add first draft of async slides

materials/d1-9002-async/index.qmd

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+---
+title: "Asynchronous Processing"
+subtitle: "posit::conf(2023) <br> Shiny in Production: Tools & Techniques"
+author: "TBD"
+footer: "[{{< var workshop_short_url >}}]({{< var workshop_full_url >}})"
+format: 
+ revealjs:
+ theme: [default, ../slides.scss] # moon= teal bg | dark
+ scrollable: true
+ incremental: false
+ slide-number: c/t # c/t | c | h/v | h.v
+ slide-tone: false #true
+ code-line-numbers: true
+ history: false
+revealjs-plugins:
+ - codewindow
+---
+
+## Single (threaded) Line {background-image="assets/img/lego_line_pay.jpg" background-size="cover"}
+
+* A single R process managing the different tasks in a Shiny application
+* Executed one-by-one
+
+# Should I care?
+
+## It Depends ...
+
+If you are the __only__ user for a quick and efficient app: Likely not
+
+::: {.notes}
+TODO: Find a way to center the sentence vertically in the slide
+:::
+
+## Crowd Pleaser
+
+Multiple users accessing the app __concurrently__: 
+
+* Single-threaded R process serving multiple users in typical deployments
+
+## Asynchronous Processing (circa 2018)
+
+:::: {.columns}
+
+::: {.column width="50%"}
+
+### 📦 [`{promises}`](https://rstudio.github.io/promises/index.html)
+
+Handle objects representing the (eventual) result of an async operation
+
+:::
+
+::: {.column width="50%"}
+
+### 📦 [`{future}`](https://future.futureverse.org/)
+
+Launch tasks without blocking current R session
+
+:::
+
+::::
+
+::: footer
+[Using promises with Shiny](https://rstudio.github.io/promises/articles/promises_06_shiny.html)
+:::
+
+## Introducing [`{crew}`](https://wlandau.github.io/crew/)
+
+> A distributed worker launcher for asynchronous tasks
+
+* Extends use of the [mirai](https://github.com/shikokuchuo/mirai) task scheduler to multiple computing backends
+* Central controller object manages tasks (scales on fly)
+* Supports multiple [controller groups](https://wlandau.github.io/crew/articles/controller_groups.html) for specialized worker types
+* Fits nicely with [`{targets}`](https://docs.ropensci.org/targets/) and ...
+
+. . .
+
+![](assets/img/shiny.png){.absolute top=0 left=200}
+
+## Setting up for Success
+
+1. Create functions for long-running tasks
+1. Create multiple [`reactiveVal`](https://shiny.posit.co/r/reference/shiny/latest/reactiveval) objects for bookkeeping
+1. Set up a `{crew}` controller 
+1. Establish an event-driven push of task to the controller with monitoring of worker status

units/d1-9002-async.qmd

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+---
+title: "Async Processing"
+subtitle: "TBD"
+author: "Eric Nantz & Michael Thomas"
+date: "2023-09-18"
+listing:
+ - id: exercises
+ contents:
+ - ../materials/d1-9002-async/ex-*.qmd
+ type: table
+ fields: [subtitle, title]
+ field-display-names: 
+ subtitle: "Exercise"
+ sort: [filename]
+ sort-ui: false
+ filter-ui: false
+ image-placeholder: assets/img/placeholder.png
+tbl-colwidths: [5,20,75]
+---
+
+## Slides
+
+::: callout-warning
+These slides are under construction and will be finalized prior to the workshop date.
+:::
+
+[View slides in full screen](../materials/d1-9002-async/index.html)
+
+```{=html}
+<iframe class="slide-deck" src="../materials/d1-9002-async/" height="420" width="747" style="border: 1px solid #2e3846;"></iframe>
+```
+