Research Article

Multiobjective Level-Wise Scientific Workflow Optimization in IaaS Public Cloud Environment

Algorithm 3

Workflow optimization using NSGA-II.
Input: Task Objects, Search Space (SP), total number of levels (), : Population size, : number of generations,
: number of objectives, MP: mutation probability, CP: crossover probability.
Output: Pareto optimal solutions, .
Processing
Step 1. Generate random initial population, IP.
(1.1) Randomly generate integer chromosome .
(1.2) Calculate the fitness of each random chromosome
(1.3) Rank population according to non-domination
Step 2. Evolve population .
(2.1) Select parents using tournament selection,
(2.2) Perform two-point dynamic crossover operation on parents with probability CP to produce
offspring population.
(2.3) Perform mutation operation with probability MP on random points applied to offspring
(2.4) Calculate fitness of new offspring population and update population
(2.5) Use non-dominated sorting to divide into several non-domination levels .
(2.6) Calculate Crowding Distance of all solutions
(2.7) Identify the worst solution and set .
Step 3. Repeat Step 2 until termination condition is met.
Step 4. Output the list of optimal solutions at Pareto front, .