# [Greenline] Research: I/O in python driver

- Shaped by: Magdalena
- Appetite (FTEs, weeks):
- Developers: <!-- Filled in at the betting table unless someone is specifically required here -->

## Problem
<!-- The raw idea, a use case, or something we’ve seen that motivates us to work on this -->
We need to enable IO for the greenline. The IO system needs work at scale with large paralel datasets on distributed system, and it should somehow integrate in a prospective Weather&Climate platform or workflows at CSCS/C2SM

Similar problems have likely been tackled by other scientific communities, many of them relying on Python as a tool of choice for data handling.

With this project we want to gather more precise requirements for the system and assess what tools there are that we can use.

## Appetite
<!-- Explain how much time we want to spend and how that constrains the solution -->

## Solution
<!-- The core elements we came up with, presented in a form that’s easy for people to immediately understand -->
- Understand and document minimal requirements of IO system for icon4py greenline
- Assess exsting libraries and approaches in hindsight of these requirements
- Sketch a first draft of an architecture.
- Solution should handle grid and

### sources
- [Enriques notes](https://hackmd.io/0x-YtL00Qq6G97C1oVaWkw)
- [CF conventions](https://cfconventions.org/)
- [MetPy](https://unidata.github.io/MetPy/latest/index.html)
### preliminary investigations
#### input
- the icon grid file can be loaded in uxarray after patching the contents to follow UX conventions. see
- There is interest by groups at MCH and EMPA to have a joint python grid interface instead of everybody doing its own version. It should allow them to access neighbor information. (contact: David Leutwyler, Viktoria Cherkas (MCH), )
## Rabbit holes
<!-- Details about the solution worth calling out to avoid problems -->
Do not get lost in too many details.

## No-gos
<!-- Anything specifically excluded from the concept: functionality or use cases we intentionally aren’t covering to fit the ## appetite or make the problem tractable -->

## Progress
<!-- Don't fill during shaping. This area is for collecting TODOs during building. As first task during building add a preliminary list of coarse-grained tasks for the project and refine them with finer-grained items when it makes sense as you work on them. -->

- [x] Task 1 ([PR#xxxx](https://github.com/GridTools/gt4py/pulls))
- [x] Subtask A
- [x] Subtask X
- [ ] Task 2
- [x] Subtask H
- [ ] Subtask J
- [ ] Discovered Task 3
- [ ] Subtask L
- [ ] Subtask S
- [ ] Task 4