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Lifecycle of a Plugin

Alteryx_IO_Team
Alteryx
Alteryx
Created

Lifecycle of a Plugin

Prerequisites

This overview refers to Plugins, in reference to any new PluginV2 class developed with the SDK.

Overview

The lifecycle of a Plugin in Alteryx Designer can be broken down into 2 different types of runs:

  1. Workflow Run
  2. Update Only Run

Workflow Run

When you select the Run button in Designer, an instance of your PluginV2 class is created for each of your tools on the canvas.

The PluginV2 is constructed via its __init__ method, just like in normal Python. An instance of a ProviderV2 class is given to the plugin. Any resources required to read from and write to Designer can be obtained via methods/properties on the ProviderV2.

In Alteryx Designer, input anchors can have 1 or many connections. If you have any input connections, the next stage of the lifecycle consists of each of those input connections sending data downstream. From the PluginV2 perspective, the on_incoming_connection_complete method is called for each connection once the engine is done sending records. The parameter that on_record_batch receives is the connection that a new record packet is available on.

Once all record batches for all connections are received, the Plugin's on_complete method is called in order to do any cleanup.

If your PluginV2 class does not have any input anchors, the lifecycle is the same, however, on_incoming_connection_complete, and on_record_batch never get called, since there are no connections/received records. This means that any records that you wish to output must be written to the output anchor during the on_complete method (you shouldn't write them during __init__, for reasons described below).

In order to write records to your Plugin's output anchors, they must first be opened with metadata. This Metadata object describes the record schema for that output anchor (for example, field names, types, etc.).

Refer to this sequence diagram for a visual representation of this lifecycle:

install screenshotinstall screenshot

Update Only Run

Update only is a mode that runs in Designer any time...

  1. A new tool is added to the canvas.
  2. Any tool on the canvas has a change in configuration (typically, via the user interface or Configuration panel).

The purpose of this run mode is to generate the metadata that each tool will output during the next time a workflow runs. This allows new tools on the canvas to know what columns they can operate on. The metadata that comes out of a tool typically depends on...

  1. The incoming metadata.
  2. The configuration of the tool (via the user interface).

In this mode, only the __init__ method is called.

Since the goal of an update-only run is to build output metadata, the __init__ method is run. This method has an instance of the AMPProviderV2, which sets incoming and outgoing anchor information, including the name and metadata. Additionally, since __init__ runs in update-only mode, you should aim to perform a minimal amount of processing in this method, since a fast update makes users happy.

Refer to the sequence diagram for a visual representation of this lifecycle:

install screenshotinstall screenshot