In the soap/rest test write a loop that uses the dataset Load a set of File Names, which you then target to the file system folder (ex. {{LISA_PROJ_ROOT}}/Data) and file pattern (ex. *.xml), and give the dataset a variable name. Then use a Read A File step, that takes in the variabe name from the Load a set of File Names dataset. Now use that variable name in the consequent request payload of the soap/rest call. At end of the dataset end the test, so that it does not go into infinite loop