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Data Structure In Ethereum. Episode 4: Diving Into Examples.

Data Structure In Ethereum. Episode 4: Diving Into Examples.

Data structure in Ethereum. Episode 4: Diving into examples. It seems to be a long journey from first episodes to here, we have gotten all we need and this time, it will be the last shot to make everything clear about how Ethereum data organized in practice. In my opinion, practising with examples is the best way to approach and get deep into any problems. By creating an example, I truly hope it can help you understand clearly about data structure in Ethereum. You can clone my git (develop branch) for more convenient if you dont want to get your hands dirty. Subject of the study: state trie (stateRoot) Following this link, you will know the way to setup geth as a full node in your computer. To start full sync mode of Ropsten testnet and open RPC, you can use this command: geth --testnet --datadir "~/Library/Ethereum/ropsten" --rpc --rpcapi "eth,net,personal,web3" --rpcaddr "0.0.0.0" --rpccorsdomain "*" --ws --wsapi "eth,net,personal,web3" --wsorigins "0.0.0.0" And remember that you should change the parameter after --datadir flag to be available to you. Because we run geth in full sync mode, it means geth need time (its pretty long in my situation, around 3 days) to sync entire blockchain data. When you see the logs like that, Im pretty sure it done. First of all, we need to create a nodeJS project and then install web3 package. Try running getStateRoot function with blockNumber is nearly newest block number on Ropsten. We avoid to get the newest because it will lead to risk of delaying sync, so nearly newest block number is a wise choice. My choice is 2596315 and it may be different at the moment you read this article. Be careful. My result of running getStateRoot(2596315): stateRoot: 0x1a63facb2a82966504a643f7c6cce28ddb47ea056b02009975c665bdada64c81 At this time, we Continue reading >>

Blockchain - What Is The Exact Data Structure Of Each Block? - Ethereum Stack Exchange

Blockchain - What Is The Exact Data Structure Of Each Block? - Ethereum Stack Exchange

What is the exact data structure of each block? is there any document / diagram describing Ethereum block structure in similar way as ? I know I can find implementation at but I am still missing some information as bytesize and similar... Yes, the Ethereum Yellow Paper (YP) and related Ethereum block architecture . Here are the main pieces of a block and the YP has all the sizes: 4.3. The Block. The block in Ethereum is the collection of relevant pieces of information (known as the block header), H, together with information corresponding to the comprised transactions, T, and a set of other block headers U that are known to have a parent equal to the present blocks parents parent. Here's an illusatration adapted from another answer -> definitions summarised from the yellow paper : See also Equation (35) of the yellow paper . On github here , Latex format: The component types are defined thus:\begin{equation}\begin{array}[t]{lclclcl}H_p \in \mathbb{B}_{32} & \wedge & H_o \in \mathbb{B}_{32} & \wedge & H_c \in \mathbb{B}_{20} & \wedge \\H_r \in \mathbb{B}_{32} & \wedge & H_t \in \mathbb{B}_{32} & \wedge & H_e \in \mathbb{B}_{32} & \wedge \\H_b \in \mathbb{B}_{256} & \wedge & H_d \in \mathbb{P} & \wedge & H_i \in \mathbb{P} & \wedge \\H_l \in \mathbb{P} & \wedge & H_g \in \mathbb{P} & \wedge & H_s \in \mathbb{P}_{256} & \wedge \\H_x \in \mathbb{B} & \wedge & H_m \in \mathbb{B}_{32} & \wedge & H_n \in \mathbb{B}_{8}\end{array}\end{equation}where\begin{equation}\mathbb{B}_n = \{ B: B \in \mathbb{B} \wedge \lVert B \rVert = n \}\end{equation} Continue reading >>

Analysis Of Data Structures On The Ethereum Blockchain/current Draft

Analysis Of Data Structures On The Ethereum Blockchain/current Draft

Analysis of Data Structures on the Ethereum Blockchain/Current draft A smart, connected toaster is of no value unless it produces better toast. The Scenario Overview in chapter 1 demonstrates the many envisioned use-cases for the blockchain. Ethereum is in rapid development and is planning on releasing four major versions within the next year, with the last version changing the fundamental consensus algorithm. What these upgrades will change the platform in detail, is uncertain. Hence will this thesis assume the Ethereum platform as it stands at the time of writing, and will avoid too much speculating on coming changes. The scenario selected is consequently a scenario which has a short time to market and could use todays version of Ethereum. published the idea of using the blockchain for the IoT in the . The corresponding scenario examines the idea of a smart IoT washing machine [1] . The report states that the motivation behind IoT has to be creating better products for the end-user. It is argued that better products can be achieved through new digital economies and creating collaborative value, and that these elements can be achieved with P2P, trustless communication and decentralized autonomy [p.8]. These three underlying technologies will be examined in chapter 3. caption Illustration of the IBM ADEPT washers operations Pureswaran et al. explains new digital economies this way: The IoT creates the ability to digitize, sell and deliver physical assets as easily as with virtual goods today. [...] In a device driven democracy, conference rooms, hotel rooms, cars and warehouse bays can themselves report capacity, utilization and availability in real-time. [p.13] Pureswaran et al. further claims that By reducing transaction and marketing costs, and enabling partnerships Continue reading >>

From Bitcoin To Ethereum

From Bitcoin To Ethereum

In response to: Cryptocurrencies and Blockchains (Vol. 2, No. 4). Jean-Paul Delahaye explains clearly in his article how the bitcoin protocol works, as well as the enthusiasm and fear it elicits. The major innovation behind bitcoin is the creation of an ecosystem that allows for a decentralized consensus. Users no longer need a reliable central authority to interact with each other. While it is difficult to predict how blockchain technology will become important in our everyday activities over the next few yearsincreasing our happiness, or notthe enthusiasm it elicits is growing. It could have many applications, of which cryptocurrencies are only an initial example. Among the platforms arousing great interest is Ethereum, which allows users to manage and interact with smart-contracts. Ethereum promises applications that work exactly as they were programmed and cannot be interrupted, censored, or modified in any way. It has been spoken of as one of the building blocks of web 3.0! Understanding precisely how all this works in practice is a fascinating subject. How can a user, interacting with the network via only his smartphone, quickly verify that a transaction has been saved on the blockchain? One approach uses the concept of a Merkle tree. This is an important data structure used in computing and cryptography, and I would like to follow up Delahayes article by explaining this point. Another legitimate question that one might ask with reference to the mechanism of transaction validation is: why do bitcoins have real economic value? There is more to bitcoin than simply a currency of exchange. To illustrate this, I will examine in some detail a transaction inscribed in the bitcoin blockchain. This has nothing to do with any financial transaction, on the contrary, it is c Continue reading >>

The Ethereum-blockchain Size Will Not Exceed 1tb Anytime Soon.

The Ethereum-blockchain Size Will Not Exceed 1tb Anytime Soon.

The Ethereum-blockchain size will not exceed 1TB anytime soon. Before diving into this article, please read the two disclosures about my involvement (1,2) and the one on data accuracy (3) at the bottom of the article. At least once a month someone posts a chart on r/ethereum predicting the blockchain size of Ethereum will soon exceed 1 TB. I want to take that chance to clean up with some stories around the Ethereum-blockchain size in this article and try to explain why this chart is technically correct, but not the full picture. Let's have a look at this chart first. It shows the complete data directory size of an Ethereum node (red), Geth in this case, and a Bitcoin node (blue), probably Bitcoin-Core , plotted over time. While the Bitcoin graph is moving slightly upwards in a seemingly linear inclination, the Ethereum graph reminds the reader of an exponential growing slope. On Blocks, Block-History, States, and State-History Users accusing Ethereum of blockchain-bloat are not far off with their assumptions. But actually, not the chain is bloated but the Ethereum state. I want to examine some terminology from the Whitepaper before proceeding. Block. A bundle of transactions which, after proper execution, update the state. Each transaction-bundling block gets a number, has some difficulty, and contains the most recent state. State. The state is made up of all initialized Ethereum accounts. At the time of writing, there are around 12 million known accounts and contracts growing at a rate of roughly 100k new accounts per day . Block-History. A chain of all historical blocks, starting at the genesis block up to the latest best block, also known as the blockchain. State-History. The state of each historical block makes up the state history. I will get into the details on t Continue reading >>

How Ethereum Works - Coindesk

How Ethereum Works - Coindesk

CoinDesk Launches 2017 Year in Review Opinion and Analysis Series Now that we've covered what ethereum is, let's dive deeper into how the platform functions under the hood. Consider the online notebook application described in " What is Ethereum? " Using ethereum, the appdoesn't require one entityto store and control its data. To accomplish this, ethereum borrows heavily from bitcoin's protocol and its blockchain design, but tweaks it to support applications beyond money. Ethereum aims to abstract away bitcoin's design, however, so that developers can create applications or agreements that have additional steps, new rules of ownership, alternative transaction formats or different ways to transfer state. The goal of ethereum's 'Turing-complete' programming language is to allow developers to write more programs in which blockchain transactions could govern and automate specific outcomes. This flexibility is perhaps ethereum's primary innovation, as explained in the guide " How Ethereum Smart Contracts Work ". The structure of the ethereum blockchain is very similar to bitcoin's, in that it is a shared record of the entire transaction history. Every node on the network stores a copy of this history. The big difference withethereum is that its nodes store the most recent state of each smart contract, in addition to all of the ether transactions. (This is much more complicated than described, but the text below should help you get your feet wet.) For each ethereum application, the network needs to keep track of the 'state', or the current information of all of these applications, including each user's balance, all the smart contract code and where it's all stored. Bitcoin uses unspent transaction outputs to track who has how muchbitcoin. While it sounds more complex, the id Continue reading >>

A Gentle Introduction To Ethereum

A Gentle Introduction To Ethereum

Ethereum builds on blockchain and cryptocurrency concepts, so if you are not familiar with these, its worth reading a gentle introduction to bitcoin and a gentle introduction to blockchain technology first. This article assumes the reader has a basic familiarity with how Bitcoin works. Ethereum is software running on a network of computers that ensures that data and small computer programs called smart contracts are replicated and processed on all the computers on the network, without a central coordinator. The vision is to create an unstoppable censorship-resistant self-sustaining decentralised world computer. The officialwebsite is Itextends the blockchain concepts from Bitcoin which validates, stores, and replicates transaction data on many computers around the world (hence the term distributed ledger). Ethereum takes this one step further, and also runs computer code equivalently on many computers around the world. What Bitcoin does for distributed data storage, Ethereum does for distributed data storage plus computations. The small computer programsbeing run are called smart contracts, and the contractsare run by participants on their machines using asort ofoperating system called a Ethereum Virtual Machine. To run Ethereum, you can download (or write yourself if you have the patience) some software called an Ethereum client. Just like BitTorrent or Bitcoin, the Ethereum client will connect over the internet to other peoples computers running similar client softwareand start downloading the Ethereum blockchain from them to catch up. It will also independently validate that each block conforms to the Ethereum rules. What does the Ethereum client software do? You can use itto: Create new transactions and smart contracts Your computer becomes a node on the network, r Continue reading >>

Ethereum-blocks

Ethereum-blocks

Process blocks from an Ethereum web3 instance robustly. This library uses web3.eth.filter to listen for the latest blocks on achain. When a block is received all registered handlers are invoked to perform anyrequired processing on the block data. Can catch up on all missed blocks when restarted Detects if connection has dropped and waits until re-established Customizable logging, can be turned on/off at runtime No dependencies - works in Node, Electron apps and browsers constweb3=newWeb3(/*connecttorunningGethnode*/); constblocks=newEthereumBlocks({web3:web3}); //registerahandlercalled"myHandler" blocks.registerHandler('myHandler',(eventType,blockId,data)=>{ The start() and stop() methods are used for starting and stopping the block processor. Both are asynchronous and return Promise objects which resolve to a boolean indicating whether therewas a change of state. console.log(stopped?'Stopped':'Wasnotrunning'); As shown above, the isRunning property can be used to check the current status of the processor at any point in time. If you are re-starting the block processor after having previously stopped it(e.g. if your app restarted) then it is useful to be able to catch up on anyblocks you may have missed in the intervening period. To do this you first need the id/number of the last block which got processed.This can be obtained at any time using the lastBlock property. You could storethis value in storage for use later on: window.localStorage.set('lastBlock',blocks.lastBlock); Then next time your app starts up you can retrieve this value and tell theblock processor to process all blocks which came after this one up untilthe current block, before then watching for new blocks: constlastBlockProcessed=window.localStorage.get('lastBlock'); catchupFrom:lastBlockProcessed?Num Continue reading >>

Is There An Api To Download Raw Blocks?

Is There An Api To Download Raw Blocks?

Is there an API for ethereum similar to blockchain.info's for bitcoin which allows one to download the raw data per block (by hash or height)? For example, this blockchain.info URL shows the value inputs and outputs for all transactions in a given block. New comments cannot be posted and votes cannot be cast I havent done too much research but have you checked etherscan? The blocks API on etherscan appears limited to only requesting reward per block. Please let me know if I am missing something. I am playing with etherchain.org's API. I has the requisite ether amount per transaction I am looking for, but I appear to have exceed their request rate and have been unable to download new data. Only got one hour's worth of blocks. :\ Why use web services with rate limits when you could just run a node and query it direct? This api approach is far harder than it needs to be. Thanks. Can you provide documentation on how to direct query the blockchain? 2 points 6 months ago edited 6 months ago What language do you use to query the api's? There's very likely an ethereum library for you already, the call would depend on the library. Then just a build a thin Python wrapper around geth... You can look into the Python clients too but I'm not sure they can sync the blockchain (yet, it's WIP). No need for REST/web API, if you run a node you literally have all the data needed on your machine. And the obvious benefit is that your system is going to be decentrally designed as opposed to having a central point of failure (e.g., the web API you'd query). Continue reading >>

How Ethereum Mining Works

How Ethereum Mining Works

Today, miners play an important role in making sure ethereum works. This role isn't immediately obvious, though. Many new users think that the sole purpose of mining is to generate ethers in a way that doesn't require a central issuer (seeour guide" What is Ether? "). This is true. Ethereum's tokens are created through the process of mining at a rate of 5 ether per mined block. But mining also has another at least asimportant role. Usually, banks are in charge of keeping accurate records of transactions. They ensure that money isn't created out of thin air, and that users don't cheat and spend their money more than once. Blockchains, though, introduce an entirely new way of record-keeping, one where the entire network, rather than an intermediary, verifies transactions and adds them to the public ledger. Although a 'trustless' or 'trust-minimizing' monetary system is the goal, someone still needs to securethe financial records, ensuring that no one cheats. Mining is one innovation that makes decentralized record-keeping possible. Miners come to consensus about the transaction history while preventing fraud (notably the double spending of ethers) an interesting problem that hadnt been solved in decentralized currencies before proof-of-work blockchains. Although ethereum is looking into other methods of coming to consensus about the validity of transactions, mining currently holds the platform together. Today, ethereum's mining process is almost the same as bitcoins . For each block of transactions, miners use computers to repeatedly and very quickly guess answers to a puzzle until one of them wins. More specifically, the miners will run the blocks unique header metadata (including timestamp and software version) through a hash function (which will return a fixed-length, Continue reading >>

Introduction To Smart Contracts

Introduction To Smart Contracts

Let us begin with the most basic example. It is fine if you do not understand everythingright now, we will go into more detail later. pragma solidity ^0.4.0;contract SimpleStorage { uint storedData; function set(uint x) public { storedData = x; } function get() public view returns (uint) { return storedData; }} The first line simply tells that the source code is written forSolidity version 0.4.0 or anything newer that does not break functionality(up to, but not including, version 0.5.0). This is to ensure that thecontract does not suddenly behave differently with a new compiler version. The keyword pragma is called that way because, in general,pragmas are instructions for the compiler about how to treat thesource code (e.g. pragma once ). A contract in the sense of Solidity is a collection of code (its functions) anddata (its state) that resides at a specific address on the Ethereumblockchain. The line uint storedData; declares a state variable called storedData oftype uint (unsigned integer of 256 bits). You can think of it as a single slotin a database that can be queried and altered by calling functions of thecode that manages the database. In the case of Ethereum, this is always the owningcontract. And in this case, the functions set and get can be used to modifyor retrieve the value of the variable. To access a state variable, you do not need the prefix this. as is common inother languages. This contract does not do much yet (due to the infrastructurebuilt by Ethereum) apart from allowing anyone to store a single number that is accessible byanyone in the world without a (feasible) way to prevent you from publishingthis number. Of course, anyone could just call set again with a different valueand overwrite your number, but the number will still be stored in the his Continue reading >>

How To Get The Data Of An Ethereum Block Using Geth

How To Get The Data Of An Ethereum Block Using Geth

How can i get a block info from a running ethereum node using geth or nodejs or any other language? For example to get a block data from bitcoin, there is a config file which run a blocknotify.sh file when a transaction is confirmed and in that blocknotify.sh file there is this command : bitcoin-cli getblock "[email protected]" >> "[email protected]" which gets the block data then i can send a post request of that block data to an api. So i want to do the same thing that is to get the block data from ETH nodes and send a post request to an api when a transaction is confirmed. How can i do this ? While running in geth console, you can use the web3 library to get block information: > var blockNumber;undefined> var blockInfo;undefined> web3.eth.getBlockNumber(function(e, r) { blockNumber = r; });undefined> blockNumber;2515149> web3.eth.getBlock(blockNumber, function(e, r) { blockInfo = r; });undefined> blockInfo{ difficulty: 1319089762, extraData: "0xd58301070d8650617269747986312e32332e30826c69", gasLimit: 4700036, gasUsed: 0, hash: "0xf9c495b5e5bcd3935aa4a6fd5a43009de29ca7d7be77d4b7cc4c68b8704bc422", logsBloom: "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", miner: "0x94cd009bbba97f30a36845e2025edf7544d62439", mixHash: "0xb8794a6d1b777f8c6fdf509f04896642f67dab82dc872ae9cbe9bcbf85172972", nonce: "0x264c013815697c2f", number: 2515149, p Continue reading >>

Units And Globally Available Variables

Units And Globally Available Variables

msg.gas (uint): remaining gas - deprecated in version 0.4.21 and to be replaced by gasleft() msg.sender (address): sender of the message (current call) msg.sig (bytes4): first four bytes of the calldata (i.e. function identifier) msg.value (uint): number of wei sent with the message now (uint): current block timestamp (alias for block.timestamp) tx.gasprice (uint): gas price of the transaction tx.origin (address): sender of the transaction (full call chain) The values of all members of msg, including msg.sender andmsg.value can change for every external function call.This includes calls to library functions. Do not rely on block.timestamp, now and blockhash as a source of randomness,unless you know what you are doing. Both the timestamp and the block hash can be influenced by miners to some degree.Bad actors in the mining community can for example run a casino payout function on a chosen hashand just retry a different hash if they did not receive any money. The current block timestamp must be strictly larger than the timestamp of the last block,but the only guarantee is that it will be somewhere between the timestamps of twoconsecutive blocks in the canonical chain. The block hashes are not available for all blocks for scalability reasons.You can only access the hashes of the most recent 256 blocks, all othervalues will be zero. abi.encode(...) returns (bytes): ABI-encodes the given arguments abi.encodePacked(...) returns (bytes): Performes packed encoding of the given arguments abi.encodeWithSelector(bytes4 selector, ...) returns (bytes): ABI-encodes the given arguments starting from the second and prepends the given four-byte selector abi.encodeWithSignature(string signature, ...) returns (bytes): Equivalent to abi.encodeWithSelector(bytes4(keccak256(signature), ...) Continue reading >>

Ethereum Chain Spec Format

Ethereum Chain Spec Format

This is a format to describe any Ethereum-like chain. It is derived from the genesis.json format but includes parameters to change and configure the consensus algorithm, to specify infrastructure information, to specify boot nodes and to specify any built-in contracts together with their cost. It is JSON, with the top level being an object with six keys: name: A string value specifying the chain name. e.g. "Frontier/Homestead", "Morden", "Olympic". forkName: An optional string value specifying a sub-identifier, in case two different chains have equivalent genesis blocks. engine: A enum value specifying the consensus engine. e.g. "Ethash", "Null". params: An object specifying various attributes of the consensus engine, allowing configuration. genesis: An object specifying the header of the genesis block. nodes: An array of strings, each one a node address in enode format. accounts: An object specifying accounts of the genesis block. This includes builtin contracts and premines. There are two valid engines, Ethash and Null. minimumDifficulty: Integer specifying the minimum difficulty a block may have. gasLimitBoundDivisor: Integer specifying the according value in the Yellow Paper. difficultyBoundDivisor: Integer specifying the according value in the Yellow Paper. durationLimit: Integer specifying the boundary point at which difficulty is increased. blockReward: Integer specifying the reward given for authoring a block. registrar: 0x-prefixed, 40-nibble datum of the address of the registrar contract on this chain. Different consensus engines may allow different keys in the params object, however there exist a few common to all: accountStartNonce: Integer specifying what nonce all newly created accounts should have. frontierCompatibilityModeLimit: Integer specifying the n Continue reading >>

Heres How I Built A Private Blockchain Network, And You Cantoo

Heres How I Built A Private Blockchain Network, And You Cantoo

Heres how I built a private blockchain network, and you cantoo Nothing helps understand blockchains better than building oneyourself This is PART-4 of The Product Managers guide to the Blockchain series! If you somehow landed on my publication for the first time, Welcome! I recommend you start from part 1 , and then read part 2 and part3 before reading this post. However If you are the explorer type, read on! (Update: Heres the latest part 5 of the blockchain series ) In Part 3 of this series, we looked at the mechanics of Ethereum and also talked about the concept of Ethereum Accounts, Smart Contracts and Gas the fuel that helps all these pieces to work together. Its been a lot of reading so far, but while you can read all the blockchain content available on the internet, nothing helps understand blockchains better than building one yourself. So thats what I did. You can simply follow this post and build a little prototype to see how everything weve talked about so far comes together. Here is what we will accomplish in this post, Weve seen this before , but basically the Ethereum blockchain network is simply lots of EVM (Ethereum Virtual Machines) or nodes connected to every other node to create a mesh. Each node runs a copy of the entire blockchain and competes to mine the next block or validate a transaction. Whenever a new block is added, the blockchain updates and is propagated to the entire network, such that each node is in sync. To become a node in the Ethereum network, your computer will have to download and update a copy of the entire Ethereum blockchain. To achieve this Ethereum provides tools that you can download, connect to the Ethereum network with and then interact with it. These are: Geth if you have experience with web development and are interested i Continue reading >>

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