Let's assume we want to use the temperature conversion service from grails. In order to make the project minimal, we will modify the default view of the project, add a controller proxying to the service and generate a minimal view to display the result. Here we go:

grails create-app hotstuff
cd hotstuff
vi grails-app/views/index.gsp

Modify the default view to

<html>
  <head>
    <title>Welcome to Grails</title>
    <meta name="layout" content="main" />
  </head>
  <body>
    <g:form name="temperature" controller="temperature" action="conversion">
      <p>
        <g:set var="units" value="${['Fahrenheit', 'Celsius']}" />
        Convert <g:textField name="value" value="10.0" /> <g:select name="from" from="${units}" /> in <g:select name="to" from="${units}"/>
      </p>
      <g:submitButton name="submit" value="Convert" />
    </g:form>
  </body>
</html>

grails create-controller temperature

Here is the controller code:

import groovyx.net.ws.WSClient

class TemperatureController {

    def index = { }

    def conversion = {
        def proxy = new WSClient("http://www.w3schools.com/webservices/tempconvert.asmx?WSDL", this.class.classLoader)
        proxy.initialize()

        def message

        if (!params?.value || params.from.equals(params.to)) {
            message = "Units are probably the same. Don't aske me :)"
        } else {
            def result
            if ("Celsius".equals(params.from)) {
                result = proxy.CelsiusToFahrenheit(params.value)
            } else {
                result = proxy.FahrenheitToCelsius(params.value)
            }
            message = "${params.value} degrees ${params.from} are ${result} degrees ${params.to}"
        }

        flash.message = message
    }

}

Then, we create the view to display the result

mkdir grails-app/views/temperature
vi grails-app/views/temperature/conversion.gsp

Here is the simplistic view:

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
        <meta name="layout" content="main" />
        <title>Here we are</title>
    </head>
    <body>
        <div class="body">
            <g:if test="${flash.message}">
            <div class="message">${flash.message}</div>
            </g:if>
        </div>
    </body>
</html>

(error) Currently, the Grab annotation cannot be used without interfering with native grails jars, so you have to add the following jars into your application lib directory

$ ls -lrt lib/
total 31960
-rw-r--r--  1 alleon  alleon    26072 Apr 15 11:01 groovyws-0.5.0-SNAPSHOT.jar
-rw-r--r--  1 alleon  alleon  4201229 Apr 15 11:03 cxf-bundle-2.1.4.jar
-rw-r--r--  1 alleon  alleon   520969 Apr 15 12:48 wstx-asl-3.2.7.jar
-rw-r--r--  1 alleon  alleon    60686 Apr 15 13:31 commons-logging-1.1.1.jar
-rw-r--r--  1 alleon  alleon  1485863 Apr 15 13:31 bcprov-jdk15-140.jar
-rw-r--r--  1 alleon  alleon   143806 Apr 15 13:31 XmlSchema-1.4.4.jar
-rw-r--r--  1 alleon  alleon   291779 Apr 15 13:31 FastInfoset-1.2.2.jar
-rw-r--r--  1 alleon  alleon   226915 Apr 15 13:31 jaxen-1.1.1.jar
-rw-r--r--  1 alleon  alleon  3127729 Apr 15 13:31 jaxb-xjc-2.1.9.jar
-rw-r--r--  1 alleon  alleon   856752 Apr 15 13:31 jaxb-impl-2.1.9.jar
-rw-r--r--  1 alleon  alleon    89967 Apr 15 13:31 jaxb-api-2.1.jar
-rw-r--r--  1 alleon  alleon    14611 Apr 15 13:31 geronimo-ws-metadata_2.0_spec-1.1.2.jar
-rw-r--r--  1 alleon  alleon    28804 Apr 15 13:31 geronimo-stax-api_1.0_spec-1.0.1.jar
-rw-r--r--  1 alleon  alleon    47817 Apr 15 13:31 geronimo-jaxws_2.1_spec-1.0.jar
-rw-r--r--  1 alleon  alleon   204851 Apr 15 13:31 geronimo-javamail_1.4_spec-1.5.jar
-rw-r--r--  1 alleon  alleon    12452 Apr 15 13:31 geronimo-annotation_1.0_spec-1.1.1.jar
-rw-r--r--  1 alleon  alleon    34126 Apr 15 13:31 geronimo-activation_1.1_spec-1.0.2.jar
-rw-r--r--  1 alleon  alleon   444503 Apr 15 13:31 xmlsec-1.4.2.jar
-rw-r--r--  1 alleon  alleon    84091 Apr 15 13:31 xml-resolver-1.2.jar
-rw-r--r--  1 alleon  alleon  3176148 Apr 15 13:31 xalan-2.7.1.jar
-rw-r--r--  1 alleon  alleon   313982 Apr 15 13:31 wss4j-1.5.6.jar
-rw-r--r--  1 alleon  alleon   148429 Apr 15 13:31 wsdl4j-1.6.2.jar
-rw-r--r--  1 alleon  alleon   278281 Apr 15 13:31 serializer-2.7.1.jar
-rw-r--r--  1 alleon  alleon   278145 Apr 15 13:31 saaj-impl-1.3.2.jar
-rw-r--r--  1 alleon  alleon    18817 Apr 15 13:31 saaj-api-1.3.jar
-rw-r--r--  1 alleon  alleon    32900 Apr 15 13:31 neethi-2.0.4.jar
-rw-r--r--  1 alleon  alleon   153115 Apr 15 13:31 jdom-1.1.jar

(warning) If you have been running our very first example all these jars are probably in your 

~/.groovy/grapes/

directory

BuildConfig.groovy

If you reference groovyws in your grails app then you will need a set of exclusions to prevent version conflicts ( from list Nabble - Ronny Løvtangen ):

compile("org.codehaus.groovy.modules:groovyws:0.5.2") {
    excludes 'geronimo-servlet_2.5_spec', 'servlet-api', 'jaxb-xjc', 'jaxb-impl', 'xml-apis', 'saaj-impl', 'junit', 'slf4j-jdk14', 'xmlParserAPIs', 'jaxb-api', 'saaj-api', 'xmlbeans', 'jaxen', 'geronimo-stax-api_1.0_spec', 'geronimo-activation_1.0.2_spec', 'abdera-client', 'geronimo-activation_1.1_spec'
}