A Realistic Approach for Representing and Scheduling Workflows in Cloud Computing Environment

Workflow consists of set of tasks used to automate any scientific or business process. Workflows are usually represented as a Directed Acyclic Graph (DAG), in which the nodes represent the tasks involved in the process and the edges represents the dependency between the tasks. Workflow scheduling is the process of assigning the tasks to suitable resources for execution. Even though DAG is the efficient format for representing workflow, it cannot be used directly as input to programs that perform workflow scheduling and execution. Hence representing workflow in a suitable format for scheduling is a major challenge for researchers working in this area. This paper proposes a Realistic Workflow Scheduler that accepts the workflow in graphical format, converts it into a suitable text format and perform appropriate scheduling. The scheduler implements the Workflow Definition Converter (WDC) to convert the workflow represented in graphical format to text file format that can be directly given as input to any program or simulator for scheduling and execution. The Critical Path Finder is used to identify the critical path of the workflow. In addition to that the Deadline Constrained (DC) and Cost Constrained (CC) workflow scheduling algorithms have been implemented to schedule the workflow in a suitable cloud computing environment. The correctness of this work is also verified by scheduling popular workflows like Montage and Inspiral using the proposed scheduler.