Cloud Computing is a major current trend to distribute processing and data virtually on configurable execution environments.
The development and deployment of software for the Cloud proposes a new scientific challenge in terms of expression and consideration
of variability. Indeed, cloud computing is based on principles of heterogeneity and elasticity, which allows many choices of configuration
and sizing. Then the migration of existing applications remains the main challenge to be taken into account. Indeed, there are several types
of migration depending on the three services offered by the Cloud. In this article we conduct a study on the migration of applications to the
cloud in general and specifically the migration of IAAS to the PaaS (Platform as a Service) service of Cloud Computing. The migration of
existing systems to the PaaS model has several advantages, but also poses new challenges, particularly with regard to the restrictions
imposed by the service provider. In addition, factors such as time, training and extensive re-engineering have been taken into account
making the migration process time consuming and error prone. Although there are several techniques for partial or full migration of legacy
applications to the cloud, only a few of them solve these constraints. Our work mainly consists of firstly to clearly elucidate the notions of
Cloud, “Information Access Assistance Service” (IAAS) and then to study the existing migration strategies in order to propose the most
ideal one for the migration from IAAS to PaaS

Application's migrations, Big Data, Cloud computing, Data migration, IAAS, Recommendation system.