https://github.com/Appsilon/experimental-plumber-example

https://github.com/Appsilon/experimental-plumber-example

Last synced: about 1 month ago
JSON representation

• Host: GitHub
• URL: https://github.com/Appsilon/experimental-plumber-example
• Owner: Appsilon
• Created: 2023-09-22T11:38:46.000Z (12 months ago)
• Default Branch: main
• Last Pushed: 2023-12-15T05:30:37.000Z (9 months ago)
• Last Synced: 2024-06-04T23:02:29.888Z (4 months ago)
• Language: R
• Size: 134 KB
• Stars: 14
• Watchers: 15
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• jimsghstars - Appsilon/experimental-plumber-example - (R)

README

        
## Plumber Example

> Plumber API paired with a Shiny App that displays data and plots renders in API

The Plumber API implemented in this repository is a simple wrapper over the `EuStockMarkets` dataset allowing to query and plot this dataset.

It shows the potential usages of Plumber by creating a REST api that is async _(handles multiple requests in parallel)_ and caches the results.

#### Plumber technical features:

- Using `{future}` to allow for async requests;

- Using `{memoise}` to allow for caching of the results;

  - re-using the results cache on following request with same parameters.

#### Endpoints

  - `/plot` :: returns HTML that can be embedded in a Web page;

  - `/query` :: returns the data that supports the plot;

  - `/ranges` :: returns metadata for the available date ranges;

  - `/indexes` :: returns metadata that provides the available indexes in the data.

##### Example links

Note: it needs `connect.appsilon.com` creadentials.

- API documentation: https://connect.appsilon.com/plumber-example/

- Shiny example (see below): https://connect.appsilon.com/plumber-example-shiny/

- Sample plot: https://connect.appsilon.com/plumber-example/plot?from=1990-01-01&to=2000-01-01

- Sample metadata _(date ranges)_: https://connect.appsilon.com/plumber-example/ranges

#### Security

The example also implements a origin validation check when configured.

A secret key shared known only to the Plumber API and the client allows the creation of a token that validates that the requests originated from a trusted source.

The example Plumber API is deployed via the Posit Connect infrastructure, which ensures that the traffic is encrypted behind the HTTPS protocol.

#### Load Balancing

Multiple instances of the Plumber API can be run behind a load balancer to provide with more capacity to a stateless service.

For example, this can be achieved via a `Docker`-based solution `haproxy`.

#### Shiny _(paired with Plumber)_

Shiny _(or any other web application)_ can be paired with Plumber to render plots or perform complex data-manipulations.

As an add-on to the plumber example we implement a web application that uses the API for all it's data and plotting needs.

- Calls Plumber API to retrieve metadata

- Plot is rendered by the browser (bypassing Shiny server)

  - Using an `iframe` HTML element _(browser calls on Plumber API endpoint and renders it)_

  - Shiny process is not blocked by the rendering of the plot

A diagram of the communication happening once the page is loaded _(and everytime the parameters are modified)_:

```mermaid

sequenceDiagram;

    autonumber

    participant Browser

    participant Shiny

    participant Plumber API

    Browser->>Shiny: Open App

    Shiny->>Plumber API: Get metadata

    Plumber API-->>Shiny: Return metadata

    Note over Plumber API,Shiny: Available
"Date ranges" & "Indexes"

    Shiny-->>Browser: Render App

    Note over Shiny,Browser: Input slider &
Parameters for plot (iframe)

    Browser-)Plumber API: GET iframe contents

    Plumber API--)Browser: Render Plot

```