`etm.wccoa.msa.vrpc`

vRPC — the MSA protocol that carries a WinCC OA value as its payload.

This is the package applications import. It is deliberately flat and hides the split between MSA and the protocol: the re-exported names are the very same types as in etm.wccoa.msa.base, so vrpc.Status is base.Status.

These names are re-exported unchanged and documented where they are defined: AsyncUnaryCall, Metadata, PayloadEncryptionMode, Responder, RpcError, ServerContext, ServiceContainer, ServiceHostingReplica, ServiceHostingType, ServiceOptions, ServiceStatus, Status, StatusCode, StubOptions, StubStatus.

Example

>>> from etm.wccoa.msa import vrpc
>>> stub = vrpc.Stub.create_and_initialize(mgr, "Greeter")
>>> stub.call_function("SayHello", "Bob")

Package Contents

Classes


`ServiceBase`	Derive from this to offer a service, and register the methods in `__init__`.
`Stub`	Calls methods of a service that another manager offers.

Data


`UnaryHandler`	Form S1 — the return value is the response.
`UnaryResponderHandler`	Form S3 — the response is sent later, from any thread.

API

class etm.wccoa.msa.vrpc.ServiceBase(service_name: str)

Bases: etm.wccoa.msa.base.ServiceBase

Derive from this to offer a service, and register the methods in __init__.

Handlers run on the service’s own thread, one after another, so they need not be thread safe. Returning a value answers the call (S1); taking a third parameter defers the answer (S3).

Example

>>> class GreeterService(ServiceBase):
...     def __init__(self) -> None:
...         super().__init__("Greeter")
...         self.register_function("SayHello", self._say_hello)
...
...     def _say_hello(self, ctx: ServerContext, request: OaVariant) -> OaValueLike:
...         return f"Hello {request}"

Initialization

Build the native service; the protocol layer supplies its identity.

register_function(method: str, handler: etm.wccoa.msa.vrpc._server._service.UnaryHandler | etm.wccoa.msa.vrpc._server._service.UnaryResponderHandler) → None

Bind a wire name to a handler.

The name is always given explicitly; nothing is derived from the Python method name and no case conversion takes place.

Raises:
- ValueError – if the name is already registered, or if the handler is neither of the two forms.

property service_name : str

class etm.wccoa.msa.vrpc.Stub(manager: etm.wccoa.manager.Manager, service_base_name: str, options: etm.wccoa.msa.base.StubOptions | None = None)

Calls methods of a service that another manager offers.

The constructor does not communicate. Initialization happens explicitly via initialize(), through create_and_initialize(), or implicitly on the first call.

Example

>>> with Stub(mgr, "Greeter") as stub:
...     stub.call_function("SayHello", "Bob")

Initialization

classmethod create_and_initialize(manager: etm.wccoa.manager.Manager, service_base_name: str, options: etm.wccoa.msa.base.StubOptions | None = None) → etm.wccoa.msa.vrpc._client._stub.Stub

Construct and initialize in one step.

Returns: The initialized stub.

initialize() → None

Look the service up and prepare the connection.

The call is idempotent.

Raises:
- RpcError – if the service cannot be reached.

property status : etm.wccoa.msa.base.StubStatus

Where this stub stands in its lifecycle.

This can be found at: etm.wccoa.msa.base.StubStatus

property is_initialized : bool

True once status is INIT_DONE.

call_function(method: str, request: etm.wccoa.datatypes.OaValueLike, *, deadline: datetime.datetime | None = None, headers: etm.wccoa.datatypes.Metadata | None = None) → etm.wccoa.datatypes.OaVariant

Call method and wait for the response.

method is the wire name and is compared ignoring case only — say_hello is a different method than sayHello. A naive deadline is read as local time.

Only the response value is returned. Use call_function_async() when the status or the response and trailing headers are needed as well.

Returns: The response value.
Raises:
- RpcError – if the call failed.

call_function_async(method: str, request: etm.wccoa.datatypes.OaValueLike, *, deadline: datetime.datetime | None = None, headers: etm.wccoa.datatypes.Metadata | None = None) → etm.wccoa.msa.base.AsyncUnaryCall

Start method and return the handle at once.

Returns: The handle of the running call.

close() → None

Release the native invoker. Idempotent.

etm.wccoa.msa.vrpc.UnaryHandler : TypeAlias

None

Form S1 — the return value is the response.

etm.wccoa.msa.vrpc.UnaryResponderHandler : TypeAlias

None

Form S3 — the response is sent later, from any thread.