About FlowFileSource

Class nifiapi.flowfilesource.FlowFileSource

All NiFi flows start with a Source Processor that creates new Flow Files either internally or from an external source, the FlowFileSource class provides a way to implement a Source Processor in Python.

Processors implementing the FlowFileSource class are expected to implement the create(ProcessContext) method, which should return an instance of FlowFileSourceResult.

The FlowFileSource class supports both life-cycle methods: onScheduled and onStopped.

By default there is a single relationship available for this class: success. Additional relations can be define and declared using getRelationships method. See Relationship for details.

It is possible to register custom properties by defining a getPropertyDescriptors method. See PropertyDescriptor for details.

Limitations

The create method can only return one FlowFileSourceResult, which means that only one FlowFile can be created at a time.

Implementation

See a boilerplate implementation.

from nifiapi.flowfilesource import (
    FlowFileSource,
    FlowFileSourceResult
)
from nifiapi.properties import (
    ProcessContext,
    PropertyDescriptor
)
from nifiapi.relationship import Relationship
from typing import List


class CreateFlowFile(FlowFileSource):

    class Java:
        implements = ['org.apache.nifi.python.processor.FlowFileSource']

    class ProcessorDetails:
        version = '0.0.1-SNAPSHOT'
        description = '''
        '''
        tags = []
        dependencies = []

    def __init__(self, *args, **kwargs):
        super().__init__()

    def getRelationships(self) -> List[Relationship]:
        '''
        Register additional processor relationships.

        Returns:
            list(Relationship)
        '''
        return []

    def getPropertyDescriptors(self) -> List[PropertyDescriptor]:
        '''
        Register property descriptor required to successfully run the
        processor.

        Returns:
            list(PropertyDescriptor)
        '''
        return []

    def onScheduled(self, context: ProcessContext) -> None:
        '''
        The onScheduled method in Apache NiFi is a life-cycle method that is 
        called when a processor is scheduled to run, allowing for 
        initialization tasks such as setting up resources, loading 
        configurations, or validating properties. 
        
        Parameters:
            context (ProcessContext)

        Return:
            None
        '''
        pass

    def onStopped(self, context: ProcessContext) -> None:
        '''
        The `onStopped` method in Apache NiFi is a life-cycle method invoked
        when a processor is stopped. It is used to perform cleanup tasks, such
        as releasing resources or closing connections.
        
        Parameters:
            context (ProcessContext)

        Returns:
            None
        '''
        pass

    def create(self, context: ProcessContext) -> FlowFileSourceResult:
        '''
        
        Parameters:
            context (ProcessContext)
            
        Returns:
            FlowFileSourceResult
        '''
        return FlowFileSourceResult("success")