IEC 62656-8:2020 specifies a web service interface to exchange data parcel(s) conformant to IEC 62656-1, between a parcel server and a parcel client or between parcel servers. This interface comprises three basic services: a registration service, resolution service and subscription service. This document includes the following: – holistic use scenario; – detailed specification of the three basic services; – JSON and XML notation schemas for data parcel(s). The following items are outside the scope of this document: – user identification and authorization; – query language for a data parcel; – transportation protocol; – data and communication security techniques.