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Questions tagged [blockchain]

The Ethereum blockchain is a distributed database based on the Ethereum whitepaper specification and stores both the full transaction list and the most recent state.

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391 views

miner.start(1) triggers but not starting the mining

I am creating my own private ethereum blockchain. sudo geth --rpcapi eth,web3,personal --rpc --networkid=15 Above command gives the below logs. INFO [09-18|10:16:42.151] Maximum peer count ...
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210 views

How can we get other transactions result like using window.web3.eth.getTransactionReceipt on our own transaction?

If I send a transaction, I can watch the result using window.web3.eth.getTransactionReceipt like this: tradeContract.methods.test(...args).send({ from: pubData.user.address, gas: gasAmount }) ....
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140 views

0 ETH Airdrop function with ICO contract

I see many airdrops that have been done by sending 0 ETH to the ICO contract address my question is: how to add this function to the ICO contract with the ability to start and stop at any time? and ...
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0answers
112 views

Monitoring Eth Transactions and Syncing Native Database transactions with Etherium Blockchain

Currently, I have a node.js application which interacts with geth through web sockets. I have a listener, web3.eth.subscribe( 'pendingTransactions', function(err, result) { if(!err) { ...
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0answers
80 views

Interact with a contract using Web3 Wallet

I am trying to interact with a contract without a provider as Metamask/Mist. I know that web3 has an option to create a new Wallet and I have been seeing code examples about that but all of them ...
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1answer
150 views

Installing Ganache GUI on windows 8.1

How to install Ganache UI on windows 8.1 ? I downloaded from Official website but after downloading i am unable to install it on my machine. I tried to install it through power shell but facing ...
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1answer
153 views

Implementing Blockchain and Converting Web App to DApp

I have my web-application which is in Angular2 (Front end) and Rails (Back end-API), now I want to implement Blockchain to this Web application, so needs to make it DApp. Here while making the DApp, ...
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0answers
166 views

What does total number of blocks per day mean in Etherscan?

I tried to figure out what does total number of blocks per day means here and on the Internet, but i failed. For example, the number of blocks on 26 Aug is 5947 [here https://etherscan.io/chart/blocks]...
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1answer
75 views

In what way does Sharding allocate transactions for each shard? state? or node selection?

In what way does Sharding allocate transactions for each shard? I know that accounts are assigned to each shard based on prefix in the account's address and each shard processes the transactions ...
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0answers
34 views

Is “EthArmbian” an OS for running Ethereum client on “micro-processors”?

Is "EthArmbian" an OS for running Ethereum light client on "micro-processors" or "micro-controllers" ? And if yes, which micro-processors ?
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78 views

Port requirements for a Light-Node?

For a light client (geth --light or parity --light) running the light client protocol what are the port requirements? Incoming: Does a light client expose a port where he accepts incoming ...
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0answers
48 views

rinkeby inconsistent state?

I've got a very strang behaviour when running a oraclize call like in the following example: class Test is Oraclize... { uint64[] timestamps; uint64[] numbers; function pushItem(uint64 number)...
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334 views

download Ethereum blockchain

the blockchain now has 6,170,500 blocks. To speed up the download I'm using the method at https://mudra.cloud/ethereum/blockchain.html Is this the fastest method? Does anyone know another faster ...
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1answer
47 views

Payable contract with multiple “options”?

I'm trying to create a contract that behaves differently based on the user's selection. I, however, have no idea how to let the user "select" the option. Currently I have a basic fallback function ...
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0answers
55 views

“consensus over state” vs. “consensus over events”?

Does someone know what is difference between "consensus over state" and "consensus over events" ? I found just title of a reference i.e. "Ian Grigg, blog post “The Message is the Medium,” 2017." ...
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36 views

MIME types in Ethereum

Yesterday evening, an individual(at a french meetup haha) asked me what ethereum was and kept asking me if there was something similar to MIME types on Ethereum. I did not know what MIME types were ...
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24 views

trading a secret message with some person only after money is paid

I want to build a DAPP where person A trades a message with person B for ether. Since the message is secret, person A encrypts the message by using public key of person B and stores the message in ...
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0answers
32 views

How to check last block in which storage variable was modified?

I am looking for method to quick chceck in which block variable was modified last. Assuming I have geth database synced in archive mode, that means I have all previous world states tries and accounts ...
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0answers
135 views

Fork Crypto from go-ethereum (geth)

I have clone the source code of go-ethereum from github and i want to modify it so i can get owner crypto. Step 1: go run mkalloc.go genesis.json from go-ethereum/core it gen hex for ...
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1answer
305 views

oraclize calling a REST API

I am trying to call a third party REST API that I developed using spring boot, and I want to call a function(param1,param2) in the API from the oracle using the oraclize_query() (POST request), but I ...
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0answers
44 views

how can validators validate blocks?

I have a question about how POS (ethereum casper) works. I am a little bit confused. So let's say User A decides to be a validator. So he has to have at least 1000Ether in his account to become a ...
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0answers
23 views

Augur Project compile and debug

I starting to work on blockchain and dapps, would like to help with issues in augur can anyone explain how to debug or test run the application on my local machine to know how it works? i tried to use ...
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178 views

Parity: with 'warp' sync enabled by default, is there still any advantage in using fast pruning?

From Parity Ethereum Documentation: Warp Sync is an extension to the Ethereum Wire protocol, which involves sending snapshots over the network to get the full state at a given block extremely ...
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0answers
133 views

There is any open source for mnemonic (recovery) phrase can be used in react project?

I want to know how to implement 12 words or 24 words mnemonic(recovery) phrase screen as "Create Wallet" part in the ethereum, ERC20 token wallet project built with React Native like as coinomi wallet....
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39 views

Same Transaction is getting mined twice

I have a smart contract which generates a random number and compares it with the user's input to check if both are equals, and based on that it updates a mapping. But anyhow the same transaction is ...
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83 views

Showing block confirmations on a user transaction, best practices?

I'm working on a site that allows users to deploy smart contracts via MetaMask. Basically they customize it, it gets compiled, and then the user deploys it by via a MetaMask transaction. I would like ...
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1answer
48 views

How to increase stored block states from 128 to 10 000 in Geth?

AFAIK Geth preserves states for the last 128 blocks by default. I would like to keep states for, say 10000 blocks (not turning myself into archive node). Is it possible?
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1answer
432 views

Error occurred when trying to send rpc requests(s)

I am using the nethereum package in .Net and trying to invoke a smart contract with web3. Initially it was working fine, but suddenly I am getting an error while trying to get the transaction count. ...
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0answers
18 views

Benefit of replacing the middle man?

It seems like instead of paying to the middle man, blockchain offers to pay the transaction fee to the nodes (it is not clear which one is bigger). Thus, there is not much benefit money-wise. Is the ...
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1answer
306 views

Miner and Validator, who can validate a contract?

I am still confused with the process from creation to validation of transaction or contract verification. Actually the terminology makes me confused such as voter, validation, miner, honest node, ...
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3answers
209 views

How do i add to a nested array within a struct

I am unable to add elements to a array within the struct struct D { string name; address key; } struct Aone { string aid; B[] blist; D[] dlist; } ...
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0answers
101 views

web3 got duplicate events and make data in server different from blockchain

I use web3j to listen ethereum smart contract events to synchronize data for the server, but sometimes I got duplicate events in one function. Let's consider Birth evens in CryptoKitties smart ...
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1answer
41 views

Can I implement the blockchain technology to build my own app that decentralizes renewable energy in the place I live?

Probably someone has already asked this question but I searched for quite a while and could not find a "simple" answer. So I would like to implement the blockchain tech into my app that will regulate ...
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0answers
83 views

How does one connect to a blockchain? (technical)

Maybe this was asked sometimes, but I wasn't able to find an answer. I want to ask how does one connect to a blockchain in general - not the configuration part how to download it, but from the ...
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1answer
79 views

How many non-empty accounts are there?

I am researching into the statistics of Ethereum and I an looking for a datum of how many non-zero balance account currently exist in Ethereum? I know that in total 30M of accounts were created but ...
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0answers
147 views

how distributed cloud storage works with ethereum blockchain?

Distributed Cloud storage is a great concept , I have been doing a lot of search on this topic but couldn't get the exact information i am looking for:- How the projects like Storj are using the ...
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0answers
125 views

How to determine whether block is orphaned?

I've been working on a high stakes contract, which is deployed using the web3 v1.0 library. An important condition for robustness is ensuring the contract has been confirmed 12 blocks prior (at the ...
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44 views

Can I download the old Olympic testnet blockchain?

A client of me would like to download the old Olympic blockchain for any unknown reason. Does anyone know any source where it could be downloaded from?
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1answer
273 views

Why my geth system daemon not sync?

I've a machine with Ubuntu Server 16.04.4 LTS, the purpose of this machine is run a Geth process reachable by a web services. This is my "unit service": [Unit] Description=Ethereum go client [...
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0answers
311 views

How can I create public-private key for a ERC20 wallet that using user's email address?

I am working on a side project that provides a wallet (Think Coinbase, Binance, etc) like interface to users where they will sign in using username and password. To be able to provide a clearer ...
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0answers
87 views

Uncle blocks and their Relationship to Chain Size

How much do uncle blocks affect the overall chain size? Is the amount of added security they provide for the chain comparable to how much extra data they add to the chain? If, for some reason, all ...
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2answers
51 views

accessing unpredictable numbers

I see that this has been a widely discussed topic in the past but I still don't understand why the future block hashes shouldn't be used for lottery-type games. As long as the incentive for a miner to ...
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0answers
45 views

self-aware smart contracts using multi-agent system

My question is: What can be the role and working of multi-agent system in smart contract to make it self-aware smart contracts that ensure legal enforcement??
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117 views

Remix: Contract exceeds gaslimit even tho blocks have a high enough gas limit

I am trying to deploy my smart contract to a blockchain that was setup for me. The genesisblock specifies the gaslimit (something around 4mil), however that was not enough for me. Instead of deleting ...
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463 views

How to mint tokens before crowdsale

I want to make a crowdsale with pre-ICO and ICO, so people can swap tokens directly by sending to the smart-contract. The pre-Ico should have a certain rate for the swap and the ICO should have a ...
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1answer
250 views

How to connect IPC and RPC to transact fake ethers?

I have setup 2 nodes, 1 on testRPC and the other on geth(using cmd and mist). How to sync both the nodes so that I can write a crowdfunding smartcontract for the accounts in both the private nodes to ...
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0answers
93 views

geth only syncing s few blocks at a time

I am running geth with syncmode = full (because I need the full state tree of old blocks) and even though it was syncing over 200-300 blocks at a time a while ago, it is now only syncing a few blocks. ...
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0answers
30 views

Calculating data amount being mined. Server

Does anyone know how to calculate hardware being used by mining activity on a blockchain? I'm curious what the equivalent hardware usage is in a blockchain. I'm looking for a formula of blockchain ...
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0answers
368 views

How can I parse local Ethereum blockchain?

I need to parse live Ethereum blockchain to retrieve all transactions that belongs to particular smart contract's address. So my general question is how can I do it properly? My thought about it so ...
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306 views

Bad Block Error: Insufficient balance to pay for gas

I was syncing on full mode on my Ubuntu OS but when I was approaching the nearest latest block, I was shown this error: ########## BAD BLOCK ######### Chain config: {ChainID: 1 Homestead: 1150000 DAO:...