WSDL Namespaces - Seriously Confused!

The more I read on WSDL, the more I'm getting confused about namespaces and urn etc... please help me! Here's my WSDL file atm...


<?xml version="1.0" encoding="ISO-8859-1"?>
<definitions name="TestService"
targetNamespace="http://myserver:1618/testing/soap/soap_test.wsdl"
xmlns:tns="http://myserver:1618/testing/soap/soap_test.wsdl"
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/"
xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"
xmlns="http://schemas.xmlsoap.org/wsdl/">

<message name="helloResponse">
<part name="hellomsg" type="xsd:string"/>
</message>

<portType name="TestServicePortType">
<operation name="hello">
<output message="tns:helloResponse"/>
</operation>
</portType>

<binding name="TestServiceBinding" type="tns:TestServicePortType">
<soap:binding style="rpc"
transport="http://schemas.xmlsoap.org/soap/http"/>
<operation name="hello">
<soap:operation soapAction="hello"/>
<output>
<soap:body use="encoded" namespace="urn:examples:helloservice"
encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"/>
</output>
</operation>
</binding>

<service name="TestService">
<port name="TestServicePort" binding="TestServiceBinding">
<soap:address location="http://myserver:1618/testing/soap/soap_test_server.php"/>
</port>
</service>
</definitions>


I've obviously replaced my server name with "myserver" in the WSDL file I've posted here. This WSDL file doesn't seem to work correctly when called though :( The function available in the PHP SOAP server script is hello(). If someone could explain namespaces and urn etc. to me and what's wrong with this WSDL file I'd be very grateful!

Thanks a lot,

Simon