Exploration of Secured Workflow Scheduling Models in Cloud Environment: A Survey

Cloud computing (CC) is a useful tool for executing complex applications. As a result of this, it has become so popular and used in diverse domains such as science, engineering, medicine. etc. CC structure is composed of a number of virtual machines(VMs) provisioned on demand and charged on a "Pay-as-you-go" basis, it is deployed in different form of access levels. Complex applications needed to be executed on clouds are represented as workflows. Workflow scheduling (WS) is one of the most important concepts in cloud computing. WS model contributes to minimizing cost, makespan and energy as well as maximize the quality of service(QoS) of applications in clouds. Despite the security constraints set by each provider, CC has become so critical due to the considerations of applications with sensitive intermediate data, this thereby requires a security level known as Secured workflow Scheduling(SWS). This security is on the level of executing workflows. It indicates that applications with sensitive interdependent data have to be protected during their execution across different cloud VMs. The addition of security in workflow execution generates time overhead, making it complex to meet up with the QoS required by the users. Some research works have proposed algorithms for providing the QoS requirements and security at the same time. In this work, we survey some existing works, by defining the factors needed in securing workflows during execution, clarifying the domains for security, sources of security threats and their solutions as well as cloud computing services that needs security and lastly classify the proposed algorithm depending cloud computing components.