Smartphones and other connected devices rely on data services,such as Web Services (WS),Google Cloud Messaging (GCM) and Firebase Cloud Messaging (FCM),to share the information they collect or use.Traditionally,these services were classified according to the average number of bytes transmitted or their delivery time.However,when dealing with battery-operated devices,another important parameter to be taken into account is their power consumption.Furthermore,software designers and developers often do not consider the efficiency of a data communication system,but are simply conced about ease-of-use and response time.In this paper,we compare FCM,GCM and two types of WS,namely Simple Object Access Protocol (SOAP) and REpresentational State Transfer (REST) WS in terms of delay,data efficiency,and power consumption.The final outcome is that RFSTful WS outperforms all others,making GCM and FCM a viable altative only when the amouat of data to be transmitted is very limited,or when the mobile application requires the advanced services offered by FCM or GCM only.