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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.

103
votes
4answers
115k views

What is a DApp?

There are new terms in Ethereum like smart contract. What is a DApp and how is it different from smart contracts?
25
votes
3answers
13k views

How to create a Dapp from scratch on Ethereum?

Let's say we have someone who knows about blockchain but who doesn't have any background in blockchain-based application. That person wants to code an ethereum-based Dapp (decentralized application) ...
6
votes
2answers
3k views

What elements of a Dapp's backend are usually stored in a decentralised location?

I'm unclear as to what elements of a Dapp's backend code are actually decentralised. The following link states that a Dapp's backend is stored entirely on the blockchain. However, if I was to create ...
28
votes
1answer
3k views

How do I make my DAPP “Serenity-Proof?”

When Serenity comes around, the network will undergo many changes, some of which may have unexpected consequences on existing Smart Contracts. How can I plan so that I am best prepared to take ...
14
votes
5answers
2k views

How will regular users be able to use dApps without buying ether?

Requiring users to get ether before they can use a dApp, is too much of a barrier for any kind of mainstream adoption. If dApps offer free ether in a naive way, they can be attacked by Sybils where a ...
17
votes
4answers
13k views

How do I send an arbitary message to an Ethereum address?

How can I send a message to another Ethereum address? And how would that user receiving know that its a message? Is there an Ethereum wallet that will show that I sent a message to that address? And ...
26
votes
1answer
13k views

What does the keyword “memory” do exactly?

I've been looking through the code of Etherdice and noticed that some variables are declared like ParserResult memory result; and I haven't found the keyword "memory" in any documentation. What I ...
15
votes
1answer
1k views

How should I handle blockchain forks in my DApp?

In the user interface of my DApp, how can I detect that a blockchain reorganization happened and what should I do to update the UI state once the fork is resolved?
13
votes
6answers
16k views

Is there a list of DAPPS that are already useable? [closed]

Is there a list of DAPPs that are already useable? Useable means there is an easy accessible GUI, that can interact with the contract.
14
votes
6answers
9k views

How can dapps work on smartphones?

How can dapps on mobile web browsers interact with web3.js? Is there any tool like Metamask or Mist on the roadmap for mobile?
9
votes
3answers
1k views

How would stablecoins work on Ethereum?

The idea of a stablecoin in Ethereum is to create a token that is pegged to the price of say $1 USD. What are the main ways of achieving a stable cryptocurrency? What DApps are implementing them and ...
7
votes
5answers
6k views

Trying to connect Mist/Ethereum wallet with testrpc

I need someone who can explain to me, step by step, in simple terms how can I connect the ethereum wallet with the local blockchain. I found the following link: Connect Mist to ethereum-js testrpc ...
38
votes
1answer
14k views

What is Whisper and what is it used for?

It's admittedly a very general question, but I've heard "Whisper" mentioned in several places when reading about certain DApps. I understand it allows peer-to-peer messaging of some kind, but what ...
6
votes
2answers
3k views

Deploying contract from contract

I try something like this: Child.sol pragma solidity ^0.4.6; contract Child { address owner; function Child() { owner = msg.sender; } } Parent.sol pragma solidity ^0.4.6; import "./...
20
votes
3answers
7k views

Are there any public/free nodes to connect a Dapp front end?

I have a small Dapp written in Meteor (client only) that reads some contract and account info from the blockchain. I can deploy my front-end code for free on meteor.com (or a variety of other places),...
6
votes
2answers
3k views

Typical architecture of a Dapp with a browser client

I am trying to understand the typical architecture of a Dapp with browser clients. Is the below understanding correct? [Web Browser (end user)] <==> [Server (web application/javascript <==> ...
1
vote
2answers
2k views

How to verify MetaMask account holder is the real owner of the address?

I'm making a dapp that will make calls to a Node.js server. I expect the user to have MetaMask installed and I want to verify that he is the real owner of the current address on MetaMask (i.e. ...
9
votes
2answers
4k views

How to connect a web site to a geth node?

Before the DApp-browser Mist was available, this web3 library seems the way to go on building a bridge from contract to a frontend (web site). But, I cannot get the very basic examples to work. ...
1
vote
1answer
370 views

Is it possible to embedd the UI of DApp in the blockchain?

I have read the answers for this question as well as their linked resources, but I didn't found the answer for the following question: is it possible to embedd the UI of ÐApp in the blockchain? If I ...
2
votes
1answer
331 views

sendTransaction from iPhone app

How do I call sendTransaction from within an iPhone app? I was thinking of running a web to Geth proxy where the iPhone app would call the Api exposed by the proxy which in turn calls my self hosted ...
2
votes
2answers
645 views

How to receive ether in wallet address and forward to another address on successful deposit?

I want to implement a feature in which users will send ether to wallet address(0x123) and on successful deposit, it needs to automatically transfer to my cold wallet(0x983). I can able to achieve ...
8
votes
1answer
12k views

Where can I learn how to develop DApps using the solidity programming language? [closed]

What resources exist to help people learn the solidity programming language and create smart contracts & DApps on Ethereum?
18
votes
2answers
12k views

How can we integrate IPFS with ethereum in DApps?

How can integration of IPFS with ethereum be done in DApps? Which parts of a DApp will be on IPFS? Do any examples exist? If a DApp's site is hosted on github, is it not centralized?
12
votes
2answers
4k views

Do users of ERC20 coins need to hold Ether?

Suppose there exists Fancycoin, an ERC20 altcoin which has some functionality implemented by the EVM. It does some nontrivial things that take up gas. According to my understanding, I can receive ...
11
votes
3answers
4k views

What are the best practices to allow user signup and login for a dapp?

From what I have researched, it seems that all of the methods for allowing a user to signup and login for an Ethereum dapp are very cumbersome for the user to use. What are the best practices to allow ...
23
votes
6answers
18k views

web3.eth.contract is not a function when making contract

Whenever I try and make a contract, I get: web3.eth.contract is not a function I'm using this code: const path = require('path'); const fs = require('fs'); const solc = require('solc'); ...
7
votes
2answers
2k views

Storing private data on the ethereum blockchain

I plan to make an app utilising Ethereum that will store private data about a user. Eventually, I want this data to be accessible by selected users. I have seen conflicting answers & discussions ...
8
votes
1answer
3k views

Unlock account permanently

I have created a dapp where the user can sign a contract using metamask. However, the account that gets the money send to keeps getting locked. Sure, I can manually unlock it, but this is really ...
1
vote
1answer
2k views

How to map a web3 to a react.js state

How would you map a changing variable from web3 to react.js component? Example: class App extends Component { constructor(props){ super(props); this.state = { blockNumber: web3.eth....
10
votes
4answers
4k views

What are the different GUI's available for Ethereum?

Are there any easy to use GUI's for Ethereum?
7
votes
2answers
10k views

How to build a front end for dApp

I am studying about DApps and Ethereum. I did get the Solidity part but I am confused about the front-end apps. Is it possible that I use web framework like PHP Laravel/Rails for Frontend/Db ...
6
votes
1answer
297 views

What features are possible on Ethereum than can never be implemented with Rootstock

I understand that there are limitations to what type of code can run on the Bitcoin network and how much data can be stored in each transaction. With a 2 way pegging like Rootstock many of the smart ...
4
votes
1answer
982 views

Deploying Meteor Dapps

What are currently the best architectural and deployment options for building and deploying a Dapp built with Meteor/Web3? For building the Dapp, a few Meteor packages are currently available : "...
6
votes
2answers
457 views

Customized oracle to access and make changes to data on a cloud service

Although, there is some literature mentioning the possibilities of oracles to supply external data to smart contracts in a blockchain, I am a newb and was wondering whether there is a successful ...
1
vote
2answers
218 views

Storing a document with multiple large video files

What's the best way to store a document with multiple large video and CAD files on Ethereum. I am just a beginner to Ethereum. The document is a science experiment with multiple documents linked. I'd ...
0
votes
3answers
323 views

Dapp not conecting (through web3) when called from browser which dont have node running on it

trying to connect dapp through browser,when doing the same through the browser on machine which has running geth node is getting connect through public ip (eg :http175.xxx.xxx.xx:xxxxlogin) but the ...
0
votes
0answers
30 views

javascript : how can pass the data to other Function

I am currently building a Dapp. I want to know how can I pass the data to the other Function. picture1 : Contract.FunOp_02( "1", ... this "1" if I input 1, it will display data1 like a picture1 //...
8
votes
2answers
2k views

DApp storage for data other than tranactions?

For the purpose of illustration, say I would like to create a decentralized version of Yelp. A centralized approach would be to have a restaurants table and a reviews table in an Mysql database. In ...
6
votes
1answer
2k views

How is hosting of a DApp done?

I don't understand how deployment and hosting of a DApp works. My quesitons are: 1.Is DApp's code stored on Ethereum servers or do I have to get my own server and store it there? 2.Do I have to run ...
10
votes
2answers
4k views

Can I run a website 'on' ethereum or only 'with' ethereum?

Do you run a website 'on' ethereum or 'with' ethereum and if the latter, is that only with 'nodejs'?
9
votes
1answer
6k views

Create a two-dimensional array in Solidity

How to create arrays addresses using solidity? And we can write two-dimensional array? bool[2][] m_pairsOfFlags; Here is an example of the array, but it does not work
7
votes
2answers
817 views

Does Ethereum offer encrypted peer to peer communication applications?

I am wondering if Ethereum can be used for encrypted peer to peer communication like delivering encrypted short messages or encrypted data in bulk between two or multiple parties. Are there any ...
6
votes
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 ...
10
votes
2answers
560 views

Is there a tool that creates a basic HTML interface from an ABI?

I am looking for a tool that builds a basic interface for a contract so that I can use this generated HTML as a starting point to build the front end. I am aware that Mist, https://chriseth.github.io/...
5
votes
1answer
842 views

What is BlockApps and how can it be used with Ethereum?

BlockApps says: Customized, permissioned private Blockchain ledger to your specifications. Based on Turing-complete Ethereum standards, your Blockchain has full Smart Contract support built-in. ...
4
votes
1answer
696 views

Exposing Geth to Hybrid mobile app

I'm making a Hybrid mobile app and planning to use web3.js to access Geth. What's the best way to expose Geth to the hybrid mobile app? I will be running Geth on ubuntu 14.04 on Aws
3
votes
1answer
5k views

Account is locked, after running Truffle migrate command [duplicate]

I am new to this technology and I am trying to Deploy the contract to Ropsten test network. I have my geth running in one terminal. In my truffle console I have an account with some ether. I unlock it,...
1
vote
2answers
1k views

Connect Mist to ethereum-js testrpc

I need to test a DAPP which will run in Mist, but I don't want to run it in TestNet or MainNet, I want to run it in a ethereum-js testrpc instance. Is it possible to do that? Does anybody has tried ...
1
vote
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
5k views

What are the advantages of creating a dapp over a normal web application?

A lot of dapps seem like nothing new to me and the added benefit of creating a dapp seems very minimal besides decentralization.