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Npm Ethereum Bridge

Oraclize Documentation

Oraclize Documentation

Welcome to the Documentation of Oraclize! The documentation is divided in the following sections: Background : the rationale behind the Oraclizes Oracle Model General Concepts : the main concepts behind Oraclize Data-Sources : information regarding the types of data sources Oraclize supports Integrations : how to integrate a blockchain application with Oraclize Development Tools : a list of tools to aide development of Oraclize-integrated smart contracts Security Deep Dive : how Oraclizes Authenticity proofs works Pricing : information on our pricing model for production uses Oraclize is the leading oracle service for smart contracts and blockchain applications, serving thousands of requests for day every day on Ethereum, Bitcoin and Rootstock. In the blockchain space, an oracle is a party which provides data. The need for such figure arise from the fact that blockchain applications, such as Bitcoin scripts and smart contracts cannot access and fetch directly the data they require: price feeds for assets and financial applications; weather-related informations for peer-to-peer insurance; random number generation for gambling. But to rely on a new trusted intermediary, the oracle in this case, it would be betraying the security and reduced-trust model of blockchain applications: which is what makes them interesting and useful in first place. One solution is to accept data inputs from more than one untrusted or partially trusted party and then execute the data-dependent action only after a number of them have provided the same answer or an answer within some constrains. This type of system can be considered a decentralized oracle system. Unfortunately, this approach has severe limitations: It requires a predefined standard on data format It is inherently inefficient: all Continue reading >>

Giveth-bridge - Npm

Giveth-bridge - Npm

Giveth specific bridge between 2 ethereum based blockchains GivethBridge contract will be deployed on the home chain. When one donate functions are called, the sent value is locked in the bridge and an event is emitted. A node app will be watching for events and relay to the foreignChain, calling the deposit function. This will mint tokens and forward the donation to the liquidPledging contract. ForeignGivethBridge contract will be deployed on the foreign chain. When a user wants to move tokens to the home chain they will call the withdraw function. The tokens will then be burnt and an event is emitted. A node app will be watching for events and relay to the homeChain, calling the authorizePayment function.Once the payment is approved, the sender will be able to collect their funds from the GivethBridge contract. The GivethBridge contract is an extension of the vault, which provides a safe and secure way to store funds. Vist the vault repo to lean more about the vault. Currently these contracts are a temporary solution until, a more robust bridging system is ready. Both contracts are pausable which will allow use to migrate to a new bridge at a future date. See config/default.json for example. This will be loaded and extended by additional configuration if found. You can specify the ENVIRONMENT env variable to load the file config/${ENVIRONMENT}.json if found. ENVIRONMENT defaults to local. homeNodeUrl: ethereum node connection url for homeBridgehomeBridge: address of the home bridgehomeConfirmations: # of confirmations required before relaying tx to foreignBridgeforeignNodeUrl: ethereum node connection url for foreignBridgeforeignBridge: address of the foreign bridgeforeignConfirmations: # of confirmations required before relaying tx to homeBridgepollTime: how often i Continue reading >>

Why We Have Banned Default Exports In Javascript And You Should Do Thesame

Why We Have Banned Default Exports In Javascript And You Should Do Thesame

Lead developer at Neufund. Writing about Javascript, Typescript, testing and blockchain. Why we have banned default exports in Javascript and you should do thesame ES2015 was the most important improvement to Javascript in years. Among many great features it brought brand new module system Ecma Script Modules which finally solved the problem of sharing code between files (modules) on a language level. It was a huge step forward but it needed to work with already existing modules, especially CommonJS used by node (require). Thats why it required some compromises, one of them is the existence of default exports. In this article, I want to explain why here at Neufund , we decided to ban default exports and use solely named ones. Default exports dont export any name ie. symbol that can be easily associated with a exported value. Named exports, on the other hand, are all about having a name (pretty obvious right ). This makes possible for IDEs to find and import dependencies for you automatically, which is a huge productivity boost. Default exports make large-scale refactoring impossible since each importing site can name default import differently (including typos). Using named exports can reduce your bundle size when you dont use all exported values (especially useful while building libs). Default exports were introduced mostly for easier interoperability with thousands CommonJS modules that were exporting single values like: They dont bring many benefits when used internally in your codebase, so please avoid them and thus make world a better place For more news, tips & tricks about Typescript, Javascript and blockchain, follow me on Twitter ! Krzysztof Kaczor is the Lead Blockchain Developer at Neufund , a community-owned fundraising platform bridging the worlds of equit Continue reading >>

Problems Installing Java Module In Node.js

Problems Installing Java Module In Node.js

During installation I have following error: C:\Users\me\Desktop\myproject> npm install java-> [email protected] install C:\Users\me\Desktop\myproject\node_modules\java> node-gyp rebuildC:\Users\me\Desktop\myproject\node_modules\java>node "C:\Program Files\nodejs\node_modules\npm\bin\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuildBuilding the projects in this solution one at a time. To enable parallel build, please add the "/m" switch.VCBUILD : error Message: [C:\Users\me\Desktop\myproject\node_modules\java\build\binding.sln]VCBUILD : System error : -2147154687. [C:\Users\me\Desktop\myproject\node_modules\java\build\binding.sln]gyp ERR! build errorgyp ERR! stack Error: `C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild.exe` failed with exit code: 1gyp ERR! stack at ChildProcess.onExit (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\build.js:267:23)gyp ERR! stack at ChildProcess.emit (events.js:98:17)gyp ERR! stack at Process.ChildProcess._handle.onexit (child_process.js:810:12)gyp ERR! System Windows_NT 6.1.7601gyp ERR! command "node" "C:\\Program Files\\nodejs\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"gyp ERR! cwd C:\Users\me\Desktop\myproject\node_modules\javagyp ERR! node -v v0.10.30gyp ERR! node-gyp -v v0.13.1gyp ERR! not oknpm ERR! [email protected] install: `node-gyp rebuild`npm ERR! Exit status 1npm ERR!npm ERR! Failed at the [email protected] install script.npm ERR! This is most likely a problem with the java package,npm ERR! not with npm itself.npm ERR! Tell the author that this fails on your system:npm ERR! node-gyp rebuildnpm ERR! You can get their info via:npm ERR! npm owner ls javanpm ERR! There is likely additional logging output above.npm ERR! System Windows_NT 6.1.7601npm ERR! command "C:\\Program Files\ Continue reading >>

Blockchain - Urgent Help Setting Up Ethereum Bridge - Ethereum Stack Exchange

Blockchain - Urgent Help Setting Up Ethereum Bridge - Ethereum Stack Exchange

I've currently download nodejs truffle, testrpc etc etc to set up my development environment. All I need to do is demonstrate the oracle service working. I've found that I need to 'set up an ethereum bridge' through this answer . But all it says is to "set it up" which is proving to be easier said than done for me at least. I'm not the most experienced with these things so every time I try to via PowerShell I'm unsuccessful. Here's what appears when I simply type in "npm install" when in the directory of the git I've cloned. npm WARN read-shrinkwrap This version of npm is compatible with [email protected], but npm-shrinkwrap.json was generated for [email protected] I'll try to do my best with it!> [email protected] install C:\Users\User\desktop\ethereum-bridge\node_modules\sha3> node-gyp rebuildC:\Users\User\desktop\ethereum-bridge\node_modules\sha3>if not defined npm_config_node_gyp (node "C:\Program Files\nodejs\node_modules\npm\node_modules\npm-lifecycle\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild ) else (node "C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\bin\node-gyp.js" rebuild )gyp ERR! configure errorgyp ERR! stack Error: Can't find Python executable "C:\Users\User\AppData\Local\Programs\Python\Python36\python.EXE", you can set the PYTHON env variable.gyp ERR! stack at PythonFinder.failNoPython (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:483:19)gyp ERR! stack at PythonFinder. (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:508:16)gyp ERR! stack at C:\Program Files\nodejs\node_modules\npm\node_modules\graceful-fs\polyfills.js:284:29gyp ERR! stack at FSReqWrap.oncomplete (fs.js:170:21)gyp ERR! System Windows_NT 10.0.16299gyp ERR! command "C:\\Program Files\\nod Continue reading >>

Github - Oraclize/ethereum-bridge: Independent Bridge To Link Any Ethereum Network With The Oraclize Engine

Github - Oraclize/ethereum-bridge: Independent Bridge To Link Any Ethereum Network With The Oraclize Engine

Independent bridge to link any Ethereum network with the Oraclize engine If nothing happens, download GitHub Desktop and try again. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. This tool enables any non-public blockchain instance to interact with the Oraclize service. Please note that at this point this tool is still experimental and subject to change without notice. run sudo apt-get install build-essential -y You should run the following commands from within the ethereum-bridge folder. active mode (deploy and query contracts using one account on your main node) [DEFAULT] broadcast mode (deploy and query contracts using a local account (the node will be used only to broadcast the txs)) After you have correctly deployed the address resolver and the connector on your blockchain you can load the previous instance using the --oar flag (with the latest oar address generated) or using --instance latest if you are not using the deterministic OAR you also need to update your contract constructor with the new address resolver generated (deploy contracts using the account 1 found on the localhost:8545 node) node bridge -H localhost:8545 --broadcast --new (generate a new address locally and deploy contracts (txs broadcasted to localhost:8545 node)) or if you already have one or more account in your keys.json file: node bridge -H localhost:8545 --broadcast -a 0 (load the first account in your keys.json file (index n.0) and deploy contracts (txs broadcasted to localhost:8545 node)) Add OAR = OraclizeAddrResolverI(EnterYourOarCustomAddress); to your contract constructor, example: Where EnterYourOarCustomAddress is the address resolver gen Continue reading >>

@wings_platform/wings-bridgepublic

@wings_platform/wings-bridgepublic

This Wings bridge contract works like communication contract, allows to message to Wings amount that ICO collecting during crowdsale. Install this package as dependency for your smart contracts. Inherit your main Crowdsale contract from Connector contract. Call method notifySale when sale/exchange of your tokens happen. Call method closeBridge and impelement movement of rewards to bridge contract. Deploy your token/crowdsale etc contracts, deploy bridge contract, call method changeBridge on your crowdsale contract and pass there address of deployed bridge contract. Create project on Wings, as 3rd party crowdsale contract provide address of bridge contract. Call transferManager method on bridge contract and pass there DAO contract address generated by Wings. Call start for bridge before crowdsale start. For more details read next part of this tutorial. On example of standard crowdsale contract we will do bridge integration. Important: this is just tutorial and shows one of the many ways to integrate bridge contract, everything based on your own crowdsale contract. Don't use this example on mainnet. Let's take a standard token and crowdsale contract. Token contract is mintable, so we will use token to issue new tokens, manage issue will be done by crowdsale contract (that will be owner of token contract). Now let's add support of Connector contract to crowdsale contract. npm i @wings_platform/wings-bridge --save Connector is already inherits from Ownable so we don't need to inherit again. Now our goal to call notifySale on each call, method looks so in Connector contract: functionnotifySale(uint256_ethAmount,uint256_tokenAmount)internalbridgeInitialized{ bridge.notifySale(_ethAmount,_tokenAmount); uint256 _ethAmount - is amount of ETH that was sent to buy tokens. uint256 Continue reading >>

Oracles In Ethereum - A Simple Guide

Oracles In Ethereum - A Simple Guide

Motivation: Ive been trying to find a tutorial on building an Oracle in Ethereum, only problem is that the articles online are either out of date (pre web3 v1.0.x) or the source code provided is structured in such a way that makes it incredibly tough to follow (having python, c# and javascript in one project with no clear description of what each language is doing and why its necessary). This guide assumes you have a basic understanding of the solidity language Goal: By the end of this guide, I hope to have helped you build and deploy your Oracle onto your own private testnet >>> Click here for the boilerplate project <<< An Oracle is, simply put, a smart contract that is able to interact with the outside world, in the world of Ethereum that is known as off-chain. I put smart contracts in quotations because some people argue that Oracles arent exactly a real smart contract. Example: Say youre writing a smart contract that needs to retrieve weather data, however your contract cant make arbitrary network requests on-chain. You need something that trustable (all user input arent) and is able to listen and respond to specific events on the blockchain. The solution: Oracles. This guide will be building a simple Oracle that retrieves bitcoins total market cap from coinmarketcap and store it into the blockchain. { "total_market_cap_usd": 198558465250.0, // This is that we want to store "total_24h_volume_usd": 4974818568.0, "bitcoin_percentage_of_market_cap": 61.65, "active_currencies": 896, "active_assets": 360, "active_markets": 6442} Ill be using the truffle framework and testrpc for this guide. You can install them by running: npm install -g truffle ethereumjs-testrpc Im using truffle because is has some really nice abstractions that allows me to interact with web3 (almost Continue reading >>

How To Create A Dapp Using Truffle, Oraclize, Ethereum-bridge Andwebpack

How To Create A Dapp Using Truffle, Oraclize, Ethereum-bridge Andwebpack

How to create a DApp using Truffle, Oraclize, ethereum-bridge andWebpack A simple guide on using external API data in a Smart Contract front-end After completing this tutorial youll have a working DApp (Decentralised Application) reacting to Events emitted via a Solidity Smart Contract using Oraclize to fetch external API data from Coinbase . For science! Writing & deploying a simple Smart Contract Setting up a local ethereum-bridge for Oracle communication Fetching external data from the Coinbase API using an Oracle Creating a custom front-end to show the API data Doing this in a local development environment Theres a screenshot of what well be making at the bottom of the article Hi, my name is Lander . Im a Digital Consultant and product builder from Belgium. When Im not dabbling in Solidity, Im working on TeamHut , a SaaS to help freelancers and digital teams organise & share their digital content. Youre able to clone a git repository & install its dependencies via npm You have basic knowledge of HTML, JavaScript, Webpack , terminal, Youre looking to learn more about using Oraclize & Solidity Events Well be writing a Smart Contract that fetches external API Data using a locally running Oracle. Well do this by emulating the Oracle using ethereum-bridge. The contract fetches the current Ethereum USD price from the Coinbase ETH-USD spot price API . Well be creating a simple HTML page that shows our contracts total ETH balance both in ETH and in USD. The total USD value of your contract is calculated using the Coinbase API. The values auto-update until the contract runs out of funds. Smart contracts, by their nature, are able to run calculations and store and retrieve data. Because every node runs every calculation, its not practical (and presently impossible) to make a Continue reading >>

Tutorial: How To Build A Graphqlserver

Tutorial: How To Build A Graphqlserver

(Updated for 2018!) Talk to MongoDB, SQL and REST with these simplesteps Apollo is a set of tools for building GraphQL applications, especially suited for building on top of your existing data. There are three main components that you can use to build a production-ready GraphQL app: Apollo Client : A GraphQL client for every frontend platform. Apollo Server : A library for writing GraphQL servers with JavaScript. Apollo Engine : A GraphQL gateway that provides caching, error tracking, and performance tracing. This is a tutorial for the second and third parts how to build a GraphQL server that connects to multiple backends: a SQL database, a MongoDB database and a REST endpoint. Well be combining all of them to build a very basic blog with authors, posts and views. Jonas Helfer originally wrote this post in April 2016, but weve updated it since (most recently in December 2017) to make sure its using the newest Apollo and GraphQL packages available. Huge thanks to Johanna Griffin for adding those updates and thoroughly testing everything! This tutorial assumes that youve already set up Node.js and npm for your computer, and that you know how to copy-paste things to the command line. Naturally, youll also need a text editor of sorts. To follow along with the MongoDB part (optional), youll also need a MongoDB server running somewhere. If you have all of that, there is just a little bit more boilerplate to set up: Babel for ES6 features, and a simple express server. You can do this yourself if you like, but you can also just clone the starter kit for this tutorial: git clone This will download the starter kit from GitHub and install all the npm packages you need to get started. Once the installation is finished, you can launch the server with this command: If all goes well, Continue reading >>

How To Connect An Ethereum Node To The Web Browser

How To Connect An Ethereum Node To The Web Browser

How to connect an Ethereum node to the web browser Software Developer at ASSIST Nodes are instances of the Ethereum network. Each node hosts all the Ethereum transactions ever made and syncs constantly with all the other nodes in the network. Ethereum Nodes: Go Ethereum - Geth, Ethereum - cpp, Parity, MetaMask (a bridge between nodes and your browser). Ethereum Blockchain node implements Ethereum Protocol, with a node you can: Interacting with an Ethereum blockchain can be done via transactions or calls. The differences between these are: if is valid written to the blockchain (update the state of the blockchain); the return value is transaction-hash after the transaction is verified; the return value is returned immediately; Because every time we want to update the state of blockchain will cost Ether (gas) and our smart-contracts cant be changed once are deployed, we should first implement contracts on private blockchain or public Testnet blockchain. Also, you need to know that on these networks Ether is worthless. 3. Connect your blockchain to the browser. First, we need an Ethereum node (Mainet or Testnet). We have at least 3 different ways to do this: use Mist wallet (Testnet or Mainet) which will run a node in the background. After that, you will need to sync the blockchain and also, you will need some Ether for deploying your code (this could take from few hours to days); create a private blockchain and run the node on local. Here we must pay attention to our own contracts (we have to verify the transactions) and also, its important to mention that you dont need to have a node explorer; use Metamask bridge to connect to a Mainet or Testnet node. So in this way, we will not have to worry about syncing the node, verifying our transactions or mining Ether (you can al Continue reading >>

Blockchain - Urgent Help Setting Up Ethereum Bridge - Ethereum Stack Exchange

Blockchain - Urgent Help Setting Up Ethereum Bridge - Ethereum Stack Exchange

I've currently download nodejs truffle, testrpc etc etc to set up my development environment. All I need to do is demonstrate the oracle service working. I've found that I need to 'set up an ethereum bridge' through this answer . But all it says is to "set it up" which is proving to be easier said than done for me at least. I'm not the most experienced with these things so every time I try to via PowerShell I'm unsuccessful. Here's what appears when I simply type in "npm install" when in the directory of the git I've cloned. npm WARN read-shrinkwrap This version of npm is compatible with [email protected], but npm-shrinkwrap.json was generated for [email protected] I'll try to do my best with it!> [email protected] install C:\Users\User\desktop\ethereum-bridge\node_modules\sha3> node-gyp rebuildC:\Users\User\desktop\ethereum-bridge\node_modules\sha3>if not defined npm_config_node_gyp (node "C:\Program Files\nodejs\node_modules\npm\node_modules\npm-lifecycle\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild ) else (node "C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\bin\node-gyp.js" rebuild )gyp ERR! configure errorgyp ERR! stack Error: Can't find Python executable "C:\Users\User\AppData\Local\Programs\Python\Python36\python.EXE", you can set the PYTHON env variable.gyp ERR! stack at PythonFinder.failNoPython (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:483:19)gyp ERR! stack at PythonFinder. (C:\Program Files\nodejs\node_modules\npm\node_modules\node-gyp\lib\configure.js:508:16)gyp ERR! stack at C:\Program Files\nodejs\node_modules\npm\node_modules\graceful-fs\polyfills.js:284:29gyp ERR! stack at FSReqWrap.oncomplete (fs.js:170:21)gyp ERR! System Windows_NT 10.0.16299gyp ERR! command "C:\\Program Files\\nod Continue reading >>

Package - Solium

Package - Solium

Linter to identify and fix Style & Security issues in Solidity Last updated 22 days ago by the-mad-king . Solium analyzes your Solidity code for style & security issues and fixes them. Standardize Smart Contract practices across your organisation. Integrate with your build system. Deploy with confidence! .soliumignore - contains names of files and directories to ignore while linting .soliumrc.json - contains configuration that tells Solium how to lint your project. You should modify this file to configure rules, plugins and sharable configs. { "extends": "solium:recommended", "plugins": ["security"], "rules": { "quotes": ["error", "double"], "indentation": ["error", 4] }} To know which lint rules Solium applies for you, see Style rules and Security rules . Solium does not strictly adhere to Solidity Style Guide . It aims to promote coding practices agreed upon by the community at large. Comment Directives can be used to configure Solium to ignore specific pieces of code.They follow the pattern solium-disable. If you only use the directive, Solium disables all rules for the marked code. If that's not desirable, specify the rules to disable after the directive, separated by comma. contract Foo { /* solium-disable-next-line */ function() { var bar = 'Hello world'; // solium-disable-line quotes // solium-disable-next-line security/no-throw, indentation throw; }} Solium automatically fixes your code to resolve whatever issues it can. Continue reading >>

Oo7 Parity Reference - Wiki Parity Tech Documentation

Oo7 Parity Reference - Wiki Parity Tech Documentation

oo7-parity is a Parity-centric Ethereum middleware designed to sit between your front-end and a Parity Ethereum node. It is based on oo7 and parity.js (our low-level JS API for the Parity/Ethereum RPC). It makes heavy use of Bonds to deliver an effortless UI development experience that results in a responsive, reactive UI. It works best with the Parity Ethereum node, but is partially compatible with other clients, too. A Bond is like a Promise in that its an asynchronously provided value. However, unlike a Promise it autonomously stays up to date. Bonds may be subscripted, transformed and composed. oo7-react.js exists for tying Bonds into the React library, trivially allowing the UI to display up-to-date information from the block chain. It brings in oo7, the underlying Bonds library items of which you will probably want to use and @parity/parity.js, the low-level Parity/Ethereum API library. If you are working on the UI with React, youll probably want to install parity-reactive-ui.js too (which brings in oo7-react, the oo7 bindings for React and semantic-ui, a nice front-end UI toolkit): Most of the API oo7-parity provides is contained within a single object: bonds. The majority of this document details each of the members of this object and how to use them. The rest of the API is compose of a number of utility functions to facilitate certain common actions required when working with oo7-parity. There are several utility functions in oo7-parity: asciiToHex(String) => Bytes: Convert some 7-bit ASCII to its 0x-prefixed hex representation. bytesToHex(Array) => String: Convert an array of integers between 0 and 255 inclusive to its 0x-prefixed hex representation. hexToAscii(Bytes) => String: Convert a 0x-prefixed hex representation of binary data to 7-bit ASCII. isAddress Continue reading >>

Ethereum Light-client With React Native

Ethereum Light-client With React Native

In the Blockchain world, a light-client is an application which runs its own p2p node and is therefore connected to the whole network without any centralized intermediaries. This is, at least from a decentralized mindset perspective, a desirable property. From a purely technical perspective however, this presents several problems. Besides the classic performance and reliability issues of a p2p network, one big problem inherent to blockchain systems is, that the data-structure underlying these blockchain systems is usually very large (GBs - TBs), so its simply not feasible to download it on a mobile device or sometimes even on a desktop. Because of this issue, the concept of light clients was developed. Such a light client, in the case of ethereum only downloads block-headers and verifies a lot less. With such a light client, its possible to be a part of the whole p2p network and directly interact with the blockchain by deploying contracts, sending transactions, querying balances etc. This concept has been working ok for BitCoin in the past and is one of the things which successful blockchain-platforms seem to need at some point. In the ethereum space however, this is, at the time of this blog post, an experimental feature. When I researched the subject superficially, I didnt find many ethereum projects using a light client yet. Most prominently there is status , who wrote their own wrapper of go-ethereum . I also found walleth , which is a new project and a Kotlin-based light client using the cross-compiled Android package of go-ethereum. This cross-compiled package is what I will also use in this blog post, as it seems to be the suggested and most standard way of approaching this problem at the moment. I will use react-native in this example, because Im familiar with Continue reading >>

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