A Novel Ant Colony Optimization Algorithm for Large Scale QoS-Based Service Selection Problem

Algorithm 2

CASS.

   Set parameters and Initialize pheromone trails

Begin

   for  each service class  do

      use the skyline query process to identify its skyline services;

      Clustering the skyline services into several different clusters;

   endfor;

   build the clustering graph and make it as the initial construct graph;

   repeat

      ElitistsofCycle = {};

      for  each ant 𝑘  do

          construct an assignment 𝐴_𝑘 using Procedure 1;

          if fit(𝐴_𝑘)<fit(𝑏𝑒𝑠𝑡𝐴) then

           𝑏𝑒𝑠𝑡𝐴 = 𝐴_𝑘;

      endfor;

      find the best  𝑁 assignments and add them into ElitistsofCycle;

      update pheromone trails using Procedure 2;

      if  (eighty percent ants obtained the same assignment) then

                  use the expanding process to fractionize the construction graph;

      endif.

   until the maximum evaluation number is arrived or

    the other termination condition is satisfied;

   return  𝑏𝑒𝑠𝑡𝐴;

End