Variable: stream

stream: Stream

What

stream represents the stream which is being processed at the time. The stream object is available in any script-based Processor, e.g. the Python Processor.

How to use

You can access it directly without the need to instantiate it. It provides a number of functions which can - and sometimes have to - be invoked to control stream processing.

Please check the Stream documentation for more information.

Example

# Get stream information
stream_id = stream.getId()
stream_name = stream.getName()

# Emit a message to an output port
output_port = processor.getOutputPort('MyOutput')
stream.emit(message, output_port)

# Log information
stream.logInfo(f"Processing stream: {stream_name}")
stream.logWarning("Unusual data encountered in stream")
stream.logError("An error occurred during stream processing")

# Get stream metadata
metadata = stream.getMetadata()
file_size = metadata.data.Size  # For a file-based stream

# Set stream properties
stream.setOutputName('new_stream_name')
stream.setOutputPath('/new/output/path')

# Request retry or rollback
if error_condition:
    stream.requestRetry(Status.create(VENDOR, 'TEMPORARY_ERROR'), 30000)  # Retry after 30 seconds
if fatal_error:
    stream.requestRollback(Status.create(VENDOR, 'FATAL_ERROR'))

# Using stream in lifecycle hooks
def onStreamStart():
    global stream_id, file_name
    stream_id = stream.getId()
    file_name = stream.getName()
    stream.logInfo(f"Started processing stream: {file_name}")

def onStreamEnd():
    stream.logInfo(f"Finished processing stream: {file_name}")

def onMessage():
    # Process the message
    # ...
    # Emit the processed message
    stream.emit(message, output_port)

def onCommit():
    stream.logInfo(f"Stream {stream_id} committed successfully")

def onRollback():
    stream.logError(f"Stream {stream_id} rolled back due to errors")

Note: The exact methods and properties available on the stream object may vary depending on your specific layline.io configuration and the type of stream being processed. Always refer to the most up-to-date documentation provided by layline.io for the definitive guide on using the stream object in Python scripts.