In Devcon 5, Osaka, I saw Ethereum's diverse DeFi ecology.

Devcon5 is over, it's time to write a review!

This time Tmono took me and Tina, Feng Liu, Cao and Suji to a group to go to Ethereum Devcon5.

The ticket is a discount ticket for the book before the old days, but in fact, it is not expensive to buy a few days before the departure (or even cheaper), and the ticket is near when it is finally obtained. Let me talk about Devcon’s tickets and have to vomit. Devcon’s tickets are really expensive. In order to get the free ticket, I first prepared a 2 hour Smart Contract CTF Workshop, but it was brushed. It now seems that it should take too long for the setup, and the whole meeting will not exceed the 1hour workshop.

After the Workshop failed, I went to the TPE to help me see if I could get some volunteers to mix in, but the number of volunteers who reported too late was over, and TPE said that they considered that many people want to go but can't make tickets, so Do you want to come to Taipei as a volunteer next week, we will get a parallel Round in Taipei, called Crosslink, so I will go to Taipei next week…

Anyway, I finally bought a builder ticket with a discount from Eric on the wheat wallet (ah, although 50% discount is still expensive). However, it seems that, in addition to the ticket price is not so approachable, there seems to be nothing to vent outside the venue wifi conditions explosion?

To understand the progress of the Ethereum community, it is more worthy of attention than the 30mins speech of everyone in the main venue. This time the venue was arranged in a shopping mall, B1 is the main venue and sponsor display area, 1F is the reception desk, then the breakout venue and workshop are arranged in 6F, the commercial area is separated, and everyone is daily. I will send 2 coupons for 500 yuan to eat for you, but it seems that only 500 yuan is enough to eat ice cream, so you can choose to join in the last day to eat a beef. Although I have already done my homework before departure, the amount of information in the conference is still larger than expected. It is very difficult to miss the important things.

Day 0

In fact, since the 7th, the activities around Osaka have been filled up. There is an Event Calendar called Offdevcon on the Internet to record the various branch plots around. I have been filling Tina for the weeks before the departure. Not only did the previously agreed CPC algorithm discussion class have no time to do it, I continued to fill the pit on the plane the day before and on the same day. This directly led to a serious lack of rest during our Day 1, but fortunately Day 1 seems to be mainly warming up.

DeFi.WTF in Osaka Japan

The advertisement that Liu teacher saw on the road seems to be exactly the same as the design style of DeFi.WTF…

About the Day0 activity, which is the main Defi.WTF I participated in, I wrote half of it here and will continue to fill the hole tomorrow.

  • Youtube live address
  • Slides
  • Filling record (WIP)

Ethereum Lightning Talks

Day 0 Another event is Ethereum Lightning Talks, which is jointly organized by Unitimes and ETHPLANET, and is actually in the same event venue…

Day 1

Day 1 The first thing to do is to get Swag. First, sign in outside, then take the Swag place in the sponsor hall (make sure you go to the sponsor counter). The volunteer brother is especially jealous of me. If these Swag are not finished, you can come back once again at the end of Friday.

In addition, the most interesting record of Day 1 is that I actually bumped into my former colleague Ivan Bogatyy on Lightning Talk! After the meeting, I sneered a few words. This buddy left the investment bank after leaving Google and has more time to do his favorite research. The speech brought this time is zkSNARK Ethereum mixer, the content is very impressive, the content is obviously one level higher than the other speakers competing in the same stage. I passed the video of this speech on Bilibili.

Day 2

Important events start with Day 2, and live playback can be seen on slideslive.

Day 2 There is a Vitalik warm-up in the morning.

This year's warm-up speech was – Cryptoeconomics in 30 minutes. Https:// 1:15:30

Then in the afternoon, Chih-Cheng Liang and Hsiao-Wei Wang of Vitalik and Taipei Ethereum Meetup also had a talk about Eth2 setup – Eth2 Phase 0 Technical Deep Dive.

Probably asked a bit annoying, so Vitalik replied that she would write an article next week about how to migrate from eth1 to eth2, and the result came out the next morning… /the-eth1-eth2-transition/6265

In fact, in the past few days Vitalik has sent a total of six articles in ethresear, four of which are about Sharding:

  • Formalizing and improving eth2's approach toward finalization of invalid shard blocks,Oct 9, 9:04 PM
  • Cross-shard DeFi composability, Oct 10, 10:49 AM
  • Partially sharding single-threaded apps: a design pattern,Oct 11, 8:53 AM
  • On-beacon-chain saved contracts,Oct 11, 3:17 PM

Two other migrations about eth1 to eth2:

  • The eth1 -> eth2 transition, Oct 10, 9:55 AM
  • Two-way bridges between eth1 and eth2,Oct 11, 8:21 AM

It is very worth reading.


In the afternoon, I saw someone wearing a 2100 T-shirt in the venue. We all know that the circulation of Bitcoin is not 2100w. I didn't expect anyone to use this number directly to make meme. I just saw the Orange Book in the afternoon and I mentioned this project. It seems that the people in the afternoon met the project side.

According to official Twitter, they should be conducting an alpha test during Devcon.


The essence of communication is to make Meme. Speaking of Meme, the most impressive activity was the MCC2019 held in Silicon Valley. They put a cow in the venue that symbolizes the bull market. Interestingly, the bitcoin rebounded in those days. It really rose.

For Meme, see Day4's morning presentation, Weaving Cultural Fabrics With Tokens.

This time, Devcon officially invited one of Vitalik's two favorite Memes, Doge Sauce (the other should be an alpaca).

Doge Sauce also wrote a blog review for this purpose.


Day3 I listened to Gitcoin, Uniswap and OpenZepplin. But miss lost Tang Feng's Radical Democracy. Fortunately, she uploaded the slide in the first time…

Building on Uniswap

The founder of Uniswap, Hayden Adams gave a presentation on the topic of Uniswap V2 on Devcon. From this talk, you can see how the DeFi project implements Interoperability.

I will be giving a talk titled “Building on Uniswap” about how @UniswapExchange can be used as a building block for other financial applications and how its utility will be increased in V2.


How can we improve Uniswap to serve more use cases?

Hayden first introduced the current situation of Uniswap today, and then asked How can we improve Uniswap to serve more use cases? Then started to introduce Uniswap V2, not so much vision as Uniswap V2 is more like a roadmap.


  • Decentralized Onchain Price Oracles.
  • ERC20/ERC20 pairs
  • More flexible and secure codebase.

The first one is well understood, if a trading pair in Uniswap occupies 100% of the liquidity of the transaction, then the information provided by Oracle is completely accurate. For example, in the Harberger Tax Billboard designed for DeFi.WTF, Uniswap can be used as Unchain Price Oracle to support the use of both DAI and ETH tokens to purchase billboards.

The second point is still not known how Uniswap is designed. Uniswap currently needs to deploy a contract for each transaction pair, so all transaction pairs are first connected through ETH, so that not only can the order of the contract be controlled. O(n) also ensures that liquidity can be concentrated to ETH. Even with many centralized exchanges, several central currencies (such as BTC) currently occupy core liquidity. Hayden here gives cDAI/cUSDC as an example.

How can we scale Uniswap while retaining its utility

Next, Hayden describes how Uniswap scales in the ETH2 architecture. It can be roughly divided into three phases, Plasma, ZK Rollup and Optimizetic Rollup.

Hayden also credited the contributions of the Plasma team and the Vitalik team to Scability, just as Karl Floerach of Plasma was also in the last row.


Talk is Cheap, show me the code. Some time ago, Hayden developed a Dapp called Unisocks to show how to use the Uniswap protocol for token distribution. It seems that this protocol can be used directly to deal with fried shoes or fried skirts.

This time, to illustrate that the Optimize Rollup can be used with Dapp like Scale Uniswap, Hayden, with the help of the Plasma team, spent another two weeks doing another Proof of Concept to demonstrate how Layer 2 can help improve UI/UX – this It was the Unipig that he had previously shill on Twitter, and the audience present had already played before.

However, it seems that the interaction of this gadget is very small, and it is all counterfeit, so the effect of Demo is not very good in my opinion.


The final QA link.

Q: If the trading is Optimestic, how soon people realize they are lying? A: Hayden explained the process of block verification with data, some one submit that block to Ethereum, and then you can do verify.

Q: Have you ever thought about uniswap to trade baseball card? That would be really really cool. A: I think it would be cool to do a cryptokitties-like to stop the Ethereum network and then attract much much more fresh leeks.

Q: Regarding the transaction pair of ERC20/ERC20, will there be a problem of liquidity? A: This is a very good question. I believe that most trading pairs are based on Ether and DAI.

Q: Question about Uniswap's handling fee. A: There has been a lot of research in the workshop.

Q: About Native meta-transactions. A: Explain the difference between Native meta-transactions and In-Broswer Burner Wallet.


In the end, Day4 was only half a day. Everyone hurriedly listened and began to think about how to spend all the coupons, and then began to avoid the typhoon in the afternoon. The most exciting thing about Day4 is the big dance of the final closing ceremony. dai^2 was a little moved in the group. Roger Ver was directly infected and saw the culture of BTC.

Even mediocre developers wouldn't have destroyed a functioning network in favor of a Rube-Goldberg machine that barely even works. And yet that's the path BTC has gone down. Now Ethereum has the most developer talent in crypto.

—— @Rrogerkver, 1:47 am · October 10, 2019 from Osaka City, Osaka City

Reference material

Seeing this is equal to the vitality and chaos of Devon5: ETH2.0

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