XCSP2.1 format (.xml)
CSP and weighted CSP in XML format XCSP 2.1, with constraints in extension only, can be read. See a description of this deprecated format here http://www.cril.univ-artois.fr/CPAI08/XCSP2_1.pdf.
Warning, toulbar2 must be compiled with a specific option XML in the cmake.
XCSP3 format (.xml)
CSP and COP format in XML format XCSP3 core can be read (still on-going work for including globals). See a description of this format here http://xcsp.org.
Warning, toulbar2 must be compiled with specific options XML and XCSP3 in the cmake.