Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

0
votes
1answer
25 views

Transaction not getting confirmed because of transfer function even after making the address payable

The finaliseRequest transaction is not getting confirmed no matter what I do. I am sure it is failing at the transfer function. I had made the address to address payable also and changed the function ...
1
vote
1answer
9 views

Unknown Ethereum folder on my C drive

I have an Ethereum folder which weights 2.5GB in this path: C:\Users\xxx\AppData\Roaming which has two folders in it: geth keystore Do i need 'em ? It's not going to broke my ...
1
vote
0answers
10 views

How to get live mempool transactions whitout full blokchain

I just want to analyse all mempool txs in realtime. I cant use an api because after several requests my ip gets blocked for some minutes, so I dont get the txs in this time. Thank you for help.
1
vote
1answer
27 views

How the hashing of the block data ensures the data integrity?

In ethereum, as a node controller I can able to access the leveldb. If I try to modify some value directly into the db, the value of the new hash and the next block's parent hash doesn't match right ?...
1
vote
1answer
23 views

How long you can consider a pending transaction as invalid?

I saw here that the time that a transaction can be at pending status changed, but didn't say how much Due to overwhelming amounts of pending transactions during ICOs, many public nodes (etherscan, ...
1
vote
1answer
33 views

Peering over a direct L2 link without IP addresses

As part of a big solution incorporating blockchain and data networking, I'd like to know how would 2 nodes establish a blockchain peering on their direct L2 Ethernet Link that has no IP addresses ...
0
votes
1answer
115 views

TypeError: Type contract InsuranceClaim is not implicitly convertible to expected type address

I am confused why the following code is not working. Any help would be greatly appreciated. pragma solidity >=0.4.22 <0.6.0 contract InsuranceClaimFactory{ address public claimer; ...
0
votes
1answer
31 views

How do you get the UTXOs a transaction is spending using web3.js?

I'm unsure how to get the UTXOs that a transaction is spending. Here's what I have so far. I get transaction details from txhash web3.eth.getTransaction("...
0
votes
2answers
42 views

Can I use the blockchain as a web server?

Is it possible to use the blockchain as "web server"? Even if a web app stores all data per smart contracts on the blockchain I still need a central server to get the web app initially. Is there an ...
2
votes
1answer
33 views

How to calculate token buy and sell prices?

I have a ERC20 token string public name = "Token ZIZ"; string public symbol = "ZIZ"; uint8 public decimals = 18; uint256 public totalSupply = 1000000 * 10 ** uint256(decimals); //...
0
votes
1answer
30 views

TypeError: ajtokenSaleInstance.tokensSold is not a function

I am following this tutorial on youtube "Code Your Own Cryptocurrency on Ethereum (Full)" i stuck at one of the part where i am trying to return the value of TokensSold but i keep on getting error as ...
1
vote
1answer
40 views

Understanding what happens between transaction creation and block creation in Proof of Authority

I am currently writing my thesis where I'm investigating the potential of blockchain technology to become the underlying technology in a system that is create and record qualifications. I'm at the ...
3
votes
0answers
20 views

How to access txpool pending transactions using Netherum?

I want to get list of transactions which are in pending state & queued state in txpool. I can see these transactions in pool using txpool.inspect command. I tried code given in nethereum sample ...
1
vote
0answers
36 views

How can I run smart contract locally on my computer?

We all know that Ethereum nodes can run smart contract. But I'm wondering whether can I setup contract run-time environment from Ethereum source code locally so I can run smart contract without ...
0
votes
1answer
27 views

Run testnet in a cluster

I have launched a blockchain testnet in a cluster with different nodes and I have some questions about how it works. If I run more than one geth client(a node in the blockchain) in one node of the ...
0
votes
1answer
66 views

IPFS versioning - How to get all files from the IPFS key?

Based on the below code, im able to add a file**(dataobj.txt --QmUUHKjR5ZdrrYmxpXyPrYP3eMyhv9FnRKo1Duv9stzmmw)** and publish a file and then assign to the key "myIPFSKey". Step 1: ipfs add -r ipfs/...
0
votes
0answers
17 views

Library to get a graphic representation of the blockchain

I'm trying to find a library to make a graphic representation of the blockchain. Something similar to Gource but instead with git versions, with ethereum Any idea if something like that exists?
1
vote
1answer
40 views

Decentralizing DNS using Blockchain

I intend to do a project on Decentralizing DNS using Blockchain. As I was researching this topic, Namecoin was a name that popped up a lot. On searching further, I got to know that Namecoin hosts ....
2
votes
2answers
34 views

Identify the block which contains a tx

I am deploying a Smart Contract to a private blockchain. Is it possible to get when your node receives the smart contract? Is it possible to identify the block which contains the smart contract? how?
0
votes
1answer
21 views

Incorrect Usage. flag needs an argument: -rpcaddr = Ethereum private blockchain

I'm trying to make Ethereum private blockchain. But facing a error while running this "geth --nodiscover --networkid 42 --datadir .ethereum/ --unlock 0x526d8a6baa472da27215f748236af96bc9f256d7--mine ...
1
vote
1answer
29 views

Is there any period of custody for block rewards in Ethereum?

In Bitcoin, some block heights are required for spending coinbase transaction. But in Ethereum, there's no input/output. Then, is there any maturity time for using block rewards in Ethereum? If yes, ...
1
vote
2answers
26 views

What is meant by locking of ether in proof of stake?

In PoS, forgers stake their ether on a block. These ether are locked and can't be used. What does it mean by locking of ether and how does it work?
1
vote
1answer
58 views

Invalid sender when sending Raw Transaction, signed w/ ethereum-tx on PHP

I am using PHP and ethereum-tx library https://github.com/web3p/ethereum-tx to sign transactions but when trying to send them to the node I got an "invalid sender" error. Besides, exactly the same ...
1
vote
0answers
28 views

Ethereum Blocksci parser tool

I need a blocksci parser for ethereum. I am using https://github.com/citp/BlockSci for bitcoin . Is any similar blocksci parsing tool for ethereum?.
1
vote
0answers
26 views

When locate a block with both the hash and block number?

In the go-ethereum code, I see functions use both the number and block hash to locate a block. Why is that? Isn't block hash enough? An example function: https://github.com/ethereum/go-ethereum/blob/...
-1
votes
3answers
43 views

Blockchain flow in food industry [closed]

I am trying to learn blockchain by doing small projects. I was able to complete a small project in blockchain for cryptocurrency using c#. Now, I am trying to understand the flow of a blockchain in ...
1
vote
0answers
16 views

simulation or performance evaluation with Ethereum testnet

I was if you could help me about simulation. How can I simulate the performance of my following IoT-based Application with Ethereum testnet? In my senario,there are some nodes that store sensor data ...
-1
votes
0answers
33 views

Simulation with private Ethereum

I need a simulator or environment to simulate my Internet of things network with following scenario: There are N number nodes as Miners(Roadside Unit in a smart city) that store transactions sent by ...
0
votes
1answer
62 views

Cloning geth and adding a POS consensus algorithm? [closed]

I am currently learning how to use geth, so far I was able to create a private POW and POA blockchain using one of its consensus types (Clique). I am wondering how feasible it would be to clone the ...
1
vote
1answer
42 views

ERC 721 card game

The general concept of ERC 721 is clear to me. My question is more about the contract deployment. I want to have 100 unique cards, So I thought of these two implementations: Having an initial supply(...
2
votes
0answers
19 views

Transactions are not mining for accounts created by Nethereum.Accounts.Account method but works for accounts created by web3.Personal.NewAccount

Transactions are not mining & in pending state for long time, for transactions with accounts created using Nethereum.Accounts.Account(privateKey). But mining works for accounts created using web3....
2
votes
1answer
34 views

create multiple transactions between two accounts using SendTransactionAsync method nethereum

I am trying to create multiple transactions between two accounts using SendTransactionAsync method. But I am getting "replacement transaction underpriced" message. I found some links which says we ...
1
vote
2answers
8 views

Will a transfer go through on a testnet transaction on meta mask to luno

What if you sent your ETH on the Ropsten testnet via Metamask to an ETH platform gateway like Luno (https://www.luno.com) ? Will you receive your Ether and will it reflect on that account? I've done ...
0
votes
1answer
39 views

How to limit latest block in Geth

I need some test Ethereum blockchains for development purposes. I need only part of blocks synced for example, blochain synced from 0 to 10'000`th block, because for example Rinkeby synced in archive/...
1
vote
1answer
59 views

Creation of test network using ganache

Can we reuse the values stored in the ganache test network which is running in the local machine, even if the terminal which is running ganache test network is closed or what are the possible ways to ...
1
vote
0answers
56 views

Questions with Building a dapp using Quorum [closed]

I am working on a project to build a dapp for a trust system using Quorum, which needs a permissioned blockchain for data privacy. Only the admin, beneficiary, caregivers, case manager and authorized ...
1
vote
0answers
16 views

Read args object from particular block transaction in truffle console.

Hi I have question on how to read args from specific block transaction that are passed when event was called. I have triggered an event, my block is created and i got transaction tx. In the ' Logs: ' ...
0
votes
1answer
42 views

Ropsten Ethereum not showing transaction information

I am using geth 1.7.3-stable-4bb3c89d to sync with Ropsten network. I started synchronization with fast mode and restarted the service. When I type eth.syncing in geth console it always shows false ...
0
votes
1answer
119 views

web3 not connecting to Infura / Rinkeby Testnet

I've successfully deployed my Smart-Contract to the Rinkeby TestNet via Remix. Everything works perfectly from within Remix. But when I try to get my web DApp to fire methods in my Smart-Contract - ...
0
votes
1answer
67 views

What does Error: Provided address “1.2870172725867908e+48” is invalid, the capitalization checksum test failed

I have assigned my variables here > var contractAddress = 0xb5A5F22694352C15B00323844aD545ABb2B11028 > var cont = new web3.eth.Contract(abi, contractAddress) I am getting the error : ...
0
votes
1answer
43 views

difference between return and returns

contract Helloworld { uint private simpleInt; function getValue() public view returns (uint) { return simpleInt; } } What is the difference between "return" and "returns", I am a ...
0
votes
2answers
31 views

Solidity can't modify block.timestamp due to lvalue xpression

I have a problem regarding modifying block.timestamp. I would like to modify timestamp in my network and change block.timestamp to unix timestamp, but I got an error at modification: TypeError: ...
1
vote
3answers
41 views

What is Metamask?

I know it's a dApp web3 browser, a wallet. But which ethereum client is used in the back end to interact with block chain? How the same account is able to connect with all networks (mainnet,testnet, ...
0
votes
1answer
19 views

Which type of Projects/Apps are suitable/best to be developed in blockchain/dapp technology? [closed]

Which kind of Apps are best to be developed on the base of blockchain/dapp/web3 technology. Suggest me please as I am looking for an advice for an academic final year project.
0
votes
1answer
22 views

Contract's transaction count in a certain period

I want to determine the number of transactions of a contract in a certain period. My question is that in the transaction receipt, if we want to say that contract A has x number of transactions will ...
0
votes
1answer
14 views

how to fix a fact that the recipient received the file so that the recipient could not dispute it?

how to fix a fact that the recipient received the file so that the recipient could not dispute it? How to do this by a smart contract? thanks in advance.
0
votes
1answer
83 views

Unable to interact with DApp deployed on quorum

I am unable to interact with contract using Dapp deployed on Quorum blockchain (using metamask). I am following "https://truffleframework.com/tutorials/building-dapps-for-quorum-private-enterprise-...
1
vote
1answer
68 views

Is there a way to prevent any client connected using web3.js to Quorum from deploying a contract?

I am planning on using Quorum for a permissioned setup,Is it possible to prevent anyone having a web client and connected to any quorum node deployed in the network from deploying a contract?
0
votes
1answer
36 views

Ideal Blockchain decentralized app [closed]

I want to know your opinions about what do you think the best architecture for building a decentralized application? Taking into consideration the global adoption, and how to avoid telling the users ...
0
votes
1answer
29 views

how to deploy dapps into production (mainnetwork) [closed]

i'm newbee as a blockchain developer.I have deployed smart contract into ethereum test network.as part of next step i want to know what are the steps invovled in deploying blockchain at production ...