public class MegentoCategory {

    String user = "xxx";
    String pass = "xxx";
    String host = "http://www.xxx.co.xx/index.php/api/soap/?wsdl";


    public MegentoCategory() throws MalformedURLException
    {

try{
                // Create SOAP Connection
                SOAPConnectionFactory soapConnectionFactory = SOAPConnectionFactory.newInstance();
                SOAPConnection soapConnection = soapConnectionFactory.createConnection();

                // Send SOAP Message to SOAP Server
                SOAPMessage soapResponse = soapConnection.call(createSOAPRequest(), host);

                // print SOAP Response
                System.out.print("Response SOAP Message:");
                soapResponse.writeTo(System.out);
                soapConnection.close();
}
        catch(Exception e)
        {
                e.getMessage();
        }
    }

    private static SOAPMessage createSOAPRequest() throws Exception {
        MessageFactory messageFactory = MessageFactory.newInstance();
        SOAPMessage soapMessage = messageFactory.createMessage();
        SOAPPart soapPart = soapMessage.getSOAPPart();

        String serverURI = "<?xml version='1.0' encoding='UTF-8'?><soapenv:Envelopexmlns:soapenv='http://schemas.xmlsoap.org/soap/envelope/'><soapenv:Body><mag:loginxmlns:mag='urn:Magento'<mag:username>xxx</mag:username<mag:apiKey>xxx</mag:apiKey></mag:login></soapenv:Body></soapenv:Envelope>";

        MimeHeaders headers = soapMessage.getMimeHeaders();
        headers.addHeader("SOAPAction", serverURI  + "login");

        soapMessage.saveChanges();


        /* Print the request message */
        System.out.print("Request SOAP Message:");
        soapMessage.writeTo(System.out);
        System.out.println();

        return soapMessage;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns:typens="urn:Magento" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
    xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns="http://schemas.xmlsoap.org/wsdl/"
    name="Magento" targetNamespace="urn:Magento">
    <types>
        <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:Magento">
<!--            <import namespace="http://schemas.xmlsoap.org/soap/encoding/" schemaLocation="http://schemas.xmlsoap.org/soap/encoding/" />-->
            <complexType name="FixedArray">
                <complexContent>
                    <restriction base="soapenc:Array">
                        <attribute ref="soapenc:arrayType" wsdl:arrayType="xsd:anyType[]" />
                    </restriction>
                </complexContent>
            </complexType>
        </schema>
    </types>
    <message name="call">
        <part name="sessionId" type="xsd:string" />
        <part name="resourcePath" type="xsd:string" />
        <part name="args" type="xsd:anyType" />
    </message>
    <message name="callResponse">
        <part name="callReturn" type="xsd:anyType" />
    </message>
    <message name="multiCall">
        <part name="sessionId" type="xsd:string" />
        <part name="calls" type="typens:FixedArray" />
        <part name="options" type="xsd:anyType" />
    </message>
    <message name="multiCallResponse">
        <part name="multiCallReturn" type="typens:FixedArray" />
    </message>
    <message name="endSession">
        <part name="sessionId" type="xsd:string" />
    </message>
    <message name="endSessionResponse">
        <part name="endSessionReturn" type="xsd:boolean" />
    </message>
    <message name="login">
        <part name="username" type="xsd:string" />
        <part name="apiKey" type="xsd:string" />
    </message>
    <message name="loginResponse">
        <part name="loginReturn" type="xsd:string" />
    </message>
    <message name="resources">
        <part name="sessionId" type="xsd:string" />
    </message>
    <message name="resourcesResponse">
        <part name="resourcesReturn" type="typens:FixedArray" />
    </message>
    <message name="globalFaults">
        <part name="sessionId" type="xsd:string" />
    </message>
    <message name="globalFaultsResponse">
        <part name="globalFaultsReturn" type="typens:FixedArray" />
    </message>
    <message name="resourceFaults">
        <part name="resourceName" type="xsd:string" />
        <part name="sessionId" type="xsd:string" />
    </message>
    <message name="resourceFaultsResponse">
        <part name="resourceFaultsReturn" type="typens:FixedArray" />
    </message>
    <message name="startSession" />
    <message name="startSessionResponse">
        <part name="startSessionReturn" type="xsd:string" />
    </message>
    <portType name="PortType">
        <operation name="call">
            <documentation>Call api functionality</documentation>
            <input message="typens:call" />
            <output message="typens:callResponse" />
        </operation>
        <operation name="multiCall">
            <documentation>Multiple calls of resource functionality</documentation>
            <input message="typens:multiCall" />
            <output message="typens:multiCallResponse" />
        </operation>
        <operation name="endSession">
            <documentation>End web service session</documentation>
            <input message="typens:endSession" />
            <output message="typens:endSessionResponse" />
        </operation>
        <operation name="login">
            <documentation>Login user and retrive session id</documentation>
            <input message="typens:login" />
            <output message="typens:loginResponse" />
        </operation>
        <operation name="startSession">
            <documentation>Start web service session</documentation>
            <input message="typens:startSession" />
            <output message="typens:startSessionResponse" />
        </operation>
        <operation name="resources">
            <documentation>List of available resources</documentation>
            <input message="typens:resources" />
            <output message="typens:resourcesResponse" />
        </operation>
        <operation name="globalFaults">
            <documentation>List of resource faults</documentation>
            <input message="typens:globalFaults" />
            <output message="typens:globalFaultsResponse" />
        </operation>
        <operation name="resourceFaults">
            <documentation>List of global faults</documentation>
            <input message="typens:resourceFaults" />
            <output message="typens:resourceFaultsResponse" />
        </operation>
    </portType>
    <binding name="Binding" type="typens:PortType">
        <soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" />
        <operation name="call">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
        <operation name="multiCall">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
        <operation name="endSession">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
        <operation name="login">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
        <operation name="startSession">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
        <operation name="resources">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
        <operation name="globalFaults">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
        <operation name="resourceFaults">
            <soap:operation soapAction="urn:Action" />
            <input>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </input>
            <output>
                <soap:body namespace="urn:Magento" use="encoded" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
            </output>
        </operation>
    </binding>
    <service name="MagentoService">
        <port name="Port" binding="typens:Binding">
            <soap:address location="http://www.gsequestrian.co.uk/index.php/api/soap/index/" />
        </port>
    </service>
</definitions>