# PIN-1: Introduce Prefect Improvement Notices

Date: 2019-01-23

Author: Jeremiah Lowin

# Status


# Context

Prefect is a complex framework for building workflows. As such, changes to its architecture require consideration and input from various stakeholders.

In addition, we desire a way to memorialize why decisions were made. This narrative will allow future contributors to understand not only the way things are (by reading code) but also how they came to be, and the objectives they were designed to meet.

This document is the first Prefect Improvement Notice: a proposed change to how Prefect works. Going forward, large architecture decisions can be proposed, debated, and ultimately accepted in this format.

# Why "PIN" and not "ADR"?

"PIN" - Prefect Improvement Notice - follows the example set by Python's PEP. It's quick and easy to say, requiring just one syllable, and while it is a common word, its all-caps variant is not commonly used for anything else in Prefect. It has a nice verb form as well: "PINNED".

"ADR" is an acronym only an engineer could love. It combines three non-harmonious syllables, making it difficult and time-consuming to remember and pronounce: ("Aiy. Dee. Are."). Furthermore, the acronym ADR is already far more widely known as an "American Depository Receipt".

# Proposal

We will adopt PINs for proposing, debating, and ultimately accepting or rejecting modifications to Prefect. PINs will be sequentially numbered and not reuse numbers. They will be published as part of Prefect's documentation, providing an architectural narrative of the project's history.

# Format

We will use the following format for PINs:

A PIN is a sequentially-numbered document with a short, imperative title. PINs are written with complete sentences and proper structure. They are conversational documents; reading a series of PINs should emulate the experience of learning why Prefect was built a certain way.

Each PIN has five important sections: Status, Context, Proposal, Consequences, and Actions

Status is initially "Proposed" and can ultimately become "Accepted" or "Rejected." Future PINs may result in past PINs becoming "Deprecated" or "Superseded."

Context gives background for the PIN. It should be complete, including any information relevant to the PIN even if it might lead to its rejection. The goal of this section is to prepare readers so that they fully understand the decision being proposed.

Proposal discretely explains what the PIN proposes. While the same information may be discussed in the context section (in order to provide arguments for and against), the "proposal" represents a specific idea or implementation.

Consequences describes the context after adopting the proposal. This section should include both positive and negative ramifications.

Actions contains any actions taken in response to this PIN. This section may be added later, for example to add links to PRs or to explain why a PIN was declined.

# Process

PINs are often the reflection of offline work and discussions, but we will attempt to integrate them in our online processes when possible.

PINs will be submitted as issues on the appropriate repo. Issues are an appropriate, archivable forum for discussing the content and nature of the PIN. In addition, as an issue the PIN's content can easily be modified. Once some consensus is reached, the PIN will be submitted as a PR.

When a PIN is submitted as a PR, its proposal does NOT need to be accepted in order for the PR to be merged. The repo's maintainers may merge PRs for PINs that have yet to be accepted or even ones that have been rejected. The acceptance of a PIN PR should be judged similarly to one for documentation: it helps explain how the software evolved to its current state.

Any PIN that generated sufficient discussion to affect the course of Prefect's software is worthwhile to include permanently, even if it, itself, remained pending or was rejected. These "negative decisions" are just as important. However, the maintainers may use editorial judgement for non-accepted PINs. A polluted narrative can be worse than no narrative at all.

# Consequences

Going forward, large-scale modifications to Prefect will be proposed via PIN.

# Actions