pypz.core.channels.misc module

class pypz.core.channels.misc.BlankChannelReader(channel_name: str, context: InputPortPlugin, executor: ThreadPoolExecutor | None = None, **kwargs)

Bases: ChannelReader

_abc_impl = <_abc._abc_data object>

_close_channel() → bool

This method shall implement the logic to close a channel. Normally closing a channel is the last step so clean up of used resource shall happen here as well.

Returns:

True, if done, False if it is still in progress

_commit_offset(offset: int) → None

This method shall implement the logic that commits the provided offset using the underlying technology.

Parameters:

offset – provided offset to commit

_configure_channel(channel_configuration: dict) → None

This method shall implement the logic to interpret the provided configuration.

Parameters:

channel_configuration – config string

_create_resources() → bool

This method shall implement the logic of creating resources of the channel. IMPORTANT NOTE - this method shall be invoked before the open_channel() to make sure that the resources are existing beforehand.

Returns:

True, if done, False if it is still in progress

_delete_resources() → bool

This method shall implement the logic of deleting resources of the channel. IMPORTANT NOTE - this method shall be invoked after the close_channel()

Returns:

True, if done, False if it is still in progress

_load_input_record_offset() → int

This method shall implement the logic to retrieve stored read offset from the underlying technology. This can be arbitrary, but the method shall return the stored offset.

Returns:

stored offset

_open_channel() → bool

This method shall implement the logic to open a channel. The meaning of ‘open’ however is to be defined by the actual implementation. One developer can define it like an opened connection, other as created file etc.

Returns:

True, if done, False if it is still in progress

_read_records() → list[Any]

This method shall implement the logic to read records from the input channel. An ArrayList of records is expected.

Returns:

list of records OR empty ArrayList if no records read. Null is not accepted.

_retrieve_status_messages() → list

This method shall implement the logic that retrieves the status messages published by the counterpart channel. Notice that in case of ChannelWriter, there can be multiple InputChannels sending messages and in case of ChannelReader there can be multiple messages sent by the ChannelWriter, therefore this method shall return a list of messages. Note as well that in case you are using callbacks for your technology, you can directly use the method onStatusMessageReceived. In this case simply return null from this method to ensure that it will be ignored.

Returns:

list of retrieved status messages or null if method is not used

_send_status_message(message: str) → None

This method shall implement the logic that publishes the channel’s state to the counterpart channel. The state string is provided by the channel itself. Note that there is defined schema, how and what will be provided by the channel as string, however you can append your own custom information, you only need to append as string separated by StateMessageSeparatorChar.

Parameters:

message – message that shall be sent

has_records() → bool

This method shall implement the logic to check, if the reader can still read records.

Returns:

True if channel has still records, False if not

class pypz.core.channels.misc.BlankChannelWriter(channel_name: str, context: OutputPortPlugin, executor: ThreadPoolExecutor | None = None, **kwargs)

Bases: ChannelWriter

_abc_impl = <_abc._abc_data object>

_close_channel() → bool

This method shall implement the logic to close a channel. Normally closing a channel is the last step so clean up of used resource shall happen here as well.

Returns:

True, if done, False if it is still in progress

_configure_channel(channel_configuration: dict) → None

This method shall implement the logic to interpret the provided configuration.

Parameters:

channel_configuration – config string

_create_resources() → bool

This method shall implement the logic of creating resources of the channel. IMPORTANT NOTE - this method shall be invoked before the open_channel() to make sure that the resources are existing beforehand.

Returns:

True, if done, False if it is still in progress

_delete_resources() → bool

This method shall implement the logic of deleting resources of the channel. IMPORTANT NOTE - this method shall be invoked after the close_channel()

Returns:

True, if done, False if it is still in progress

_open_channel() → bool

This method shall implement the logic to open a channel. The meaning of ‘open’ however is to be defined by the actual implementation. One developer can define it like an opened connection, other as created file etc.

Returns:

True, if done, False if it is still in progress

_retrieve_status_messages() → list

This method shall implement the logic that retrieves the status messages published by the counterpart channel. Notice that in case of ChannelWriter, there can be multiple InputChannels sending messages and in case of ChannelReader there can be multiple messages sent by the ChannelWriter, therefore this method shall return a list of messages. Note as well that in case you are using callbacks for your technology, you can directly use the method onStatusMessageReceived. In this case simply return null from this method to ensure that it will be ignored.

Returns:

list of retrieved status messages or null if method is not used

_send_status_message(message: str) → None

This method shall implement the logic that publishes the channel’s state to the counterpart channel. The state string is provided by the channel itself. Note that there is defined schema, how and what will be provided by the channel as string, however you can append your own custom information, you only need to append as string separated by StateMessageSeparatorChar.

Parameters:

message – message that shall be sent

_write_records(records: list[Any]) → None

This method shall implement the logic that writes the records to the output resource. It will automatically be invoked by the plugin via the corresponding invoker method.

Parameters:

records – list of records to be written