IBM Streams 4.2.1

SPL File command.spl

SPL standard and specialized toolkits > com.ibm.streamsx.iot 1.1.0.commit_67acf7a > com.ibm.streamsx.iot > command.spl

Content

Operators

Composites

composite CommandTupleToPayload(output stream<DeviceCmd> DeviceCommands; input Commands)

Convert tuples to device commands. Convert input tuples to device commands that can be submitted to CommandPublish or SendCommandToDevice. The input port schema must include:
  • Attributes defining the device to receive a command matching DeviceCmdId.
  • A nested tuple with attribute name specified by the payload parameter.

The contents of the nested tuple are converted to JSON and used as the payload of the device command.

An example of how to invoke this operator. First have an SPL type that forms the content of the command's payload. The values in the type will be converted to JSON and used as the command's payload.

type StatusMsg = rstring message, rstring severity;

The input schema to this operator requires DeviceCmdId and the payload type as a nested tuple, for example:

stream<DeviceCmdId, tuple<StatusMsg msgs>> StatusMsgCommands = ...

Stream StatusMsgCommands is fed into this operator and then CommandPublish or SendCommandToDevice. The invocation of this operator specifies which nested tuple attribute maps to the command payload using the payload parameter. In this case setting payload to msgs.

// Convert them into the required schema
stream<DeviceCmd> StatusMsgCommandsJson = CommandTupleToPayload(StatusMsgCommands)
{
  param
    payload: msgs;
}

// And then publish them
() as PublishStatusMsgCmds = CommandPublish(StatusMsgCommandsJson) {}

This will result in a device command payload of:

{"message": "Warning Black Ice Ahead", "severity": "HIGH"}

Parameters

  • payload: Attribute of nested tuple that will be the command payload.

Input Ports

  • Commands: Input stream of commands, must be a super-set of DeviceCmdId.

Output Ports