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Kestrel for the NEOS Server


Kestrel is an interface to the NEOS Server that allows remote access to the solvers from a user's locally installed AMPL or GAMS modeling environment. It provides an easy mechanism for users to submit jobs to the NEOS solvers and receive the results within a local AMPL or GAMS modeling session.

Guide to Installing and Using the Kestrel AMPL Client

Installing AMPL and Kestrel

To use Kestrel with AMPL, you need to have the AMPL interactive environment installed on your local computer. If you do not have the AMPL environment installed, you can download a test version that accepts problems with up to 300 variables and 300 constraints; see the AMPL website for instructions.

There are two versions of Kestrel for AMPL, one for Linux/Mac OS X and one for Windows. Download the correct version for your system and unzip the file. As of March 28, 2017, both versions have been updated to work with HTTPS.

  • Linux/Mac OS X: Python must be installed.
    • Download kestrel.tar.gz.
    • Unzip kestrel.tar.gz into a directory in the path. We recommend the same directory as the AMPL binary.
  • Windows:
    • Download kestrel.zip.
    • Unzip kestrel.zip into same directory as the AMPL executable.

Using Kestrel

  1. Develop your model within the AMPL environment.
  2. Set the solver options.
    • Choose option solver kestrel; as the solver.
    • Specify the remote solver name, e.g., CPLEX:
      option kestrel_options 'solver=cplex';
    • Specify the URL of the NEOS Server:
      option neos_server 'www.neos-server.org:3333';
    • Note: If you do not know what solvers are available via Kestrel, omit the solver name and submit the job. The list of enabled solvers will be returned.
  3. Submit the job to the NEOS Server by typing solve;.
  4. If you are disconnected from the Kestrel server during your job execution, type
    option kestrel_options 'job=<jobNumber> password=<password>';
    and then
    solve;
    If your job is still in progress, your AMPL session will resume waiting. Otherwise, your results will be retrieved.

Note: On Windows, you will get an error message that the client requires python24.dll to run. Please ignore this message, since the client can execute without this library.


Guide to Installing and Using the Kestrel GAMS Client

Installing GAMS and Kestrel

To use Kestrel with GAMS, you need to have GAMS 24.8 or newer installed on your local computer. Since GAMS 23.7, the Kestrel GAMS client has been included in the standard GAMS distribution for all supported architectures, so you only need Python version 2.5 or above to be installed on your machine.

Using Kestrel with GAMS

  1. Develop your model within the GAMS environment.
  2. Create an options file called kestrel.opt.
    • Specify the name of the solver and the URL for the NEOS Server.
      kestrel_solver <solverName>
      neos_server <hostname:port>

      Example:
      kestrel_solver conopt
      neos_server neos-server.org:3333

    • Include any solver specific options.
    • Note: If you do not know what solvers are available via Kestrel, omit the solver name and submit the job. The list of enabled solvers will be returned.
  3. To run your GAMS job on the command line, set the solver to kestrel and set optfile=1. The Kestrel solver accepts all model types.
  4. If you are disconnected from the Kestrel server, you can retrieve the results for your job from the NEOS Server admin page using your <jobNumber> and <password>.