sffej/gs-producing-web-service

Producing a SOAP web service :: Learn how to create a SOAP-based web service with Spring.

Table of Contents

• What You Will build
• What You Need
• Starting with Spring Initializr
  • Manual Initialization (optional)
• Add the Spring-WS dependency
• Create an XML Schema to Define the Domain
• Generate Domain Classes Based on an XML Schema
• Create Country Repository
• Create Country Service Endpoint
• Configure Web Service Beans
• Make the Application Executable
• Test the Application
• Summary
• See Also

This guide walks you through the process of creating a SOAP-based web service server with Spring.

What You Will build

You will build a server that exposes data from various European countries by using a WSDL-based SOAP web service.

Note	To simplify the example, you will use hardcoded data for the United Kingdom, Spain, and Poland.

What You Need

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Starting with Spring Initializr

If you use Maven, visit the Spring Initializr to generate a new project with the required dependencies (Spring Web and Spring Web Services).

The following listing shows the pom.xml file that is created when you choose Maven:

link:initial/pom.xml[role=include]

If you use Gradle, visit the Spring Initializr to generate a new project with the required dependencies (Spring Web and Spring Web Services).

The following listing shows the build.gradle file that is created when you choose Gradle:

link:initial/build.gradle[role=include]

Manual Initialization (optional)

If you want to initialize the project manually rather than use the links shown earlier, follow the steps given below:

1. Navigate to https://start.spring.io. This service pulls in all the dependencies you need for an application and does most of the setup for you.

2. Choose either Gradle or Maven and the language you want to use. This guide assumes that you chose Java.

3. Click Dependencies and select Spring Web and Spring Web Services.

4. Click Generate.

5. Download the resulting ZIP file, which is an archive of a web application that is configured with your choices.

Note	If your IDE has the Spring Initializr integration, you can complete this process from your IDE.

Note	Both the pom.xml and build.gradle files show additional build information, which you will add in the next step.

Add the Spring-WS dependency

The project needs to include spring-ws-core and wsdl4j as dependencies in your build file.

The following example shows the changes you need to make to the pom.xml file if you use Maven:

link:complete/pom.xml[role=include]

The following example shows the changes you need to make to the build.gradle file if you use Gradle:

link:complete/build.gradle[role=include]

Create an XML Schema to Define the Domain

The web service domain is defined in an XML schema file (XSD) that Spring-WS will automatically export as a WSDL.

Create an XSD file with operations to return a country’s name, population, capital, and currency. The following listing (from src/main/resources/countries.xsd) shows the necessary XSD file:

link:complete/src/main/resources/countries.xsd[role=include]

Generate Domain Classes Based on an XML Schema

The next step is to generate Java classes from the XSD file. The right approach is to do this automatically during build time by using a Maven or Gradle plugin.

The following listing shows the necessary plugin configuration for Maven:

link:complete/pom.xml[role=include]

Generated classes are placed in the target/generated-sources/jaxb/ directory.

To do the same with Gradle, you first need to configure JAXB in your build file, as the following listing shows:

link:complete/build.gradle[role=include]

Note	The build files have tag and end comments. These tags make it easier to extract bits of it into this guide for a more detailed explanation. You do not need these comments in your own build file.

The next step is to add the genJaxb task, which Gradle uses to generate Java classes. We need to configure gradle to find these generated Java classes in build/generated-sources/jaxb and add genJaxb as a dependency of compileJava task. The following listing shows the necessary addition:

link:complete/build.gradle[role=include]

Because Gradle does not have a JAXB plugin (yet), it involves an Ant task, which makes it a bit more complex than in Maven.

In both cases, the JAXB domain object generation process has been wired into the build tool’s lifecycle, so there are no extra steps to run.

Create Country Repository

In order to provide data to the web service, create a country repository. In this guide, you create a dummy country repository implementation with hardcoded data. The following listing (from src/main/java/com/example/producingwebservice/CountryRepository.java) shows how to do so:

link:complete/src/main/java/com/example/producingwebservice/CountryRepository.java[role=include]

Create Country Service Endpoint

To create a service endpoint, you need only a POJO with a few Spring WS annotations to handle the incoming SOAP requests. The following listing (from src/main/java/com/example/producingwebservice/CountryEndpoint.java) shows such a class:

link:complete/src/main/java/com/example/producingwebservice/CountryEndpoint.java[role=include]

The @Endpoint annotation registers the class with Spring WS as a potential candidate for processing incoming SOAP messages.

The @PayloadRoot annotation is then used by Spring WS to pick the handler method, based on the message’s namespace and localPart.

The @RequestPayload annotation indicates that the incoming message will be mapped to the method’s request parameter.

The @ResponsePayload annotation makes Spring WS map the returned value to the response payload.

Note	In all of these chunks of code, the io.spring.guides classes will report compile-time errors in your IDE unless you have run the task to generate the domain classes based on the WSDL.

Configure Web Service Beans

Create a new class with Spring WS-related beans configuration, as the following listing (from src/main/java/com/example/producingwebservice/WebServiceConfig.java) shows:

link:complete/src/main/java/com/example/producingwebservice/WebServiceConfig.java[role=include]

• Spring WS uses a different servlet type for handling SOAP messages: MessageDispatcherServlet. It is important to inject and set ApplicationContext to MessageDispatcherServlet. Without that, Spring WS will not automatically detect Spring beans.

• Naming this bean messageDispatcherServlet does not replace Spring Boot’s default DispatcherServlet bean.

• DefaultMethodEndpointAdapter configures the annotation-driven Spring WS programming model. This makes it possible to use the various annotations, such as @Endpoint (mentioned earlier).

• DefaultWsdl11Definition exposes a standard WSDL 1.1 by using XsdSchema

Important

You need to specify bean names for MessageDispatcherServlet and DefaultWsdl11Definition. Bean names determine the URL under which the web service and the generated WSDL file are available. In this case, the WSDL will be available under http://<host>:<port>/ws/countries.wsdl.

This configuration also uses the WSDL location servlet transformation: servlet.setTransformWsdlLocations(true). If you visit http://localhost:8080/ws/countries.wsdl, the soap:address will have the proper address. If you instead visit the WSDL from the public facing IP address assigned to your machine, you will see that address instead.

Make the Application Executable

Spring Boot creates an application class for you. In this case, it needs no further modification. You can use it to run this application. The following listing (from src/main/java/com/example/producingwebservice/ProducingWebServiceApplication.java) shows the application class:

link:complete/src/main/java/com/example/producingwebservice/ProducingWebServiceApplication.java[role=include]

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Logging output is displayed. The service should be up and running within a few seconds.

Test the Application

Now that the application is running, you can test it. Create a file called request.xml that contains the following SOAP request:

link:complete/request.xml[role=include]

The are a few options when it comes to testing the SOAP interface. You can use something similar to SoapUI or use command-line tools if you are on a *nix/Mac system. The following example uses curl from the command line:

# Use data from file
curl --header "content-type: text/xml" -d @request.xml http://localhost:8080/ws

# Use inline XML data
curl <<-EOF -fsSL -H "content-type: text/xml" -d @- http://localhost:8080/ws \
  > target/response.xml && xmllint --format target/response.xml

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
                                  xmlns:gs="http://spring.io/guides/gs-producing-web-service">
   <soapenv:Header/>
   <soapenv:Body>
      <gs:getCountryRequest>
         <gs:name>Spain</gs:name>
      </gs:getCountryRequest>
   </soapenv:Body>
</soapenv:Envelope>

EOF

As a result, you should see the following response:

<?xml version="1.0"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
  <SOAP-ENV:Header/>
  <SOAP-ENV:Body>
    <ns2:getCountryResponse xmlns:ns2="http://spring.io/guides/gs-producing-web-service">
      <ns2:country>
        <ns2:name>Spain</ns2:name>
        <ns2:population>46704314</ns2:population>
        <ns2:capital>Madrid</ns2:capital>
        <ns2:currency>EUR</ns2:currency>
      </ns2:country>
    </ns2:getCountryResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Note

Odds are that the output will be a compact XML document instead of the nicely formatted one shown above. If you have xmllib2 installed on your system, you can curl -fsSL --header "content-type: text/xml" -d @request.xml http://localhost:8080/ws > output.xml and xmllint --format output.xml see the results formatted nicely.

Summary

Congratulations! You have developed a SOAP-based service with Spring Web Services.

See Also

The following guides may also be helpful:

• Consuming a SOAP web service

• Building an Application with Spring Boot

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