The majority of next generation information systems will be working on portable mobile devices such as smartphones. REST Open API web services have quickly become popular among mobile application development. The use of REST web services are not only growing in popularity but totally changing the way of mobile applications development. This is because REST web services could be used in application development as a form of building blocks, which is completely independent, compatible, to any platforms. With this strength, REST web services encourage third party application to build add-on functionality. This research proposes the use of REST web service to replace the use of socket APIs into major internet communication APIs. To this end, this paper also provide performance evaluation of the REST web services compared to the conventional socket APIs, focusing on scalability by analytical and experimental evaluations. Finally, we summarize the possibility whether REST Open API web services have enough performance as future major internet communication primitive APIs.