The package org.springframework.ws.client.core provides the core functionality for using
the client-side access API. It contains template classes that simplifies the use of Web services, much like
the JdbcTemplate
does for JDBC. The design principle common to Spring template
classes is to provide helper methods to perform common operations and for more sophisticated usage, delegate
the essence of the processing task to user implemented callback interfaces. The Web service template
follows the same design. The classes offer various
convenience methods for the sending and receiving of XML messages, marshalling objects to XML before sending,
and allows for multiple transports,
The WebServiceTemplate
is the core class for client-side Web service access in
Spring-WS. It contains methods for sending Source
objects, and receiving response
messages as either Source
or Result
. Additionally, it can
marshal objects to XML before sending them across a transport, and unmarshal the response XML into an
object again.
The WebServiceTemplate
requires a reference to a
MessageSender
. The message sender is responsible for sending the XML message
across a transport layer.
There are two implementations of the MessageSender
interface for sending messages
via HTTP. The simplest implementation is the HttpUrlConnectionMessageSender
,
which uses the facilities provided by Java SE itself. The alternative is the
CommonsHttpMessageSender
, which uses the Jakarta Commons HttpClient. Use the
latter if you need more advanced and easy-to-use functionality. Both HTTP message senders require an
URL to be set using the url property.
In addition to a message sender, the WebServiceTemplate
requires a Web service
message factory. As explained in Section 4.1.3, “Message Factories”, there are two message factories
for SOAP: SaajSoapMessageFactory
and
AxiomSoapMessageFactory
. If no message factory is specified, Spring-WS will
use the SaajSoapMessageFactory
by default.
The WebServiceTemplate
contains many convenience methods to send and receive
web service messages. There are methods that take and return Source
and those that return a Result
. Additionally, there are methods which
marshal and unmarshal objects to XML. Here is an example that sends a simple XML message to a Web
service.
import java.io.IOException; import java.io.StringReader; import javax.xml.transform.stream.StreamResult; import javax.xml.transform.stream.StreamSource; import org.springframework.ws.WebServiceMessageFactory; import org.springframework.ws.client.core.WebServiceTemplate; import org.springframework.ws.transport.WebServiceMessageSender; public class WebServiceClient { private static final String MESSAGE = "<message xmlns=\"http://tempuri.org\">Hello World</message>"; private WebServiceTemplate webServiceTemplate = new WebServiceTemplate(); public void setMessageFactory(WebServiceMessageFactory messageFactory) { webServiceTemplate.setMessageFactory(messageFactory); } public void setMessageSender(WebServiceMessageSender messageSender) { webServiceTemplate.setMessageSender(messageSender); } public void simpleSendAndReceive() throws IOException { StreamSource source = new StreamSource(new StringReader(MESSAGE)); StreamResult result = new StreamResult(System.out); webServiceTemplate.sendAndReceive(source, result); } }
Here is the corresponding configuration:
<beans xmlns="http://www.springframework.org/schema/beans"> <bean id="webServiceClient" class="WebServiceClient"> <property name="messageSender"> <bean class="org.springframework.ws.transport.http.HttpUrlConnectionMessageSender"> <property name="url" value="http://localhost:8080/WebService"/> </bean> </property> </bean> </beans>
This example uses the template to send a hello world message to the web service located at
http://localhost:8080/WebService
, and writes the result to the console.
The WebServiceTemplate
is injected with the message sender.
A zero argument constructor and messageFactory /
messageSender bean properties are provided and can be used for constructing
the instance (using a BeanFactory or plain Java code). Alternatively, consider deriving from
Spring-WS's WebServiceGatewaySupport
convenience base class, which provides
pre-built bean properties for configuration.
In order to facilitate the sending of plain Java objects, the WebServiceTemplate
has a send methods that take an object as an argument for a message's data content.
The method marshalSendAndReceive
in WebServiceTemplate
delegates the conversion of the request object to XML to a Marshaller, and
the conversion of the response XML to an object to an Unmarshaller.
For more information about marshalling and unmarshaller, refer to Chapter 8, Marshalling XML using O/X Mappers.
By using the marshallers, you and your application code can focus on the business object that is being
sent or received and not be concerned with the details of how it is represented as XML.
In order to use the marshalling functionality, you have to set a marshaller and unmarshaller with the
marshaller/unmarshaller properties of the
WebServiceTemplate
.
To accommodate the setting of a SOAP headers, and other settings on the message, the
WebServiceMessageCallback
interface gives you access to the message
after it has been created, but before it is sent. The example below demonstrates how to set the SOAP
Action header on a message that is created by marshalling an object.
public void marshalWithSoapActionHeader(MyObject o) { webServiceTemplate.marshalSendAndReceive(o, new WebServiceMessageCallback() { public void doInMessage(WebServiceMessage message) { ((SoapMessage)message).setSoapAction("http://tempuri.org/Action"); } }); }