OsiSolverInterface
Abstract base class defining the Open Solver Interface (OSI)
Abstract base class defining the Open Solver Interface (OSI)
OSI provides a uniform API for accessing different LP/MIP solvers (Clp, CPLEX, Gurobi, GLPK, etc.) through a common interface. This allows solver-independent application code.
Key capabilities:
- LP relaxation solving (initialSolve, resolve)
- Model query (getColLower, getRowUpper, getObjCoefficients)
- Solution query (getColSolution, getRowPrice, getReducedCost)
- Problem modification (setColBounds, addRow, addCol)
- Warm starting (getWarmStart, setWarmStart)
- Cut management (applyCuts, applyRowCuts)
- MIP support (setInteger, branchAndBound)
Typical workflow:
- Create solver-specific instance (e.g., OsiClpSolverInterface)
- Load problem via loadProblem() or readMps()
- Call initialSolve() for first LP solution
- Call resolve() after modifications
- Query solution via getColSolution(), getObjValue()
Algorithm
Design Pattern: Abstract Factory + Strategy
- Factory: concrete implementations (OsiClpSolverInterface, etc.) instantiate solver-specific backends
- Strategy: algorithm choice (simplex vs barrier) delegated to underlying solver; OSI provides uniform control interface
- Bridge: decouples client code from solver implementation details
@invariant Solution pointers (getColSolution, getRowPrice, etc.) are invalidated by any problem modification or subsequent solve call. Client code must copy data if needed across modifications.
@invariant Warm start objects must be compatible with the solver that created them. Cross-solver warm starting requires basis translation.
Complexity: All query methods (getColSolution, etc.): $O(1)$ pointer return initialSolve/resolve: delegated to solver, typically $O(m·n·iterations)$ applyCuts: $O(cuts × row_length)$ for constraint matrix update
References:
- Lougee-Heimer et al. (2003). "The Common Optimization INterface for Operations Research". IBM J. Research & Development 47(1):57-66.
See Also
- OsiClpSolverInterface for Clp implementation
- OsiCuts for cut pool management
- CoinPackedMatrix for constraint matrix format
Source
Header file: `src/Osi/OsiSolverInterface.hpp`