Create a custom tile for Discovery

Discovery is a powerful dashboarding tool and allows for totally custom data visualization. Learn how to create a Discovery plugin.

Create a custom tile for Discovery

Since Discovery-widgets 1.1.4, we integrate a plugin system in order to add your own tiles which will interact with Discovery Dashboards. It becomes quite easy to create a custom chart.

Tiles are based on Web Components, so your plugin must also be a Web Component.

In this tutorial, we will build a radar chart based upon the nice ChartJS library and embed it into a StencilJS Web Component.

What exactly is Discovery? Learn more

Bootstrap the project

In a new folder, we will scaffold a StencilJS Web Component:

$ npm init stencil

$ cd discovery-plugin-radar
$ npm install
$ rm -fr src/components/* 
$ npm install chart.js
$ npm install -D @senx/discovery-widgets

Bootstrap your component

$ npm run generate

In order to parse your package.json to add some of its fields in your plugin definition, edit tsconfig.ts:

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "allowUnreachableCode": false,
    [ ... ]
    "jsxFactory": "h",
    "resolveJsonModule": true
  },
[ ... ]
}

Just add "resolveJsonModule": true to the compilerOptions.

To facilitate the packaging of your component, edit stencil.config.ts:

import { Config } from '@stencil/core';

export const config: Config = {
  namespace: 'discovery-plugin-radar',
  globalScript: './src/plugin.ts',
  outputTargets: [
    {
      type: 'dist',
      esmLoaderPath: '../loader',
    },
    {
      type: 'dist-custom-elements',
    },
    {
      type: 'docs-readme',
    },
    {
      type: 'www',
      serviceWorker: null, // disable service workers
    },
  ],
};

We add a globalScript field to allow your component to be registered by Discovery.

Create src/plugin.ts to allow your component to be registered:

import {PluginDef, PluginManager} from "@senx/discovery-widgets";
import * as pack from "../package.json"

export default () => {
  PluginManager.getInstance().register(new PluginDef({
    type: 'radar',                                                                    
    name: pack.name,
    tag: 'discovery-plugin-radar',
    author: pack.author,
    description: pack.description,
    version: pack.version,
  }));
}

This code will be called when the browser loads the component. It creates a plugin definition:

  • type: the chart type that you will use in your dashboards tiles definition (must be unique across Discovery)
  • name: we fetch the package name as declared in package.json, it will act as a unique key to register your plugin
  • tag: the HTML tag corresponding to your component
  • author: we fetch the author field of the package.json file (do not forget to fill it)
  • description: we fetch the description field of the package.json file (do not forget to fill it)
  • version: your package version

The radar component

Stencil should have created 2 files:

  • src/components/discovery-plugin-radar/discovery-plugin-radar.css
  • src/components/discovery-plugin-radar/discovery-plugin-radar.tsx

Edit src/components/discovery-plugin-radar/discovery-plugin-radar.css:

:host {
  display: block;
  width: 100%;
  height: 100%;
}

.chart-container {
  width: 100%;
  height: 100%;
}

StencilJS also supports Less, Sass, Stylus, and PostCss (Learn more about StencilJS plugins).

Edit src/components/discovery-plugin-radar/discovery-plugin-radar.tsx.

Start with the imports:

import { ChartType, ColorLib, DataModel, DiscoveryEvent, GTSLib, Logger, Param, Utils } from '@senx/discovery-widgets';
import { Component, Element, Event, EventEmitter, h, Listen, Method, Prop, State, Watch } from '@stencil/core';
import { Chart, registerables } from 'chart.js';

Now, have a look at the mandatory parts of a Discovery plugin.

The attributes

As it is a Web Component, you can define custom HTML attributes. Some of them are mandatory for a Discovery Plugin:

  @Prop() result: DataModel | string;                 // mandatory, will handle the result of a Warp 10 script execution
  @Prop() type: ChartType;                            // optionnal, to handle the chart type if you want to handle more than one
  @Prop() options: Param | string = new Param();      // mandatory, will handle dashboard and tile option
  @State() @Prop() width: number;                     // optionnal
  @State() @Prop({ mutable: true }) height: number;   // optionnal, mutable because, in this tutorial, we compute it
  @Prop() debug: boolean = false;                     // optionnal, handy if you want to use the Discovery Logger

The events

As it will interact with other tiles, your component needs to emit events:

@Event() draw: EventEmitter<void>;                  // mandatory

Other inner variables

  @Element() el: HTMLElement;

  @State() innerOptions: Param;               // will handle merged options
  @State() innerResult: DataModel;            // will handle the parsed execution result

  private LOG: Logger;                        // The Discovery Logger
  private divider: number = 1000;             // Warp 10 time unit divider
  private chartElement: HTMLCanvasElement;    // The chart area
  private innerStyles: any = {};              // Will handle custom CSS styles for your tile
  private myChart: Chart;                     // The ChartJS instance

Watchers

Watchers will be called each time an attribute is updated. Those are mandatory:

  /*
   * Called when the result is updated
   */
  @Watch('result') // mandatory
  updateRes(newValue: DataModel | string, oldValue: DataModel | string) {
    if (JSON.stringify(newValue) !== JSON.stringify(oldValue)) {
      this.innerResult = GTSLib.getData(this.result);
      setTimeout(() => this.drawChart());   // <- we will see this function later
    }
  }

  /*
   * Called when the options are updated
   */
  @Watch('options') // mandatory
  optionsUpdate(newValue: string, oldValue: string) {
    if (JSON.stringify(newValue) !== JSON.stringify(oldValue)) {
      if (!!this.options && typeof this.options === 'string') {
        this.innerOptions = JSON.parse(this.options);
      } else {
        this.innerOptions = { ...this.options as Param };
      }
      setTimeout(() => this.drawChart());
    }
  }

Public methods

The dashboard can invoke some methods on tiles, some methods are mandatory:

  /*
   * Mandatory
   * Called by Discovery when the component must be resized
   */
  @Method()
  async resize() {
    if (!!this.myChart) {
      this.myChart.resize();
    }
  }

  /*
   * Optionnal
   * Called by Discovery when the component has to export its content to PNG or SVG
   */
  @Method()
  async export(type: 'png' | 'svg' = 'png') {
       // insert your own implementation
  }

Events handler

Those handlers will compute things when an event is trapped by the tile:

  /* Handy if you want to handle Discovery events coming from other tiles */
  @Listen('discoveryEvent', { target: 'window' })
  discoveryEventHandler(event: CustomEvent<DiscoveryEvent>) {
    const res = Utils.parseEventData(event.detail, this.innerOptions.eventHandler);
    if (res.data) {
      this.innerResult = res.data;
      setTimeout(() => this.drawChart());
    }
    if (res.style) {
      this.innerStyles = { ...this.innerStyles, ...res.style as { [k: string]: string } };
    }
  }

Component lifecycle methods

As your component will be loaded in a browser, StencilJS provide handy lifecycle methods (learn more):

  /* 
   * Mandatory
   * Part of the lifecycle
   */
  componentWillLoad() {
    Chart.register(...registerables);                                               // ChartJS specific loading
    this.LOG = new Logger(DiscoveryPluginRadar, this.debug); // init the Discovery Logger
    // parse options
    if (typeof this.options === 'string') {
      this.innerOptions = JSON.parse(this.options);
    } else {
      this.innerOptions = this.options;
    }
    // parse result
    this.innerResult = GTSLib.getData(this.result);
    this.divider = GTSLib.getDivider(this.innerOptions.timeUnit || 'us'); // Warp 10 default time unit
    // Get tile dimensions of the container
    const dims = Utils.getContentBounds(this.el.parentElement);
    this.width = dims.w;
    this.height = dims.h;
  }

  /* 
   * Mandatory
   * Part of the lifecycle
   */
  componentDidLoad() {
    setTimeout(() => this.drawChart());
  }

  /* 
   * Mandatory
   * Render the content of the component
   */
  render() { 
    return (
      <div class="chart-container">
        {this.innerResult ? <canvas id="myChart" ref={(el) => this.chartElement = el as HTMLCanvasElement}></canvas> : ''}
      </div>
    );
  }

The logic part

Now, I will show you how to handle the execution result and feed ChartJS with it (learn more about the data structure of ChartJS) :

drawChart() {
    // Merge options
    let options = Utils.mergeDeep<Param>(this.innerOptions || {} as Param, this.innerResult.globalParams) as Param;
    this.innerOptions = { ...options };
    const labels = [];
    const datasets = [];
    // Flatten the data structure and add an id to GTS
    const gtsList = GTSLib.flattenGtsIdArray(this.innerResult.data as any[], 0).res;
    // For each GTS
    gtsList.forEach((gts, i) => {
      // if the GTS is a list of values
      if (GTSLib.isGtsToPlot(gts)) {
        const data = [];
        // Compute the GTS color
        const c = ColorLib.getColor(gts.id || i, this.innerOptions.scheme);
        const color = ((this.innerResult.params || [])[i] || { datasetColor: c }).datasetColor || c;
        // For each value
        gts.v.forEach(d => {
          // Handle date depending on the timeMode and the timeZone
          const date = GTSLib.utcToZonedTime(d[0], this.divider, this.innerOptions.timeZone);
          const dateLabel = (this.innerOptions.timeMode || 'date') === 'date'
            ? GTSLib.toISOString(GTSLib.zonedTimeToUtc(date, 1, this.innerOptions.timeZone), 1, this.innerOptions.timeZone, this.innerOptions.timeFormat)
              .replace('T', '\n').replace(/\+[0-9]{2}:[0-9]{2}$/gi, '')
            : date;
          // add the label
          if (!labels.includes(dateLabel)) {
            labels.push(dateLabel);
          }
          // add the value
          data.push(d[d.length - 1]);
        });
        // add the dataset
        datasets.push({
          label: ((this.innerResult.params || [])[i] || { key: undefined }).key || GTSLib.serializeGtsMetadata(gts),
          data,
          borderColor: color,
          backgroundColor: ColorLib.transparentize(color, 0.5)
        })
      }
    });
    if (!!this.chartElement) {
      const ctx = this.chartElement.getContext('2d');
      if (!this.myChart) {
        this.myChart = new Chart(ctx, {
          type: 'radar',
          data: { labels, datasets },
          options: {
            animation: false,
            responsive: true,
            maintainAspectRatio: false
          }
        });
      } else {
        this.myChart.data = { labels, datasets };
        this.myChart.update();
      }
    }
  }

That is all.

Test and run

At first edit src/index.html:

<!DOCTYPE html>
<html dir="ltr" lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=5.0" />
    <title>Stencil Component Starter</title>

<!-- Import Discovery -->
    <script nomodule src="https://unpkg.com/@senx/discovery-widgets/dist/discovery/discovery.js"></script>
    <script type="module" src="https://unpkg.com/@senx/discovery-widgets/dist/discovery/discovery.esm.js"></script>

<!-- Import your plugin -->
    <script type="module" src="./build/discovery-plugin-radar.esm.js"></script>
    <script nomodule src="./build/discovery-plugin-radar.js"></script>
 
 </head>
  <body>
<!-- Define a one tile dashboard with "radar" as a chart type and random values -->
    <discovery-dashboard url="https://sandbox.senx.io/api/v0/exec" dashboard-title="Test" debug>
      {
        'title' 'Test'
        'description' 'Dashboard test'
        'tiles' [
          {
            'title' 'test'
            'x' 0 'y' 0 'w' 12 'h' 2
            'type' 'radar'
            'macro' <%
              NOW 'now' STORE
              1 4 <% 
                  DROP NEWGTS 'g' STORE
                  1 10 <% 
                      'ts' STORE $g $ts STU * $now + NaN NaN NaN RAND ADDVALUE DROP
                  %> FOR
                  $g 
              %> FOR 
            %>
          }
        ]
      }
      </discovery-dashboard>
  </body>
</html>

And now, start your dev server:

$ npm run start

Here you are:

The result
The result

Going further

Now, you can develop your own tiles and charts. Feel free to publish them on NPMjs.org.

Let us know about your creations.

A final thought

But how to use the plugin mechanism with Discovery Explorer? It handles plugins since 1.0.12.

Create a conf file, like conf.json:

{
  "dashRoot": "/data",
  "plugins": [
    {
      "name": "radar-module",
      "src": "https://unpkg.com/discovery-plugin-radar/dist/discovery-plugin-radar/discovery-plugin-radar.esm.js",
      "isModule": true
    },
    {
      "name": "radar-nomodule",
      "src": "https://unpkg.com/discovery-plugin-radar/dist/discovery-plugin-radar/discovery-plugin-radar.js",
      "isModule": false
    }
  ]
}

The "dashRoot" field must remain like that.

The conf file defines a list of plugins to include, the module version and the nomodule version like we saw in the previous index.html file.

And now start the docker image:

$ docker run --rm -d -p9090:3000 \
   -v /path/to/your/conf.json:/opt/discovery-dashboard/conf.json \
   -v /path/to/your/dashboards:/data discovery-test:latest

Discover more articles and tutorials about Discovery.

Read more

Working with Time Series in Spark
Learn how you can scale your Time Series analytics using Spark and the Warp 10 Analytics Engine
Warp 10 Office Hours #1 Recap
Our first Office Hours session got 5 great questions asked, discover what the answers were, the fifth one will blow your mind!
All you need to know about interactions between Warp 10 and Python
In this blog post, we summarize resources and tips on interactions between Python and Warp 10.
© Copyright 2018