weka.knowledgeflow

## Class StepManagerImpl

- java.lang.Object
- - weka.knowledgeflow.StepManagerImpl

- All Implemented Interfaces:
    StepManager

      public class StepManagerImpl
      extends java.lang.Object
      implements StepManager

  Concrete implementation of the StepManager interface. Has a number of methods, beyond those aimed at Step implementations, that are useful for applications that manipulate Steps and their connections.
  Version:
    $Revision: $
  Author:
    Mark Hall (mhall{[at]}pentaho{[dot]}com)

- - ### Field Summary

    - ### Fields inherited from interface weka.knowledgeflow.StepManager

      `CON_AUX_DATA_BATCH_ASSOCIATION_RULES, CON_AUX_DATA_CHART_DATA_POINT, CON_AUX_DATA_CHART_LEGEND, CON_AUX_DATA_CHART_MAX, CON_AUX_DATA_CHART_MIN, CON_AUX_DATA_CLASS_ATTRIBUTE, CON_AUX_DATA_GRAPH_TITLE, CON_AUX_DATA_GRAPH_TYPE, CON_AUX_DATA_INCREMENTAL_STREAM_END, CON_AUX_DATA_IS_INCREMENTAL, CON_AUX_DATA_LABEL, CON_AUX_DATA_MAX_SET_NUM, CON_AUX_DATA_SET_NUM, CON_AUX_DATA_TEST_INSTANCE, CON_AUX_DATA_TESTSET, CON_AUX_DATA_TEXT_TITLE, CON_AUX_DATA_TRAININGSET, CON_BATCH_ASSOCIATOR, CON_BATCH_CLASSIFIER, CON_BATCH_CLUSTERER, CON_CHART, CON_DATASET, CON_GRAPH, CON_IMAGE, CON_INCREMENTAL_CLASSIFIER, CON_INCREMENTAL_CLUSTERER, CON_INFO, CON_INSTANCE, CON_TESTSET, CON_TEXT, CON_THRESHOLD_DATA, CON_TRAININGSET, CON_VISUALIZABLE_ERROR`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `StepManagerImpl(Step step)` Constructor

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addIncomingConnection(java.lang.String connectionName, StepManagerImpl step)` Add an incoming connection (comprising of the type of connection and associated step component) to this step of the specified type
    `boolean` | `addOutgoingConnection(java.lang.String connectionName, StepManagerImpl step)` Add an outgoing connection (comprising of the type of connection and associated target step) to this step of the specified type.
    `boolean` | `addOutgoingConnection(java.lang.String connectionName, StepManagerImpl step, boolean force)` Add an outgoing connection (comprising of the type of connection and associated target step) to this step of the specified type.
    `void` | `addStepOutputListener(StepOutputListener listener, java.lang.String outputConnectionName)` Register non-step third party to receive data from the managed step for the specified outgoing connection type.
    `void` | `clearAllConnections()` Clear all connections to/from the step managed by this manager.
    `void` | `clearAllStepOutputListeners()` Clear all registered StepOutputListeners
    `void` | `clearStepOutputListeners(java.lang.String outputConnectionName)` Clear all the StepOutputListeners that are registered to receive the supplied connection type.
    `void` | `disconnectStep(Step toDisconnect)` Remove the supplied step from connections (both incoming and outgoing of all types) for the step managed by this manager.
    `void` | `disconnectStepWithConnection(Step toDisconnect, java.lang.String connType)` Disconnect the supplied step under the associated connection type from both the incoming and outgoing connections for the step managed by this manager.
    `java.lang.String` | `environmentSubstitute(java.lang.String source)` Substitute the values of environment variables in the given string
    `StepManager` | `findStepInFlow(java.lang.String stepNameToFind)` Finds a named step in the current flow.
    `void` | `finished()` Finished all processing.
    `ExecutionEnvironment` | `getExecutionEnvironment()` Get the execution environment the managed step is running in
    `java.util.List<StepManager>` | `getIncomingConnectedStepsOfConnectionType(java.lang.String connectionName)` Get a list of steps providing incoming connections of the specified type
    `StepManager` | `getIncomingConnectedStepWithName(java.lang.String stepName)` Get a named step connected to this step with an incoming connection
    `java.util.Map<java.lang.String,java.util.List<StepManager>>` | `getIncomingConnections()` Get the man of upstream (incoming connections) connected steps
    `Instances` | `getIncomingStructureForConnectionType(java.lang.String connectionName)` Attempt to get the incoming structure (as a header-only set of instances) for the named incoming connection type.
    `Instances` | `getIncomingStructureFromStep(StepManager sourceStep, java.lang.String connectionName)` Attempt to get the incoming structure (as a header-only set of instances) from the given managed step for the given connection type.
    `Step` | `getInfoStep()` Returns a reference to the step being managed if it has one or more outgoing CON_INFO connections.
    `Step` | `getInfoStep(java.lang.Class stepClass)` Returns a reference to the step being managed if it has one or more outgoing CON_INFO connections and the managed step is of the supplied class
    `Logger` | `getLog()` Get the log to use
    `LoggingLevel` | `getLoggingLevel()` Get the logging level in use
    `Step` | `getManagedStep()` Get the step managed by this manager
    `java.lang.String` | `getName()` Get the name of the Step being managed
    `java.util.List<StepManager>` | `getOutgoingConnectedStepsOfConnectionType(java.lang.String connectionName)` Get a list of downstream steps connected to this step with the given connection type.
    `StepManager` | `getOutgoingConnectedStepWithName(java.lang.String stepName)` Get a named step connected to this step with an outgoing connection
    `java.util.Map<java.lang.String,java.util.List<StepManager>>` | `getOutgoingConnections()` Get the map of downstream (outgoing connections) connected steps
    `Settings` | `getSettings()` Get the current knowledge flow settings
    `java.util.List<java.lang.String>` | `getStepOutgoingConnectionTypes()` Used by the rendering routine in LayoutPanel to ensure that connections downstream from a deleted connection get rendered in grey rather than red.
    `java.lang.Object` | `getStepProperty(java.lang.String name)` Get a named property for this step.
    `StepVisual` | `getStepVisual()` Get the step visual in use (if running in a visual environment)
    `void` | `interrupted()` Finished processing due to a stop being requested.
    `boolean` | `isStepBusy()` Returns true if, at the current time, the managed step is busy with processing
    `boolean` | `isStopRequested()` Return true if a stop has been requested by the runtime environment
    `boolean` | `isStreamFinished(Data data)` Returns true if this data object marks the end of an incremental stream.
    `void` | `log(java.lang.String message, LoggingLevel level)` Log a message at the supplied logging level
    `void` | `logBasic(java.lang.String message)` Log a message at the basic logging level
    `void` | `logDebug(java.lang.String message)` Log a message at the debugging logging level
    `void` | `logDetailed(java.lang.String message)` Log a message at the detailed logging level
    `void` | `logError(java.lang.String message, java.lang.Throwable cause)` Log an error
    `void` | `logLow(java.lang.String message)` Log a message at the low logging level
    `void` | `logWarning(java.lang.String message)` Log a warning message
    `int` | `numIncomingConnections()` Get the number of incoming connections to the managed step
    `int` | `numIncomingConnectionsOfType(java.lang.String connectionName)` Get the number of incoming connections to the managed step of a given type
    `int` | `numOutgoingConnections()` Get the number of outgoing connections from the managed step
    `int` | `numOutgoingConnectionsOfType(java.lang.String connectionName)` Get the number of outgoing connections from the managed step of a given type
    `void` | `outputData(Data... data)` Output one or more Data objects to all relevant steps.
    `void` | `outputData(java.lang.String outgoingConnectionName, Data data)` Output a Data object to all downstream connected Steps that are connected with the supplied connection name.
    `void` | `outputData(java.lang.String outgoingConnectionName, java.lang.String stepName, Data data)` Outputs the supplied Data object to the named Step.
    `void` | `processing()` Started processing.
    `void` | `removeIncomingConnection(java.lang.String connectionName, StepManagerImpl step)` Remove an incoming connection to this step of the specified type
    `void` | `removeOutgoingConnection(java.lang.String connectionName, StepManagerImpl step)` Remove an outgoing connection from this step of the specified type
    `void` | `removeStepOutputListener(StepOutputListener listener, java.lang.String outputConnectionName)` De-register non-step third party from receiving data from the managed step
    `void` | `setLog(Logger log)` Set the log to use
    `void` | `setLoggingLevel(LoggingLevel newLevel)` Set the logging level to use
    `void` | `setManagedStep(Step step)` Set the step managed by this manager
    `void` | `setStepIsResourceIntensive(boolean resourceIntensive)` Set whether the managed step is resource (cpu/memory) intensive or not
    `void` | `setStepProperty(java.lang.String name, java.lang.Object value)` Set a property for this step
    `void` | `setStepVisual(StepVisual visual)` Set the step visual to use when running in a graphical environment
    `void` | `setStopRequested(boolean stopRequested)` Set the status of the stop requested flag
    `void` | `statusMessage(java.lang.String message)` Output a status message to the status area of the log
    `boolean` | `stepIsResourceIntensive()` Get whether the managed step is resource (cpu/memory) intensive or not
    `java.lang.String` | `stepStatusMessagePrefix()` Gets a prefix for the step managed by this manager.
    `void` | `throughputFinished(Data... data)` Clients can use this to indicate that throughput measuring is finished (i.e.
    `void` | `throughputUpdateEnd()` Clients can use this to record a stop point for streaming throughput measuring
    `void` | `throughputUpdateStart()` Clients can use this to record a start point for streaming throughput measuring

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### StepManagerImpl

          public StepManagerImpl(Step step)

      Constructor
      Parameters:
        `step` - the Step to manage

  - ### Method Detail

    - #### getName

          public java.lang.String getName()

      Get the name of the Step being managed
      Specified by:
        `getName` in interface `StepManager`
      Returns:
        the name of the Step being managed

    - #### getManagedStep

          public Step getManagedStep()

      Get the step managed by this manager
      Specified by:
        `getManagedStep` in interface `StepManager`
      Returns:
        the step managed by this manager

    - #### setManagedStep

          public void setManagedStep(Step step)

      Set the step managed by this manager
      Parameters:
        `step` - the step to manage

    - #### setStepIsResourceIntensive

          public void setStepIsResourceIntensive(boolean resourceIntensive)

      Set whether the managed step is resource (cpu/memory) intensive or not
      Specified by:
        `setStepIsResourceIntensive` in interface `StepManager`
      Parameters:
        `resourceIntensive` - true if the managed step is resource intensive

    - #### stepIsResourceIntensive

          public boolean stepIsResourceIntensive()

      Get whether the managed step is resource (cpu/memory) intensive or not
      Specified by:
        `stepIsResourceIntensive` in interface `StepManager`
      Returns:
        true if the step is resource intensive

    - #### getStepVisual

          public StepVisual getStepVisual()

      Get the step visual in use (if running in a visual environment)
      Returns:
        the step visual in use

    - #### setStepVisual

          public void setStepVisual(StepVisual visual)

      Set the step visual to use when running in a graphical environment
      Parameters:
        `visual` - the step visual to use

    - #### setStepProperty

          public void setStepProperty(java.lang.String name,
                                      java.lang.Object value)

      Set a property for this step
      Parameters:
        `name` - the name of the property
        `value` - the value of the property

    - #### getStepProperty

          public java.lang.Object getStepProperty(java.lang.String name)

      Get a named property for this step.
      Parameters:
        `name` - the name of the property to get
      Returns:
        the value of the property or null if the property is not set

    - #### getExecutionEnvironment

          public ExecutionEnvironment getExecutionEnvironment()

      Get the execution environment the managed step is running in
      Specified by:
        `getExecutionEnvironment` in interface `StepManager`
      Returns:
        the execution environment

    - #### getSettings

          public Settings getSettings()

      Get the current knowledge flow settings
      Specified by:
        `getSettings` in interface `StepManager`
      Returns:
        the current knowledge flow settings
      Throws:
        `java.lang.IllegalStateException` - if there is no execution environment available

    - #### getLoggingLevel

          public LoggingLevel getLoggingLevel()

      Get the logging level in use
      Specified by:
        `getLoggingLevel` in interface `StepManager`
      Returns:
        the logging level in use

    - #### setLoggingLevel

          public void setLoggingLevel(LoggingLevel newLevel)

      Set the logging level to use
      Parameters:
        `newLevel` - the level to use

    - #### getLog

          public Logger getLog()

      Get the log to use
      Specified by:
        `getLog` in interface `StepManager`
      Returns:
        the log in use or null if no log has been set

    - #### setLog

          public void setLog(Logger log)

      Set the log to use
      Parameters:
        `log` - the log to use

    - #### isStepBusy

          public boolean isStepBusy()

      Returns true if, at the current time, the managed step is busy with processing
      Specified by:
        `isStepBusy` in interface `StepManager`
      Returns:
        true if the managed step is busy with processing

    - #### isStopRequested

          public boolean isStopRequested()

      Return true if a stop has been requested by the runtime environment
      Specified by:
        `isStopRequested` in interface `StepManager`
      Returns:
        true if a stop has been requested

    - #### setStopRequested

          public void setStopRequested(boolean stopRequested)

      Set the status of the stop requested flag
      Parameters:
        `stopRequested` - true if a stop has been requested

    - #### processing

          public void processing()

      Started processing. Sets the busy flag to true.
      Specified by:
        `processing` in interface `StepManager`

    - #### finished

          public void finished()

      Finished all processing. Sets the busy flag to false and prints a finished message to the status area of the log.
      Specified by:
        `finished` in interface `StepManager`

    - #### interrupted

          public void interrupted()

      Finished processing due to a stop being requested. Sets the busy flag to false.
      Specified by:
        `interrupted` in interface `StepManager`

    - #### isStreamFinished

          public boolean isStreamFinished(Data data)

      Returns true if this data object marks the end of an incremental stream. Note - does not check that the data object is actually an incremental one of some sort! Just checks to see if the CON_AUX_DATA_INCREMENTAL_STREAM_END flag is set to true or not;
      Specified by:
        `isStreamFinished` in interface `StepManager`
      Parameters:
        `data` - the data element to check
      Returns:
        true if the data element is flagged as end of stream

    - #### throughputUpdateStart

          public void throughputUpdateStart()

      Clients can use this to record a start point for streaming throughput measuring
      Specified by:
        `throughputUpdateStart` in interface `StepManager`

    - #### throughputUpdateEnd

          public void throughputUpdateEnd()

      Clients can use this to record a stop point for streaming throughput measuring
      Specified by:
        `throughputUpdateEnd` in interface `StepManager`

    - #### throughputFinished

          public void throughputFinished(Data... data)
                                  throws WekaException

      Clients can use this to indicate that throughput measuring is finished (i.e. the stream being processed has ended). Final throughput information is printed to the log and status
      Specified by:
        `throughputFinished` in interface `StepManager`
      Parameters:
        `data` - one or more Data events (with appropriate connection type set) to pass on to downstream connected steps. These are used to carry any final data and to inform the downstream step(s) that the stream has ended
      Throws:
        `WekaException` - if a problem occurs

    - #### disconnectStepWithConnection

          public void disconnectStepWithConnection(Step toDisconnect,
                                                   java.lang.String connType)

      Disconnect the supplied step under the associated connection type from both the incoming and outgoing connections for the step managed by this manager. Does nothing if this step does not have any connections to the supplied step, or does not have connections to the supplied step of the required type.
      Parameters:
        `toDisconnect` - the step to disconnect
        `connType` - the connection type to disconnect

    - #### disconnectStep

          public void disconnectStep(Step toDisconnect)

      Remove the supplied step from connections (both incoming and outgoing of all types) for the step managed by this manager. Does nothing if the this step does not have any connections to the supplied step
      Parameters:
        `toDisconnect` - the step to disconnect

    - #### clearAllConnections

          public void clearAllConnections()

      Clear all connections to/from the step managed by this manager. Also makes sure that all directly connected upstream and downstream steps remove their respective outgoing and incoming connections to this step

    - #### addIncomingConnection

          public void addIncomingConnection(java.lang.String connectionName,
                                            StepManagerImpl step)

      Add an incoming connection (comprising of the type of connection and associated step component) to this step of the specified type
      Parameters:
        `connectionName` - the name of the type of connection to add
        `step` - the source step component that is connecting with given connection type

    - #### removeIncomingConnection

          public void removeIncomingConnection(java.lang.String connectionName,
                                               StepManagerImpl step)

      Remove an incoming connection to this step of the specified type
      Parameters:
        `connectionName` - the name of the type of connection to remove
        `step` - the source step component associated with the given connection type

    - #### addOutgoingConnection

          public boolean addOutgoingConnection(java.lang.String connectionName,
                                               StepManagerImpl step)

      Add an outgoing connection (comprising of the type of connection and associated target step) to this step of the specified type. Connection is only made if the target step will accept the connection type at this time
      Parameters:
        `connectionName` - the name of the type of connection to add
        `step` - the target step component that is receiving the given connection type it can't accept the connection at the present time
      Returns:
        true if the connection was successful

    - #### addOutgoingConnection

          public boolean addOutgoingConnection(java.lang.String connectionName,
                                               StepManagerImpl step,
                                               boolean force)

      Add an outgoing connection (comprising of the type of connection and associated target step) to this step of the specified type. Connection is only made if the target step will accept the connection type at this time
      Parameters:
        `connectionName` - the name of the type of connection to add
        `step` - the target step component that is receiving the given connection type
        `force` - whether to force the connection, even if the target step says it can't accept the connection at the present time
      Returns:
        true if the connection was successful

    - #### removeOutgoingConnection

          public void removeOutgoingConnection(java.lang.String connectionName,
                                               StepManagerImpl step)

      Remove an outgoing connection from this step of the specified type
      Parameters:
        `connectionName` - the name of the type of connection to remove
        `step` - the target step component associated with the given connection type

    - #### getIncomingConnectedStepsOfConnectionType

          public java.util.List<StepManager> getIncomingConnectedStepsOfConnectionType(java.lang.String connectionName)

      Get a list of steps providing incoming connections of the specified type
      Specified by:
        `getIncomingConnectedStepsOfConnectionType` in interface `StepManager`
      Parameters:
        `connectionName` - the type of connection being received by this step
      Returns:
        a list of connected steps

    - #### getOutgoingConnectedStepsOfConnectionType

          public java.util.List<StepManager> getOutgoingConnectedStepsOfConnectionType(java.lang.String connectionName)

      Description copied from interface: `StepManager`
      Get a list of downstream steps connected to this step with the given connection type.
      Specified by:
        `getOutgoingConnectedStepsOfConnectionType` in interface `StepManager`
      Parameters:
        `connectionName` - the name of the outgoing connection
      Returns:
        a list of downstream steps connected to this one with the named connection type

    - #### getIncomingConnectedStepWithName

          public StepManager getIncomingConnectedStepWithName(java.lang.String stepName)

      Get a named step connected to this step with an incoming connection
      Specified by:
        `getIncomingConnectedStepWithName` in interface `StepManager`
      Parameters:
        `stepName` - the name of the step to look for
      Returns:
        the connected step

    - #### getOutgoingConnectedStepWithName

          public StepManager getOutgoingConnectedStepWithName(java.lang.String stepName)

      Get a named step connected to this step with an outgoing connection
      Specified by:
        `getOutgoingConnectedStepWithName` in interface `StepManager`
      Parameters:
        `stepName` - the name of the step to look for
      Returns:
        the connected step

    - #### getOutgoingConnections

          public java.util.Map<java.lang.String,java.util.List<StepManager>> getOutgoingConnections()

      Get the map of downstream (outgoing connections) connected steps
      Specified by:
        `getOutgoingConnections` in interface `StepManager`
      Returns:
        the map of downstream connected steps

    - #### getIncomingConnections

          public java.util.Map<java.lang.String,java.util.List<StepManager>> getIncomingConnections()

      Get the man of upstream (incoming connections) connected steps
      Specified by:
        `getIncomingConnections` in interface `StepManager`
      Returns:
        the map of upstream connected steps

    - #### addStepOutputListener

          public void addStepOutputListener(StepOutputListener listener,
                                            java.lang.String outputConnectionName)

      Register non-step third party to receive data from the managed step for the specified outgoing connection type. Output listeners are not serialized into the JSON flow when flows are saved.
      Parameters:
        `listener` - the output listener to register
        `outputConnectionName` - the name of the connection type

    - #### removeStepOutputListener

          public void removeStepOutputListener(StepOutputListener listener,
                                               java.lang.String outputConnectionName)

      De-register non-step third party from receiving data from the managed step
      Parameters:
        `listener` - the output listener to de-register
        `outputConnectionName` - the name of the connection type the listener is registered against

    - #### clearAllStepOutputListeners

          public void clearAllStepOutputListeners()

      Clear all registered StepOutputListeners

    - #### clearStepOutputListeners

          public void clearStepOutputListeners(java.lang.String outputConnectionName)

      Clear all the StepOutputListeners that are registered to receive the supplied connection type.
      Parameters:
        `outputConnectionName` - type of the connection to clear the listeners for

    - #### outputData

          public void outputData(java.lang.String outgoingConnectionName,
                                 Data data)
                          throws WekaException

      Output a Data object to all downstream connected Steps that are connected with the supplied connection name. Sets the connection type on the supplied Data object to the supplied connection name. Also notifies any registered StepOutputListeners.
      Specified by:
        `outputData` in interface `StepManager`
      Parameters:
        `outgoingConnectionName` - the type of the outgoing connection to send data to
        `data` - a single Data object to send
      Throws:
        `WekaException`

    - #### outputData

          public void outputData(Data... data)
                          throws WekaException

      Output one or more Data objects to all relevant steps. Populates the source in each Data object for the client, HOWEVER, the client must have populated the connection type in each Data object to be output so that the StepManager knows which connected steps to send the data to. Also notifies any registered `StepOutputListeners`. Note that the downstream step(s)' processIncoming() method is called in a separate thread for batch connections. Furthermore, if multiple Data objects are supplied via the varargs argument, and a target step will receive more than one of the Data objects, then they will be passed on to the step in question sequentially within the same thread of execution.
      Specified by:
        `outputData` in interface `StepManager`
      Parameters:
        `data` - one or more Data objects to be sent
      Throws:
        `WekaException` - if a problem occurs

    - #### outputData

          public void outputData(java.lang.String outgoingConnectionName,
                                 java.lang.String stepName,
                                 Data data)
                          throws WekaException

      Outputs the supplied Data object to the named Step. Does nothing if the named step is not connected immediately downstream of this Step. Sets the supplied connection name on the Data object. Also notifies any StepOutputListeners.
      Specified by:
        `outputData` in interface `StepManager`
      Parameters:
        `outgoingConnectionName` - the name of the outgoing connection
        `stepName` - the name of the step to send the data to
        `data` - the data to send
      Throws:
        `WekaException`

    - #### getStepOutgoingConnectionTypes

          public java.util.List<java.lang.String> getStepOutgoingConnectionTypes()

      Used by the rendering routine in LayoutPanel to ensure that connections downstream from a deleted connection get rendered in grey rather than red.
      Returns:
        a list of outgoing connection types that the managed step can produce (adjusted to take into account any upstream broken connections)

    - #### numIncomingConnections

          public int numIncomingConnections()

      Get the number of incoming connections to the managed step
      Specified by:
        `numIncomingConnections` in interface `StepManager`
      Returns:
        the number of incoming connections

    - #### numIncomingConnectionsOfType

          public int numIncomingConnectionsOfType(java.lang.String connectionName)

      Get the number of incoming connections to the managed step of a given type
      Specified by:
        `numIncomingConnectionsOfType` in interface `StepManager`
      Parameters:
        `connectionName` - the name of the connection type
      Returns:
        the number of incoming connections of this type

    - #### numOutgoingConnections

          public int numOutgoingConnections()

      Get the number of outgoing connections from the managed step
      Specified by:
        `numOutgoingConnections` in interface `StepManager`
      Returns:
        the number of incoming connections

    - #### numOutgoingConnectionsOfType

          public int numOutgoingConnectionsOfType(java.lang.String connectionName)

      Get the number of outgoing connections from the managed step of a given type
      Specified by:
        `numOutgoingConnectionsOfType` in interface `StepManager`
      Parameters:
        `connectionName` - the name of the connection type
      Returns:
        the number of outgoing connections of this type

    - #### getIncomingStructureForConnectionType

          public Instances getIncomingStructureForConnectionType(java.lang.String connectionName)
                                                          throws WekaException

      Attempt to get the incoming structure (as a header-only set of instances) for the named incoming connection type. Assumes that there is only one incoming connection of the named type. If there are zero, or more than one, then null is returned
      Specified by:
        `getIncomingStructureForConnectionType` in interface `StepManager`
      Parameters:
        `connectionName` - the name of the incoming connection to get the structure for
      Returns:
        the structure as a header-only set of instances or null if there are zero or more than one upstream connected steps producing the named connection, or if the upstream step can't tell us the structure, or if the upstream step can't represent the structure of the connection type as a set of instances.
      Throws:
        `WekaException` - if a problem occurs

    - #### getIncomingStructureFromStep

          public Instances getIncomingStructureFromStep(StepManager sourceStep,
                                                        java.lang.String connectionName)
                                                 throws WekaException

      Attempt to get the incoming structure (as a header-only set of instances) from the given managed step for the given connection type.
      Specified by:
        `getIncomingStructureFromStep` in interface `StepManager`
      Parameters:
        `sourceStep` - the step manager managing the source step
        `connectionName` - the name of the connection to attempt to get the structure for
      Returns:
        the structure as a header-only set of instances, or null if the source step can't determine this at present or if it can't be represented as a set of instances.
      Throws:
        `WekaException` - if a problem occurs

    - #### logLow

          public void logLow(java.lang.String message)

      Log a message at the low logging level
      Specified by:
        `logLow` in interface `StepManager`
      Parameters:
        `message` - the message to log

    - #### logBasic

          public void logBasic(java.lang.String message)

      Log a message at the basic logging level
      Specified by:
        `logBasic` in interface `StepManager`
      Parameters:
        `message` - the message to log

    - #### logDetailed

          public void logDetailed(java.lang.String message)

      Log a message at the detailed logging level
      Specified by:
        `logDetailed` in interface `StepManager`
      Parameters:
        `message` - the message to log

    - #### logDebug

          public void logDebug(java.lang.String message)

      Log a message at the debugging logging level
      Specified by:
        `logDebug` in interface `StepManager`
      Parameters:
        `message` - the message to log

    - #### logWarning

          public void logWarning(java.lang.String message)

      Log a warning message
      Specified by:
        `logWarning` in interface `StepManager`
      Parameters:
        `message` - the message to log

    - #### logError

          public void logError(java.lang.String message,
                               java.lang.Throwable cause)

      Log an error
      Specified by:
        `logError` in interface `StepManager`
      Parameters:
        `message` - the message to log
        `cause` - the optional Throwable to log

    - #### statusMessage

          public void statusMessage(java.lang.String message)

      Output a status message to the status area of the log
      Specified by:
        `statusMessage` in interface `StepManager`
      Parameters:
        `message` - the message to output

    - #### log

          public void log(java.lang.String message,
                          LoggingLevel level)

      Log a message at the supplied logging level
      Specified by:
        `log` in interface `StepManager`
      Parameters:
        `message` - the message to write
        `level` - the level for the message

    - #### environmentSubstitute

          public java.lang.String environmentSubstitute(java.lang.String source)

      Substitute the values of environment variables in the given string
      Specified by:
        `environmentSubstitute` in interface `StepManager`
      Parameters:
        `source` - the source string to substitute in
      Returns:
        the source string with all known environment variables resolved

    - #### getInfoStep

          public Step getInfoStep(java.lang.Class stepClass)
                           throws WekaException

      Returns a reference to the step being managed if it has one or more outgoing CON_INFO connections and the managed step is of the supplied class
      Specified by:
        `getInfoStep` in interface `StepManager`
      Parameters:
        `stepClass` - the expected class of the step
      Returns:
        the step being managed if outgoing CON_INFO connections are present and the step is of the supplied class
      Throws:
        `WekaException` - if there are no outgoing CON_INFO connections or the managed step is the wrong type

    - #### getInfoStep

          public Step getInfoStep()
                           throws WekaException

      Returns a reference to the step being managed if it has one or more outgoing CON_INFO connections.
      Specified by:
        `getInfoStep` in interface `StepManager`
      Returns:
        the step being managed if outgoing CON_INFO connections are present
      Throws:
        `WekaException` - if there are no outgoing CON_INFO connections

    - #### findStepInFlow

          public StepManager findStepInFlow(java.lang.String stepNameToFind)

      Finds a named step in the current flow. Returns null if the named step is not present in the flow
      Specified by:
        `findStepInFlow` in interface `StepManager`
      Parameters:
        `stepNameToFind` - the name of the step to find
      Returns:
        the StepManager of the named step, or null if the step does not exist in the current flow.

    - #### stepStatusMessagePrefix

          public java.lang.String stepStatusMessagePrefix()

      Gets a prefix for the step managed by this manager. Used to uniquely identify steps in the status area of the log
      Returns:
        a unique prefix for the step managed by this manager