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Questions tagged [dapps]

Questions about applications and projects on Ethereum: a decentralized application (dapp) does not require any servers or backends and runs independent on a distributed blockchain.

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0answers
186 views

module.js:538 throw err

I am getting below error while executing "node start run" command: module.js:538 throw err; ^ Error: Cannot find module '/home/rahat/blockchain-ethereum/dapps/openship/start' at Function....
0
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1answer
44 views

iexec: is tokens on ropsten network cost some real money

I am studying iexec for writing smart contract. I follow tutorial at this link. In this tutorial, at the last part, they say: Be nice and give back your RLC and ETH to the faucet by sweeping your ...
0
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1answer
252 views

I want to create a Dapp, but I'm not a programmer

I'm 52 and used to program in 'Basic' growing up. That and basic html is pretty much all the experience that I have. I have a few questions and would immensely appreciate your advice. What do I need ...
0
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1answer
341 views

can i get specified ERC20 token holders details?

can i get specified ERC20 token holders details,example token holder address,how many token holding that address like this details
3
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1answer
111 views

Can any one pretend as a contract owner?

I am new to ethereum and solidity , i created a Token app using zeppelin and truffle which generates and sends tokens to others. My question is if i deployed the contract then msg.sender is my public ...
0
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1answer
75 views

Serving DApp on webserver or IPFS won't work

I can succesfully run the webpack truffle box on my webserver, but if I try to run a DApp which I made by using the pet-shop truffle box as template, I can only use it on localhost. When I upload the /...
1
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1answer
27 views

Local ethereum node returns different than Javascript vm

contract Marketplace { uint256 transferBudget = 1 ether; bytes32[] ids; enum Position{ Goalkeeper, Defender, Midfielder, Attacker, Coach } struct Footballer{ ...
0
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1answer
115 views

Use multiple version of truffle in linux

Can we use multiple version of truffle in linux just like python ? If yes then how can we use specific version ?
0
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3answers
466 views

How do Dapps work with ERC20 tokens?

I just finished reading which explains how to build a Dapp with Metamask sending Ethereum to a smart contract (Reference: https://medium.com/@merunasgrincalaitis/the-ultimate-end-to-end-tutorial-to-...
1
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1answer
419 views

Frontend side of DApp

I am (totally new to DApp) currently involved in a research project that regarding the Front-end side (Js Libraries and Frameworks) of the DApp. I read many articles but still confused. My ...
0
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0answers
39 views

How can I get a limited number of recent event logs?

I think Ethereum's indexed events can act as the getter of the database system. In order to perform this role, it is essential to return a specific number of events in the most recent sequence (...
2
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1answer
40 views

Duplicating data on server and contract

If I'm building a dapp, is it worthwhile to store information that is in the contract on a server for speed purposes, and only using the contract to track ownership of tokens. I.e. for something ...
4
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0answers
204 views

Truffle hangs forever with parity with PoA

I'm trying to create a private chain using parity (PoA) and truffle but when I do truffle migrate it hangs forever with the following output: > [ > { > "jsonrpc": "2.0", &...
0
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1answer
34 views

Should I use Ethereum blockhain for its immutability in my project?

First of all, I am completely new to blockchains so sorry if I'm asking any silly questions:) I would like to build a test web project: users can create accounts and manage various kinds of ...
1
vote
2answers
37 views

Is it really not possible to write a js function that takes address and returns public key?

I find it hard to believe that something like this is not possible, as the use of public/private keys is a major bonus of digital identities. I need to write a Javascript function to take in an ...
1
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0answers
227 views

how to send and receive unlimited bytes(data) to and from another contract in Solidity? [closed]

I am working on a project that in which we need two contract send unpredicted amount of data to each other. those data actually are kind of structures that need to be serialized in a proper way. So ...
3
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1answer
352 views

Does quorum support privacy between accounts when multiple accounts use same quorum-node?

From what I understand by this wiki on Transaction processing, quorum-nodes which are privy to a private Tx, will update their private stateDbs. My question is, can two different accounts access ...
0
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2answers
467 views

Create a DApp using Geth

I need to create a sample DApp from scratch within a private blockchain using Geth. Can anyone post links of sample apps which have been made in such a way for reference.
3
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1answer
32 views

Thoughts on copying state over multiple contract generations?

I recently published a toy dapp (http://etherdate.co/) to the mainnet with a webapp and after deployment found some breaking bugs that necessitate deploying an updated version of the contract. I ...
2
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1answer
22 views

eth.balance() shows random alphanumeric content

const HttpProvider = require('ethjs-provider-http'); const Eth = require('ethjs-query'); const eth = new Eth(new HttpProvider('https://rinkeby.infura.io/')); eth.getBalance("...
6
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1answer
1k views

How should I secure a private key in my dapp?

We are currently building an app that interacts with the blockchain. It needs to be able to make transactions on the blockchain on it's own - for instance to add addresses to a whitelist. This means ...
1
vote
1answer
144 views

Dapp fundamental q about listening solidity events

Sol: I created contract with events that are raised when is called some function. Html fo: Those functions are called via web3.js with abi and address - easy. Backend (no js) asp or php: I am not ...
0
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1answer
102 views

Would the users still need to use Metamask or Mist if the dapp has a built in wallet?

If a dapp has a built-in wallet, can the users intearact with the dapp without the need of Metamask or Mist?
1
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1answer
96 views

Ability to easily manage attributes in Solidity Struct

Below is a very simple smart contract which has a struct Instructor which has 3 attributes right now i.e. age, fName, and lName. Now if tomorrow I wish to add a new attribute I will need to update all ...
0
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0answers
162 views

How to add an extra node to a blockchain?

I'm writing a Dapp for my university. The students and professors can take part in the blockchain. The blockchain has to be: 1. permissioned 2. private So far, I've found Monax and Quorum (with ...
0
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1answer
188 views

If I set private blockchain, will the dapp be private only?

I have an ethereum private blockchain, and I need to build a web application, in which the content of blocks in private blockchain would be visible from anywhere after logging in on the web page. Is ...
0
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1answer
79 views

How add payment method to a private blockchain [closed]

I have a question about private blokchain: I like to develop an Dapp in my own private blockchain. but i like to add payment method : i means, how users account pay (with stripe,..) and load his ...
0
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0answers
215 views

Transaction with HD wallet & ganache

i try to create a HD wallet with eth-lightwallet & ganache ui for testing an ERC-20 Token. After creating the wallet i had im my response the public key, the private key, the mnemonic seed and i ...
3
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2answers
146 views

Using Multiple Accounts from a single physical machine

​Hey all, I was wondering something. I am planning to create a simple Voting Dapp for a closed election, where a number of accounts will be set up ahead of time and pre-authorised to vote. The Voting ...
1
vote
3answers
2k views

List of successfully running smart contract applications that solve a real world problem?

I'm still diving into smart contracts and learning the way it works, but what are some successfully running smart contracts applications that solve a real world problem? Is there a list of these ...
0
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1answer
56 views

Is there a solidity library to create msgHash?

Messages are hashed with a “\x19Ethereum Signed Message” for some reason. I'm writing a smart contract that authenticates a message to a signature, and it needs to be able to generate msgHash to do ...
1
vote
1answer
1k views

How do I automatically mint ERC-20 Tokens Every time the owner wallet transfers coins

I want to start with a total_supply of 1,000 Tokens in the owner wallet. Each token will represent a gram of gold. Every time 1 token is transferred from owner wallet to another wallet, the owner ...
1
vote
1answer
175 views

Does it make sense to have a Node.js backend serving json to frontend for dapp?

Currently, the architecture I am looking at is that the smart contract (SC) sits on the ethereum network, but it is a complex and multilevel contract system. Just navigating through the tiers of the ...
0
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1answer
190 views

Correct way to easily call function with web3j from deployed contract

I am trying to call a function from a modified ERC20 contract and I can't manage to make it work. I am doing this with web3j from Android. I can connect to Infura. The contract is already deployed on ...
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0answers
69 views

Blocking an application untill metamask shows the transaction is complete

I’m creating a DAPP where I’m using Metamask for submitting the transaction. I have a requirement where when a user accepts/submits the transaction, a modal needs to appear on the page, blocking the ...
2
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2answers
152 views

Mining, Ethers and Private Blockchain DAPPs

I am building a private Blockchain cluster DAPP envisaged to have 5 to 10 parties owning their own nodes (or node clusters). At this moment, there is no specific mandate to incentivize miners, though ...
0
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3answers
797 views

How to get blockNumber of contracts deployed with truffle?

We deploy our contracts with truffle migrate. We need the blockNumber of the contract deployment transaction in the webapp. We could use web3.eth.getTransaction(txhash).blockNumber() but can't get ...
0
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1answer
30 views

If I wanted to host a site that used the web3 api, would I need it to interact with the blockchain?

I want to host a site to interact with Web3 clients (MetaMask, etc.). I want my site to be able to send transactions, etc. to the clients through the Web3 API for educational purposes. I don't care ...
0
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1answer
123 views

Environment to run Daap

I already run test apps online on a rinkeby test network and have a good understanding of how to dev and publish my apps on this particular blockchain. HOWEVER, I have been in trouble understanding ...
2
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0answers
498 views

What is the best practice of a Dapp development mixed with Python/Django?

I've written and tested the Smart Contracts in Truffle, and now want to develop a front-end and a small back-end for my Dapp. So far, I preferred MVP frameworks, particularly Django. Therefore, what ...
1
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3answers
3k views

How to generate Private key, public key and address

I can't find any documentation online about doing this in Javascript other than this. I want to know how does authentication work in a ethereum dApp's.. As per my understanding user seed somehow gets ...
1
vote
2answers
324 views

Is Ethereum the only way to develop Dapps?

I have searched a couple of resources about the implementation of Dapps, most of them redirected to ethereum itself. Is Ethereum the de facto platform for developing Dapps or do we have any other?
3
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1answer
127 views

Can i delete some old files inside chaindata folder?

I am running geth with fast sync, Can i delete some old files inside chaindata folder so that my ssd will have some empty space or it will create some problems ?
1
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1answer
259 views

Convert Block Number Hash to Readable Block Number?

When i use this command : curl --data '{"method":"eth_getBlockByNumber","params":["latest", true],"id":1,"jsonrpc":"2.0"}' -H "Content-Type: application/json" -X POST localhost:8544 Then I am ...
0
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3answers
637 views

Truffle: Migrate to ropsten, unknown network “true” error

I am trying to deploy a work in progress dapp to the ropsten network using: truffle migrate --network ropsten I have a geth instance running in terminal and I receive the following error: Unknown ...
0
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3answers
783 views

How to deploy a truffle app in heroku?

I have working truffle app that interacts with Ropsten Testnet but currently, I'm on my local machine environment at localhost:3000. I want to deploy this app to heroku such that my ropsten testnet ...
1
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1answer
51 views

Is there any way to run multiple nodes on Ethereum?

Does anyone know that how to run multiple nodes on one PC in private test network? like running several Ethereum Wallets which could be used for testing contract or transfers. Thanks.
0
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1answer
327 views

Unable to replicate tx.origin attack

I was reading the solidity docs and decided to replicate tx.origin attack . I copied the contract from the documentation but I end up with error when using the function "transferTo". Check the remix ...
0
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1answer
21 views

Can a Coin be liquid during its ICO period?

I am planning to run a Coin's ICO for several years, not interested in the gains to be made from selling out ICO in 3 days NO, but interested in using the COin to end Global Poverty as i deem fit. So ...
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2answers
296 views

Is it possible to write an online browser game in ASP.net and integrate a smart contract to buy assets in that game for example?

I am fairly new to solidity, and i am exploring decentralized game development. This said, let us go more into the details. Imagine i want to develop a 2d game, where you can buy for example assets, ...