In the context of PrEstoCloud, application micro-services, or fragments, can be placed either in a public cloud (e.g. Amazon Web Services), a private cloud (e.g. an on-site OpenStack instance), and on IoT devices located at the extreme edge of the network.
Due to the pay-as-you-go nature of public cloud, it is essential to carefully select (i) the cloud provider, and (ii) the location in which to deploy a fragment, so as to meet operational constraints (such as latency), but also ensure the deployment cost is acceptable to the application owner.
Image source: https://dollarsandsense.sg/wp-content/uploads/2015/03/Divergence-Trading.jpg