The ParMETIS library (in contrast to METIS) is distributed under a custom, non-free license and can thus not be shipped with BoSSS. Compiling/installing ParMETIS on a Linux machine is usually not a problem and thus not discussed here.
For Windows, you have to compile your version of ParMETIS yourself. You can obtain a copy of the source code [here](http://glaros.dtc.umn.edu/gkhome/metis/parmetis/download). BoSSS has been tested succesfully with ParMETIS 4.0.3, which is why recommend this version. The compilation process requires [CMAKE](https://cmake.org/) and some version of Visual Studio with a C++ compiler (any version, including the free community versions, should work). The compilation process is explained in detail [here](https://github.com/INMOST-DEV/INMOST/wiki/0204-Compilation-ParMETIS-Windows). In addition to the instructions given there, you should the boolean entry SHARED to the cmake configuration such that the corresponding Visual Studio solution is configured to create a shared dll instead of a lib file.
Finally, there is one additional caveat when using Visual Studio 2013 or newer: When the Visual Studio solution has been created, you should receive error messages concerning the function rint within math.h. This is because METIS/ParMETIS assumes that the Microsoft C++ Compiler does not know this function (which used to be the case in earlier versions shipped with Visual Studio) and thus redefines them in metislib.h (within the metis project) and gk_arch.h (within the parmetis project). If you uncomment the correpsonding lines (metislib.h, lines 34 to 39; gk_arch.h, lines 63), everything should work.
