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Understanding Indexers and Delegators in The Graph

April 25, 2021
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Here is a great video explaining the concents of Indexers and Delegators and the relationship between them in The Graph ecosystem. Source: https://thegraph.com/docs/network#overview
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A catch up with John Mackie from BlockchainNZ

April 19, 2021
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John Mackie is a Chartered Professional Engineer specialising in water and is currently involved with the significant reforms occurring in the water industry in New Zealand. His interest in blockchain technology piqued when he understood how this distributed ledger technology could be applied to address global water management challenges. John is a co-founder of the smart meter start-up MeterMe Ltd, which is developing the concept of a distributed ledger for water. On joining the Blockchain Executive Council in 2020, John took on the passion project to assist in improving digital education in blockchain and its related applications.
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A catch up with Viktoriya Pashorina-Nichols

March 30, 2021
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Viktoriya Pashorina-Nichols is a general commercial Senior Solicitor at Simpson Grierson who enjoys, in particular, advising startups/early stage companies and seeing them grow on their journey. As part of this role, Viktoriya developed a lot of interest in blockchain technology and the world of cryptocurrencies, which has resulted in her participation as an Executive Council member and Chair of BlockchainNZ. Aside from blockchain and startups, Viktoriya assists with business acquisitions, corporate governance and administration, business structuring (eg through companies, limited partnerships, or joint ventures), capital raising and venture capital funds, and other general commercial/trading arrangements.
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A catch up with Shahid Saiyad from BlockchainNZ

February 9, 2021
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Shahid Saiyad is the financial services and blockchain lead at IBM New Zealand and was actively involved in the blockchain community in Asia Pacific before relocating to New Zealand in 2017. Shahid has extensive experience in business transformation, ecosystem development and contributes his experience as a member on the executive council of BlockchainNZ. He has an interest in intelligent workflows, Economics, privacy, data economy and blockchain.
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Deploy Solidity helloWorld to Ethereum testnet

January 22, 2021
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Building on from the previous article on creating a helloWorld smart contract, here we will show how to deploy a contract to an Ethereum testnet. The testnet we will use is called Ropsten but there are others can you can choose such as Koven, Rinkeby or Goerli. Step 1: Install Metamask Metamask is a browser plugin that can serve as a crypto wallet and also as a connection to various blockchains to communicate and sign transactions. Install this by visiting: https://metamask.io/download.html Step 2: Change the Metamask network Change the network to the Ropsten testnet. Step 3: Get some test ether To get some test ether, click buy, and then click Get Ether in the Test Faucet section below. Step 4: Deploy your smart contract Change your environment from Javascript VM to Injected Web3. Now when you click deploy, Metamask will pop up and ask you to confirm the transaction. Click confirm. Step 5: Interacting with your smart contract Now you can interact with your smart contract the same way but each time you try and store a message, you will have to pay a small fee (gas) and sign the transaction using Metamask. Here is a link to the smart […]
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A catch up with Ann Ibrahim from BlockchainNZ

January 11, 2021
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Ann Ibrahim is an expert in the domain name industry with over 10 years’ experience. Ann currently works at the Domain Name Commission, the regulator of the .nz domain name space and is on the executive council of BlockchainNZ. She has an interest in the technology of decentralisation and is keen to see how the future unfolds in the blockchain world.SHOW LESS
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Solidity HelloWorld (updated for 2021) with Remix

December 22, 2020
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It is really easy to get up and running with Solidity smart contracts using Remix which is an online IDE for developing smart contracts in Solidity. If you visit https://remix.ethereum.org/, you’ll see some sample code Removing all the comments to make it less scary, you can see that the name of the contract is “Storage”, there is one variable called number of type uint256 which stands for an unsigned integer that is 256 bits long and then two functions. One to store the number and one to retrieve the number. And that is it really. Read this explanation of functions to demystify the key words such as public, view and returns and this smart contract should be easy to understand. Below I’ve changed the code to store a string instead and changed the contract name to “helloWorld” To run this, you will have to compile the contract first. Then deploy the contract. Now you can store a string and retrieve the string.
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A catch up with Daniel Bar from BlockchainNZ

November 30, 2020
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Daniel is an entrepreneur and investor with primary focus on decentralized web technologies. He leads global Blockchain collaborations that involve grassroots developer communities, high performance tech projects, venture funding activities, academic research groups, NFPs and governmental advisory. Here, Daniel talks about what DAOs are, the value they add and shows how to create a simple DAO on DAOStack’s Alchemy.
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Understanding DAOStack and joining a DAO

November 22, 2020
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What is a DAO? A DAO stands for Decentralised Autonomous Organisation and with the invention of blockchain technology, in a nut shell has allowed a group of people to make decisions where trust is placed within the technology and the blockchain network. What is DAOstack? From their whitepaper, DAOstack defines themselves as “an operating system for DAOs”. From their website, “DAOstack is an open source project advancing the technology and adoption of decentralized governance.“ Both these definitions don’t mean much to beginner so to explain it another way, DAOstack is a “stack” or a group of technologies that has been invented using smart contracts and blockchains to allow the easy creation of DAOs or Distributed Autonomous Organisations. A more detailed article here goes into much more depth for those inclined. What is Alchemy? Alchemy is a nice user friendly interface for creating DAOs coz let’s face it, this technology is complicated enough without having to do everything in a command line terminal! On https://daostack.io/ you can “Explore DAO’s in Alchemy” which takes you to https://alchemy.daostack.io/ What is xDAI chain? “xDai Chain is a stable payments blockchain designed for fast and inexpensive stable transactions.” ie it is another blockchain network and […]
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Update of IRDs guidance on crypto assets

September 8, 2020
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Inland Revenue has provided an update on its guidance of how it treats what it calls “cryptoassets” at: https://www.ird.govt.nz/cryptoassets A link to the IRD media release can be found at: https://media.ird.govt.nz/articles/new-inland-revenue-guidance-on-cryptoassets/ The high level summary is: There are no special tax rules for cryptoassets in New Zealand. The guidance clarifies how ordinary income tax rules apply to cryptoassets to help people understand their tax obligations. Essentially, cryptoassets are treated as a form of property for tax purposes. What people make from selling, trading or exchanging crypto-assets is taxable
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Chat with Mark Pascal, The DAO Agency

September 3, 2020
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Mark Pascall is a leader in the NZ blockchain space. He organised New Zealand’s biggest blockchain conference, is the past president/executive director of Blockchain NZ and currently leading the conversation around decentralised autonomous organisation in NZ. Learn about Mark’s rabbit hole story, DAO’s and visit https://www.thedao.agency/​ to get in touch with Mark and learn more.
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Catching up with Jerome Faury from Centrapay

July 22, 2020
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A short chat with CEO of CentraPay Jerome Faury. “Who’s gonna pay with a credit card?” was the response Jerome got when he cold called manufacturers of parking and vending machines back in the mid 2000’s offering credit card payments. Fast forward 15 yrs, he’s back at it offering crypto payments with Centrapay. Learn about digital assets, pocket vouchers and the Sylo wallet. Also check out where you can by coke with crypto with this neat map: https://centrapay.com/merchant-acceptance-locations/ Jerome also explained digital currencies to John Campbell as well.
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Error: Callback was already called – Ganache

July 9, 2020
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OpenZeppelin has some neat docs to show how to create, deploy and interact with smart contracts centered around installing node, using the OpenZeppelin libraries, compiling via CLI, and deploying via Ganache which is a local blockchain environment for development and testing. Some of you may remember TestRPC. Ganache is the new name of TestRPC.  The TestRPC quickly became more powerful than simply a blockchain environment used for testing. To stay with the sweet Truffle brand, we decided to rename it Ganache, as Ganache is (often) the core of your favorite chocolate truffle. It’s a much catchier name (and a much tastier one too). https://www.trufflesuite.com/blog/testrpc-is-now-ganache The problem though is when you follow the docs at https://docs.openzeppelin.com/learn/deploying-and-interacting and run: npx ganache-cli --deterministic to get a list of all the available accounts, you might encounter this error: Ganache CLI v6.9.1 (ganache-core: 2.10.2)Error: Callback was already called. The problem is because you probably have node v14 installed. Run: node -v to check. For me, I installed node initially with the brew command brew install node which downloaded the latest version which was v14.5.0 The reason is an issue related to ganache-core’s internals not yet being Node v14 compatible. https://github.com/trufflesuite/ganache-cli/issues/732 Workaround Install Node v12 for […]
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Solidity events

June 30, 2020
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In Solidity, firing or emitting events is a handy tool that you can employ not only to log messages for simple debugging but more importantly Dapps or anything connected to the Ethereum JSON-RPC API can listen to these events and act accordingly. Events can also be indexed so that the event history is searchable later as well. Here is a very simple example of creating an event. pragma solidity ^0.6.0; contract EmitEvent { event log(); function triggerLog() public { emit log(); } } You first have to declare the event and then give it a name along with the parameters you want to pass around. The above example does not have any parameters. The example below has one parameter. pragma solidity ^0.6.0; contract EmitEvent { event log(string _logmessage); function triggerLog() public { emit log("hi"); } } The event gets displayed in the logs of the transactions in remix. Watch the video below for a walkthrough.
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Which is cheaper, a public function or an external function?

June 17, 2020
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Here is a quick video explaining which function is cheaper, a public function or an external function in Solidity. I’ve also included a demonstration to prove it as well.
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The way training should be … free

May 28, 2020
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I got this email in my inbox recently about free training material from Corda, which is an “open source blockchain platform for business“. I decided to take a look and the content at https://training.corda.net/ is very well designed and presented. It is definitely a lot more user friendly than the documentation! It provides key concepts at the start and interestingly enough put blockchain fundamentals at the very end. I would have had it at the top as well but assume that because it wasn’t Corda specific, it is like an Appendix of sorts. There is an introduction to your first code or “CorDapp” which is very important, and then introduction to libraries and SDK’s because there is usually no need to write things from scratch nowadays. It jumps into Corda specific details and then rounds off with a nice summary. The content is very high quality and neatly packaged as well. The only thing I would add is a Hello World type application for the absolute newbie (which also serves as a system check), and a stronger “Where to next” section. The Corda blog is also very informative and consistent so hats off to them. This is all self paced learning […]
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Your Site Has Been Hacked

April 16, 2020
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I received the following email recently and initially was very worried. I scrolled down and saw the demand for USD $2000 in Bitcoin! They wanted it sent to this address “1Q1DF9rJS6fNDSpiV2iEA46BS1mNEaELtC”. (FYI: The address is empty). Firstly, the site in question has no sensitive information there. In fact, it is just a new blogging site with only 4 or 5 blog posts so this made me raise my eyebrow and not be too concerned. However, if it was a more important website, I would have been a lot more nervous only to calm down having seen this Google search. I then sent an email to my hosting provider and they confirmed that this was a scam. Thanks for getting in touch regarding this. Unfortunately we’ve beenseeing an increase in these type of scam attempts but rest assured it isjust scam. A security scan shows there is no indication that your site isvulnerable or that it has been compromised. As such you can safely ignorethe threat message. What the scammers do is use a template and automate the email replacing the website URL for each site. They typically use the contact us form websites usually have and shame on me for […]
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Installing Hyperledger Besu

January 18, 2020
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Installing the Enterprise Ethereum client Hyperledger Besu may seem daunting at first but the key is to break it down step by step. The following is a set of short videos demonstrating how this can be done. a) System Requirements You’ll ideally need 8Gb of Ram and a lot of hard drive space. Around 3Tb if you want to do a full sync with Ethereum mainnet. b) Install Besu on MacOS Installing on a Mac is very quick. You’ll need Homebrew (https://brew.sh) and also Java 11 or above (brew cask install adoptopenjdk) Then all you do is run: brew tap hyperledger/besu brew install besubrew -- version c) Uninstalling Besu on MacOS Here are the shortcut commands to uninstall Besu: brew cask uninstall adoptopenjdk brew untap hyperledger/besu brew uninstall besu d) Building Besu from source Here are the shortcut commands to install Besu from source: > git clone --recursive https://github.com/hyperledger/besu.git > cd besu > ./gradlew installDist > cd build/install/besu > ./bin/besu
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Installing Besu quick commands

December 25, 2019
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besu --version //check if Besu is installedbrew uninstall besu //uninstall Besubrew install besu //install Besu (assuming you have already tapped it first with brew tap hyperledger/besu)brew cask install adoptopenjdk Starting Besu To start Besu, just type besu This will start Besu pointing it to mainnet. This means that the blockchain will start to synchronise with the real Ethereum blockchain. A database folder (where the blockchain will be stored) will appear at usr/local/Cellar/besu/1.3.8/ which is where homebrew installed besu. For testing purposes, start Besu with the network flag of dev besu --network=dev The other option is to use a config file and then specific the network, as well as other parameters there. data-path="besudata"network="dev"miner-enabled=trueminer-coinbase="0xfe3b557e8fb62b89f4916b721be55ceb828dbd73"rpc-http-cors-origins=["all"]host-whitelist=["*"]rpc-ws-enabled=truerpc-http-enabled=true Then reference the config file with: besu --config-file="/User/sean/config.toml" Note that flags in the command line override flags in the config file. For a complete list of other command line options, visit: http://besu.hyperledger.org/en/stable/Reference/CLI/CLI-Syntax/ Checking Besu network To confirm the network you are connected to, you want to query the Besu API for the net_version. curl -X POST --data '{"jsonrpc":"2.0","method":"net_version","params":[],"id":1}' localhost:8545 You can find out what net_version does along with all the other API options here. However, in order for this to work, Besu must be started with the flag: […]
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Crypto wallets live webinar

December 16, 2019
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One of the first steps when embarking on your blockchain journey is to understand about wallets because when you get your bitcoins, ether or any other token for that matter, where are you going to store them? It can be a bit confusing when you first come across terms such as hot wallets, cold wallets, HD wallets, paper wallets, or hardware wallets. I’ll be hosting a webinar this Thursday at 6am AEST running through all you need to know about wallets and more. Yes, there are thousands of YouTube videos on this topic but I’ll be speaking from my own personal experience on these matters and not what I read in some book or web article. As a bonus, we’ll also have a special guest from MetaMask, Ethereum’s most popular wallet as well. You’ll also have the chance to ask some questions as well! (It is a live webinar after all!). The intended audience are those curious about the blockchain space but have yet to venture into it, or beginners who may have some experience but want to learn some more. The webinar agenda is roughly 20 minutes about wallets, 20 minutes from our MetaMask guest and then 15 minutes […]
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