Web service = WSDL + SOAP + UDDI
And so it was said on the Mastering Enterprise Java Beans 3.0, chapter 5. I didn't understand the relationship of UDDI with Web services. If I understand it right, UDDI is some sort of directory lookup if a a webservice is availbale on a given end(e.g., a URL). UDDI however is not needed all the time since you could manually point your web service client to a URL that returns a WSDL document. So I think you could simplify the equation to
Web service = WSDL + SOAP
I've been hearing about SOAP since I was in my senior College days(back in the year 2005). I've read a couple of things about it but never really had the chance to write a SOAP message from scratch(and I know those who did would say, you're lucky you never did).