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Documentation

General

Terms

  • Element
    • A logical, independent unit of executable code
    • Visualized on the GUI
    • Can be connected with other elements
  • Configuration Data
    • Element parameters passed over the GUI by the user
  • Input Data
    • Data which is forwarded from other elements (left connection)
  • Output Data
    • Data which is forwarded to other elements (right connection)

Logging

The execution of elements is logged in a file that changes daily. The log files are archived under ~/Pythonic/log (Linux) or %HOMEPATH%\Pythonic\log (Windows). Pythonic's web service provides an overview of available log files at http://<address-info>:7000/log. Single log files can be accessed witch the following scheme: http://<address-info>:7000/<year><month><day>.txt.

  • INFO
    • Ordinary debug trace messages
    • Can be switched on or off by the user (checkbox in element configuration)
    • Implementation in own code is optional
  • WARNING
    • Signalize a failed execution
    • Can be switched on or off by the user (checkbox in element configuration)
    • A log entry of this type is created when the element returns data of type PythonicError
    • Implementation in own code is optional
  • ERROR (Unhandled exception):
    • Caused by an unhandles exception
    • Is signalized in the GUI ("Exception occured, open log for details")
    • Is always active (implementation not optional)

Exception handling

  1. Elements should throw an exception when configuration data is missing or cannot be processed.
  2. Elements should try to handle all possible exceptions internally and only throw critical exceptions.
  3. The result of a operation (if successfull or not (see #2)) should always be forwarded to subsequent elements in order to react to a possible failed call. If the result of a failed call could be processed by an subsequent element, it should be wrapped in the PythonicError type.
  4. In case of a failed call, a meaningful message or the exception text should returned (PythonicError as data parameter in returned Record type)
  5. Don't to use logging.error or logging.warning as it has no effect if used in combination with multiprocessing.

Elements

Basic Elements

Scheduler

Scheduler

The Scheduler activates subsequent elements depending on the set schedule.

  • Start subsequent elements
  • Start by hand
  • Optional: Autostart on startup

Generic Pipe

Scheduler

The Generic Pipe processes the input data and terminates immediately after completion.

Intendet use:

  • Simple data processing
  • Tranformation of data between two elements

Generic Process

Scheduler

The Generic Process executes an infinite loop. The executions stops when a stop signal is received or, in case of multiprocessing, when the process is killed.

Attention: Every time the element is triggered another instance of the Generic Process is created.

Intendet use:

  • Listener application
  • Waiting for external events (e.g. TCP/IP related)

Process Pipe

Scheduler

The Process Pipe executes an infinite loop. In contrast to Generic Process additional activations of the Process Pipe element won't cause the creation of additional instances. The payload of subsequent activations can be processed within the loop.

Intendet use:

  • Stream processing
  • Long running processes
  • Machine learning
  • Feed process with varying data

Connectivity

Telegram

Scheduler

Use Telegram to send or receive data This Telegram bot allows you to send or receive messages, pictures or files to or from multiple user which subscribed to the bot. Talk to the BotFather to get a token, the process is described on telegram.org.

On first invocation, the bot is started and an attempt is made to establish a connection to the Telegram server. If succeeded, the payload of subsequent invocations is forwarded to registered chat Ids. Use the stop command to disconnect the bot and exit the process.

Bot commands:

/start : This command will register the chat id of a user. The chat Ids are saved persistent in ~/Pythonic/executables/chat_ids.obj and are automatically loaded on startup. When a certain chat Id cannot be reached anymore it is automatically removed.

<message>: Each message is forwarded to subsequent elements within Pythonic.