the best solution for your requirement is a Lookup in your mapping where you send the names al return the list of IDs.
take a look to my document about how to do a SOAP Lookup, also consider that RFC and JDCB lookup are avialable as standar functionality.
http://scn.sap.com/community/pi-and-soa-middleware/blog/2013/08/07/how-to--soap-lookup
rgds