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Python

opensysml is the Python client for parsing, inspecting and executing SysML v2 models through the sysml-grpc service. Choose it when you want a Python API, not a subprocess around the sysml command.

Install

Python 3.10 or newer is required. Install the published package from PyPI:

python -m pip install opensysml

opensysml 0.9.1 and earlier do not download the service automatically. Set OPENSYSML_GRPC_VERSION=v0.9.1 (or another release tag), or provide a service binary through OPENSYSML_BINARY or $PATH.

To work from a repository checkout, run this at its root:

python -m pip install -e client/python/

The PyPI package includes the client code and its release-digest table. It does not bundle the service executable.

First model

When no service is configured, the first operation starts a private service child. If its built-against release is not already cached, the client downloads that release and verifies it against the digest pinned in the package or, for a release newer than the package's table, the release's signed checksum manifest. The cache is shared with the other clients. See The service for binary resolution and trust details.

import opensysml

source = """\
package Demo {
    part def Vehicle {
        attribute mass default = 1500.0;
    }
    part sedan : Vehicle {
        attribute :>> mass = 1800.0;
    }
}
"""

model = opensysml.loads(source)
if not model.ok:
    for diagnostic in model.diagnostics:
        print(diagnostic)
    raise SystemExit("The model has errors.")

print(model.eval("mass", subject="Demo::sedan"))
1800.0

model.ok is false when any diagnostic has error severity. Inspect model.diagnostics to report warnings and errors, or call opensysml.load(path, strict=True) / opensysml.loads(text, strict=True) to raise ModelError when errors are present. A strict-load error retains both the diagnostics and the partially parsed model.

Service unavailable

If the built-against release is unavailable, the client keeps a working cache or tries sysml-grpc on $PATH. If neither is usable, ConnectionError describes the attempted release and how to fix it, for example:

Could not download the sysml-grpc release ... Looked at: $OPENSYSML_BINARY,
~/.opensysml/bin/sysml-grpc, $PATH.
  fix: build it (`make build-grpc`) and set $OPENSYSML_BINARY to the result, or
       ask for another release by setting $OPENSYSML_GRPC_VERSION ...

A missing platform asset or a network outage is an availability failure. It may use an already-working cache or a binary on $PATH; otherwise the connection fails with the diagnostic above. A checksum mismatch or invalid signature is an integrity failure, not an availability fallback: the client raises an error instead of starting unverified release bytes.

To use a build you manage, build from the repository and name it explicitly:

make build-grpc
export OPENSYSML_BINARY="$PWD/bin/sysml-grpc"

An explicitly named binary is used as found and is not checked against release digests. Alternatively, set OPENSYSML_GRPC_VERSION to request another release, or install sysml-grpc on $PATH.

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