Serverless Development

In Traditional

Application Server

Database Server

Have to:

Knowledge about Linux

Docker or Systemd for Daemon

Port Proxy on nginx (Virtual Host)

Issue on:

System-wide Security

Surplus System Performance

In the feture

Java / Golang / Node.js / Python / Ruby / C#

Golang / Node.js / Python

Cost

Server

Serverless

hourly-use on VM

bandwidth

storage

requests

In Practice

// In Basic Model

const functions = require('firebase-functions');

exports.sampleFunction = functions.https.onRequest((req, res) => {
  const {
    requestSize,
  } = req.body;
  
  res.json({
    text: `Received Request: ${requestSize}`,
  });
});

Data Model

Cloud SQL

Traditional RDBMS
(MySQL / PostgresSQL...etc)

Cloud Firestore

No-SQL Database
Key-Value based scalable

In Practice

const functions = require('firebase-functions');
const admin = require('firebase-admin');
const moment = require('moment');

admin.initializeApp();

exports.listCaseCodes = functions.https.onRequest(async (req, res) => {
  const snapshot = await admin
    .firestore()
    .collection('cases')
    .where('numberCode', '>=', Number(`${moment().format('YYYYMM')}00001`))
    .where('numberCode', '<', Number(`${moment().format('YYYYMM')}99999`))
    .orderBy('numberCode', 'desc')
    .get();
   
  const responseList = [];

  snapshot.docs.forEach(doc => {
    const {
      name,
      numberCode,
      creator,
    } = doc.data();

    responseList.push(`- *RC${numberCode}* ${name}${creator ? ` - ${creator}` : ''}`);
  });
  
  res.json(responseList);
});

Bot Webhook Handler

Issues

No shared memory to keep context

Establish connection to Firestore is very slow

https://www.serverless.com

One more thing

Flow Control

Talking about data

[map] N ⇢ N

[filter] N ⇢ N-M

[reduce] N ⇢ 1

Array

Promise

const asyncTask = new Promise((resolve, reject) => {
  // ... working
});

asyncTask()
  .then(() => {
    // work after async task
  })
  .catch(() => {
    // if error occured
  })
  .finally(() => {
    // after task settled (no matter resolved or rejected)
  });

In Practice

const payloadData = [1, 2, 3, 5, 8, 13];

// Parallels Request
Promise.all(payloadData.map(async (payload) => {
  // do something async task
  
  return payload * 2;
})).then((result) => {
  // on all finish correctly;
  
  console.log(result);
  // [2, 4, 6, 10, 16, 26]
});

// Sequence Request
payloadData.map((payload) => async () => {
  // do something async task
}).reduce((prev, next) => prev.then(next), Promise.resolve());

// Sequence Request with Response
payloadData.map((payload) => async (results) => {
  // do something async task
  
  return [
    ...results,
    payload * 2,
  ];
}).reduce((prev, next) => prev.then(next), Promise.resolve([]))
  .then((result) => {
    // on all finish correctly
    
    console.log(result);
    // [2, 4, 6, 10, 16, 26]
  });

https://caolan.github.io/async/v3/

Last thing 👻

CSS Variables

Scope w/ Components

import { css } from '@emotion/core';

const styles = {
  title: css`
    color: var(--title-color);
    font-size: 20px;
  `,
  titleRed: css`
    --title-color: red;
  `,
  titleBlue: css`
    --title-color: blue;
  `,
};

function Title({ children }) {
  return (
    <h3 css={styles.title}>
      {children}
    </h3>
  );
}

function SampleComponent() {
  return (
    <div css={styles.wrapper}>
      <div css={styles.titleRed}>
        <Title>
          Red Title
        </Title>
      </div>
      <div css={styles.titleBlue}>
        <Title>
          Blue Title
        </Title>
      </div>
    </div>
  );
}

var with property

// @flow

import { css } from '@emotion/core';
import { 
  useRef,
  useEffect,
} from 'react';

const styles = {
  title: css`
    color: var(--title-color);
    font-size: 20px;
  `,
  titleRed: css`
    --title-color: red;
  `,
  titleBlue: css`
    --title-color: blue;
  `,
  titleDynamic: css`
    --title-color: black;
  `,
};

function Title({ children }) {
  return (
    <h3 css={styles.title}>
      {children}
    </h3>
  );
}

function SampleComponent() {
  const colorRef = useRef();
  
  useEffect(() => {
    funtcion onMove({ clientX }) {
      const { current } = colorRef;
      const width = document.body.clientWidth;
      const percentage = clientX / width;

	  current?.style.setProperty('--title-color', `hsl(240, ${percentage * 100}%, 30%)`);
    }
  
    window.addEventListener('mousemove', onMove, false);
    
    return () => window.removeEventListener('mousemove', onMove, false);
  }, []);

  return (
    <div css={styles.wrapper}>
      <div css={styles.titleRed}>
        <Title>
          Red Title
        </Title>
      </div>
      <div css={styles.titleBlue}>
        <Title>
          Blue Title
        </Title>
      </div>
      <div ref={colorRef} css={styles.titleDynamic}>
        <Title>
          Dynamic Color Title
        </Title>
      </div>
    </div>
  );
}

Au revoir

serverless-development

By Chia Yu Pai

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serverless-development

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