An Invocation Cost Optimization Method for Web Services in Cloud Environment

Algorithm 1

CS-COM  .

Input: user: a cloud user

    cs: a cloud service ready to be invoked by user

    job_size: user’s job (or task) size

    : service quality level of cs requested by user

    : execution_duration = in (1)

    : in (2)

Output: : optimal service invocation start time of cs

     : optimal invocation cost of cs by user

()   Set variable // service invocation start time

()   Get models and from service provider

()   Get parameters and in (4) from service provider based on

()   Estimate cs’s execution_duration based on job_size and (1)

()   Calculate based on , execution_duration and (3)

    // : original service invocation cost of cs by user

()   Calculate based on , , and (4)

    // : comprehensive invocation cost of cs by user

()   Set objective function: Minimize

()   Determine by combining (1)–(5)

()   Determine based on (6)

() Return to user

() Return to user