Decentralised Applications Development Club
Kickoff Session
20/02/2019
1 / 27
Today
- Intro
- Partners
- Sessions
- Focus
- Build what?
- Just enough blockchain
- What's a DApp?
- Next session
- Announcements
2 / 27
Intro
Brendan
- Work mostly with NodeJs
- Started DApps Dev Club
3 / 27
Intro
Brendan
Kenneth
- Work mostly with Solidity
- Runs the Blockchain & DApps meetup
4 / 27
Intro
Brendan
Kenneth
Why DADC?
- Many blockchain meetups
- None that focus on
- teaching the underlying technology
- how to develop apps
5 / 27
Intro
Brendan
Kenneth
Why DADC?
Book Club
- Run like a book club meets tech meetup
- Will actually be using a book
- Mastering Ethereum
- Format is heavily inspired by SingaporeJS' book club
6 / 27
Community
series of meetups- meet + learn + build
- workshops in person
- work on projects between Sessions
12 / 27
- We're not merely running a series of meetups
- We're building a club, where members can meet with, learn from, and work with each other
- In person component is like a workshop
- In between sessions, work on further building what you've started during the sessions
- https://dappsdev.org
- be sure to check back on this site regularly for updates
- emphasise RSS feed
- show twitter
- sessions page orientation
- go through the list to see what's coming up
- when venues and dates are confirmed, check back here for updates
- discord
- everyone here can join, and chat with each other between sessions
- don't have to wait till the next one
- certificates (optional)
- Attendance, not attainment
- Fun project that we as organisers will be building alongside the course itself
- projects (optional)
- Publish your WIP and completed projects here
Focus
- Sessions: Freedom within a framework
- Required knowledge
- Too simple? Too advanced?
- What you'll be learning
slides < code < discussions (unlike today)
15 / 27
- Freedom within a framework
- The sessions are designed around a loose idea of what DApp development is about
- The actual space that DApps cover is far greater than what we can possibly hope to achieve
- You as members can shape the direction of the series
- Required knowledge
- No need to know anything about blockchain
- No need to know anything about smart contracts
- No need to know anything about web3
- What you'll be learning in the first series
- Very briefly cover "just enough blockchain" as background info
- Learn smart contracts from scratch, including solidity
- Learn web3js from scratch, not including javascript
- You do not need to already know JS to attend the series, but you'll need to learn it at a basic level
Build what?
- DApps and CApps
ERC20"wen ico? wen moon?"- Bring your ideas along to the next session!
break;
16 / 27
- Over the course of these session it will become apparent:
- How a DApp differs from a CApp
- Which types of applications are suited to DApps and which are not
- DApps and CApps can co-exist in the same ecosystem, in fact can even build a DCApp
- ERC20 tokens and "wen ico? wen moon?"
- That is not what we'll be doing in these sessions
- Building an ERC20 token almost seems to be the "Hello World" as far as DApp tutorials go
- Here we'd like to build something less cliche, and more interesting
- Bring your ideas along to the next session!
- When we break between topics, mingle with others
- Ask each other what idea they would like to build for a DApp
- If you're itching to get started on something, please introduce yourself and your idea to everyone here at the end of the session
break;- discuss ideas
Just enough blockchain
Blockchain
- Debuted by Bitcoin
- Transactions
- So many things!
- cryptography
- p2p networking
- distributed consensus
- data structures
- immutable ledger
17 / 27
- DApps are built on top of a technology called blockchain
- Bitcoin debuted the concept of a blockchain - 10 years ago
- The blockchain is a very complex topic, and we could spend many sessions just talking about that alone
- However, that is not our focus here - instead we are going to learn the minimum viable blockchain, in order to delve right into DApps development
Just enough blockchain
Blockchain
Ethereum Virtual Machine
- Global computer
- Transactions + Apps
- Smart contracts
- Pay a gas fee per function call
- Similar to serveless
18 / 27
- Ethereum first made it possible to build applications on top of the block chain
- EVM is a global computer - every single node participating in the network runs the programs
Just enough blockchain
Blockchain
Ethereum Virtual Machine
Anders' Demo
- Possibly the best explanation out there of how these fit together:
- hashes
- blocks
- blockchain
- https://anders.com/blockchain
- https://www.youtube.com/watch?v=_160oMzblY8
- Show of hands: Who is already familiar with this?
break;
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- What is a hash?
- What is block?
- What is a singly-linked list?
- (optional) What is a merkle tree?
- What is distributed consensus?
- What is the double-spend problem?
- Demo the Anders blockchain demo
- show of hands who has watched this video or used this demo before
Just enough blockchain
Blockchain
Ethereum Virtual Machine
Anders' Demo
Smart contracts
- Blocks
- Previously: Stored transactions
- Now: Also store code & state
- Mining
- Previously: Verify & proof-of-work
- Now: Also execute code & update state
20 / 27
- previously -> bitcoin; now -> what ethereum adds
DApps?
Theory
- What a blockchain gives us:
- Distributed ledger
- Distributed consensus
- Immutable state
- Tamper proof transactions
- Smart contracts
- Tamper proof transactions as well
- ... not only for units of "coin"
- also for state transitions
- append-only TX logs in SQL databases
- http://blog.notdot.net/2009/12/Damn-Cool-Algorithms-Log-structured-storage
21 / 27
- so now we have covered what a blockchain is
- what that gets us is a distributed ledger, plus distributed consensus, which equals immutable state
- that in itself is an amazing feat, because that enables tamper-proof transactions
- the meteoric rise of bitcoin in itself is testament to that
- but what if that was not enough? we'd like to do more than process transactions please!
- enter smart contracts
DApps?
Theory
Practice
- (mostly) written in Solidity
- deployed onto blockchain as data
- ethereum wallets send messages to smart contracts
- via nodes mining on the network
- signature + calldata (+ ether)
- node executes the specified function
- run through the ethereum virtual machine
22 / 27
- smart contracts in ethereum are largely written in solidity
- these smart contracts are deployed onto the blockchain as data
- clients use ethereum wallets to send messages to these smart contracts
- signature + calldata + amount of ether
- ethereum nodes execute the smart contract function specified by the messages
- ethereum virtual machine, which we'll get into more
- the new state of the contract is recorded oin the next block
DApps?
Theory
Practice
Limitations
- smart contracts are just programs
- EVM programs are currently limited
- transaction speed
- storage costs
- query capabilities
- UX
23 / 27
- You cannot build everything you can in a CApp in a DApp - today
- Progress is being made in these areas
- When solved, the decentralised web/ web3 will likely be used by the average person
- By learning to dev DApps now, you're way ahead of the mass adoption curve
DApps?
Theory
Practice
Limitations
Vision
- Web 3, or the decentralised Internet
- Web 2 - our current internet - is heavily centralised
- Centralised technologies are inherently not tamper resistant
- Censorship
- Control & visibility of data + code
- Levelling the playing field
24 / 27
- smart contracts are merely programs
- what makes them special is that they run in a completely decentralised, and thus a tamper proof manner
- this makes apps developed using them unlike apps that are developed today using centralised technologies
- "web 3"
Next session
- https://dappsdev.org
- Anders' blockchain demo
- Ethereum Book:
- Bring your DApp ideas!
25 / 27
- anyone here already have some ideas for DApps you'd like to build with the club, pls come to the front
- if you're shy, just stick around and talk about it with those around you, or to kenneth and myself
Partners
- Venues wanted!
- 2 sessions per month
- Consistent venue
- Thank you sponsors!
26 / 27
- The plan is to run two sessions per month
- We need venues for the remaining sessions
- If you work at a company, and your company has a space that it is not using on week nights, why not tell them about DApps Dev Club?
- We have been lucky to be sponsored for this session
- Would anyone here from Microsoft, Spartan, NBC19, or Engineers.SG like to say a few words?
- be sure to check out the sessions page for updates, and join our discord
- any other announcements?