Functions (Azure Stream Analytics)

 

Updated: February 8, 2016

A (User-Defined) Function provides an extensible way for a Streaming Job to transform input data to output data using a facility that is not completely described by the Transformation query. Currently Azure Machine Learning Request-Response Service (RRS) is the supported UDF framework.

Request

The Function property is a properties bag needed to completely specify the information needed to make use of an Azure Machine Learning function.

{
  "type": <function type>,
  "properties": {
    .
    .
    .
  }
}

Type: Scalar

Properties

Azure Machine Learning Request-Response Service (RRS) Endpoint

A transformation query can call out to an operationalized Azure ML Request-Response Service (RRS) endpoint to perform scoring against a trained model. The properties in the property bag are just those needed to call the operationalized RRS endpoint.

Example payload to create an Azure Machine Learning scalar function

{
  "name": "scoreTweet",
  "properties": {
    "type": "Scalar",
    "properties": {
      "inputs": [
        {
          "dataType": "nvarchar(max)",
          "isConfigurationParameter": false
        }
      ],
      "output": {
        "dataType": "nvarchar(max)"
      },
      "binding": {
        "type": "Microsoft.MachineLearning/WebService",
        "properties": {
          "endpoint": "https://ussouthcentral.services.azureml.net/workspaces/f80d5d7a77fa4a46bf2a30c63c078dca/services/b7be5e40fd194258896fb602c1858eaf/execute",
          "apiKey": "apiKey",
          "inputs": {
            "name": "input1",
            "columnNames": [
              {
                "name": "tweet",
                "dataType": "String",
                "mapTo": 0
              }
            ]
          },
          "outputs": [
            {
              "name": "Sentiment",
              "dataType": "String"
            }
          ],
          "batchSize": 100
        }
      }
    }
  }
}

Property	Description
name	Name of the UDF
Type	Scalar
inputs	An array of inputs, describing the parameters of the UDF.
Inputs.dataType	Data type of the UDF parameter. List of valid Azure Stream Analytics data types are described at Azure Stream Analytics data types.
Input.isConfigurationParameter	Optional. True if this parameter is expected to be a constant. Default is false.
output	Described output of the UDF.
Output.dataType	Data type of UDF output. List of valid Azure Stream Analytics data types are described at Azure Stream Analytics data types.
Binding	Described the physical binding for the UDF. For example, in Azure Machine Learning RRS's this described the endpoint.
Binding.Type	Type of the binding. Currently Microsoft.MachineLearning/WebService is the only valid binding at this time.
Binding.Properties	Properties for the binding. Values are dependent on the type of binding.

Binding properties for Microsoft.MachineLearning/WebService.

Property	Description
Endpoint	Request-Response execute endpoint of Azure Machine Learning Webservice. This endpoint is available from the Request-Response Endpoint documentation page in the Azure Management portal.
apiKey	API key used to authenticate with Request-Response endpoint. This is available from the Azure Management portal.
batchSize	Optional. Value between 10 and 1000 describing maximum number of rows for every Azure Machine Learning RRS execute request. Default is 10.
Inputs	Describes the set of inputs for RRS enpoint.
Inputs.name	Name of the input. This is the name provided while authoring the endpoint. The name is available from Azure Machine Learning Studio or from the RRS endpoint documentation page.
Input.ColumnNames	Array describing inputs to Azure Machine Learning endpoint

Element properties of Input.ColumnNames

Property	Description
Name	Name of the input column.
dataType	Azure Machine Learning data type. List of valid types are available at Azure Machine Learning data types. These are also described in RRS endpoint documentation.
MapTo	Zero based index of the UDF parameter this input maps to.
Outputs	Array describing outputs from an Azure Machine Learning RRS endpoint execution.

Element properties of Outputs

Property	Description
Name	Name of the output column.
dataType	Azure Machine Learning data type. List of valid types are available at Azure Machine Learning data types. These are also described in RRS endpoint documentation.