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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 >>

Blockchain - How Can A Contract Run Itself At A Later Time? - Ethereum Stack Exchange

Blockchain - How Can A Contract Run Itself At A Later Time? - Ethereum Stack Exchange

How can a contract run itself at a later time? In my blockchain application, I would like to have an event triggered at a later time, hours or perhaps even days after the application has most recently received a transaction from a user. How can I create an "event" that will trigger after a certain amount of time has passed? Disclaimer: I am the developer behind the Ethereum Alarm Clock service and I directly benefit from its usage. There are two fundamental ways of designing a contract to be called at a later time: lazy evaluation or eager evaluation. Lazy evaluation means that the contract's state will be updated only when needed. This often makes sense for contracts that naturally incentivise users to call them at a future date. An example of this might be a trust fund contract that will remain locked until someone's 18th birthday. This individual would be motivated to execute the dispersal of those funds at that time. A more complex example is an interest-bearing contract. Say I deposit 1 ETH, and every month I get 1% interest, compounding. The lazy way: When I want to withdraw my money, I call the contract and it calculates my balance, based on the interest rate, my last known balance, and the elapsed time. The eager way: I use the Ethereum Alarm Clock or some similar service to call the claimInterest() function of the contract, which calculates that month's interest and debits my balance. In this case, lazy evaluation makes sense, because it is easy to calculate the current state based on the past state and elapsed time. Eager evaluation is useful when state transitions are If the contract needs to accept input from or send transactions to another contract Call Scheduling with Ethereum Alarm Clock The Ethereum Alarm Clock service supports scheduling a contract to Continue reading >>

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Schedule any contract function to be called a specified block number in the future. Fully implemented as an ethereum contract with no external services. Call execution can be done by anyone operating an ethereum node. No single point of failure. Contract code can be verified against the published source. Service implements no administrative functionality or special access to any address. The Alarm service does not implement suicide. You can count on it remaining available forever. The Alarm service is thoroughly documented with plenty of examples to help get you started. The Alarm service supports designation of certain addresses as authorized schedulers. Contracts can trust authorized calls were scheduled by an address that they authorized, allowing you to schedule calls to functions that would normally not be publicly callable. Anyone can execute scheduled calls, earning ether by doing so. Continue reading >>

Eth Usd | Ethereum Us Dollar Bitfinex - Investing.com

Eth Usd | Ethereum Us Dollar Bitfinex - Investing.com

To use this feature, make sure you are signed-in to your account To use this feature, make sure you are signed-in to your account Make sure you are signed-in with the same user profile Add to/Remove from a Portfolio Add to Portfolio 04:58:50 GMT - Real-time Data. ( Disclaimer ) National Futures Association (United States), U.S. Commodity Futures Trading Commission (United States), The Financial Conduct Authority (United Kingdom), Australian Securities and Investments Commission (Australia), Financial Industry Regulatory Authority (United States), Investment Industry Regulatory Organization of Canada (Canada), Securities and Exchange Board of India (India), Securities and Exchange Commission (United States), The Securities and Futures Commission (Hong Kong), Securities Investor Protection Corporation (United States) U.S. Commodity Futures Trading Commission (United States) Monetary Authority of Singapore (Singapore), National Futures Association (United States), U.S. Commodity Futures Trading Commission (United States), The Financial Conduct Authority (United Kingdom), Australian Securities and Investments Commission (Australia), Dubai Financial Services Authority (United Arab Emirates), Investment Industry Regulatory Organization of Canada (Canada) We encourage you to use comments to engage with users, share your perspective and ask questions of authors and each other. However, in order to maintain the high level of discourse weve all come to value and expect, please keep the following criteria in mind: Stay focused and on track. Only post material thats relevant to the topic being discussed. Be respectful. Even negative opinions can be framed positively and diplomatically. Use standard writing style. Include punctuation and upper and lower cases. NOTE: Spam and/or pro Continue reading >>

Is It Possible To Schedule Function Calls To An Ethereum Smart Contract?

Is It Possible To Schedule Function Calls To An Ethereum Smart Contract?

I am wondering - is it possible to schedule or somehow trigger function calls to an Ethereum smart contract based on the current block height or timestamp? This would involve some pre-payment of gas for execution understandably, but it might be beneficial to have something like: If current block height is 1'000'000, send 1000 ether to the block miner If it's 2016-01-01 00:00:00, release funds from escrow Of course those functions could be triggered by transactions at an appropriate time, but some sort of "execution scheduling" might be a useful automation of the process. why couldn't this be done? this should be super simple to program... user26705 May 30 '15 at 2:39 I can see why - timers require that you keep your contract topped up with Ether, and making them too easy to create could litter the blockchain with them and impose an overhead on miners. You either have to have an external caller for your function (as in chriseth's solution), or use a PHP-style "poor man's cron" function that you call from every function in the contract to check and see which periodic tasks should fire - It is not in "the" ethereum spec, so no. But it is a feature that has been discussed for "ethereum 2.0" or similar. It is possible that there may even be a hard fork that will enable it in the then-existing network, but there are none currently planned. This feature can be easily realised outside the Ethereum virtual machine (and thus keeping the VM simple): Create a (reusable) contract where contracts can register to be called at a certain time (and provide a reward as compensation for the gas costs). A script can poll this contract from outside and call it at the appropriate times. The contract could be similar to the following. contract CallbackRegistry{ struct Entry { uint time; addre Continue reading >>

Timers For Blockchain

Timers For Blockchain

Pluggable consensus is one of the hottest buzzwords in the blockchain ecosystem and the Hyperledger beehive is where this buzz on pluggable consensus is emanating from most deafeningly. It has been conjectured one reason for this state of affairs is that, while IBMs blockchain product offering could liberally be categorized as a blockchain of sorts, Intel Corporation- the second industrial pillar of the Hyperledger consortium- has created not a blockchain, but rather a consensus algorithm. Pluggable consensus in the context of Hyperledger means that one could conceivably adopt the IBM data interchange protocol while simultaneously employing Intels PoET system in place of the mysterious membersrvc of Fabric. The PoET system provides an interesting jumping off point for a further exploration of the role of time in blockchain. In this article we will examine the two fundamental ways that time can be incorporated into a distributed system such as a blockchain, by actions performed internally in the underlying protocol of the software and alternatively by forces external to the system itself. Activiti is an Open source business process engine that allows us to model any process and is of interest to the time analysis problem insofar as it enables users to set up timers on the Activiti software directly. Furthermore, it allows integration with the blockchain and facilitates the execution of code that can set triggers at the predetermined times, dynamically by the user. With a simple interface users can add the needed times directly to the timer properties. Alternatively, one can set up tasks within the process to execute code that will track time, launch processes and implement the timely execution of any process. The go-ethereum (geth/goethe) client maintains an implentatio Continue reading >>

Ethereum/solidity - Gitter

Ethereum/solidity - Gitter

The Solidity Contract-Oriented Programming Langauge I am encountering a strange behaviour when trying to release my contract on testnet.. I do have about 70 test ether, am on latest dev 1.4.0, and a test contract doing just multiply mines fine.. but when i try to mine my contract, the console just somehow "stalls", I cannot type anything anymore, at least not visible, the contract is not mined (at least there is no output), the only way to get out is to induce a panic (10x cmd+c) and this results in non-visible input in terminal as well, forcing me to kill that terminal and use a new one. Ubuntu 14.04. Verbosity 4 shows a lot of VM call err: but I do not know if this is related.. Any ideas what is going wrong? Using web3 deploy code from the online solidity compiler Could a modifer be used as a timer for a function? For example if I wanted a function to fire one month after a specified call (which begins the timer), could you do something like modifier interval(uint days) { if (now + days) _ } And could you using a timing modifer on a function simply by invoking "interval" after the function declaration? (perhaps you could suggest better ways of doing this). The goal is to leave the timing interval open to user input- if they user wants to set the timer for t+5 days or t+30 days it shouldn't matter. Continue reading >>

Notes On Ethereum Hard Fork Procedures

Notes On Ethereum Hard Fork Procedures

A countdown timer can be seen at fork.codetract.io Below are the official notes from the Ethereum team regarding the start of the Byzantium hard fork, which is a two part series of upgrades to the network. While there were some Ethereum and ERC20 deposit and withdrawal suspensions lasting up to 5 hours to 24 hours on some exchanges, many companies such as Coinbase and others are only bumping up the number of confirmations before a transaction is confirmed, thus causing some temporary delays. The Ethereum network hard fork will be in progress atblock number 4.37mil (4,370,000), approximately occurring between 12:00 UTC and 13:00 UTC today, MondayOctober 16, 2017. The Ropsten test network underwent a hard fork on September 19th (UTC) at block number 1.7mil (1,700,000). What is Metropolis, Byzantium, and Constantinople? Metropolis is a planned Ethereum development phase that includes two hard forks: Byzantium and Constantinople. Byzantium is occurring at block number 4.37mil. Constantinople does not currently have a release date, but is expected in 2018. Download the latest version of your Ethereum client: What if I am using a web or mobile Ethereum wallet like MyEtherWallet or Jaxx? Ethereum websites and mobile applications that allow you to store ether and/or make transactions are running their own Ethereum client infrastructure to facilitate their services. If you use a third-party web-based or mobile Ethereum wallet, your wallet provider may need to update for the hard fork. It is recommended that you check with them to see what actions they are taking to update for the hard fork and if they are asking their users to take other steps. A hard fork is a change to the underlying Ethereum protocol, creating new rules to improve the system. The protocol changes are activat Continue reading >>

Aigang (aix) Token

Aigang (aix) Token

Release v4.0. Fully autonomous Insurance DAO. Augustas has 10+ years experience in creating, growing & managing online and consumer businesses. He works in emerging digital finance industry and has co-founded peer-to-peer lending and investment platform with 15K+ users. He also helped blockchain project successfully raise 14M USD financing. Reda has 10+ years of experience in various finance, digital and marketplace businesses. She previously worked as Product manager and actuary at SEB Life Insurance, one of the biggest insurance companies in Scandinavia and Baltics. She has experience in product management, fundraising & business development. Lead Engineer & Smart contracts developer Darius worked as a Senior Software Engineer in Adform - a reporting platform for media agencies, trading desks and advertisers. He is a full stack developer with over eight years experience in enterprise software solutions and is responsible for the Aigang architecture and smart contracts. Marius is a bright, hard-working and ambitious developer with proven communication and team work skills developed while working within a software engineering development as an individual and team member. Highly energetic and takes initiative, able to multi-task effectively, and eager for new challenges. Mindaugas is a BSc in Computer Software Engineering. He has considerable experience working on large scale projects, having worked on the Vinted application, which has over 15 million users. He has a particular interest in and enthusiasm for iOS architecture. Naglis is a BSc in Computing Software Engineering. As well as being a developer hes the co-founder of ItWorks Mobile, a small app development company. Naglis has built secure and intuitive Android applications for banks and large music festivals an Continue reading >>

The Hitchhikers Guide To Smart Contracts Inethereum

The Hitchhikers Guide To Smart Contracts Inethereum

The Hitchhikers Guide to Smart Contracts inEthereum Updated Oct 6th 2017, for Truffle v3.4.11 and Solidity v0.4.15. Ive been working with smart contracts for 4 years , mainly in the Bitcoin blockchain. Some projects I participated in are Proof of Existence , bitcore , and Streamium . In the past months, Ive been exploring and working with the Ethereum platform. Ive decided to compile a short guide to ease the way of future programmers learning Ethereum smart contract development. Ive divided the guide in two sections: how to get started building smart contracts in Ethereum, and a quick note on smart contract security. Getting started with Smart Contracts onEthereum This guide assumes you have a basic level of technical understanding on how cryptocurrencies and blockchains work. If you dont, I recommend skimming over Andreas Antonopoulos Mastering Bitcoin book , Consensys Just Enough Bitcoin for Ethereum guide , or at least watching this short video by Scott Driscoll . To continue ahead you should know what a public and private key are, why a blockchain needs miners, how decentralized consensus is reached, what a transaction is, and the concepts of transaction scripting and smart contracts. Two other important and related concepts youll need to understand before working with Ethereum are the Ethereum Virtual Machine and gas. Ethereum was designed as a smart contract platform. Its origin is actually linked to a critique made by Vitalik Buterin on bitcoin as a very limited smart contract platform. The Ethereum Virtual Machine (EVM) is where smart contracts run in Ethereum. It provides a more expressive and complete language than bitcoin for scripting. In fact, it is a Turing Complete programming language. A good metaphor is that the EVM is a distributed global computer wh Continue reading >>

Etc Callisto Hard Fork Countdown Timer

Etc Callisto Hard Fork Countdown Timer

Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here. About all wallets of which you own the private key (like MEW or Coinomi) but be careful with exchanges: some do, some don't, there is no guarantee... About all wallets of which you own the private key (like MEW or Coinomi) but be careful with exchanges: some do, some don't, there is no guarantee... I never participated in some Ethereum fork. Can you give me more information's about it? Do I need to have Ethereum or Ethereum Classic? I have some Ethereum in my MEW wallet , Thanks for all the answers, I will check for myself how it goes, but I like this forum and answer's from members here, I trust you more. I will appreciate any answers. If I manage to find some nre information's in my search I will About all wallets of which you own the private key (like MEW or Coinomi) but be careful with exchanges: some do, some don't, there is no guarantee... I never participated in some Ethereum fork. Can you give me more information's about it? Do I need to have Ethereum or Ethereum Classic? I have some Ethereum in my MEW wallet , Thanks for all the answers, I will check for myself how it goes, but I like this forum and answer's from members here, I trust you more. I will appreciate any answers. If I manage to find some nre information's in my search I will you need ETC and keep your ETC at block 55,00,000 (about 5th march) Continue reading >>

Why Many Smart Contract Use Cases Are Simply Impossible - Coindesk

Why Many Smart Contract Use Cases Are Simply Impossible - Coindesk

Why Many Smart Contract Use Cases Are Simply Impossible Dr Gideon Greenspan is the founder and CEO of Coin Sciences, the company behind the MultiChain platform for private blockchains. In this opinion piece, Greenspan discusses blockchain-enabled smart contracts and why this application of the technology may be suffering from inflated expectations. As the developer of a popular blockchain platform, Isometimes gets asked whether Ethereum-like smart contracts are on the MultiChain roadmap. The answer I always give is always: 'No, or at least not yet'. But in the hype-filled world of blockchains, smart contracts are all the rage, so why ever not? Well, the problem is, while we now know of three strong use cases for permissioned bitcoin-style blockchains (provenance, company recordkeeping and lightweight finance), we've yet to find the equivalent for Ethereum smart contracts. It's not that people don't understand what they want smart contracts to do. Rather, it's that so many of these ideas are simply impossible. When smart people hear the term "smart contracts", their imaginations tend to run wild. They conjure up dreams of autonomous intelligent software, going off into the world, taking data along for the ride.Unfortunately, the reality of smart contracts is more mundane. A smart contract is a piece of code that isstored on an blockchain, triggered by blockchain transactions and which reads and writes data in that blockchain's database.That's it. Really. A smart contract is just a fancy name for code that runs on a blockchain, and interacts with that blockchain's state. And what is the code? It's Pascal, it's Python, it's PHP. It's Java, it's Fortran, it's C++. If we're talking databases, it's stored procedures written in an extension of SQL. All of these languages are Continue reading >>

Scheduling Ethereum Alarm Clock 1.0.0 Documentation

Scheduling Ethereum Alarm Clock 1.0.0 Documentation

Function calls are scheduled with the scheduleCall function on the Alarmservice. Solidity Function Signature: scheduleCall(address contractAddress, bytes4 signature, bytes32 dataHash, uint targetBlock, uint8 gracePeriod, uint nonce); The scheduleCall function takes the following parameters: address contractAddress: The contract address that the function should becalled on. bytes4 abiSignature: The 4 byte ABI function signature for the call. bytes32 dataHash: The sha3 hash of the call data for the call. uint targetBlock: The block number the call should be executed on. uint8 gracePeriod: The number of blocks after targetBlock that it isok to still execute this call. uint nonce: Number to allow for differentiating a call from another onewhich has the exact same information for all other user specified fields. Prior to scheduling a function call, any call data necessary for the call musthave already been registered. The scheduleCall function has two alternate invocation formats that can beused as well. Solidity Function Signature: scheduleCall(address contractAddress, bytes4 abiSignature, bytes32 dataHash, uint targetBlock, uint8 gracePeriod) public When invoked this way, the nonce argument is defaulted to 0. Solidity Function Signature: scheduleCall(address contractAddress, bytes4 abiSignature, bytes32 dataHash, uint256 targetBlock) public When invoked this way, the gracePeriod argument is defaulted to 255 andthen nonce set to 0. Contracts can take care of their own call scheduling. In this example Lottery contract, every time the beginLottery functionis called, a call to the pickWinner function is scheduled for approximately24 hours later (5760 blocks). Alternatively, calls can be scheduled to be executed on other contracts The Alarm service operates under a scheduler p Continue reading >>

Any Plan For Having On-chain

Any Plan For Having On-chain "timer" Transactions? : Ethereum

Are there any plans to allow an address to submit a transaction that will occur at a later time? It's submitted like a normal transaction, but includes some minimum block number or time. This signifies it is a "timer" transaction. Let's say I include 300k gas @ 20GWei. Miners see this special request and take some fixed gas cost from it. Say, 100k. A "timed transaction" gets written to the blockchain, and the rest of the gas and gas price (200k @ 20 GWei) is attributed to its balance. At any time, the original sender can "clear" the timed transaction for another fixed fee, say, 20k gas, and the remaining balance (gas * gas price) in the timed transaction is refunded. When miners mine, they look for any mature "timed" transactions on the queue and add them in into the current block, using the remaining gas to execute the call (on behalf of the original sender). I know there are services which will invoke functions at a given time, but they are off chain and are subject to off-chain service issues. I see a lot of value in this living on-chain. Continue reading >>

Testing Time-based Ethereum Smart Contracts In Solidity Without A Test Suite

Testing Time-based Ethereum Smart Contracts In Solidity Without A Test Suite

Testing Time-Based Ethereum Smart Contracts in Solidity Without a Test Suite Blockchain , Ethereum , Smart contracts , Solidity , Testing When I first got started with Solidity , I immediately went down a rabbit-hole of How do I write tests for this? and found a lot of answers, all of which required fairly heavy-handed setup for someone just starting out. So I did what everyone else does: I started manually deploying contracts to the testnet with Ethererum Wallet and manually invoking their public functions. This soon becomes annoying, repetitive, and the biggest bottleneck in getting your contract written. Obviously, longer-term, you want to be a good citizen and set up a test suite. When youre just hacking around on something for fun, however, thats kind of a drag. Even worse, if your contract revolves around time as a key mechanic, youll find yourself waiting for extended periods of time or frequently missing important time windows as you switch back and forth from code editor to wallet. You already know how to use Ethereum Wallet , and you already know how to write Solidity code using inheritance. I devised a strategy for quicker semi-manual testing for Ethereum Smart Contracts: Refactor time-based code to make the concept of now overridable by child contracts. Create a child contract that makes a series of assertions in its constructor. Start to deploy the test contract in Ethereum Wallet. If Ethereum Wallet complains that execution will fail, your tests failed. If it doesnt, they succeeded. Warning: now is an alias for block.timestamp, which is known to be cheatable within shorter time windows. Please seek professional guidance before using it in financially important code. This is a contract Lockbox with behavior based upon the current block time. The owner can Continue reading >>

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