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Blockchain Api Java

Creating Your First Blockchain With Java. Part1.

Creating Your First Blockchain With Java. Part1.

pineapple express, star trek, late night programming, Desperados ( with lime ) & looking beyond 22338618. Creating Your First Blockchain with Java. Part1. The aim of this tutorial series, is to help you build a picture of how one could develop blockchain technology. Create your first (very) basic blockchain. Implement a simple proof of work ( mining ) system. ( I will assume you have a basic understanding of Object Oriented Programming ) Its worth noting that this wont be a fully functioning, ready for production block chain. Instead this is a proof of concept implementation to help you understand what a blockchain is for future tutorials. You can support this and future tutorials:) We will be using Java but you should be able to follow along in any OOP language. Ill be using Eclipse but you can use any new fancy text editor ( though youll miss out on a lot of good bloat ). Dont worry if your eclipse looks different to mine. Ill be using a dark theme in eclipse because^ Optionally, you can grab GSON library by google (who are they???). This will allow us to turn an object into Json \o/. Its a super useful library that we will also be using further down the line for peer2peer stuff, but feel free to use an alternate method. In Eclipse create a (file > new > ) Java project. Ill call my Project noobchain and create a new Class by the same name (NoobChain). Dont be copying my project name now ( ) A blockchain is just a chain/list of blocks. Each block in the blockchain will have its own digital signature, contain digital signature of the previous block, and have some data ( this data could be transactions for example ). Each block doesnt just contain the hash of the block before it, but its own hash is in part, calculated from the previous hash. If the previous blocks data Continue reading >>

Is Java Or C++ Better For Blockchain?

Is Java Or C++ Better For Blockchain?

TL;DR: The blockchain is just another software engineering tool. To determine the best tool to interact with blockchain you need to define your requirements. The C++ clients are currently the most feature rich, but IMHO the java clients will catch up pretty soon (maybe 6 months). Blockchain is a technology that was designed to meet several primary requirements/constraints (there are other things you can do with it, but they typically stem from these properties): 1. Decentralisation: no single entity is wholly responsible for the data. 2. Immutability: the chains are essentially a write-only database (once data is written, it cannot be updated) There are 2 primary actors involved in achieving this: A. Miners: these are the machines/actors that are the gateways to the immutable data store. They provide CPU power to perform writes to the chain, and they are rewarded (paid) for providing this. B. Users: these are the machines/actors to want to perform writes and reads to the database. They essentially pay the miners to borrow their processing power to perform actions on the chain. Like any other area of engineering, the best tool for the job will provide the most straightforward solution to your requirements. If you want to build a decentralised application (i.e. all of your actors are B) you might use: 1. Ethereum Dapps : the primary application language will be javascript in the frontend (web3.js) and most likely go in the backend (geth is the most useful ethereum development client at the moment) 2. Lisk : as a developer, I only need to know javascript to develop an application on lisk. If you you solution relies on control of the mining (maybe something in financial settlement, or regulatory compliance) you might use: 1. Ethereum Clients : there are implementations in Continue reading >>

Java Code Examples

Java Code Examples

*OnlyoneBlockchainobjectiscreatedperinstanceofthedaemon.ItkeepstrackofALLpossiblechains,andinternallyhandleschainreorganization. *ThedecisiontoputLedgerManagerasanobjectownedbyBlockchainwasforpurposesofsimplicity--there'sonlyoneBlockchain,andonlyoneLedgerManager. *TheBlockchainhasforkmanagementintegrated,andshouldbeabletoappropriatelyhandleanyunexpectedcircumstances.Forkmanagementisoneof *themajorthingsI'mwatchingforduring2.0.0a1.Ifyouwanttotrytoforkthenetwork,pleasedo.I'msurethereareways. *Astheblockchainhasthemostup-to-dateinformationaboutblockchaindata,itmakesperfectsensefortheledger,whichisbasedpurelyontheblockchain, *tobemanagedbytheBlockchainobject.InitialplansweretohaveseparateBlockchainobjectsforeachforkinachainbuttheoverheadofcloningBlockchain *objectsseemedunwarranted.Significantoptimizationstillneedstobedoneontheforkmanagement--climbingallthewaydowntheshorterchainandbackup *thelongerchainisNOTapermanantsolution,andIhopetohaverespectableforkmanagementoverheadby2.0.0a2. *Additionally,thereisnoneedtostoreidenticalblocksbetweenmultipleforks.Theoverheadofaforksuddenlyrequiringdoubletheblockchainstorageis *unacceptable.Itworks,Ithink.Butunacceptableforproductioncode,sothat'llcertainlychange,hopefullyby2.0.0a2or2.0.0a3,dependingonmyschedule. *Asblocksareaddedtotheblockchain,theledgerisupdated.Whileworkingbeautifullyinsmall-scaletesting,I'msurethesignaturecountsynchronization *betweensignedtransactionsandblockswilltripupatsomepoint,andsendtheBlockchainobjectintoeitheraloopofdispair,oranirrecoverableerror. *Faulttolerancewithdesynchronizationbetweenledgerandblockchainforsignatureaccountswillbea2.0.0a3or2.0.0a4feature.I'vegottathinklongand *hardaboutthebestapproachesthatdon'tcompromisesecurityinthenameoffault-tolerance,whileremainingusable,reliable,andfast. *You'llnot Continue reading >>

The Blockchain Explained To Web Developers, Part 1: The Theory

The Blockchain Explained To Web Developers, Part 1: The Theory

The Blockchain Explained to Web Developers, Part 1: The Theory The blockchain is the new hot technology. If you haven't heard about it, you probably know Bitcoin. Well, the blockchain is the underlying technology that powers Bitcoin. Experts say the blockchain will cause a revolution similar to what Internet provoked. But what is it really, and how can it be used to build apps today? This post is the first in a series of three, explaining the blockchain phenomenon to web developers. We'll discuss the theory, show actual code, and share our learnings, based on a real world project. To begin, let's try to understand what blockchains really are. Although the blockchain was created to support Bitcoin , the blockchain concept can be defined regardless of the Bitcoin ecosystem. The literature usually defines a blockchain as follows: A blockchain is a ledger of facts, replicated across several computers assembled in a peer-to-peer network. Facts can be anything from monetary transactions to content signature. Members of the network are anonymous individuals called nodes. All communication inside the network takes advantage of cryptography to securely identify the sender and the receiver. When a node wants to add a fact to the ledger, a consensus forms in the network to determine where this fact should appear in the ledger; this consensus is called a block. I don't know about you, but after reading these definitions, I still had troubles figuring out what this is all about. Let's get a bit deeper. Decentralized peer-to-peer networks aren't new. Napster and BitTorrent are P2P networks. Instead of exchanging movies, members of the blockchain network exchange facts. Then what's the real deal about blockchains? P2P networks, like other distributed systems, have to solve a very dif Continue reading >>

The Top 3 Blockchain Libraries For Java Devs

The Top 3 Blockchain Libraries For Java Devs

The Top 3 Blockchain Libraries for Java Devs The Top 3 Blockchain Libraries for Java Devs If you want to incorporate blockchain into a Java project, here's a breakdown of the three biggest OSS players in the space right now. Oct. 19, 17 Java Zone Take 60 minutes to understand the Power of the Actor Model with "Designing Reactive Systems: The Role Of Actors In Distributed Architecture". Brought to you in partnership with Lightbend . Alright folks, we all have heard about Bitcoin, Ethereum, or other cryptocurrencies with funky names rolling around our news feeds, but do we as Java developers know how to easily interact with these blockchain technologies? Here are the top three Java projects that can be used to takeadvantage of the blockchain trend right now. The list is ordered based on GitHub repository stars. Comments and opinions are very appreciated. The name is very descriptive, don't you think? If you have wondered how to create a bitcoin wallet and manage transactions between nodes, then you should give BitcoinJ a try . The project has a growing community and very good documentation, which makes it extremely lucrative for every developer. Of course, as most open source projects that try to gain popularity, it has limitations at the beginning. There are several known security issues aligned with open bugs and scalability problems. Still, it is extremely helpful if you want to understand how the bitcoin protocol operates. Personal opinion: Not suitable for production applications. One word Ethereum. It's the second most talked-about cryptocurrency based on this cutting-edge technology. The Web3j project allows you to work with the Ethereum blockchain without the additional overhead of having to write your own integration code for the platform. Again, core features a Continue reading >>

Bitcoin For Beginners, Part 3: The Bitcoinj Api

Bitcoin For Beginners, Part 3: The Bitcoinj Api

Bitcoin for beginners, Part 3: The BitCoinJ API Build a Java-based Bitcoin transaction client Use commas to separate multiple email addresses Open source Java projects: Spring Integration For Java developers, BitCoinJ is an entry point to developing applications that interact with the Bitcoin network. In this final article in a three-part series, Dirk Merkel helps you set up BitCoinJ in an Eclipse development environment, then walks through several short exercises that will familiarize you with this lightweight implementation of the Bitcoin transaction protocol. Previous installments in this three-part series have introduced the conceptual and technological framework of Bitcoin, a virtual currency and peer-to-peer network . This article, a tutorial introduction to the BitCoinJ API, assumes that you are familiar with Bitcoin addresses, transactions, blocks, and the block chain. BitCoinJ is an open source Java implementation of the Bitcoin protocol. As such, it's a handy tool to have if you want to write Java applications that interact with the Bitcoin network. In order to explore the BitCoinJ API, we'll construct various sample applications that illustrate the programming steps necessary to construct more complex Bitcoin applications in Java. After using Maven to built and set up a project in the Eclipse IDE, we'll practice creating a Bitcoin address, storing it in a wallet, and saving the wallet to disk. We'll then establish a connection to the Bitcoin test network and retrieve its genesis block. Finally, we'll tie together our sample code so far by sending some Bitcoins to an address on the test network. BitCoinJ is a Java implementation of the Bitcoin protocol. Written by Mike Hearn, BitCoinJ is not a full implementation of the original Bitcoin client, but a more lig Continue reading >>

Tierion Documentation | Blockchain Api

Tierion Documentation | Blockchain Api

Tierion makes it easy to create applications that record any data or business process in the blockchain. We want to build a platform that customers love. Please send us your feedback and suggestions . To get started, you'll need to signup for an account. Tierions Hash API lets you anchor data to the blockchain while keeping your data private. This API operates independently from the main Tierion application and the Data API. Use of the Hash API is free up to 100 records per second and 1,000 records per hour. The Data API is your primary API for collecting data, and managing Datastores and Records in your account. This API also offers tools to validate Blockchain Receipts. Tierion records data in the Bitcoin blockchain in accordance with the Chainpoint standard. Tierion generates a blockchain receipt for each record. This receipt provides irrefutable proof that your data was recorded at a specific time. Each receipt contains the following elements: { "header": { "chainpoint_version": "1.1", "hash_type": "SHA-256", "merkle_root": "8dbd52c5ff89b70711b06c143520ef4eb295c51040757c7a4ab56303f0f6b68f", "tx_id": "77d93bce0f0ff76f1a52424f9c0aeb165990dc37a5e3aaf85031a2f6ab2967d1", "timestamp": 1438317621 }, "target": { "target_hash": "a64f10ca86a880115cc271232dc8577606dc6223cf009a4dd1290cd55b2d6a28", "target_uri ": ""target_proof": [ { "parent": "ee32ac6eb702c289ba2a932e6562b2c45070121cacb26cabdee433a6cf2086cd", "left": "a64f10ca86a880115cc271232dc8577606dc6223cf009a4dd1290cd55b2d6a28", "right": "f07934733450ba14972b8fbea4c39ac05b0b8e2d8a45ddde9dbe03bb70942b6a" }, { "parent": "8dbd52c5ff89b70711b06c143520ef4eb295c51040757c7a4ab56303f0f6b68f", "left": "ee32ac6eb702c289ba2a932e6562b2c45070121cacb26cabdee433a6cf2086cd", "right": "07084efda9cf5488ef9d4f9ad8bca8521581aaa32331b62aeb2fe Continue reading >>

Ibm Open Sources Its Blockchain Code The Non-crazy Part Of Bitcoin

Ibm Open Sources Its Blockchain Code The Non-crazy Part Of Bitcoin

IBM has open sourced a significant chunk of the blockchain code it has been working on, putting its weight behind the Linux Foundation and its Hyperledger project . Big Blue has dumped the Apache 2.0-licensed source on GitHub , providing a limited but functional dev environment to build on. The IT giant has pledged to maintain the code as others build on top of it, including big-name Hyperledger partners that include Intel, Fujitsu, Cisco, JP Morgan, Accenture and others. Key elements in the code dump are a "consensus algorithm" which is vital for proper functioning of a decentralized system, and a contract template that helps people code agreements into the system in Java. Blockchain technology is most well-known for being the foundation to Bitcoin. Big business is not that excited about the digital currency in much the same way it wasn't excited about Napster and P2P sharing technology but it does see huge potential in the ability to shift funds based on specific criteria across computer networks. In theory, blockchain represents the future. By building in other types of information, such as RFID chip data, it is possible to develop electronic contracts that shift funds between different parties without the need to go through third parties. That could save huge sums in transactional costs. The technology is also much, much faster with funds able to be sent almost instantly. As just one example, a delivery contract could be carried out electronically. One company agrees to pay another x amount of dollars to deliver their product. Currently this approach requires multiple layers of review and approval before payment is made. The company has to reach agreement on the price and schedule, sign an agreement, deliver the product, then get confirmation it has delivered it an Continue reading >>

Blockchain Developer Api For Bitcoin, Dash, Ethereum, Testnet And More | Blockcypher

Blockchain Developer Api For Bitcoin, Dash, Ethereum, Testnet And More | Blockcypher

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Github - Blockchain/api-v1-client-java: Blockchain Bitcoin Developer Apis - Java

Github - Blockchain/api-v1-client-java: Blockchain Bitcoin Developer Apis - Java

An official Java library for interacting with the Blockchain.info API (Java 1.6 required). $ git clone cd api-v1-client-java$ mvn install We also provide a snapshot Maven repository for users who prefer managing dependencies that way. ... ... api-v1-client-java-mvn-repo true always ... ... info.blockchain api LATEST ... The above Maven repository also works with Gradle. ...repositories { ... maven { url = '}}...dependencies { ... compile 'info.blockchain:api:1.1.5'}... Note that the above procedures require Maven or Gradle. If you do not wish to use Maven or Gradle, please compile the source manually. The library consists of the following packages: In order to use createwallet and wallet you need to run an instance of service-my-wallet-v3 . All methods may throw exceptions caused by incorrectly passed parameters or other problems. If a call is rejected server-side, the APIException exception will be thrown. In case of a network error, the IOException exception will be thrown. It is possible to set arbitrary connection timeouts. info.blockchain.api.HttpClient.TIMEOUT_MS = 2000; // time out after 2000 milliseconds In order to prevent abuse some API methods require an API key approved with some basic contact information and a description of its intended use. Please request an API key here . The same API key can be used to bypass the request limiter. To generate the code coverage report, execute the following command: Continue reading >>

Network - Api Request Of Blockchain.info Over Java Stops Spontaneously - Bitcoin Stack Exchange

Network - Api Request Of Blockchain.info Over Java Stops Spontaneously - Bitcoin Stack Exchange

API request of blockchain.info over Java stops spontaneously In my java class, I extract the hash of transactions from the files of blk...dat, then obtain the data of the corresponding transactions via reading from the URL: hash. At one time, my program stopped after calling the urls for 1370 times, at the other time, my program stopped after calling the urls for 2243 times. The program is not terminated and will not proceed no matter how long I wait. Since the number of call exceeds the the hard limits described here: , I suspect that it is not a problem of I lacking an API-Key. But in the case it is the reason, how could I get an API-Key? I don't have a website (the java-application is for my bachelor thesis), and it seems that quite a few people online have issue with obtaining the API-Key from blockchain.info. Could it because of something about the network quality I am using, if yes, is there any way to work around it with my java program? If it is a inherent problem from the side of blockchain.info, could someone recommend me an alternative way to attain similar data of transactions? import org.bitcoinj.core.*;import org.bitcoinj.core.Transaction;import org.bitcoinj.utils.*;import java.io.*;import java.net.URL;import java.nio.charset.Charset;import java.util.*;import org.bitcoinj.params.MainNetParams;import org.json.*;public class ParseFromDat { private static String readAll(Reader rd) throws IOException { StringBuilder sb = new StringBuilder(); int cp; while ((cp = rd.read()) != -1) { sb.append((char) cp); } return sb.toString(); } public static JSONObject readJsonFromUrl(String url) throws IOException, JSONException { InputStream is = new URL(url).openStream(); try { BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8"))); St Continue reading >>

Getting Started In Java

Getting Started In Java

bitcoinj has logging and assertions built in. Assertions are always checked by default regardless of whether the -ea flag is specified. Logging is handled by the SLF4J library. It lets you choose which logging system youd prefer to use, eg, JDK logging, Android logging, etc. By default we use the simple logger which prints most stuff of interest to stderr. You can pick a new logger by switching out the jar file in the lib directory. bitcoinj uses Maven as its build system and is distributed via git. There are source code/jar downloads you can use, but its more secure to get it directly from the source repository. To get the code and install it, grab Maven or Gradle , and add it to your path. Also make sure you have git installed. Probably your Java IDE has some Maven/Gradle and Git integration too, but having them available via the command line is still very useful. Now get the latest version of the code. You can use the instructions on the Using Maven or Using Gradle page - just run the commands there and youll get the right version of the code (unless this website is itself compromised). This is intended to protect against compromised mirrors or source downloads - because git works using source tree hashes, if you get a source hash in the right manner, you are guaranteed to end up with the right code. A bitcoinj application uses the following objects: a NetworkParameters instance which selects the network (production or test) you are on. a Wallet instance to store your ECKeys and other data. a PeerGroup instance to manage the network connections. a BlockChain instance which manages the shared, global data structure which makes Bitcoin work. a BlockStore instance which keeps the block chain data structure somewhere, like on disk. WalletEventListener implementations, w Continue reading >>

3 Best Bitcoin App Sdk For Ios And Android With Samples

3 Best Bitcoin App Sdk For Ios And Android With Samples

Bitcoin nowadays is not only a cryptocurrency or a digital payment system. Actually, thanks to its unique features bitcoin has become a real instrument for investment, saving and even earning more money. In this article we want to talk about 3 most popular bitcoin appSDK, that can help you to develop your own app. Thank their functionality you can create bitcoin wallet, a tool for investors, bitcoin game or any other app connected with this cryptocurrency. Also to check the popularity of analyzed SDKs our team of mobile app developers created three real examples of bitcoin wallets. See them below From 2.9 to 5.8 million people use cryptocurrency wallets in 2017, most of them work with bitcoins. Blockchain is regarded as the most popular bitcoin wallet in the world. Nowadays more than 14 million wallets are registered in BC worldwide. Moreover, Blockchain has a full stack of free APIs for developers, so we start our analysis with it. Supported platforms: Android, iOS, Windows, Mac OS, Linux Blockchain is very popular service. It supports many programming languages in form of libraries for its API (Python, Java, NET, Ruby, PHP, Node etc.). Receive Payments V2 API KEY: an easy way for websites to receive payments in bitcoins. This option is completely free and safe. It is ideal for business and personal using. Blockchain Wallet API KEY: full access to all functions of this service like creating a wallet, making payments, sending transactions, address management and so on. To receive any of the keys one must request API from BC. The application contains a name of person/organization, e-mail, and URL of the website or app. Post a project or a job and get estimations and offers from developers This process is supposed to exclude different ways of fraud or using keys for unfa Continue reading >>

[sold Out] Workshop: Developing Java Applications On The Blockchain With Web3j

[sold Out] Workshop: Developing Java Applications On The Blockchain With Web3j

Grab your Blind Bird Ticket! Lowest prices Save 350 30% group discount Register now EARLY BIRDSave 350 by August 24th!on conference + workshops Register now Grab your Blind Bird Ticket! Lowest prices Save 350 30% group discount Register now EARLY BIRDSave 350 by August 24th!on conference + workshops Register now [Sold out] Workshop: Developing Java applications on the Blockchain with web3j PLEASE NOTE: Workshop will be held in a different Location:Thistle City Barbican Hotel (Central St, Clerkenwell, London) This workshop is for anyone who wants to look beyond the hype and get some hands-on experience developing with blockchain technology.Youll learn how to use and integrate Java applications with the dominant public blockchain Ethereum. Well also touch on the private blockchain technology Quorum. how the dominant public blockchain, Ethereum works what a smart contract is and how you can work with smart contracts from Java web3js reactive API and how it uses the ReactiveX Observables to greatly enhance working with Ethereum how to create and manage tokens via smart contracts on Ethereum how to use the private blockchain technology Quorum with web3j-quorum Continue reading >>

Blockchain Fr Java-entwickler: So Baut Man Eine Blockchain In Java

Blockchain Fr Java-entwickler: So Baut Man Eine Blockchain In Java

Blockchain demystified: Die am schwierigsten zu verstehende Datenbank der Welt Blockchain fr Java-Entwickler: So baut man eine Blockchain in Java Der Blockchain-Hype geistert nach wie vor durch die Technologiewelt. Mittlerweile sind auch zahlreiche Banken und Softwareunternehmen darauf aufmerksam geworden und versuchen entsprechende Produkte am Markt zu platzieren. Wer sich allerdings eingehender mit der Technik auseinandersetzt und vor allem deren Nachteile kennen lernt, wird feststellen, dass die als disruptive Technologie angesehene Blockchain eher fr spezielle Anwendungszwecke geeignet ist als fr die breite Masse. Die Blockchain ist eine vergleichsweise unzugngliche IT-Technologie. Das hngt zum einen mit den zugrunde liegenden komplexen Algorithmen zusammen, zum anderen mit den vielen verschiedenen Konzepten und Technologien, die sie enthlt. Trotzdem ist das Thema aufgrund der direkten Beziehung zu den weit verbreiteten Bitcoins ins Rampenlicht gerckt. In vielen Gesprchen mit unseren Kollegen besttigte sich allerdings der Eindruck, dass zwar die grundlegenden Ideen der Blockchain verstanden wurden (verteilt, ffentlich,), konkrete Fragen zu den Vor- und Nachteilen, Alternativen und konkreten Projekteinsatzmglichkeiten aber nicht beantwortet werden konnten. Die Ethereum Blockchain eine Einfhrung Der Grund dafr liegt vor allem in der steilen Lernkurve. Denn bis man die Blockchain grob verstanden hat, vergehen im Schnitt einige Tage, in denen man sich intensiv mit dem Thema auseinandersetzen muss. Dieses mangelnde Wissen bietet wie so oft Nhrboden fr hochtrabende Marketingkampagnen. Im Zuge dessen warten bereits groe IT-Firmen mit Blockchain as a Service auf. Insbesondere Banken interessieren sich fr das Thema. Eine Private Blockchain als Ergebnis von Kooperationsproje Continue reading >>

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