Consume web service using EJB

I am trying to consume a web service by following the tutorial listed here:

http://help.sap.com/saphelp_nw2004s/helpdata/en/2d/b9766df88f4a24967dae38cb672fe1/frameset.htm

I've created and deployed a proxy to the server.

I am now creating an EJB to call the proxy and am having trouble with the following lines of code listed in the tutorial:

InitialContext ctx = new InitialContext();

CreditLimitCheck obj = (CreditLimitCheck)

     ctx.lookup("java:comp/env/CreditLimitCheckProxy");

CreditLimitCheckViDocument port = (CreditLimitCheckViDocument)

obj.getLogicalPort("DEFAULTPort_Document",

CreditLimitCheckViDocument.class);

this.port = port;

I'm not sure which objects the CreditLimitCheck and CreditLimitCheckViDocument are referring to?