Towards Representing Time-Cost Tradeoffs for Service Compositions

Service Level Agreements have to contain the time and cost of using a service. We propose time-cost tables for representing the relationship between time and cost. Basically there can be a direct or indirect correlation between duration and cost of a service. We introduce algorithms for computing the time-cost relationship of services composed as an orchestration of other services. These services may have directly and indirectly proportional cost with respect to time resulting in more complex relationships between duration and cost. These representations allow to infer the minimum cost of a service given temporal constraints, or for checking which durations are affordable for an available budget. The time-cost tables thus offer a basis for various optimization of composed services.