ni_measurementlink_service

MeasurementLink Support for Python.

Subpackages

• ni_measurementlink_service.measurement
  • ni_measurementlink_service.measurement.info
  • ni_measurementlink_service.measurement.service

Submodules

• ni_measurementlink_service.session_management

Package Contents

Classes

DataType	Enum that represents the supported data types.
MeasurementInfo	Class that represents the measurement information.
ServiceInfo	Class the represents the service information.
MeasurementService	Class that supports registering and hosting a python function as a gRPC service.

class ni_measurementlink_service.DataType

Bases: enum.Enum

Enum that represents the supported data types.

Int32

Int64

UInt32

UInt64

Float

Double

Boolean

String

Pin

Path

Int32Array1D

Int64Array1D

UInt32Array1D

UInt64Array1D

FloatArray1D

DoubleArray1D

BooleanArray1D

StringArray1D

PinArray1D

PathArray1D

class ni_measurementlink_service.MeasurementInfo

Bases: NamedTuple

Class that represents the measurement information.

Attributes

display_name (str): The measurement display name for client to display to user.

version (str): The measurement version that helps to maintain versions of a measurement in future.

ui_file_paths (list): Absolute paths of the UI file(s) linked to the measurement.

display_name :str

version :str

ui_file_paths :List[pathlib.Path]

class ni_measurementlink_service.ServiceInfo

Bases: NamedTuple

Class the represents the service information.

Attributes

service_class (str): Service class that the measurement belongs to. Measurements under same service class expected to perform same logic. For e.g., different version of measurement can come under same service class.

description_url (str): Description URL of the measurement.

service_class :str

description_url :str

class ni_measurementlink_service.MeasurementService(service_config_path, version, ui_file_paths, service_class=None)

Class that supports registering and hosting a python function as a gRPC service.

Attributes

measurement_info (info.MeasurementInfo): Measurement info

service_info(info.ServiceInfo) : Service Info

configuration_parameter_list (List): List of configuration parameters.

output_parameter_list (list): List of output parameters.

measure_function (Callable): Registered measurement function.

context (MeasurementContext): Accessor for context-local state.

discovery_client (DiscoveryClient): Client for accessing the MeasurementLink discovery

service.

channel_pool (GrpcChannelPool): Pool of gRPC channels used by the service.

register_measurement(measurement_function)

Register a function as the measurement function for a measurement service.

To declare a measurement function, use this idiom:

``` @measurement_service.register_measurement @measurement_service.configuration(“Configuration 1”, …) @measurement_service.configuration(“Configuration 2”, …) @measurement_service.output(“Output 1”, …) @measurement_service.output(“Output 2”, …) def measure(configuration1, configuration2):

… return (output1, output2)

```

See also: configuration(), output()

configuration(display_name, type, default_value, *, instrument_type='')

Add a configuration parameter to a measurement function.

This decorator maps the measurement service’s configuration parameters to Python positional parameters. To add multiple configuration parameters to the same measurement function, use this decorator multiple times. The order of decorator calls must match the order of positional parameters.

See also: register_measurement()

Args

display_name (str): Display name of the configuration.

type (DataType): Data type of the configuration.

default_value (Any): Default value of the configuration.

instrument_type (str): Optional. Filter pins by instrument type. This is only supported when configuration type is DataType.Pin. Pin maps have built in instrument definitions using the NI driver based instrument type ids. These can be found as constants in nims.session_management. For example, for an NI DCPower instrument the instrument type is nims.session_management.INSTRUMENT_TYPE_NI_DCPOWER. For custom instruments the user defined instrument type id is defined in the pin map file.

Returns

Callable: Callable that takes in Any Python Function and returns the same python function.

output(display_name, type)

Add a output parameter to a measurement function.

This decorator maps the measurement service’s output parameters to the elements of the tuple returned by the measurement function. To add multiple output parameters to the same measurement function, use this decorator multiple times. The order of decorator calls must match the order of elements returned by the measurement fuction.

See also: register_measurement()

Args

display_name (str): Display name of the output.

type (DataType): Data type of the output.

Returns

Callable: Callable that takes in Any Python Function and returns the same python function.

host_service()

Host the registered measurement method as gRPC measurement service.

Returns

MeasurementService: Context manager that can be used with a with-statement to close the service.

Raises

Exception: If register measurement methods not available.

close_service()

Close the Service after un-registering with discovery service and cleanups.

__enter__()

Enter the runtime context related to the measurement service.

__exit__(exc_type, exc_value, traceback)

Exit the runtime context related to the measurement service.

get_channel(provided_interface, service_class='')

Return gRPC channel to specified service.

Args

provided_interface (str): The gRPC Full Name of the service.

service_class (str): The service “class” that should be matched.

Returns

grpc.Channel: A channel to the gRPC service.

Raises

Exception: If service_class is not specified and there is more than one matching service

registered.