Hack it like its hot!

@stadolf @coding_earth
Hack it like it’s hot 😅
a 1 year hackathon wrap up

2
Stefan Adolf
Developer Ambassador
#javascript #mongodb #serverless
#blockchain #codingberlin #elastic
#aws #php #symfony #react
#digitalization #agile #b2b #marketplaces
#spryker #php #k8s #largescale
#turbinejetzt #iot #ux #vuejs
@stadolf
elmariachi111

Hackathons. They’re all the same.

2. you find friendly team mates

4. you present what you’ve done.

Buy By ID
Self sovereign identity meets eCommerce
T-Labs Blockchain Group - “Decentralizing the Enterprise” - Jan 2019

Challenge: Self Sovereign Identity
•authenticate / SSO by using an
identity under your control
•enabled by self signed DID
documents on Ethereum
•support verifiable claims
• “my government claims that
I’m Stefan and over 21”

Buy By ID: Idea
•add a “login with your identity” button to an headless shop system
•integrate with Vue Storefront (headless adapter for Magento e.a.)
•use Jolocom’s Smart Wallet for claim exchange

Tools / APIs
•Jolocom: Typescript
•Vue Storefront: ECMAScript / Vue
•node / express, Redis & socket.io

Brainkillers / pitfalls
•Both projects rely on Redis (VSF: cache, Jolocom: wallet storage)
•Jolo’s samples rely on socket.io to detect phone activities (QR scanned)
•socket.io can’t be bound to express apps (only to a http.Server inst)
• socket.io relies on https
•had to activate body parser on VSF
•conflicting build setup (Jolocom / VSF) - had to align start scripts / ts-node
•asynchronous calls conflicts with express route wiring

bind Jolocom backend to VSF
const { getAsync, setAsync, delAsync } = configureRedisClient()
const registry = JolocomLib.registries.jolocom.create()
const vaultedKeyProvider = new JolocomLib.KeyProvider(seed, password)
module.exports = async (expressApp: Express, server: http.Server) => {
const identityWallet = await registry.authenticate(vaultedKeyProvider, {derivationPath:
JolocomLib.KeyTypes.jolocomIdentityKey, encryptionPass: password})
configureRoutes(expressApp, {setAsync, getAsync, delAsync}, identityWallet, password)
configureSockets(server, identityWallet, password, new DbWatcher(getAsync), {getAsync, setAsync, delAsync})
return identityWallet
}
const configureRoutes = (app: Express, redisApi: RedisApi, iw: IdentityWallet, password: string) => {
/**
* An authentication endpoint route for deep linking for demo-sso-mobile;
*/
app.get('/mobile/credentialRequest', async (req, res, next) => {
…

listen to smart wallet events in Vue
continueWithJolo () {
 
const randomId = randomString(8);
this.getQrCode(randomId).then(image => {
this.$bus.$emit('modal-show', 'modal-jolo-user', null,  
{image: image})
this.awaitUserData(randomId).then(data => {
const parsed = JSON.parse(data)
const userData = parsed.data
this.personalDetails = {
firstName: userData.givenName,
lastName: userData.familyName,
}
this.$bus.$emit('modal-hide', 'modal-jolo-user')
this.sendDataToCheckout()
})
}).catch(err => {
console.log(err)
})
},
awaitUserData(randomId: string): Promise<string> {
const socket = io(`/sso-status`, {
query: { userId: randomId }
})
return new Promise<string>(resolve => {
socket.on(randomId, (data: string) => resolve(data))
})
}
/* server: http.Server */
const baseSocket = io(server).origins('*:*')
 
baseSocket.of('/sso-status').on('connection', async socket => {
const { userId } = socket.handshake.query
console.log(`sockets.ts: waiting until ${userId} logs in`)
dbWatcher.addSubscription(userId)
dbWatcher.on(userId, async () => {
const userData = await getAsync(userId)
await delAsync(userId)
socket.emit(userId, userData)
})
})
getQrCode (randomId: string) {
const socket = io('/qr-code', {query: { userId: randomId } })
return new Promise<string>(resolve => {
socket.on(randomId, (qrCode: string) => resolve(qrCode))
})
},
Wait for auth Redis
Checkout form

💡team building
•find your team ahead of the event if possible
•be very careful of people who
• consider themselves “very senior” (they’re not pragmatic)
• are “designers” without knowing CSS (“Photoshoppers”)
• talk about everything but the hackathon (just want to hire you)
•first thing you do: agree on a messenger protocol (Slack) / channel

Tech Tinder
Customize your Tech radar
Schwarz Group - “CodeCamp Heilbronn” - Nov 2018

Challenge
•“Schwarz group”: 2nd largest grocery / supermarket in Germany / LIDL
• ~500 developers over the world
• no one knows all requirements
•Build a tool that helps their dev teams to keep track of their tech stack

Idea: Tech-Tinder
•a tech radar controlled by employees
•everyone can add new technologies
•vote on technologies using a “tinder” interface

Tools / APIs
•Backend: MongoDB Atlas / Stitch (FaaS)
•Frontend: Vue.js / Bueify
•integrate “swing” swiping library (vue-swing2)
•copy / paste and adjust Zalando’s TechRadar project

stitch FaaS editor

technology_aggregate.js (stitch)
exports = function(technologyId){
const colTech = context.services.get("mongodb-atlas").db("tech-
tinder").collection("technology");
const colVotes = context.services.get("mongodb-atlas").db("tech-
tinder").collection("votes");
const aggregationPipeline = [
{"$group": {
"_id": { tech: "$ref", opinion: "$op" },
"total": { "$sum": 1 }
}
},
{"$group": {
"_id": "$_id.tech",
"count": {"$sum": "$total"},
"stats": {
"$push": {
op: "$_id.opinion",
total: "$total"
}
}
}
}
];
var pipeline;
if (technologyId) {
pipeline = [{$match:{ref: BSON.ObjectId(technologyId)} }]
.concat(aggregationPipeline);
} else {
pipeline = aggregationPipeline;
}
return new Promise( (resolve, reject) => {
//let technology = colTech.findOne({_id: techId});
colVotes.aggregate(pipeline).toArray().then(ag => {
const techIds = ag.map(agg => agg._id); //stitch doesnt
support $lookup
colTech.find({_id: {"$in":
techIds} }).toArray().then(technologies => {
const combined = ag.map(agg => {
let base = technologies.filter(tt => {
return tt._id.toString() == agg._id.toString();
})[0];
if (!base) {
return null;
}
base.votes = {
total: agg.count,
results: {}
};
agg.stats.forEach(s => base.votes.results[s.op] =
s.total );
return base;
});
resolve(combined.filter(c => c != null));
});
});
});
};

vote.js (“tinder”)
<div class="container" v-if="technologies.length > 0">
<span class="tag is-info is-large tag-hint tag-top" :style="{ opacity: opacity.top }">interested</span>
<span class="tag is-info is-large tag-hint tag-left" :style="{ opacity: opacity.left }">discouraged</span>
<span class="tag is-info is-large tag-hint tag-right" :style="{ opacity: opacity.right }">using</span>
<span class="tag is-info is-large tag-hint tag-bottom" :style="{ opacity: opacity.bottom }">evaluating</span>
<div class="card-viewport">
<div class="card-stack">
<vue-swing
v-for="technology in technologies"
:key="technology._id"
:config="cardConfig"
@throwout="throwout"
@throwin="throwin"
>
<div class="card card-item" :data-key="technology._id" >
<div class="card-image">
<figure class="image">
<h1 class="title is-3">{{ technology.name }}</h1>
</figure>
</div>
<div class="card-content">
<p class="is-5" v-html="technology.description"/>
</div>
</div>
</vue-swing>
</div>
</div>
</div>

👍 hackers’ rules of thumb
•you can’t learn a new language during a hackathon
•use as much SaaS and PaaS services as possible
• Contentful, Heroku, AWS Lambda / RDS, Firebase, now.sh, netlify
•never do “microservices”
•use DX-friendly frontend tech stacks
• vue-cli, create-react-app, Gatsby, ionic
•don’t to TDD!

Green Fee
let drivers pay for their air pollution in real time
“Blockchain Hackathon Stuttgart 2” - Feb 2019

Challenge
•sponsored by huge German banks, Daimler, blockchain agencies
•improve “mobility” with ledger tech
• other challenges were “Industry 4.0 / IoT”, “Finance”
•they expect a “business” presentation 🙄

Idea: Green Fee
•track vehicles’ motion
•track environmental conditions (current air pollution ratio)
•price = constant * (your pollution / environmental pollution)
•track your pollution cost in “real time”
•compensate “the planet” in near realtime

Tools / APIs
•IOTA MAM (Masked Authenticated Messaging)
• write pollution costs onto an IOTA DAG ledger MAM
• every message contains an due amount of IOTA
• asnychronous process polls MAM stream and triggers payments
•open air pollution data service
• public.opendatasoft.com
•Leaflet / OSM / plain jQuery, Webpack Encore for fast asset building
•expressjs as backend

– The official IOTA project
It is possible to publish transactions to the Tangle that contain only messages, with no value. This
introduces many possibilities for data integrity and communication, but comes with the caveat that
message-only signatures are not checked. What we introduce is a method of symmetric-key
encrypted, signed data that takes advantage of merkle-tree winternitz signatures for extended
public key usability, that can be found trivially by those who know to look for it.

– Alexey Sobolev, Oct 2017
“The ID published to the tangle is the hash
of the hash of the message key seed.”
🤔

publish.js
const Mam = require('@iota/mam/lib/mam.client.js')
const { asciiToTrytes } = require('@iota/converter')
const fs = require("fs");
const mamState = Mam.init(config.provider, config.seed);
const lastState = fs.existsSync(LAST_STATE_FILENAME) ? fs.readFileSync(LAST_STATE_FILENAME).toString() : null;
if (lastState) {
mamState.channel = JSON.parse(lastState);
}
app.post('/msg', async function (req, response) {
var t = new Date()
const payload = {
d: t.toLocaleDateString() + " " + t.toLocaleTimeString(),
data: req.body
};
const trytes = asciiToTrytes(JSON.stringify(payload))
const message = Mam.create(mamState, trytes)
await Mam.attach(message.payload, message.address, 3, 9)
if (!mamState.channel.currentRoot) {
mamState.channel.currentRoot = message.root;
}
mamState.channel.lastRoot = message.root
fs.writeFileSync(LAST_STATE_FILENAME, JSON.stringify(mamState.channel))
response.json(mamState)
})

💡ideation
•if there are “sponsors”, select 1 with an API you can relate with
•don’t put all the sponsors’ APIs in one app
•do a design thinking session
• plan your idea for 2-3 hours!
•remove everything that’s not absolutely necessary
•do a “good looking” UI that’s responsive and usable on mobile
• vuetify, MUI, ionic, Bueify, Reactstrap

Blockstagram
Instagram on the blockchain
“Blockstack Hackathon Berlin” - Mar 2018

Challenge
•build something meaningful with “Blockstack”
•self sovereign “blockstack.id": a socially / stake backed identity (BTC)
•use their “Gaia” hub: file storage decentralization concept (~IPFS / Storj)
• P2P synced decentralized storage.  
Bring your own cloud or trust Blockstack

Idea: Blockstagram
•“Instagram” on Blockstack
•Upload your pictures to Gaia hub (controlled by you)
•acknowledge “friend” identities for read access
•provide a symmetric key for them to decrypt your images
•to unfriend (hide) someone, reencrypt all the images with a new key

Tools / APIs
•Blockstack
• Identity & Gaia Hub
•ReactJS / CRA (ejected)
•Netlify deployment

read your friend’s instagram data
async readSingleSubscribersImages(username) {
const indexData = await blockstack.getFile('index.json', {
username: username,
decrypt: false
})
const data = JSON.parse(indexData);
console.log('Subscribers indexData is', indexData);
data.images.forEach(async indexEntry => {
if (!this.subscriberImageLoaded({ ...indexEntry, username })) {
const imageData = await blockstack.getFile(indexEntry.path, { username,
decrypt: false })
this.updateFeed({ path: indexEntry.path, username: username, image:
imageData, created: indexEntry.created });
}
})
}

💡task distribution
•is very hard since you don’t know / trust each other
•one (experienced) guy must control the repo
• everyone must commit to the same repo!
•mock it till you make it
• https://www.mockbin.org
• use postman shared collections
•“I’m done, what can I do next?” -> “I’m done. I’d like to add xyz”

Survival Guides
Bonus

2pm: the idea wasteland
•talk to others and listen closely
•you may steal and reiterate their ideas!
• Most likely you’ll build sth else anyway!
•google the APIs and find related Stackoverflow questions
•try to come up with a real problem that you personally could have
😩

8pm: the desperation zone
•you will not get done anything until 8pm. That’s normal!
•Pair! Sitting next to each other always helps.
•look at the other teams. You’ll note that they’re also struggling *very* hard
•don’t argue or overthink! Do!
• you usually will never look back at the code!
•if you want to win: get rid of people who disturb the team. (Just ignore them)
•if you want to learn / earn karma points: discuss it out with them
🤯

4am: the blue hour of devastation
•things will start to work when you’re most desperate and expect it least
•stay awake!
• Fresh air, do a break every 10m if necessary. But stay on it!
• Bananas and cold pizza work better than coffee and Red Bull.
•tiredness goes away around ~8am (and punches you out by 1pm)
•do some simple tasks (e.g. frontend polish) for success feelings
☠

10am: prepare your presentation
•select one dedicated presentation guy
•usually your presentation will win the game, not your code
•build a story
• “my friend Dyrk called me yesterday and we’re solving his problem here”
•fake the demo if necessary but make it run!
•have 1 WOW effect
•skip “market research”, “business model” and “rollout strategy”
💁

too long, didn’t listen.
•Hackathons are for pragmatic developers, not clean coders
•solve as much as possible on the frontend (learn React or Vue & node!)
•it’s really a “thon”: you need to suffer to take away the grand prize
•it’s incredibly rewarding when your demo starts working at 4am
•the more tools and services you use, the better.
•people will remember you. Everything happens for a reason.
•never give up, never surrender.

6. not winning makes you weirder!

That’s all, folks
Stefan Adolf 
https://www.facebook.com/stadolf 
https://twitter.com/stadolf 
https://github.com/elmariachi111 
https://www.linkedin.com/in/stadolf/

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