An instance of the class MIPCallback represents a user-written callback in an application that uses an instance of Cplex to solve a mixed integer program (MIP). Cplex calls the user-written callback prior to solving each node in the branch-and-cut search. This class allows you to access an incumbent solution, an incumbent node, and an incumbent objective value from a user-written callback. It also allows you to access priority orders and statistical information, such as the number of cuts that have been generated. Methods are also available to query the number of generated cuts for each type of cut CPLEX generates. See the CPLEX User's Manual for more information about cuts.

This class also provides a common application programming interface (API) for these subclasses of control and query callbacks:

• Cplex.DisjunctiveCutCallback
• Cplex.FractionalCutCallback
• Cplex.FlowMIRCutCallback
• Cplex.ProbingCallback
• Cplex.IncumbentCallback
• Cplex.NodeCallback
• Cplex.SolveCallback
• Cplex.ControlCallback with its extensions:
  • Cplex.BranchCallback
  • Cplex.HeuristicCallback
  • Cplex.UserCutCallback
  • Cplex.LazyConstraintCallback
  • Cplex.SolveCallback

The constructor and methods of this class are protected to make sure that they are used only to derive a user-written callback class or to implement the main method in it.