OpenFactoryApp#

class openfactory.apps.ofaapp.OpenFactoryApp(app_uuid, ksqlClient, bootstrap_servers=None, loglevel='INFO')[source]#

Bases: Asset

Generic OpenFactory application.

Inherits from Asset and extends it to represent an OpenFactory application with standard metadata, logging, and lifecycle management.

APPLICATION_VERSION#

Class attribute. Version string from APPLICATION_VERSION environment variable or ‘latest’.

Type:

str

APPLICATION_MANUFACTURER#

Class attribute. Manufacturer from APPLICATION_MANUFACTURER environment variable or ‘OpenFactory’.

Type:

str

APPLICATION_LICENSE#

Class attribute. License string from APPLICATION_LICENSE environment variable or ‘BSD-3-Clause license’.

Type:

str

logger#

Instance attribute. Prefixed logger instance configured with the app UUID.

Type:

logging.Logger

storage#

Storage backend instance created from the STORAGE environment variable, or None if not configured.

Type:

Optional[FileBackend]

Example usage:
import time
import os
from openfactory.apps import OpenFactoryApp
from openfactory.kafka import KSQLDBClient

class DemoApp(OpenFactoryApp):

    def main_loop(self):
        # For actual use case, add here your logic of the app
        print("I don't do anything useful in this example.")
        counter = 1
        while True:
            print(counter)
            counter += 1
            time.sleep(2)

    def app_event_loop_stopped(self):
        # Not absolutely required as it is already done by the `KSQLDBClient` class
        self.ksql.close()

# When the Application is deployed on the OpenFactory Cluster, the
# environment variables KSQLDB_URL and KAFKA_BROKER will be set.
# The default values can be used for local development.
app = DemoApp(
    app_uuid='DEMO-APP',
    ksqlClient=KSQLDBClient(os.getenv("KSQLDB_URL", "http://localhost:8088")),
    bootstrap_servers=os.getenv("KAFKA_BROKER", "localhost:9092")
)
app.run()
__init__(app_uuid, ksqlClient, bootstrap_servers=None, loglevel='INFO')[source]#

Initializes the OpenFactory application.

Sets up the application UUID, storage backend (if configured), standard attributes (version, manufacturer, license), a prefixed logger, and termination signal handlers.

Parameters:

  • app_uuid (str) – The UUID of the application (overrides the environment variable APP_UUID if provided).

  • ksqlClient (KSQLDBClient) – The KSQL client instance.

  • bootstrap_servers (str) – Kafka bootstrap server URL, default value is read from config.KAFKA_BROKER.

  • loglevel (str) – Logging level for the app (e.g., ‘INFO’, ‘DEBUG’). Defaults to ‘INFO’.

Side effects:

  • Configures logging with the application UUID as prefix.

  • Mounts a storage backend if the STORAGE environment variable is set.

  • Registers signal handlers for SIGINT and SIGTERM.

app_event_loop_stopped()[source]#

Called when main loop is stopped.

Return type:

None

async async_main_loop()[source]#

Async main loop of the OpenFactory App.

This method must be implemented by child classes to define the main application loop behavior. It will be responsible for managing the application’s lifecycle, handling events, and maintaining any necessary state while the application is running.

Return type:

None

Raises:

NotImplementedError – If this method is not implemented by a subclass.

async async_run()[source]#

Run the OpenFactory app asynchronously.

Return type:

None

Parameters:

async_main_loop – Async function to use as the main loop

main_loop()[source]#

Main loop of the OpenFactory App.

This method must be implemented by child classes to define the main application loop behavior. It will be responsible for managing the application’s lifecycle, handling events, and maintaining any necessary state while the application is running.

Return type:

None

Raises:

NotImplementedError – If this method is not implemented by a subclass.

run()[source]#

Runs the OpenFactory app.

This method initializes the app by displaying a welcome banner, adding an availability attribute, and then starts the main application loop by calling main_loop. If an exception occurs during the execution of the main loop, the error is caught, and the app is gracefully stopped.

The following steps are performed:

  1. Display the welcome banner.

  2. Add the avail attribute with ‘AVAILABLE’ value.

  3. Start the main loop.

  4. Catch any exceptions that occur and stop the app gracefully.

Raises:

Exception – If any exception occurs during the execution of the main loop, it is caught and logged, and the app is stopped.

Return type:

None

signal_handler(signum, frame)[source]#

Handles SIGINT and SIGTERM signals, gracefully stopping the application.

This method listens for termination signals, deregisters the asset from the system, and then stops the application’s event loop. It is typically used to handle clean shutdowns when the app receives signals like SIGINT or SIGTERM.

Return type:

None

Parameters:

  • signum (int) – The signal number that was received (e.g., SIGINT, SIGTERM).

  • frame (Optional) – The current stack frame when the signal was received.

welcome_banner()[source]#

Welcome banner printed to stdout.

Can be redefined by children

Return type:

None