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Osi (Open Solver Interface) provides an abstract base class to a generic linear programming (LP) solver, along with derived classes for specific solvers. Many applications may be able to use the Osi to insulate themselves from a specific LP solver. That is, programs written to the OSI standard may be linked to any solver with an OSI interface and should produce correct results. The OSI has been significantly extended compared to its first incarnation. Currently, the OSI supports linear programming solvers and has rudimentary support for integer programming. Among others the following operations are supported:
- creating the LP formulation;
- directly modifying the formulation by adding rows/columns;
- modifying the formulation by adding cutting planes provided by CGL;
- solving the formulation (and resolving after modifications);
- extracting solution information;
- invoking the underlying solver's branch-and-bound component.
The following is a list of derived Osi classes:
|SoPlex||OsiSpx||SoPlex < 4.0|
Each solver interface is in a separate directory of Osi or distributed with the solver itself.
The main project managers are Lou Hafer (@LouHafer) and Matt Saltzmann (@mjsaltzman).
An incomplete list of recent changes to Osi are found in the CHANGELOG
Osi is written in C++ and is released as open source under the Eclipse Public License 2.0.
It is distributed under the auspices of the COIN-OR Foundation.
The Osi development site is https://github.com/coin-or/Osi.
CURRENT BUILD STATUS
What follows is a quick start guide for obtaining or building Osi on common platforms. More detailed information is available here.
Linux (see https://repology.org/project/coin-or-osi/versions for a complete listing):
$ sudo pacman -S coin-or-osi
$ sudo apt-get install coinor-osi coinor-libosi-dev
$ sudo yum install coin-or-Osi coin-or-Osi-devel
$ sudo pkg install math/osi
$ brew install osi
Windows: The easiest way to get Osi on Windows is to download an archive as described above.
Mac OS X: The easiest way to get Osi on Mac OS X is through Homebrew.
$ brew tap coin-or-tools/coinor $ brew install coin-or-tools/coinor/osi
conda (cross-platform, no Windows for now):
$ conda install coin-or-osi
Due to license incompatibilities, pre-compiled binaries lack some functionality. If binaries are not available for your platform for the latest version and you would like to request them to be built and posted, feel free to let us know on the mailing list.
Source code can be obtained either by
- Downloading a snapshot of the source code for the latest release version of Osi from the releases page,
- Cloning this repository from Github, or
- Using the coinbrew script to get the project and all dependencies (recommended, see below).
Osi has a number of dependencies, which are detailed in
config.yml. Dependencies on other COIN-OR projects are
automatically downloaded when obtaining the source with
coinbrew. For some
of the remaining third-party dependencies, automatic download scripts and
build wrappers are provided (and will also be automatically run for required
and recommended dependencies), while other libraries that are aeasy to obtain
must be installed using an appropriate package manager (or may come with your
OS by default).
BUILDING from source
These quick start instructions assume you are in a bash shell.
To download and build Osi from source, execute the following on the command line.
wget https://raw.githubusercontent.com/coin-or/coinbrew/master/coinbrew chmod u+x coinbrew ./coinbrew fetch Osi@master ./coinbrew build Osi
coinbrew (Expert users)
- Download the source code, e.g., by cloning the git repo https://github.com/coin-or/Osi
- Download and install the source code for the dependencies listed in config.yml
- Build the code as follows (make sure to set PKG_CONFIG_PTH to install directory for dependencies).
./configure -C make make test make install
If you have
Doxygen available, you can build a HTML documentation by typing
in the build directory. If Osi was built via
coinbrew, then the build
directory will be
./build/Osi/master by default. The doxygen documentation main file
is found at
If you don't have
doxygen installed locally, you can use also find the
- Code of Conduct
- COIN-OR Web Site
- Discussion forum
- Report a bug
- Doxygen-generated html documentation
- OSI2 Discussion
- The most recent tutorial on OSI can be accessed from the page on presentations from the 2004 CORS/INFORMS Joint Meeting in Banff.
- The COIN-OR Open Solver Interface: Technology Overview: An overview of the COIN-OR OSI and design issues for a next-generation version given at CORS/INFORMS 2004 by Matthew Saltzman.
Dynamically loading commercial solver libraries
At build time
It is possible to create an osi build that supports cplex, gurobi and xpress even if you don't have (yet) any of these solvers on your machine using lazylpsolverlibs. To do so, follow these steps:
- Install lazylpsolverlibs (follow the instructions of the lazylpsolverlibs wiki)
- Use the following command line to configure Osi:
./configure --with-cplex-incdir="$(pkg-config --variable=includedir lazycplex)/lazylpsolverlibs/ilcplex" \ --with-cplex-lib="$(pkg-config --libs lazycplex)" \ --with-gurobi-incdir="$(pkg-config --variable=includedir lazygurobi)/lazylpsolverlibs" \ --with-gurobi-lib="$(pkg-config --libs lazygurobi)" \ --with-xpress-incdir="$(pkg-config --variable=includedir lazyxprs)/lazylpsolverlibs" \ --with-xpress-lib="$(pkg-config --libs lazyxprs)"
- Then follow the normal installation process (make, make install)
At run time
Your build should now support cplex, gurobi and xpress, which means that if you install one of these solvers, osi will be able to use it. At run time, you just need to point one of the environment variables LAZYLPSOLVERLIBS_GUROBI_LIB, LAZYLPSOLVERLIBS_CPLEX_LIB or LAZYLPSOLVERLIBS_XPRS_LIB to the full path of the corresponding solver library. For example:
If pkg-config reports errors during the configure step, try modifying the PKG_CONFIG_PATH variable. Most likely, you need to do: