About OMBackend.jl

OMBackend.jl is one component of OMJL, the Modelica compiler infrastructure for Julia. It transforms a Hybrid DAE produced by OMFrontend.jl into a system that can be simulated with DifferentialEquations.jl and ModelingToolkit.jl.

Requirements

• Julia 1.12
• Git
• A checkout of the sibling OM*.jl packages next to this repository (see below)

Dependencies

The main runtime dependencies are pulled in by Project.toml. The most relevant ones are:

• DifferentialEquations.jl, OrdinaryDiffEq.jl, DiffEqBase.jl, DiffEqCallbacks.jl, Sundials.jl
• ModelingToolkit.jl, Symbolics.jl, SymbolicUtils.jl
• Graphs.jl, MetaGraphs.jl, DataStructures.jl, MacroTools.jl, Setfield.jl
• Plots.jl, GR.jl, CSV.jl, Tables.jl
• ExportAll.jl, DocStringExtensions.jl, JuliaFormatter.jl

The OMJL ecosystem packages are consumed as in-tree siblings via Project.toml's [sources] block. They must be checked out as sibling directories next to OMBackend.jl:

• Absyn.jl
• DAE.jl
• ImmutableList.jl
• ListUtil.jl
• MetaModelica.jl
• OMFrontend.jl
• OMParser.jl
• OMRuntimeExternalC.jl
• SCode.jl

Layout:

OMJL-workspace/
├── Absyn.jl/
├── DAE.jl/
├── ImmutableList.jl/
├── ListUtil.jl/
├── MetaModelica.jl/
├── OMBackend.jl/        <-- this repository
├── OMFrontend.jl/
├── OMParser.jl/
├── OMRuntimeExternalC.jl/
└── SCode.jl/

OMRuntimeExternalC.jl is not in the General registry. The others are served by the OpenModelica Julia registry but the local [sources] paths take precedence and are used for development.

Installation

Add the OpenModelica Julia registry once per Julia depot:

julia> import Pkg
julia> Pkg.Registry.add("General")
julia> Pkg.Registry.add(Pkg.RegistrySpec(url = "https://github.com/OpenModelica/OpenModelicaRegistry.git"))

From the OMBackend.jl directory, activate the project and build:

julia> import Pkg
julia> Pkg.activate(".")
julia> Pkg.build(verbose = true)

deps/build.jl resolves and builds the dependent OM*.jl packages (notably OMParser and OMFrontend).

Then load the package:

julia> using OMBackend

Running tests

From the OMBackend.jl directory:

julia> import Pkg
julia> Pkg.activate(".")
julia> Pkg.test()

Or directly:

julia> include("test/runtests.jl")

Example use

Given a Modelica model translated to Hybrid DAE by OMFrontend.jl, pass it to OMBackend.translate and then simulate.

model BouncingBallReals
  parameter Real e = 0.7;
  parameter Real g = 9.81;
  Real h(start = 1);
  Real v;
equation
  der(h) = v;
  der(v) = -g;
  when h <= 0 then
    reinit(v, -e * pre(v));
  end when;
end BouncingBallReals;

julia> OMBackend.translate(BouncingBallReals)
julia> OMBackend.simulate("BouncingBallReals", tspan = (0.0, 2.5))

Citation

If you use OMBackend.jl in academic work, please cite the entries in CITATION.bib.

License

OMBackend.jl is distributed under the OSMC Public License. See LICENSE.md.