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1 Table of Contents Lab Overview - - VMware s Blockchain Technology Getting Started. 2 Lab Guidance... 3 Module 1 - Lab Overview (30 minutes)... 9 Introduction Introduction to Blockchain VMware UI Screens (User/Developer) VMware UI Screens (Admin) Conclusion Module 2 - Smart Contract Setup (30 minutes) Introduction Create a Smart Contract Using the UI Working with Smart Contracts Smart Contract Creation - The Old Way Conclusion Module 3 - Transaction Management and Reliability (30 minutes) Introduction Managing Transactions with VMware's Blockchain Technology VMware's Blockchain Technology's Resilience Conclusion Page 1

2 Lab Overview - - VMware s Blockchain Technology Getting Started Page 2

3 Lab Guidance Note: It will take about 90 minutes to complete this lab. You should expect to finish all modules during your time. The modules build on each other so you should start at the beginning and proceed from there. This is an introductory blockchain lab focused on VMware's blockchain technology and smart contracts. Lab Module List: Module 1 - Lab Overview (30 minutes) (Basic) This module walks you through the basics of blockchain, explains how VMware's blockchain technology differentiates itself, and walks you through the web interface. Module 2 - Smart Contract Setup (30 minutes) (Advanced) In this module you will deploy a smart contract. You will also create, store and transfer assets using the smart contract. Module 3 - Transaction Management and Reliability (30 minutes) (Advanced) This module allows you to explore transactions in VMware's blockchain technology. You will also test VMware's consensus layer resiliency by shutting down a blockchain node, executing a transaction, and building a new block on the blockchain. Lab Captains: Anoop Jalan, Staff SE; Gintaras Pelenis, Sr. SE This lab manual can be downloaded from the Hands-on Labs Document site found here: This lab may be available in other languages. To set your language preference and have a localized manual deployed with your lab, you may utilize this document to help guide you through the process: Disclaimer This session may contain product features that are currently under development. This session/overview of the new technology represents no commitment from VMware to deliver these features in any generally available product. Features are subject to change, and must not be included in contracts, purchase orders, or sales agreements of any kind. Page 3

4 Technical feasibility and market demand will effect final delivery. Pricing and packaging for any new technologies or features discussed or presented have not been determined. These features are representative of feature areas under development. Feature commitments are subject to change, and must not be included in contracts, purchase orders, or sales agreements of any kind. Technical feasibility and market demand will affect final delivery. Location of the Main Console 1. The area in the RED box contains the Main Console. The Lab Manual is on the tab to the Right of the Main Console. 2. A particular lab may have additional consoles found on separate tabs in the upper left. You will be directed to open another specific console if needed. 3. Your lab starts with 90 minutes on the timer. The lab can not be saved. All your work must be done during the lab session but you can click the EXTEND to increase your time. If you are at a VMware event, you can extend your lab time twice, for up to 30 minutes. Each click gives you an additional 15 minutes. Outside of VMware events, you can extend your lab time up to 9 hours and 30 minutes. Each click gives you an additional hour. Page 4

5 Alternate Methods of Keyboard Data Entry During this module, you will input text into the Main Console. Besides directly typing it in, there are two very helpful methods of entering data which make it easier to enter complex data. Click and Drag Lab Manual Content Into Console Active Window You can click and drag text and Command Line Interface (CLI) commands directly from the Lab Manual into the active window in the Main Console. Accessing the Online International Keyboard You can also use the Online International Keyboard found in the Main Console. 1. Click on the Keyboard Icon found on the Windows Quick Launch Task Bar. Page 5

6 Click once in active console window In this example, you will use the Online Keyboard to enter the sign used in addresses. The sign is Shift-2 on US keyboard layouts. 1. Click once in the active console window. 2. Click on the Shift key. Click on key 1. Click on the "@ key". Notice sign entered in the active console window. Page 6

7 Activation Prompt or Watermark When you first start your lab, you may notice a watermark on the desktop indicating that Windows is not activated. One of the major benefits of virtualization is that virtual machines can be moved and run on any platform. The Hands-on Labs utilizes this benefit and we are able to run the labs out of multiple datacenters. However, these datacenters may not have identical processors, which triggers a Microsoft activation check through the Internet. Rest assured, VMware and the Hands-on Labs are in full compliance with Microsoft licensing requirements. The lab that you are using is a self-contained pod and does not have full access to the Internet, which is required for Windows to verify the activation. Without full access to the Internet, this automated process fails and you see this watermark. This cosmetic issue has no effect on your lab. Look at the lower right portion of the screen Page 7

8 Please check to see that your lab is finished all the startup routines and is ready for you to start. If you see anything other than "Ready", please wait a few minutes. If after 5 minutes your lab has not changed to "Ready", please ask for assistance. Page 8

9 Module 1 - Lab Overview (30 minutes) Page 9

10 Introduction Welcome to Module 1 - Lab Overview (30 minutes) (Basic) This Module contains the following lessons: Blockchain Overview - Here you will learn the very basics of what blockchain is and the benefits of VMware's blockchain technology. Note that this lesson has some basic introductory information on blockchain. If you are already familiar with concepts like consensus and proof of work, feel free to skip ahead in the lesson to the section on how VMware's blockchain technology differentiates itself. VMware UI Screens (User/Developer) - Here you will get a tour of the GUI that VMware has created for managing blockchain. VMware UI Screens (Admin) - Continuing the tour of the UI, with an emphasis on the administration of the system, as opposed to the blockchain itself. Page 10

11 Introduction to Blockchain This section will discuss how VMware's blockchain technology differentiates itself from other blockchain solutions. VMware Concord As a modern enterprise public or private you need to work with others in a fast-paced digital world. You want to rely on the integrity of cross-company workflows and data sharing at the velocity of today s economy. You and your partners need a new kind of shared digital trust infrastructure. VMware recently announced Concord, an opensourced, highly scalable and energy-efficient engine for digital consensus and contract execution. Concord can be used to power distributed trust infrastructures, including blockchains. As a leader in enterprise-grade distributed management and security products for over 20 years, VMware knows what enterprises need in their blockchain solutions. Our vision for blockchain is to surround Concord s consensus engine with additional technologies and to realize enterprise grade services that will enable the trusted information across organizational boundaries. Key elements of that blockchain vision include: customer hosting choice for managed data replicas (public or private cloud), developer friendly interfaces (such as Ethereum s contract language), audit and compliance capabilities, enterprise-ready security and fault tolerance, and integration with other VMware enterprise products and services. With VMware digital trust infrastructure, you and your partners will soon be able to work together in confidence that your digital transactions can be trusted *and* verified. Blockchain Overview The first step in understanding blockchain is to understand what it is. A blockchain is a way to decentralize trust by maintaining a replicated shared ledger. In a traditional centralized solution, data is stored in a central location and users must trust this central authority both for making progress, or adding transactions, and for not maliciously modifying the data. In some cases, it is impossible to find a single entity that all users trust and who is guaranteed to never fail and never be compromised. In such cases, blockchain technology can help by decentralizing the trust to multiple nodes or multiple trust domains. The shared ledger consists of transactions that are arranged into blocks. Each block is connected, or chained, to the next block using a cryptographic hash function. Blockchains that support smart contracts allow writing and executing code on their shared ledger. There are various blockchain implementations with various approaches. One of the key differentiators between different blockchain solutions is whether they are permissioned or permissionless. In a permissionless (or public) blockchain, anyone can participate as a miner. In other words, anyone can participate in creating new Page 11

12 blocks. In a permissioned blockchain, the participants are known and signed using cryptography. In this case, you need appropriate permissions to participate in the process of consensus that creates new blocks. Blockchain Consensus Since a blockchain distributes trust among a non-colluding set of nodes or trust domains, it needs to run some distributed protocol to guarantee that all nodes see the same consistent view of the committed shared ledger. This protocol is often called a consensus protocol. This is how nodes reach agreement on what transactions have been committed. There are two main ways that consensus can be achieved in blockchains: Proof of Work and Longest Fork Wins (Nakamoto consensus) - This is how Bitcoin and Ethereum currently reach consensus and what most people think of when they think of blockchain. In this case, the process used to add transactions to the ledger is called mining. Your ability to mine new blocks is based on your ability to solve a cryptographic puzzle. The more cryptographic hash functions you can compute per second means more chances for you to be the winner by being the first to solve the puzzle. Trust is distributed by assuming that the adversary controls only a small fraction of the total hashing power. Byzantine Fault Tolerance (BFT) - In a permissioned blockchain, one can use much more efficient consensus protocols. These protocols can obtain much better throughput (transactions per second) and finality time (time until a command is committed). For example, Bitcoin obtains less than 5 transactions (tx) per second and 1 hour to finalize a transaction while BFT protocols can obtain hundreds or even thousands of tx per second and may take less than a second to finalize. BFT protocols typically give each node equal voting power. Trust is distributed by assuming that the adversary controls only a small fraction of the total voting power. Many blockchain solutions are based on PBFT or its new variants like Tendermint. VMware s blockchain technology is based on Concord which is a new scalable Byzantine Fault Tolerant replication engine that obtains significantly better performance than PBFT and Tendermint in large scale deployments. Learning More Page 12

13 Blockchain is a complex set of technologies working together to provide a set of services that facilitate a distributed trust infrastructure. Because of the complexity of blockchain, it is not practical to build a primer on blockchain itself into this lab. Rather this lab will concentrate on how VMware s blockchain technology differentiates itself in various use cases. We highly recommend that anyone interested in blockchain do additional research to better understand the concepts around it. Key Differentiators of VMware's blockchain technology VMware s blockchain technology is built to help alleviate some of the complexity around managing blockchain so organizations can concentrate on building applications on top of that platform. It is a permissioned blockchain SaaS offering that leverages Concord, a new BFT replication engine that decentralizes trust in a scalable manner. There are six main differentiators in VMware s blockchain technology: 1. It provides both a SaaS solution and the ability to mix SaaS with local replicas. (Note that in the lab, we do not use the SaaS capabilities, and rely only on local replicas. This is not a supported configuration). 2. It is a multi-cloud solution with distributed trust, so that users are not locked in to a single cloud provider. 3. Because it uses Concord, a scalable BFT engine, this consensus engine scales better and has higher throughput than other forms of BFT and solutions based on mining. 4. It includes tools, such as a rich UI and API, to help you manage and audit your blockchain. 5. This solution supports management of multiple blockchains, preventing you from being locked in to a single blockchain solution. 6. There is full support for Ethereum Contracts (EVM) so you can leverage your existing development work. Use Cases Uses cases for VMware blockchain technology include: Data dissemination (e.g. epidemiology, industrial research, finance) Asset tracking (e.g. any kind of auditing) Asset transfer (e.g. financial transactions, IP control) Verifiable claims (e.g. identity management, voting) Page 13

14 Let's start our examination of VMware's blockchain technology by taking a look at one of the differentiators mentioned above: the GUI. Page 14

15 VMware UI Screens (User/Developer) VMware's blockchain technology includes an intuitive UI and the back-end. This section gives an overview of the application developer section of this UI. The user interface is designed to both share the current state of the entire network and enable individual users to trace specific blocks and transactions for tracking, auditing, troubleshooting or other purposes. Note: Parts of this lab were written with pre-release code and have been pre-populated with data to make the screens more realistic than you would see in a small lab environment. As such, some of your screens will not match exactly with the screenshots we have supplied. The use of pre-release code also means that parts of the UI are placeholders. Launch Chrome 1. Open Chrome browser in Windows by double-clicking on the Google Chrome desktop shortcut. Launch the UI 1. Navigate to the VMware blockchain UI by clicking the VMware blockchain technologies bookmark. Page 15

16 Log in to the UI At the Login screen: 1. Enter admin for the Username 2. Enter VMware1! for the Password 3. Click Next Page 16

17 The Dashboard Tab 1. The first screen you should see is the Dashboard. If it isn't showing, click on the Dashboard tab. 2. Note the graphical representation of node location on a map of the world. The light blue circles represent areas that have replicas. Larger circles represent larger numbers of nodes. 3. You also see a set of live metrics to gauge the activity and health of your environment. Node health is a function of the proportion of active to inactive nodes along with node response rates across the network and indications of malicious activity. 4. Hover your cursor over the light blue circle in South America. 5. Note that you get a pop up that shows you where the nodes are and if they are healthy. Page 17

18 Viewing Node Status in the Dashboard Tab 1. Next, hover over the blue circle with a red outline that is in the north west corner of the United States. The red outline indicates a problem. 2. In the pop-up, notice that the status is Unhealthy. You can easily identify problem areas in your implementation with this screen. 3. Now, scroll down to view a list of recent transactions. Because we are running in a lab environment, it may take up to 10 minutes for all of the blockchain nodes to start. If you don t see Transactions under the Dashboard menu tab, please wait a couple of minutes and refresh your browser. If you still do not see Transactions after waiting, please request assistance. Page 18

19 The Dashboard Tab (continued) Further down the Dashboard screen, you will see: 1. A scrolling list of the recent transactions, with the most recent on top 2. Click on the disclosure triangle (">") to see the details for one of those transactions. 3. By scrolling to the right, you will find that the table has additional columns displaying the Nonce and Status (not pictured) of each transaction. The Nonce is a sequence number. Think of it as a check number in a checkbook. Page 19

20 The Node List 1. Click on the Node List tab to see information about the nodes participating in this blockchain. 2. There is also a time series graph which depicts how busy your nodes are in terms of blocks being written across all of the nodes. 3. You will also see a set of live metrics to measure your general node health. 4. Scroll down to see details about each participating node. Page 20

21 The Node List (continued) 1. Further down the Node List tab you will see a list of all network nodes. 2. Click on the host name for one of the nodes to get more detail on that node. Page 21

22 Node Details This screen shows you a number of details for the node you clicked on, including but not limited to: 1. Node Owners, a record of who is operating the node. 2. Node Health calculated as a function of the proportion of active to inactive nodes along with node response rates across the network and indications of malicious activity 3. If you were to scroll further down the page, you would be able to see a graph depicting Network which shows the relationships of this node with others in the network, Node Activity, a map showing the Node Location, and a list of transactions with the newest on top. Page 22

23 Block List: 1. Click on Block List to open the Block List page. We will use the Block List page often as it shows committed blocks and the transactions within them. On this page you can see the following: 2. A time based representation of Block Activity in the graph. 3. A list of Blocks with their corresponding Index and the Hash for that block 6. Block zero (0) shown in the screenshot is known as the genesis block. This is the first block in a blockchain and does not have a predecessor. Note that depending on the order you do the lab modules, you may see one or more blocks here, with the newest on top. Page 23

24 Block Details 1. Click on the disclosure triangle (">") next to the genesis block (block with Index value: 0) 2. Scroll down to see: 3. The Parent Hash for that block (Note that for the genesis block the parent is all zeros. This is because it is the first block and had no parent.) 4. The Nonce for that block. 5. The Size of that block. Page 24

25 Smart Contracts 1. Click on the Smart Contracts Tab. From this tab you can create and manage smart contracts. You will learn more about smart contracts in Module 2 of this lab. 2. Note the area under System Admin. This part of the UI will change based on the role of the user logged in to the UI. In this case, the System Admin can manage Blockchains, Consortiums, Organizations, Kubernetes (not pictured), and Users (not pictured). We will examine this section of the GUI next. Page 25

26 VMware UI Screens (Admin) VMware's blockchain technology consists of a front-end UI/API and the back-end. The following images show some of the UI screens. Note: Parts of this lab were written with pre-release code and have been pre-populated with data to make the screens more realistic than you would see in a small lab environment. As such, some of your screens will not match exactly with the screenshots we have supplied. Log out of the UI In order to see the roles that a user can have, lets log out of the UI. 1. In the upper right corner of the screen, click the down arrow to the right of admin. 2. Click Log Out. User Roles Page 26

27 There are a number of roles a user can have when they login. To understand these roles, you must understand two entities within blockchain implementations. Organization or Org - This is self-contained entity, made up of users, who want to leverage a blockchain based application or a blockchain implementation. Sometimes this could be a company, but depending on the scope of the blockchain, this could be a business unit inside a company. Consortium - A blockchain deployment. For example, ten banks, each of which would be an org, might each operate a node in the blockchain, of which a certain quorum must be achieved to reach consensus. For our purposes, a Consortium is made up of Orgs. Now that you understand that, let's look at the possible roles you can have. 1. In the Login window, click on the down arrow on the same line as Systems Admin. 2. This is the list of available roles. These roles are (from the bottom): Org User - The end user who wants to use an application built on blockchain or is engaging in transactions. For example, this might be an individual buying or selling an asset. Org Developer - A person who is managing and writing smart contracts or applications that will leverage the blockchain infrastructure. Org Admin - A person who is responsible for managing an organization, including managing the Org Users. Consortium Admin - A person responsible for managing which Orgs are members of a Consortium. Systems Admin - A person responsible for managing a blockchain implementation. Page 27

28 Log in to the UI At the Login screen: 1. Enter admin for the Username 2. Enter VMware1! for the Password 3. Leave the role as Systems Admin 4. Click Next Page 28

29 Mangement Menu Items: 1. On the lower-left side of the screen notice where it says System Admin. This is the part of the menu where you would go to perform a number of administrative tasks for your blockchain environment. Because we are logged in as a Systems Admin, we see all the management options. If we had logged in with one of the other roles, it would have limited the items we see on this menu. Note that while the menu items may change, the title of the menu does not. This is because it does not refer to a specific role, but rather to the fact that this is where the system's administrative tools are. We will now look at two key sections of this menu. Page 29

30 Organization Management 1. Click on the Organizations item in the menu. From this screen you can manage the organizations in your blockchain implementation. 2. Click on the Action menu to see that this is where you would go to Add or Import an org. 3. Click Add Org. Page 30

31 Adding an Organization From this pop-up window, we would be able to add a new organization. 1. Click on the down arrow on the Type line to see the types of orgs you can add. 2. We are not going to add an Org at this time, so just click Cancel. Page 31

32 Importing an Organization 1. Back in the Organization Management Window, click Actions again. 2. This time select Import Org. Importing an Organization (continued) Page 32

33 1. This screen would allow you to import an org by uploading the appropriate cryptographic entities. We will not be importing an org at this time, so just click Cancel. Deleting an Organization 1. If there were organizations defined, you could check the box in the first column on the table heading to select all the Orgs. 2. Or you would be able to check a checkbox next to individual Orgs to manage one or more selected Orgs. 3. Click on the Action menu and notice that this is where you could delete the selected Orgs. Page 33

34 User Management 1. Click on the Users item in the menu. This screen will allow you to manage users and what they can do in your blockchain implementation. From here you can see a number of details about the users in your implementation. 2. Click on the Actions menu and 3. Select Add User Page 34

35 Adding Users From this screen you would be able to create a new user for helping to manage your implementation. 1. Click on the down arrow next to Role to see the possible roles for a user. 2. We will not be creating a new user so click on Cancel. Page 35

36 Managing Users 1. Click on the box in the first row of the table to select the first user. 2. Click on the Actions menu and note that the Edit User and Delete User items are no longer greyed out 3. Click on Edit User Page 36

37 Editing Users 1. If we had wanted to make changes to the selected user's account, this screen would allow you to do that. We will not be making any changes to this account, so just click Cancel. This concludes the first module of VMware's blockchain technology lab. Page 37

38 Conclusion In this module you: Learned about some of the basics around blockchain. Learned about the two parts of the GUI that VMware's blockchain technology provides. Took a tour of that interface. You've finished Module 1 Congratulations on completing Module 1. If you are looking for additional information on blockchain, try one of these: Go to Or use your smart device to scan the QRC Code. You can also download the VMware blockchain fling from: Proceed to any module below which interests you most. Module 2 - Smart Contract Setup (30 minutes) (Advanced) In this module you will deploy a smart contract. You will also create, store and transfer assets using a smart contract. Module 3 - Transaction Management and Reliability (30 minutes) (Advanced) This module allows you to explore transactions in VMware's blockchain technology. You will also test VMware's consensus layer resiliency by shutting down a blockchain node, executing a transaction, and building a new block on the blockchain. Page 38

39 How to End Lab To end your lab click on the END button. Page 39

40 Module 2 - Smart Contract Setup (30 minutes) Page 40

41 Introduction Welcome to Module 2 - Smart Contract Setup (30 minutes) (Advanced) This Module covers the following lessons: Create a Smart Contract Using the UI - Here you will use VMware's blockchain technology's user interface to create a Smart Contract. Working with Smart Contracts - Here you will add an asset, transfer an asset and validate ownership of the asset, using sample functions of the Smart Contract we created. Smart Contract Creation - The Old Way - Here you will learn how Smart Contracts can be created using the CLI. Page 41

42 Create a Smart Contract Using the UI Smart contracts, also called digital contracts, self-executing contracts, or blockchain contracts, are code that can help you handle the exchange of assets. This is without the use of a middle man. For example, one could set up a smart contract that says if someone pays the seller more than the equivalent of $1,000, it will transfer ownership of a used car over to that person. VMware's blockchain technology provides full support for Ethereum Virtual Machine (EVM) smart contracts. Contracts are typically written in a high level language like Solidity and then compiled into EVM bytecode. The EVM is the runtime environment used for Ethereum s smart contracts, and should not be confused with virtual machines that are run by vsphere. Being completely isolated, EVM based smart contracts run the code without any access to the network, filesystem or any other process. Because of this, smart contracts have limited access to external resources. Solidity is a contract-oriented, high-level language for implementing smart contracts. It was influenced by C++, Python and JavaScript and is designed to be compiled in EVM Bytecode. The smart contract we are going to use in the lab is already written and saved as AssetHandler_Solidity_Contract.sol file on the desktop. In this lab we will be using the UI for VMware's blockchain technology to use the smart contract. Launch Chrome If the VMware's blockchain UI is already open, skip the next few steps until you get to Managing Smart Contracts. 1. Open Chrome browser in Windows by double-clicking on the Google Chrome desktop shortcut. Page 42

43 Launch the UI 1. Navigate to VMware's blockchain UI by clicking the VMware blockchain technologies bookmark. Log in to the UI At the Login screen: 1. Enter admin for the Username 2. Enter VMware1! for the Password 3. Select the Org Developer role from drop down menu 4. Click Next Page 43

44 Managing Smart Contracts Lets begin by moving to the Smart Contracts portion of the user interface: 1. Click on the Smart Contracts tab on the menu bar. This window is where we can create new contracts and work with contracts we have created. 2. Click on Create button Page 44

45 Create a Smart Contract You will be presented with a new Create Contract window, which will provide you with several fields to create a new Smart Contract: 1. From - This field is the account address of the user deploying the contract. 2. Contract ID - This field represents the name of a created contract (for example: "Selling a Used Car", "Selling an Air Superiority Fighter", "leasing 2 Bedroom Flat in Central London, UK", "Buying a stock" or something else that describes the purpose of the contract.) 3. Version - Due to the nature of blockchain technology, and its immutability, developers may deploy different versions of the same or slightly changed Smart Contract code. The version string helps to differentiate between these updates. 4. File - This will open the File Explorer window, where you will be able to select and upload your Smart Contract, written in Solidity. For this lab, we will be using the AssetHandler_Solidity_Contract.sol contract, which you will find on your desktop. Open an Additional Chrome Tab Lets create a new Smart Contract in which we will be adding and transferring an asset from one owner to another. For demo purposes we will be using "House". Page 45

46 1. To create a Smart Contract first we need to get the address of the Entity who is initiating the Smart Contract. Click on the New tab button. Connect to the VMware Blockchain UI 1. Click on the VMware blockchain technologies bookmark in Google Chrome Select a Block to Gather Data From 1. Click on the Block List tab, on the left side menu. 2. Click on the block with Index of 0. Because we are running in a lab environment, it may take up to 10 minutes for all of the blockchain nodes to start. If you came directly to Module 2 and you don t see Blocks under the Block List menu tab, please wait a couple of minutes and refresh your browser. If you still do not see Blocks after waiting, please request assistance. Page 46

47 Examine the Genesis Block You will be presented with all the transactions recorded on block zero, which is the Genesis Block. The Genesis Block is the first block of any blockchain solution, and is configured when the blockchain is initially deployed. It is unique in each blockchain, in that it does not reference a previous block. 1. Notice the Parent Hash and Nonce are both all zeros, indicating that this is the Genesis block. 2. Click on the first Transaction in the list Examine Transaction Details Page 47

48 You will be presented with transaction details. Here you will see: 1. The transaction hash value. Think of this as the ID of the transaction. 2. The transaction status, which indicates whether it was successfully created and recorded on the blockchain 3. The transaction hash value again 4. From is which user account sent the transaction. Zeros are here because this was not user-submitted. 5. To is the user account or smart contract that this transaction was sent to. 6. Value is the amount of the blockchain's cryptocurrency that was transferred from the "From" account to the "To" account or contract. 7. Nonce is the order number of this transaction. This number is incremented each time an account sends a transaction. 8. Data: (not shown) Data that was sent to the smart contract. This will be the code of the smart contract itself for the contract-creation transaction, or the arguments for the contract's functions otherwise. Copy an Address to use in our Contract 1. Select and right click on the value in the To field. 2. Click Copy so that we capture hash value from To field. This hash will act as our source address in the Smart Contract we create. We are using this "To" address, because you must "pay" for the deployment of the smart contract. The genesis block granted each of these accounts some starting Ether (Ethereum's cryptocurrency), so they have the ability to pay for the contract deployment. Please do not close this tab, as you will be using it later through out this module Page 48

49 Enter Contract Information 1. Click on Previous Tab, to return to Smart Contract page 2. Click in the from From field, and Paste previously copied account address 3. Click in Contract ID field and type House 4. Click in Version field and type 1 5. Click on the Choose File button Page 49

50 Select the Smart Contract File 1. Select AssetHandler_Solidity_contract.sol file from Dektop. (You can select Desktop from left side menu) 2. If due to the desktop resolution you can not see the file, please use the scroll bar, to scroll down and locate it. 3. Click Open Page 50

51 Finish Creating the Contract 1. Click on the Create button View the New Smart Contract 1. You can now see that you have successfully created a new Smart Contract. Contract deployment or any other action is a transaction on a blockchain. Now lets validate that this transaction was successful. Page 51

52 Validate the Creation of the Smart Contract 1. Return to previous tab, which we used to copy the block address 2. Click on the Block List tab Page 52

53 Examine the Newly Created Block Notice that after you created a new Smart Contract there is a new block in the blockchain. 1. Lets investigate it. Click on the newest block, it will probably have an Index value of 1, unless you did the modules out of order. Examine the Newly Created Transaction 1. Click on the disclosure triangle (">") to expand the transaction details. 2. On the Status line, observe that the successful creation of a Smart Contract results in a successful transaction, which then results in the creation of a new block on the blockchain. 3. Notice that the From address is the one we copied and pasted a few steps ago. 4. The Contract Address shows the address at which the contract is now available. Please do not close this tab, as you will be using it later through out this module Page 53

54 Working with Smart Contracts You have successfully created a new Smart Contract, which enables users or organisations to create and transfer assets between accounts. In our lab we use a Smart Contract which exposes 3 functions to users: 1. addnewasset - this function adds assets to a specific user or organisation 2. ownerof - this function allows you to validate if the owner of a smart contract has a specific asset in its account 3. transfer - this function allows you to execute the smart contract and transfer assets from one account to another. Since smart contracts are automatically executed code, we can perform all those functions without the use of a middle man. In this lesson you will work with all 3 functions: First you will add a new asset called "House" to the Smart Contract owner. Second you will validate if the account has the "House" asset. Third you will execute the Smart Contract we deployed to transfer the "House" from the original account to a new owner. And finally we will validate that the asset was successfully transfered. Page 54

55 Return to the Smart Contracts View 1. Click on the First tab in Chrome, where you created the Smart Contract. 2. Click on the Smart Contracts tab 3. Click on your newly created Smart Contract Add a New Asset Using a Smart Contract Page 55

56 We need to confirm the version of the smart contract we want to work with, even if there is only one version. 1. Click on Select Version 2. Select version 1 Explore Smart Contract Details You will be presented with Smart Contract details 1. This includes the Smart Contract Name, Owner, Version and the Address of this particular Smart Contract 2. You will also see three buttons that allow you to to download Source Code, Bytecode and Metadata for the Smart Contract, respectively. 3. You will also see the functions that this Smart Contract offers. 4. Click on the down arrow in the Function field. 5. Select the AddNewAsset function. Page 56

57 Add a New Asset to the Smart Contract You may need to scroll down the page to view all the fields fully. Now lets add an asset to the current Smart Contract owner 1. Select the entire Owner hash value, and copy it. It should be similar to: 0x0ae0d7d9db3b6c7da28652e47bbc1e299ef4555c. The entire Owner hash is not shown in the UI, so please make sure you capture the entire value. You can double click the value or make sure as you drag across you capture the entire value. 2. Click on the Gas field, and enter 1. Smart contract execution is metered. You must specify how much 'energy' you are willing to pay to run this transaction on this smart contract. 3. Click on the From field and paste the owner value we had copied earlier. This is the user account that is sending this transaction to be recorded. 4. Click on the Account field and and again paste the owner value we had copied above. This is the user account that we want to mark as the owner of this new asset. 5. Click on the Asset field and enter House. This is the name of the asset. 6. Click Send. By clicking send button, you will create a new transaction, create a new block on blockchain, and record this transaction in the new block. Page 57

58 Confirm the Creation of the Transaction 1. You will see that the new transaction was created, which added "House" as an asset to the Smart Contract owner. Lets validate this transaction. The transaction hash may be different, in our example it is: 0x8c70164ced4d997b5b558d7a925eeac238077f79218fc2167f15206a4519b031 Page 58

59 Validate the Transaction 1. Click on the second tab in Chrome. 2. Click on Block List. 3. Click on the newest block on the top of the list. If you are doing the modules in order, it will be the one with an Index of 2. Page 59

60 Compare the Hashes 1. Click the down arrow next to the transaction to expand transaction details 2. You can compare the Hash value with the hash value we saw in the green box in the previous tab (you can double check, by switching between tabs.) 3. The Input value is an encoding of the arguments we used in the other tab: the function to be called, the owner of the asset, and the asset name (in hex). At this point, you have successfully created a Smart Contract, added a new asset called "House", and recorded this transaction on a new block. Page 60

61 Validating Ownership of an Asset 1. Click on the first tab in Chrome. 2. Click on Smart Contracts in the menu bar. 3. Click on the Smart Contract with the Contract ID of House. Select the Smart Contract Version Page 61

62 1. Click on the down arrow next to Select Version. 2. Select version 1 Validate who owns the Asset Named "House" Now you will use the ownerof function to validate which account has ownership of an asset named "House" 1. Select the Owner hash value and copy it. Again, the entire Owner hash is not shown in the UI, so please make sure you capture the entire value. You can double click the value or make sure as you drag across you capture the entire value. 2. Click on the down arrow on the Functions line, and select ownerof 3. Click in the Gas field, and enter 1 Page 62

63 4. Click in the From field and paste the Owner hash value we copied above. In this lab we use a simplified example, where the same account that owns an asset is querying for the ownership of that asset, but in a real life scenario any external account or application may check specific account assets. For example, when one wants to pay with crypto currency, the smart contract/seller needs to ensure that the buyer owns a certain amount of currency in its wallet. 5. Click in the asset field, and type House. 6. Click on the Call button. By clicking the Call button, the Smart Contract will only read data from the blockchain, and will not generate a new transaction or block. This is different from the Send button which does generate a new transaction and block. In this case, we only need to know which account owns the asset named House. The Preview button will show you the JSON that would be created by this command. This can be useful to developers building an application on top of VMware Blockchain. View the Output of the ownerof Function 1. After calling ownerof function in the Smart Contract, the function returns a hash value which is the same as the hash of the owner with leading zeroes added (those zeroes are added by Smart Contract code) This validates, that the current owner, has an asset named "House" in his or her account. Page 63

64 Transferring an Asset Now lets transfer the asset "House" from the current owner to a new owner 1. Select the Owner hash and copy it. The entire Owner hash is not shown in the UI, so please make sure you capture the entire value. You can double click the value or make sure as you drag across you capture the entire value. 2. Click on the down arrow next to Functions, and select transfer 3. Click in the Gas field and type 1 4. Click in the From field and paste the owner hash value which we copied above. 5. Click in the from field in the Function Parameters section and paste the owner hash value which we copied above. 6. Click in the to field and paste the owner hash value which we copied above. IMPORTANT - After you paste the value, select this field and using the keyboard move the cursor to the end of the hash and change the last letter or number a different, valid Hex character (Numbers from 0 to 9, or letters from a to f). This will create a new unique hash, which will represent the new owner. The to field doesn't have to have an address that already exists, unlike the from field. 7. Click in the asset field and type House. 8. Click the Send button. Page 64

65 Verify that the Function Completed Successfully 1. After you hit the send button, a new transaction and a new block were created. The Asset "House" was transfered from the old owner to a new owner. Lets validate the new owner of asset "House" Page 65

66 Validating the Transfer of an Asset 1. Select the Owner hash value and copy it, making sure you capture the entire value. 2. Click on the down arrow next to Functions, and select the function ownerof 3. Click in the Gas field, and enter Click in the From field and paste the owner hash value, which we copied above. Note that this address is just the address making the inquiry. It doesn't have to own the asset. 5. Click in the asset field, and type House 6. Click on the Call button. 7. Pay attention to the hash value returned in the green box. The returned hash value should have same hash value as the owner, with the last character changed, and should reflect the To field hash value in the previous exercise (transfer of assets) In this module, we have successfully created a new Smart Contract, and performed a number of function calls: We added a new Asset to an account We validated the ownership of that Asset We performed an Asset transfer from the original account to a newly created account We then validated the new ownership of the Asset Page 66

67 Smart Contract Creation - The Old Way Smart contracts are automatically executed code that can help you handle the exchange of assets. This is without the use of a middle man. For example, you could set up a smart contract that says if someone pays you more than the equivalent of $1,000, you will transfer ownership of a used car over to that person. Smart Contracts take the business rules or legal language around this exchange and build them into code on the blockchain. Smart Contracts are also called digital contracts, self-executing contracts, blockchain contracts, or chain code (HyperLedger). In the past, implementing and managing smart contracts was complicated and error prone. Just to provide context, we will walk you through the process here, but we will not actually be completing these steps. This lesson is completely optional. Feel free to skip to the end of the lesson. Hash Definitions Before we discuss creating smart contracts, let's define some of the hashes that you will see throughout the process. Each hash identifies a different thing, and they are not interchangeable. Account addresses: these will have 40 hex digits after the "0x". These name specific users of the blockchain. They are based on the public key of the account. This may appear in "from" or "to" fields of a transaction. Contract addresses: these look exactly like account addresses, because they are. They share the same namespace, and (as an exception to what was said above) *can* be used almost anywhere an account address can be used. A contract is an account with code attached. This will only appear in a "to" field, or a "contract address" field of a transaction. Transaction hashes: these will have 64 hex digits after the "0x". This is a hash of the contents of the transaction. This will not be used for anything other than looking up the contents of the transaction. Block hashes: these will also have 64 hex digits after the "0x". This is a hash of the contents of the block (the transactions). This will not be used for anything other than looking up the contents of the block. Compile the Smart Contract The first step would normally be to compile the smart contract, like any other piece of code to be executed. This would require a tool like Solidity for Ethereum contracts, and the command would look something like this: solc AssetHandler.sol --bin --abi -o target Page 67

68 Get the contract ABI in a variable Once the smart contract was complied, if you wanted to use it with Ethereum, you would need to use the geth console for Ethereum to deploy that contract. When you compiled the contract, it would have created an AssetHandler.abi file and placed it in a folder named "target" (as specified in the command above). You would then have to copy this file's contents into the AssetHandlerABI variable creation command and issue it from the geth console. The command below would take the variable definitions from our compiled contract and put them in into our new handler. var AssetHandlerABI=eth.contract([{"constant":false,"inputs":[{"name":"from","type":"address"},{"name":"to" Get the contract bytecode in a variable The compilation step would have also created an AssetHandler.bin file in the "target" folder. This is the actual contract code that we want to be executed when we call any method on that contract. You would have to copy its contents (quite a bit of text), and use them to issue the var command from the geth console. A truncated version of an example of that command might look like: var AssetHandlerBytecode='0x03405A2 - rest of file contents here' Get the deployment configuration in a variable Deploying a contract is a transaction, which requires an account. This account is represented by an account ID. In Ethereum, to make things easier, we can also use "eth.coinbase" (without quotes) instead of supplying the actual account ID (which is pretty long). Think of eth.coinbase as a convenient name for the user loged into this console. The data field in the next command provides the actual bytecode of the contract that we want to create. In the geth console you might then have to run something like: var deploy={from:"0x262c0d7ab5ffd4ede2199f6ea793f819e1abb019", data:assethandlerbytecode, gas: } The from field contains the account ID in the example above. The gas is how much you are willing to pay to execute this transaction. Page 68

69 Initiate a transaction for contract creation This command will create a new transaction and output the ID of that transaction on the console. var AssetHandlerPartialInstance=AssetHandlerABI.new(deploy) After the transaction is committed to the blockchain (via mining in Ethereum or via Concord), it will be ready to use. As you can see, the process of compiling and deploying a new smart contract is complicated and prone to error due, in part, to the long commands that need to be entered. Smart Contract management via the GUI provided by VMware's blockchain technology makes this process much easier. Page 69

70 Conclusion In this module you learned: How to create Smart Contracts using the CLI tools How to create Smart Contracts using the VMware's blockchain technology's user interface How to execute sample functions: add a new Asset, check the owner of an asset, and finally transfer the asset from one owner to another. You've finished Module 2 Congratulations on completing Module 2. If you are looking for additional information on blockchain, try one of these: Go to Or use your smart device to scan the QRC Code. You can also download the VMware blockchain fling from: Proceed to any module below which interests you most. Module 1 - Lab Overview (30 minutes) (Basic) This module walks you through the basics of blockchain, explains how VMware's blockchain technology differentiates itself, and walks you through the web interface. Module 3 - Transaction Management and Reliability (30 minutes) (Advanced) This module allows you to explore transactions in VMware's blockchain technology. You will also test VMware's consensus layer resiliency by shutting down a blockchain node, executing a transaction, and building a new block on the blockchain. Page 70

71 How to End Lab To end your lab click on the END button. Page 71

72 Module 3 - Transaction Management and Reliability (30 minutes) Page 72

73 Introduction Welcome to Module 3 - Transaction Management and Reliability (30 minutes) (Advanced) This Module covers the following lessons: Managing transactions with VMware's blockchain technology - Here you will learn how to view details of transactions using the UI for VMware's blockchain technology. VMware's blockchain technology's resilience - Here you will explore how VMware's blockchain technology can survive the loss of a node and still commit transactions and append blocks. You will also examine the self healing capabilities of VMware's blockchain technology. Page 73

74 Managing Transactions with VMware's Blockchain Technology An important part of Blockchain interaction is inspection of transactions. VMware's blockchain technology provides an easy-to-use visual interface to help you audit your transactions. Note: Parts of this lab were written with pre-release code and have been pre-populated with data to make the screens more realistic than you would see in a small lab environment. As such, some of your screens will not match exactly with the screenshots we have supplied. VMware's blockchain technology includes an intuitive UI and the back-end. This section gives an overview of how to view transactions with this UI. Launch Chrome 1. Open Chrome browser in Windows by double-clicking on the Google Chrome desktop shortcut. Launch the UI 1. Navigate to VMware's blockchain technology UI by clicking the VMware blockchain technologies bookmark. Page 74

75 Log in to the UI At the Login screen: 1. Enter admin for the Username 2. Enter VMware1! for the Password 3. Click Next Page 75

76 Accessing Transactions from the Dashboard Tab There are a number of ways you can see transactions in the UI. 1. First place to see and manage transactions is via the Dashboard tab. Click on that tab now. 2. Now drag the scrollbar on the right side of the screen most of the way down Page 76

77 Viewing Transactions on the Dashboard Tab Further down the Dashboard screen you will see: 1. A scrolling list of the recent transactions, with the most recent on top 2. Click on the disclosure triangle (">") to see the details for one of those transactions. 3. By scrolling to the right, you will find that the table has additional columns displaying the Nonce and Status (not pictured) of each transaction. 4. You can also see details about the transaction by clicking on the transaction's hash. Do so now. Because we are running in a lab environment, it may take up to 10 minutes for all of the blockchain nodes to start. If you don t see Transactions under the Dashboard menu tab, please wait a couple of minutes and refresh your browser. If you still do not see Transactions after waiting, please request assistance. Page 77

78 Transaction Details Another way to examine transactions on the blockchain is via the Block List tab. The Transaction detail page offers another view of the contents of a single transaction. Page 78

79 VMware's Blockchain Technology's Resilience In this lesson we will focus on one of the foundations of VMware's blockchain technology - the consensus layer or Concord. Concord is a scalable decentralized trust infrastructure for blockchains. Concord implements a new Byzantine Fault Tolerant algorithm that addresses the challenges of scalability and decentralization. Unlike many previous BFT systems that performed well only when centralized around less than 20 replicas, Concord is optimized for decentralization and can easily handle more than 100 active replicas. The consensus layer provides a critical layer for any blockchain solution - it is the way updates to the blockchain are agreed upon. Concord provides a fast consensus layer, with great scalability, performance and subsecond time to finality. Note that in this lab, we do not use the SaaS capabilities of VMware's blockchain technology, and rely only on local replicas. This is not a supported configuration. A core offering in this lab is showing how the VMware Blockchain provides decentralized trust. In a centralized trust system, you rely on a single entity to commit transactions and to execute them. In a decentralized trust system, the responsibility for committing transactions and executing them is distributed and replicated between multiple nodes to provide strong fault tolerance guarantees. In a permissioned blockchain like VMware Blockchain this trust decentralization is obtained by implementing a Byzantine Fault Tolerant (BFT) replication protocol. This BFT replication is the core trust decentralization technology that we are offering in Concord. When defining a BFT replication protocol there is one fundamental parameter. We use the letter f to define this parameter. This parameter captures that maximum number of malicious nodes that the attacking adversary can fully control. The adversary controls the f nodes and can adaptively decide if these nodes should crash, send fake messages or even equivocate (send different messages to different nodes). A BFT replication protocol is correct if it maintains both liveness and safety in the face of such an adversary controlling f nodes. Keep in mind that nodes can crash even if this is not done maliciously. Of course, you would still be protected in this case. Once you fix this parameter f, then this leads to the optimal minimal number of nodes or trust domains needed. This optimal number is computed by the formula n=3f+1. In this lab we run a configuration that is resilient to an adversary controlling f=1 nodes, Page 79

80 this is the reason we have 4 replicas (n=3f+1=4). In other words, to survive f malicious failures and maintain safety in asynchronous environments you need n=3f+1 nodes. In a nutshell, liveness is the property that good things will eventually happen and safety is the property that bad things will never happen. In the context of a BFT consensus protocol, liveness guarantees the client requests will be committed in a timely manner no matter how hard f malicious nodes try to block them, and safety guarantees that all replicas and all clients see the same view (there is no doublespend ) no matter how hard f malicious nodes try to cause disagreement. Concord BFT uses a primary based protocol (following Paxos, Raft and PBFT). In such protocols the system advances in virtual rounds called views. In any given view, one node is chosen to be a primary and all other nodes are designated to be replicas in this view. If the primary fails or misbehaves then a view-change protocol is used to automatically move to a new view with a new primary. The view-change protocol is typically the most complex part of a BFT replication engine. Concord provides a novel view-change protocol that provides both safety and liveness. As was mentioned, the environment consists of 4 Concord nodes. Each node is connected to a UI/API Front-end node, and a database to store the Smart Contracts. In the following steps you will validate that all 4 nodes are running, and that you can commit transactions and blocks. Then you will experiment with abruptly shutting down one of the blockchain nodes, verify the cluster state, try to write a transaction to the cluster with a failed node, and observe how Concord can handle node failure while still providing consensus and appending new blocks to the blockchain. In Modules 1 and 2 of this lab you managed VMware's blockchain technology using the GUI. In this module we will also be using the CLI. In the instructions, we will walk you through how to do this. Launch Chrome If the VMware blockchain UI is already open, skip the next few steps until you get to View Existing Blocks. 1. Open Chrome browser in Windows by double-clicking on the Google Chrome desktop shortcut. Page 80

81 Launch the UI 1. Navigate to the VMware blockchain UI by clicking on the VMware blockchain technologies bookmark. Log in to the UI 1. Click in the Username Field and enter admin 2. Click in the Password Field and enter VMware1! 3. Select the Systems Admin role 4. Click the Next Button Page 81

82 View Existing Block(s) 1. You will be presented with the VMware blockchain GUI. Click on the Block List tab. Examine the Genesis Block 1. Click on the block with an Index of 0. Page 82

83 Because this block has an index of zero, we know it was the first block in the chain, which is called the Genesis Block. If you are doing this module after completing Module 1 and/or Module 2, you may see more than one block in the UI. View the Transactions in the Genesis Block 1. You will see multiple transactions which are stored in the block you clicked on. These blocks are stored on nodes, or replicas. If you have completed Module 2, you are familiar with how new blocks can be created using Smart Contracts leveraging Ethereum Geth client calls through the APIs provided by VMware's blockchain technology. You will now generate new blocks with simple Shell script which leverages this API and observe how they are being committed. Log in to the Ubuntu Container Host 1. Click on the PuTTY icon in the taskbar Page 83

84 Start a PuTTY Session 1. Select the pre-created holuser@bcnode session. 2. Click Open. Confirm that PuTTY has Connected Successfully You will be automatically logged into the terminal of the Ubuntu server For a better experience, you may want to maximize the PuTTY window Page 84

85 Examine the Components of VMware's Blockchain Technology 1. Inside the PuTTy session, type or copy the following command docker container ls This command lists all the docker containers running on the Ubuntu host. As mentioned in introduction of this module, in this lab there are: 2. 4 vmweb containers - which are the Concord nodes vmwebui container - the UI and API front end Cockroach DB container - used as a location for Smart Contract metadata storage. Generate a New Block and Transaction Using the CLI This lab will use two scripts for testing the creation of blocks. These scripts are called sendtx1.sh and sendtx2.sh. These two scripts are located in the /home/holuser/ HOL1988 directory Please type or copy/paste following commands: cd HOL1988 sudo bash./sendtx1.sh You may need to click enter/return twice. sendtx1.sh is simple script which uses the API to create a transaction. Page 85

86 Confirm the Creation of a New Block 1. Now return to the blockchain UI (you may need to Refresh browser or click on Block List). You will see the new block that was created. You can investigate blocks and transactions on your own. Module 1 and Module 3 have detailed walkthroughs and explanations. Stop One of the Concord Nodes Now lets stop one of the nodes and try to create new blocks. 1. Please type following commands in PuTTY: docker-compose pause vmweb4 This will pause one of the nodes. This simulates the node disconnecting from the rest of the network. Page 86

87 Validate That There are Only Three Nodes Running 1. In the PuTTY terminal enter the following command: docker container ls 2. Notice that vmweb4 is shown as paused, and only three nodes are running. Attempt to Create a Transaction with Only Three Replicas Now run the SendTx2.sh script to create a new value transfer transaction with only 3 out of 4 nodes running. 1. In the PuTTY window type: sudo bash./sendtx2.sh As you can see, Concord allows you to tolerate the loss of up to a third of your nodes, while still maintaining consensus and providing finality for transactions. Page 87

88 Confirm the Creation of a New Block and Transaction Now return to the blockchain UI (may need to Refresh browser or click on Block List) to confirm that a block has been created. 1. Click on the newly created block. This is the block with highest Index number. Examine the New Transaction Page 88

89 1. Click on the transaction in the block. Confirm the Status of the New Transaction 1. Check Transaction status. Even with 3 nodes out of 4 working, Concord still provides consensus and transaction finality. Restore the Fourth Node Now lets bring the fourth node back up. VMware's blockchain technology has built in self-healing mechanisms, which allows it to recover from accidental or malicious node interrupts. This means that the fourth node or replica will sync back up with the other three replicas. 1. Return to PuTTY console and type docker-compose unpause vmweb4 2. Confirm that you see a green done message. Confirm the Health of the Cluster 1. In the PuTTY session enter: docker container ls Page 89

90 2. Notice that all 4 containers and the nodes they contain are running again, which indicates that the cluster is healthy. As we are using tech preview code in this lab, you can't see Node health in the UI in the current code. This is why we used the docker container list command to confirm all four replicas were running. This feature will be available with GA code release. In this section, we have seen how Concord can tolerate node loss and still maintain replication resiliency. Concord has been tested for deployments on a world-scale WAN. We also saw how it can still reach consensus and finality with part of the nodes down and then self heal itself after restart. Page 90

91 Conclusion In this module you learned: How to view the details of transactions using the GUI for VMware's blockchain technology. About Concord's replication technology. How to simulate the failure of a node, and execute new transactions to observe the technology's resiliency. How VMware's blockchain technology can tolerate disconnected nodes, and self heal on restart. You've finished Module 3 Congratulations on completing Module 3. If you are looking for additional information on blockchain, try one of these: Go to Or use your smart device to scan the QRC Code. You can also download the VMware blockchain fling from: Proceed to any module below which interests you most. Module 1 - Lab Overview (30 minutes) (Basic) This module walks you through the basics of blockchain, explains how VMware's blockchain technology differentiates itself, and walks you through the web interface. Module 2 - Smart Contract Setup (30 minutes) (Advanced) In this module you will deploy a smart contract. You will also create, store and transfer assets using a smart contract. Page 91