Block chain Development

BLCN532 Lab 2

Writing chaincode

Introduction

Now that you have a running business network, you can write, install, and run smart contracts, called chaincode, to interacts with your blockchain. Chancode makes up your blockchain application and provides the only way for users to read from, and append to, the blockchain.

In this lab you’ll examine several chaincode files, run the sample chaincode presented in your textbook, and run tests on the chaincode to assess its functionality.

Lab Deliverables:

To complete this lab, you must create a Lab Report file and submit the file in iLearn. The Lab Report file must be a Microsoft Word format (.docx), and have the filename with the following format:

BLCN532_SECTION_STUDENTID_LASTNAME_FIRSTNAME_Lab02.docx

· SECTION is the section number of your current course (2 digits)

· STUDENTID is your student ID number (with leading zeros)

· LASTNAME is your last name

· FIRSTNAME is your first name

To get started, create a Microsoft Word document (.docx) with the correct filename for this lab. You’ll be asked to enter text and paste screenshots into the lab report file.

NOTE: All screenshots MUST be readable. A screenshot that I cannot read (i.e. cannot read the text you are capturing) will not count for any points.

SECTION 1: Running chaincode

Step 1.1: Launch the sample trade network in development mode

First, you’ll start your sample business network in development mode (note the ‘-d’ option).

1. Open PowerShell

2. PS %HOME%> cd vagrant\hyperledger

3. PS %HOME%\vagrant\Hyperledger> vagrant up

4. Launch PuTTY -> open connection (Vagrant Hyperledger)

5. $ cd $GOPATH/src/trade-finance-logistics/network

6. $ ./trade.sh up -d true

7. Create a screenshot of the results of step 6 and paste that screenshot into your Lab Report File.

Step 1.2: Compile the chaincode

Next, you’ll use a different PuTTY connection to compile and run the chaincode.

1. Open a New PuTTY connection (Vagrant Hyperledger)

NOTE: This is the SECOND PuTTY CONNECTION for screenshots in later steps.

2. $ cd $GOPATH/src/trade-finance-logistics/network

3. $ docker exec -it chaincode bash

4. # cd trade_workflow_v1 (Note the new prompt)

5. $ go build

Step 1.3: Run the chaincode

Now you can run the chaincode you just compiled.

1. # export CORE_PEER_ADDRESS=peer:7052

2. # export CORE_CHAINCODE_ID_NAME=tw:0

3. # ./trade_workflow_v1

Step 1.4: Install and run the chaincode on the channel

1. Open a New PuTTY connection (Vagrant Hyperledger)

2. $ cd $GOPATH/src/trade-finance-logistics/network

3. $ docker exec -it cli bash

4. # peer chaincode install -p chaincodedev/chaincode/trade_workflow_v1 -n tw -v 0

5. Create a screenshot (in the current PuTTY connection) of the results of step 4 and paste that screenshot into your Lab Report File.

6. # peer chaincode instantiate -n tw -v 0 -c '{"Args": ["init","LumberInc","LumberBank","100000","Wooden Toys","ToyBank","200000","Universal Freight","ForestryDepartment"]}' -C tradechannel

7. # peer chaincode invoke -n tw -c '{"Args": ["requestTrade",”trade-12”,"50000","Wood for Toys"]}' -C tradechannel

8. Create a screenshot (in the current PuTTY connection) of the results of step 7 and paste that screenshot into your Lab Report File.

9. # peer chaincode invoke -n tw -c '{"Args": ["getTradeStatus","trade-12"]}' -C tradechannel

10. Create a screenshot (in the current PuTTY connection) of the results of step 9 and paste that screenshot into your Lab Report File.

11. In the SECOND PuTTY CONNECTION (the one you opened in step 1.2), create a screenshot of the results of step 9 and paste that screenshot into your Lab Report File.

SECTION 2: Reviewing chaincode source code

Step 2.1:

1. Open a New PuTTY connection (Vagrant Hyperledger)

2. $ cd $GOPATH/src/trade-finance-logistics/chaincode/src/github.com/trade_workflow_v1

3. nano tradeWorkflow.go

4. Follow the source code development process in the textbook, starting with the “Creating a chaincode” section.

5. Find the Invoke() method in the editor. (Make sure the line starts with “func”.)

6. Create a screenshot (in the current PuTTY connection) of the results of step 5 and paste that screenshot into your Lab Report File.

7. Find the requestTrade() method in the editor. (Make sure the line starts with “func”.)

8. Create a screenshot (in the current PuTTY connection) of the results of step 7 and paste that screenshot into your Lab Report File.

9. Find the getTradeStatus() method in the editor. (Make sure the line starts with “func”.) You invoked this method in the previous section (Step 1.4.9).

10. Scroll down to the end of the getTradeStatus() method. You should see the string “Query Response:” in the next-to-last line in the method. This is the code that prints the trade status.

11. Create a screenshot (in the current PuTTY connection) of the results of step 10 and paste that screenshot into your Lab Report File.

12. Exit nano

Section 3: Testing chaincode

Step 3.1: Test the chaincode

1. $ cd $GOPATH/src/trade-finance-logistics/chaincode/src/github.com/trade_workflow_v1

2. nano tradeWorkflow_test.go

3. Find the method that tests ShipmentInitiation.

4. Create a screenshot (in the current PuTTY connection) that shows the other methods (should be 7) the current method invokes to test its functionality. (You can find this information in a program comment. Comments start with two forward slashes. Look for lines that start with “//”.) Paste that screenshot into your Lab Report File.

5. Exit nano

6. $ go test

7. Create a screenshot (in the current PuTTY connection) of the results of step 2 and paste that screenshot into your Lab Report File.

Section 4: Wrapping up

Now that you have compiled, installed, run, and tested your chaincode, you need to properly shutdown your business network.

1. Press CTRL-C in the SECOND PuTTY CONNECTION window to return to the # prompt.

2. Type exit at the # prompt (in both PuTTY connection windows) to exit docker.

3. $ ./trade.sh down -d true

4. Exit from your Linux sessions

5. $ exit

6. In Windows PowerShell, shut down your Hyperledger virtual machine:

7. PS %HOME%\vagrant\Hyperledger> vagrant halt

8. Create a snapshot of your Ubuntu VM in VirtualBox. This allows you to easily restore to this point if you ever need to “undo” subsequent steps and return to a known point.

You should have 10 screenshots in your Lab Report File. Save your file and submit it in iLearn as a file attachment for the Lab 1 assignment.

Congratulations! You have complete lab 2.