
This file contains all of the Spring-WS-specific beans such as EndPoints,
WebServiceMessageReceivers, and such like, and is used to create a new Spring container.
The name of this file is derived from the name of the attendant servlet (in this case
'order-ws') with '-servlet.xml' appended to it.

1.6. Implementing the Endpoint
In Spring-WS, you will implement Endpoints to handle incoming XML messages.
There are two flavors of endpoints: message endpoints and
payload endpoints. Message endpoints give access to the entire XML message, including SOAP headers. Typically, the endpoint will only be interested in the payload of the message, that is the contents of the SOAP body.
In that case, creating a payload endpoint makes more sense.

1.6.1. Handling the XML Message
In this sample application, we are going to use Castor to handle
the XML message.

OrderWSEndpoint.java
------------------------------
package com.ideeksha.order.ws;

import java.util.Iterator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.ws.server.endpoint.annotation.Endpoint;
import org.springframework.ws.server.endpoint.annotation.PayloadRoot;

@Endpoint
public class OrderWSEndpoint {

private static final Log LOG = LogFactory.getLog(OrderWSEndpoint.class);

@PayloadRoot(localPart = "OrderRequest", namespace = "http://ideeksha.gotdns.com/order")
public OrderResponse receiveOrder(
OrderRequest orderRequest) {

try {
List<Item> itemList = orderRequest.getItemList();

Iterator<Item> iterator = itemList.iterator();
while (iterator.hasNext()) {
Item item = iterator.next();
System.out.println(item);
}
} catch (Exception e) {
LOG.error("", e);
}
OrderResponse orderResponse = new OrderResponse();
orderResponse.setCode("SUCCESS");

return orderResponse;
}

}

We are using annoation to mark a class as Endpoint and the method which is to be executed for the particular type of request is denoted by
"@PayloadRoot(localPart = "OrderRequest", namespace = "http://ideeksha.gotdns.com/order")" anotaion.
So "receiveOrder" ,method will get executed if any OrderRequest is come for this EndPoint.

Because we use Castor, we must add some dependencies to the Maven pom.xml, which is in the root of our project directory. Here is the part of POM file:

<dependency>
<groupId>org.springframework.ws</groupId>
<artifactId>spring-ws-core-tiger</artifactId>
<version>1.5.6</version>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>jdom</groupId>
<artifactId>jdom</artifactId>
<version>1.0</version>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>jaxen</groupId>
<artifactId>jaxen</artifactId>
<version>1.1</version>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>javax.xml.soap</groupId>
<artifactId>saaj-api</artifactId>
<version>1.3</version>
<scope>runtime</scope>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>com.sun.xml.messaging.saaj</groupId>
<artifactId>saaj-impl</artifactId>
<version>1.3</version>
<scope>runtime</scope>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.codehaus.castor</groupId>
<artifactId>castor</artifactId>
<version>1.2</version>
<exclusions>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>javax.annotation</groupId>
<artifactId>jsr250-api</artifactId>
<version>1.0</version>
</dependency>
</dependencies>

Here is how we would configure these classes in our order-ws-servlet.xml

Spring XML configuration file:

<beans xmlns="http://www.springframework.org/schema/beans">
<bean id="orderWSEndpoint" class="com.ideeksha.order.ws.OrderWSEndpoint" autowire="byName"/>
</beans>

1.6.2. Routing the Message to the Endpoint

Now that we have written an endpoint that handles the message, we must define how incoming messages are routed to that endpoint. In Spring-WS, this is the responsibility of an EndpointMapping. In this tutorial, we will route messages based on their content, by using a PayloadRootAnnotationMethodEndpointMapping. Here is how we configure a PayloadRootAnnotationMethodEndpointMapping in order-ws-servlet.xml:

<bean id="loggingInterceptor"
class="org.springframework.ws.server.endpoint.interceptor.PayloadLoggingInterceptor"/>
<bean
class="org.springframework.ws.server.endpoint.mapping.PayloadRootAnnotationMethodEndpointMapping">
<property name="interceptors">
<list>
<ref local="loggingInterceptor"/>
</list>
</property>
</bean>

This means that whenever an XML message is received it will check all the annonated EndPoint Class and check for the method which will serve the request with that particular namespace and local name.(It also adds a PayloadLoggingInterceptor,that dumps incoming and outgoing messages to the log.)

1.7. Publishing the WSDL
Finally, we need to publish the WSDL. As stated in Section 3.4, “Service contract”, we don't need to write a WSDL ourselves; Spring-WS can generate one for us based on some conventions.
Here is how we define the generation:

<bean id="orderWebService" class="org.springframework.ws.wsdl.wsdl11.DefaultWsdl11Definition">
<property name="schema" ref="orderSchema"/>
<property name="portTypeName" value="OrderResource"/>
<property name="locationUri" value="/order-ws/orderWebService"/>
<property name="targetNamespace" value="http://ideeksha.gotdns.com/order"/>
</bean>
<bean id="orderSchema" class="org.springframework.xml.xsd.SimpleXsdSchema">
<property name="xsd" value="/WEB-INF/orderService.xsd"/>
</bean>

The bean id determines the URL where the WSDL can be retrieved. In this case, the bean id is holiday, which means that the WSDL can be retrieved as holiday.wsdl in the servlet context. The full URL will typically be

http://localhost:8080/SpringWebService/order-ws/orderWebService.wsdl.

The schema property refers to the human resource schema we defined in Section 3.3, “Data Contract”, wrapped in a SimpleXsdSchema. We simply placed the schema in the WEB-INF directory of the application.

Next, we define the WSDL port type to be OrderResource.

We set the location where the service can be reached:
/order-ws/orderWebService/. We use a a relative URI and we instruct the framework to transform it dynamically to an absolute URI. Hence, if the service is deployed to different contexts we don't have to change the URI manually.
Finally, we define the target namespace for the WSDL definition itself. Setting these
is not required. If not set, we give the WSDL the same namespace as the schema.

1.8. Doing the Castor Mapping
We have to define the marshaller and unmashller for the XML messages.We define them in order-ws-servlet.xml file.

<bean id="marshaller" class="org.springframework.oxm.castor.CastorMarshaller">
<property name="mappingLocation" value="classpath:WEB-INF/castor-mapping.xml"/>
</bean>
<bean
class="org.springframework.ws.server.endpoint.adapter.GenericMarshallingMethodEndpointAdapter">
<constructor-arg ref="marshaller"/>
<constructor-arg ref="marshaller"/>
</bean>

O/X mapping is done using castor so you can assess the xml as object.Below is the OrderRequest and OrderResponse with its corresponding castor mapping:

OrderRequest.java:
-------------------
package com.ideeksha.order.ws;

import java.util.List;

public class OrderRequest {
private List<Item> itemList = null;
private String customerID;
private String orderID;

public List<Item> getItemList() {
return itemList;
}

public void setItemList(
List<Item> itemList) {
this.itemList = itemList;
}

public String getCustomerID() {
return customerID;
}

public void setCustomerID(String customerID) {
this.customerID = customerID;
}

public String getOrderID() {
return orderID;
}

public void setOrderID(String orderID) {
this.orderID = orderID;
}

}


OrderResponse.java
-----------------------

package com.ideeksha.order.ws;

public class OrderResponse {

private String code;

public String getCode() {
return code;
}

public void setCode(String code) {
this.code = code;
}

}

Item.java
--------------------
package com.ideeksha.order.ws;

public class Item {
private String id = null;
private String itemName = null;
private String sellingprice = null;
private String quantity = null;
private String discount = null;

public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getItemName() {
return itemName;
}
public void setItemName(String itemName) {
this.itemName = itemName;
}
public String getSellingprice() {
return sellingprice;
}
public void setSellingprice(String sellingprice) {
this.sellingprice = sellingprice;
}
public String getQuantity() {
return quantity;
}
public void setQuantity(String quantity) {
this.quantity = quantity;
}
public String getDiscount() {
return discount;
}
public void setDiscount(String discount) {
this.discount = discount;
}
@Override
public String toString() {
return id+ " " + itemName + " " + sellingprice + " " +quantity + " " + discount;
}


}

castor-mapping.xml
--------------------------------

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

<!DOCTYPE mapping PUBLIC "-//EXOLAB/Castor Mapping DTD Version 1.0//EN"
"http://castor.org/mapping.dtd">
<mapping>
<description>Description of the mapping</description>
<class name="com.ideeksha.order.ws.OrderResponse">
<map-to xml="OrderResponse" ns-uri="http://ideeksha.gotdns.com/order" />
<field name="code">
<bind-xml name="code" node="element" type="string"/>
</field>

</class>

<class name="com.ideeksha.order.ws.Item">
<map-to xml="item" ns-uri="http://ideeksha.gotdns.com/order" />

<field name="id">
<bind-xml name="id" node="element" type="string"/>
</field>

<field name="itemName">
<bind-xml name="itemName" node="element" type="itemName"/>
</field>

<field name="quantity">
<bind-xml name="quantity" node="element" type="string"/>
</field>

<field name="discount">
<bind-xml name="discount" node="element" type="itemName"/>
</field>

<field name="sellingprice">
<bind-xml name="sellingprice" node="element" type="itemName"/>
</field>


</class>

<class name="com.ideeksha.order.ws.OrderRequest">
<map-to xml="OrderRequest" ns-uri="http://ideeksha.gotdns.com/order" />
<field name="customerID">
<bind-xml name="customerID" node="element" type="itemName"/>
</field>
<field name="orderID">
<bind-xml name="orderID" node="element" type="itemName"/>
</field>
<field name="itemList" type="com.ideeksha.order.ws.Item" collection="arraylist">
<bind-xml name="item" node="element" type="ideeksha-spring-ws:item"/>
</field>

</class>
</mapping>


You can create a WAR file using mvn install.
If you deploy the application (to Tomcat, Jetty, etc.), and point your browser at
this location, you will see the generated WSDL. This WSDL is ready to be used by clients, such as soapUI, or other SOAP frameworks.

I will explain how to create project in SOAPUI and send a order request to our webservice.
Create new Project in SOAP UI and give the project name and the wsdl file path.In my case the Project name is SpringWebSerice and the wsdl path will be
"http://localhost:8080/SpringWebService/order-ws/orderWebService.wsdl"


The click on "Order" and then to "request1" under the SpringWebService Project menu.
Edit the default values of this request.Now send this request be clicking on run button(green arrowhead) on the top of the request message window. And the you will get "SUCCESSFUL" as response as we are sending as Order response.




This conclude spring webservice turorial. You can download the source code for this article from http://www.mediafire.com/download.php?zxlmjmnuiei

7 comments :

Scott Bale said...

Thank you! If only Castor's official documentation was this thorough...

ilmari2k said...
This comment has been removed by the author.
Anonymous said...

i hve hard time in downloading the code. Could you check the link...

Saikrishna Rao said...

Its a complete tutorial. I love it.

paul said...

awesome tutorial. i would also love to share a tutorial on Spring OXM with Castor O/X Mapping Framework for the benefit of those who are new to casptor/spring.

http://www.adobocode.com/spring/marshallingunmarshalling-java-objects-into-xml-file-using-spring-oxm

hope this is helpful to someone!

Anonymous said...

Hi,

Thanks for this post, it was very helpfull!

I just wonder how do you configure to have an argument of type "OrderRequest" in your "receiveOrder" method ?
Does it really unmarshall automatically?

Thanks
Olivier

Ashwin Raj said...

This is by far the most usable tutorial I have seen on Spring-WS, even though it is a couple of years old already. Thanks!