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‎Features/encumbrance-avatar/LICENCE‎

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Copyright 2016, R3 Limited.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.

‎Features/encumbrance-avatar/README.md‎

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<p align="center">
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<img src="https://www.corda.net/wp-content/uploads/2016/11/fg005_corda_b.png" alt="Corda" width="500">
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</p>
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# Corda encumbrance sample
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Corda supports the idea of "Linked States", using the TransactionState.encumbrance property. When building a transaction, a state x can
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point to other state y by specifying the index of y's state in the transaction output index.
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In this situation x is linked to y, i.e. x is dependent on y. x cannot be consumed unless you consume y.
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Hence if you want to consume x, y should also be present in the input of this transaction.
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Hence y's contract is also always run, when x is about to be consumed.
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In this situation, x is the encumbered state, and y is the encumbrance.
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At present, if you do not specify any encumbrance, it defaults to NULL.
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There are many use cases which can use encumbrance like -
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1. Cross chain Atomic Swaps
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2. Layer 2 games like https://github.com/akichidis/lightning-chess etc.
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## About this sample
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This is a basic sample which shows how you can use encumbrance in Corda. For this sample, we will have an Avatar
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created on Corda. We will transfer this Avatar from one party to the other within a specified time limit.
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After this time window, the Avatar will be expired and you cannot transfer it to anyone.
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Avatar state is locked up by the Expiry state which suggests that the Avatar will expire after a certain time,
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and cannot be transferred to anyone after that.
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This sample can be extended further, where the Avatar can be represented as a NFT using Corda's Token SDK, and
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can be traded and purchased by a buyer on the exchange. The tokens can be locked up using an encumbrance before
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performing the DVP for the NFT against the tokens.
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## How to use run this sample
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Build the CorDapp using below command. This will deploy three nodes - buyer, seller and notary.
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./gradlew clean deployNodes
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Execute below commands for all the nodes. This will run the migration scripts on all the nodes.
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cd buil/nodes/PartyA
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java -jar corda.jar run-migration-scripts --core-schemas
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java -jar corda.jar run-migration-scripts --app-schemas
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java -jar corda.jar
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cd buil/nodes/PartyB
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java -jar corda.jar run-migration-scripts --core-schemas
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java -jar corda.jar run-migration-scripts --app-schemas
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java -jar corda.jar
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cd buil/nodes/Notary
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java -jar corda.jar run-migration-scripts --core-schemas
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java -jar corda.jar run-migration-scripts --app-schemas
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java -jar corda.jar
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Create the Avatar on PartyA node
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start CreateAvatarFlow avatarId : 1, expiryAfterMinutes : 3
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Sell the Avatar to PartyB node from PartyA node
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start SellAvatarFlow avatarId : 1, buyer : PartyB , includeEncumbrance : true
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Confirm if PartyB owns the Avatar
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run vaultQuery contractStateType : com.template.states.Avatar
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## Reminder
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This project is open source under an Apache 2.0 licence. That means you
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can submit PRs to fix bugs and add new features if they are not currently
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available.

‎Features/encumbrance-avatar/TRADEMARK‎

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Corda and the Corda logo are trademarks of R3CEV LLC and its affiliates. All rights reserved.
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For R3CEV LLC's trademark and logo usage information, please consult our Trademark Usage Policy at
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https://www.r3.com/trademark-policy/.

‎Features/encumbrance-avatar/build.gradle‎

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buildscript {
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ext {
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corda_release_group = 'net.corda'
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corda_release_version = '4.8'
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corda_gradle_plugins_version = '4.0.42'
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junit_version = '4.12'
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quasar_version = '0.7.10'
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spring_boot_version = '2.0.2.RELEASE'
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spring_boot_gradle_plugin_version = '2.0.2.RELEASE'
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slf4j_version = '1.7.30'
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log4j_version = '2.17.0'
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corda_platform_version = '10'
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}
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repositories {
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mavenLocal()
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mavenCentral()
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jcenter()
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maven { url 'https://software.r3.com/artifactory/corda' }
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maven { url 'https://jitpack.io' }
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}
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dependencies {
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classpath "net.corda.plugins:cordapp:$corda_gradle_plugins_version"
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classpath "net.corda.plugins:cordformation:$corda_gradle_plugins_version"
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classpath "net.corda.plugins:quasar-utils:$corda_gradle_plugins_version"
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}
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}
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allprojects {
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apply plugin: 'java'
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repositories {
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mavenLocal()
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jcenter()
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mavenCentral()
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maven { url 'https://software.r3.com/artifactory/corda' }
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maven { url 'https://jitpack.io' }
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maven { url "https://repo.gradle.org/gradle/libs-releases-local/" }
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}
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tasks.withType(JavaCompile) {
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options.compilerArgs << "-parameters" // Required by Corda's serialisation framework.
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}
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jar {
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// This makes the JAR's SHA-256 hash repeatable.
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preserveFileTimestamps = false
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reproducibleFileOrder = true
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}
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}
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apply plugin: 'net.corda.plugins.cordapp'
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apply plugin: 'net.corda.plugins.cordformation'
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apply plugin: 'net.corda.plugins.quasar-utils'
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cordapp {
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info {
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name "CorDapp Template"
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vendor "Corda Open Source"
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targetPlatformVersion corda_platform_version.toInteger()
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minimumPlatformVersion corda_platform_version.toInteger()
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}
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}
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sourceSets {
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main {
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resources {
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srcDir rootProject.file("config/dev")
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}
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}
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}
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dependencies {
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testCompile "junit:junit:$junit_version"
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// Corda dependencies.
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cordaCompile "$corda_release_group:corda-core:$corda_release_version"
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cordaCompile "$corda_release_group:corda-node-api:$corda_release_version"
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cordaRuntime "$corda_release_group:corda:$corda_release_version"
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// CorDapp dependencies.
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cordapp project(":workflows")
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cordapp project(":contracts")
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// // For logging
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// cordaCompile "org.apache.logging.log4j:log4j-slf4j-impl:${log4j_version}"
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// cordaCompile "org.apache.logging.log4j:log4j-web:${log4j_version}"
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// cordaCompile "org.slf4j:jul-to-slf4j:$slf4j_version"
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}
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task deployNodes(type: net.corda.plugins.Cordform, dependsOn: ['jar']) {
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nodeDefaults {
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projectCordapp {
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deploy = false
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}
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cordapp project(':contracts')
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cordapp project(':workflows')
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}
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node {
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name "O=Notary,L=London,C=GB"
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notary = [validating : false]
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p2pPort 10002
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rpcSettings {
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address("localhost:10003")
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adminAddress("localhost:10043")
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}
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cordapps = []
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}
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node {
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name "O=PartyA,L=London,C=GB"
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p2pPort 10005
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rpcSettings {
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address("localhost:10006")
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adminAddress("localhost:10046")
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}
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rpcUsers = [[ user: "user1", "password": "test", "permissions": ["ALL"]]]
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}
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node {
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name "O=PartyB,L=New York,C=US"
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p2pPort 10008
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rpcSettings {
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address("localhost:10009")
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adminAddress("localhost:10049")
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}
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rpcUsers = [[ user: "user1", "password": "test", "permissions": ["ALL"]]]
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}
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}
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task installQuasar(type: Copy) {
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destinationDir rootProject.file("lib")
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from(configurations.quasar) {
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rename 'quasar-core(.*).jar', 'quasar.jar'
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}
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}

‎Features/encumbrance-avatar/contracts/build.gradle‎

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apply plugin: 'net.corda.plugins.cordapp'
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apply plugin: 'net.corda.plugins.cordformation'
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cordapp {
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targetPlatformVersion corda_platform_version.toInteger()
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minimumPlatformVersion corda_platform_version.toInteger()
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contract {
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name "Template CorDapp"
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vendor "Corda Open Source"
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licence "Apache License, Version 2.0"
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versionId 1
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}
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signing {
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enabled true
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}
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}
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dependencies {
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// Corda dependencies.
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cordaCompile "$corda_release_group:corda-core:$corda_release_version"
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cordaRuntime "$corda_release_group:corda:$corda_release_version"
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testCompile "$corda_release_group:corda-node-driver:$corda_release_version"
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}

‎Features/encumbrance-avatar/contracts/src/main/java/com/template/contracts/AvatarContract.java‎

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package com.template.contracts;
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import com.template.states.Avatar;
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import com.template.states.Expiry;
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import net.corda.core.contracts.CommandData;
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import net.corda.core.contracts.CommandWithParties;
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import net.corda.core.contracts.Contract;
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import net.corda.core.transactions.LedgerTransaction;
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import org.jetbrains.annotations.NotNull;
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import java.security.PublicKey;
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import java.util.List;
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import static net.corda.core.contracts.ContractsDSL.requireSingleCommand;
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import static net.corda.core.contracts.ContractsDSL.requireThat;
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public class AvatarContract implements Contract {
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public static final String AVATAR_CONTRACT_ID = "com.template.contracts.AvatarContract";
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@Override
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public void verify(@NotNull LedgerTransaction tx) throws IllegalArgumentException {
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CommandWithParties<Commands> commandWithParties = requireSingleCommand(tx.getCommands(), Commands.class);
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Commands value = commandWithParties.getValue();
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List<PublicKey> signers = commandWithParties.getSigners();
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if (value instanceof Commands.Create) {
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requireThat(require -> {
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require.using("There should be 0 input states.", tx.getInputs().isEmpty());
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require.using("There should be 2 output states.", tx.getOutputStates().size() == 2);
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require.using("There should be 1 expiry state.", tx.outputsOfType(Expiry.class).size() == 1);
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require.using("There shoule be 1 Avatar created.", tx.outputsOfType(Avatar.class).size() == 1);
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Avatar avatar = tx.outputsOfType(Avatar.class).get(0);
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require.using("Avatar Owner must always sign the newly created Avatar.", signers.contains(avatar.getOwner().getOwningKey()));
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return null;
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});
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} else if (value instanceof Commands.Transfer) {
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requireThat(require -> {
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require.using("There should be 2 inputs.", tx.getInputs().size() == 2);
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require.using("There must be 1 expiry as an input.", tx.inputsOfType(Expiry.class).size() == 1);
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require.using("There must be 1 avatar as an input", tx.inputsOfType(Avatar.class).size() == 1);
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require.using("There should be two output states", tx.getInputs().size() == 2);
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require.using("There should be 1 expiry state.", tx.outputsOfType(Expiry.class).size() == 1);
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require.using("There shoule be 1 Avatar created.", tx.outputsOfType(Avatar.class).size() == 1);
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Avatar newAvatar = tx.outputsOfType(Avatar.class).stream().findFirst().orElseThrow(() -> new IllegalArgumentException("No Avatar created for transferring."));
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Avatar oldAvatar = tx.inputsOfType(Avatar.class).stream().findFirst().orElseThrow(() -> new IllegalArgumentException("Existing Avatar to transfer not found."));
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require.using("New and old Avatar must just have the owners changed.", newAvatar.equals(oldAvatar));
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require.using("New Owner should sign the new Avatar", signers.contains(newAvatar.getOwner().getOwningKey()));
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require.using("Old owner must sign the old Avatar", signers.contains(oldAvatar.getOwner().getOwningKey()));
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return null;
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});
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}
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}
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public interface Commands extends CommandData {
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class Create implements Commands { }
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class Transfer implements Commands { }
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}
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}

‎Features/encumbrance-avatar/contracts/src/main/java/com/template/contracts/ExpiryContract.java‎

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package com.template.contracts;
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import com.template.states.Expiry;
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import net.corda.core.contracts.CommandData;
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import net.corda.core.contracts.Contract;
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import net.corda.core.contracts.TimeWindow;
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import net.corda.core.transactions.LedgerTransaction;
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import org.jetbrains.annotations.NotNull;
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import java.time.LocalDateTime;
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import java.time.ZoneId;
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public class ExpiryContract implements Contract {
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public static final String EXPIRY_CONTRACT_ID = "com.template.contracts.ExpiryContract";
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@Override
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public void verify(@NotNull LedgerTransaction tx) throws IllegalArgumentException {
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Expiry expiry;
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if (tx.getCommands().stream().anyMatch(e -> e.getValue() instanceof AvatarContract.Commands.Transfer))
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expiry = tx.inputsOfType(Expiry.class).get(0);
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else
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expiry = tx.outputsOfType(Expiry.class).get(0);
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TimeWindow timeWindow = tx.getTimeWindow();
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if (timeWindow == null || timeWindow.getUntilTime() == null) {
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throw new IllegalArgumentException("Make sure you specify the time window for the Avatar transaction.");
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}
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if (timeWindow.getUntilTime().isAfter(expiry.getExpiry())) {
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throw new IllegalArgumentException("Avatar transfer time has expired! Expiry date & time was: " + LocalDateTime.ofInstant(expiry.getExpiry(), ZoneId.systemDefault()));
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}
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}
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public interface Commands extends CommandData {
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class Create implements Commands {
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}
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class Pass implements Commands {
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}
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}
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}

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