Create a demo SunSpec server

[altendky]

Long term it would be nifty to have a server that fully implements lots of features that the embedded system has... short term, let's focus on having something we can use with the application while we are playing with it. Maybe start with these features.

• Some data points that fluctuate so a client can observe varying values
• A CLI to launch the server
• Ability to launch and stop the server from within the present basic gui

Without saying this is well organized, there is an existing fixture used with the test code that can act as an example of a static SunSpec server. I have not yet looked through to plan out what bits need to change or what this should look like overall.

ssst/src/ssst/_tests/conftest.py

Lines 35 to 63 in 46232ec

	@pytest.fixture(name="sunspec_server")
	async def sunspec_server_fixture(
	nursery: trio.Nursery,
	) -> typing.AsyncIterator[SunSpecServerFixtureResult]:
	model_summaries = [
	ssst.sunspec.server.ModelSummary(id=1, length=66),
	ssst.sunspec.server.ModelSummary(id=17, length=12),
	ssst.sunspec.server.ModelSummary(id=103, length=50),
	ssst.sunspec.server.ModelSummary(id=126, length=226),
	]
	server = ssst.sunspec.server.Server.build(model_summaries=model_summaries)
	host = "127.0.0.1"
	[listener] = await nursery.start(
	functools.partial(
	trio.serve_tcp,
	server.tcp_server,
	host=host,
	port=0,
	),
	)
	yield SunSpecServerFixtureResult(
	host=host,
	port=listener.socket.getsockname()[1],
	server=server,
	)

While we will also be adding a client to the GUI (see #26), various existing tools can be used to poke at this server as well since it will be a standard Modbus TCP server. There is the pymodbus REPL and the EPC Power SunSpec demo and presumably various other Modbus clients such as QModBus.

[altendky]

Does this actually belong in https:/altendky/sundog?