Software Engineering for Multi-tenancy Computing Challenges and Implications

Multi-tenancy is a cloud computing phenomenon. Multiple instances of an application occupy and share resources from a large pool, allowing different users to have their own ver-sion of the same application running and coexisting on the same hardware but in isolated virtual spaces. In this posi-tion paper we survey the current landscape of multi-tenancy, laying out the challenges and complexity of software en-gineering where multi-tenancy issues are involved. Multi-tenancy allows cloud service providers to better utilise com-puting resources, supporting the development of more flexi-ble services to customers based on economy of scale, reduc-ing overheads and infrastructural costs. Nevertheless, there are major challenges in migration from single tenant applica-tions to multi-tenancy. These have not been fully explored in research or practice to date. In particular, the reengineering effort of multi-tenancy in Software-as-a-Service cloud appli-cations requires many complex and important aspects that should be taken into consideration, such as security, scala-bility, scheduling, data isolation, etc. Our study emphasizes scheduling policies and cloud provisioning and deployment with regards to multi-tenancy issues. We employ CloudSim and MapReduce in our experiments to simulate and anal-yse multi-tenancy models, scenarios, performance, scalabil-ity, scheduling and reliability on cloud platforms