The CTAPI Vendor Maintenance web service is modeled after the Solomon Screen: 03.270.00
The recommended and quickest way to implement is to use the ctDynamicsSL.financial.accountsPayable.maintenance.vendorMaintenance.screen object which contains all necessary objects to create or edit a vendor entry.

All necessary pv lookups are available in the service.
Examples:
public ctDynamicsSL.Terms[] getTermsByTermsID(String termsID)
public ctDynamicsSL.VendClass[] getVendClassesByClassID(String classID)
public ctDynamicsSL.POAddress[] getPOAddressesByOrdFromId(String vendID, String ordFromID)

and more...

Contact Catalina for sample code for calling this webservice

Programmers Reference for: ctDynamicsSL.financial.accountsPayable.maintenance.vendorMaintenance