The Concerto team has built an interactive, distributed, car auction demo, backed by Hyperledger Fabric. Invite participants to join your distributed auction, list assets for sale (setting a reserve price), and watch as assets that have met their reserve price are automatically transferred to the highest bidder at the end of the auction.
The easiest way to interact with the demo is using our work-in-progress Composer web application. Composer allows you to define a business network (defining the data model and writing transaction processing logic), manage assets & participants and submit transactions.
The data model for the auction business network is defined in a CTO model file, managed in IBM GitHub Enterprise here.
The data model is very simple (less than 50 lines). It defines the structure of the assets, participants and transactions for a very simple auction.
The business logic is defined in a single Javascript file here. The logic consists of two Javascript functions that are automatically invoked by the Concerto runtime chain code when transactions are submitted for processing.
The makeOffer function is called when an Offer transaction is submitted. The logic simply checks that the listing for the offer is still for sale, and then adds the offer to the listing, and then updates the offer in the VehicleListing asset registry.
The closeBidding function is called when a CloseBidding transaction is submitted for processing. The logic checks that the listing is still for sale, sorts the offers by bid price, and then if the reserve has been met, transfers the ownership of the vehicle associated with the listing to the highest bidder. Money is transferred from the buyer's account to the seller's account, and then all the modified assets are updated in their respective registries.
Access control for the business network is defined here. There is a single access control rule that gives full access to all participants in the network to all assets in the org.acme.vehicle.auction namespace. Finer-grained access control (by introducing an auctioneer participant type is TBD).
Note that if you
git clonethe repository for the Business Network you can run a unit tests for the logic in the business network using the Concerto embedded runtime which simulates a Hyperledger Fabric using a pure Javascript runtime. Simply run:
npm install npm test
> The unit test [here](https://github.ibm.com/Blockchain-WW-Labs/CarAuction-Network/blob/master/test/CarAuction.js) simulates an entire auction and checks that the business logic functions as expected.
## Connect to Composer
You can connect to an IBM internal test instance of Composer [here](http://9.20.92.25:8080). If you have used Composer before you may need to clear your cached browser data (or use private/incognito mode).
## Setting Up the Demo
Before you can hold an auction you need to create and invite some participants to your business network and have something to sell!
### Create Your Participant & Issue an Identity Card
Click on the Participants tab, click on the `org.acme.vehicle.auction.User` participant registry, and then click on the `+` icon to create a new instance of a user.
The JSON representation of the User should be:
{ "$class": "org.acme.vehicle.auction.User", "email": "[email protected]", "firstName": "Daniel", "lastName": "Selman", "balance": 10000 }
Substitute `[email protected]` with your email address. Congratulations you are now a participant in this business network!
You now need to issue an identity card for this participant. Click the green ID card icon to the right of your participant. Enter an user id, for example `daniel.selman` and select the "Identity can be used to issue other identities?" checkbox so that this user has permission to invite other users into the business network.
You can switch between identities using the menu option at the top right of the screen.
### Create Assets
Now that you are a participant in the business network and have been issued an identity card you can own assets and take part in an auction.
#### Create a Vehicle
First, let's create a vehicle for auction.
Click on the Assets tab, click on the `org.acme.vehicle.auction.Vehicle` asset registry, and then click on the `+` icon to create a new instance of a vehicle that can be auctioned.
The JSON representation of the Vehicle should be:
{ "$class": "org.acme.vehicle.auction.Vehicle", "vin": "CAR_001", "owner": "[email protected]" }
Substitute `[email protected]` for the id of the participant you created above. Congratulations you are now the owner of the vehicle `CAR_001`!
#### Create a Vehicle Listing
The `VehicleListing` asset is used to list vehicles that are available for auction.
Click on the Assets tab, click on the `org.acme.vehicle.auction.VehicleListing` asset registry, and then click on the `+` icon to create a new instance of a vehicle listing.
The JSON representation of the `VehicleListing` should be:
{ "$class": "org.acme.vehicle.auction.VehicleListing", "listingId": "LISTING_001", "reservePrice": 4000, "description": "Ford Mustang", "state": "FOR_SALE", "vehicle": "CAR_001" }
Congratulations, you've just listed your Ford Mustang for auction, with a reserve price of $4000!
### Create Additional Participants
An auction with one person is not much fun, so you need to either invite people to use Composer to create their own participants and identities, or you can do it for them. To make it easy for participants that you've created to join the business network (auction) when an identity is issued a personalised URL is generated that you can send to allow participants to join the business network in a single click.
Here is an example:
----
Hi daniel.selman,
I'd like you to join my business network: https://ibm.biz/BdsVwK
Regards,
sstone1
----
You can send this text via email or Slack to give people an easy mechanism to launch Composer and join your business network.
## Bidding on a VehicleListing
As soon as a `VehicleListing` has been created (and is in the `FOR_SALE` state) participants can submit `Offer` transactions to bid on a vehicle listing.
Click on the Transactions tab and then click on the `+` icon to submit a new transaction for processing by the business network.
The JSON payload should be:
{ "$class": "org.acme.vehicle.auction.Offer", "bidPrice": 250.00, "listing": "LISTING_001", "user": "[email protected]" }
Substitute the id of the participant submitting the transaction for `[email protected]` and set the bid price as high as you'd like to bid. Remember the vehicle will only be sold if the reserve price is met and it will go to the highest bidder!
The `Offer` transaction is processed by the `makeOffer` function described above.
## End the Auction
To end the auction someone has to submit a `CloseBidding` transaction for the listing.
Click on the Transactions tab and then click on the `+` icon to submit a new transaction for processing by the business network.
The JSON payload should be:
{ "$class": "org.acme.vehicle.auction.CloseBidding", "listing": "LISTING_001" }
This simply indicates that the auction for `LISTING_001` is now closed, triggering the `closeBidding` function that was described above.
## Check the Results of the Auction
To see if the Vehicle was sold you need to click on the Assets tab, click on the `org.acme.vehicle.auction.Vehicle` asset registry and then check the owner of CAR_001. If the reserve price was met you should see that the owner of the vehicle has been modified.
If you check the state of the VehicleListing is should either be `SOLD` or `RESERVE_NOT_MET`.
If you click on the Participants tab you can check the balance of each User. You should see that the balance of the buyer has been debited by the amount they bid, whilst the balance of the seller has been credited.
## View the Blockchain
You can inspect the blocks and transaction created by Hyperledger during the course of the auction using the Hyperledger Explorer, which is running [here](http://9.20.92.25:9090).
## Reset the Auction
To reset the auction you need to edit the VehicleListing to reset its state to `FOR_SALE`. Simply click on the Assets tab, navigate to the VehicleListing registry and then click the pencil icon to update the VehicleListing back to its original state.
The JSON representation of the `VehicleListing` should be:
{ "$class": "org.acme.vehicle.auction.VehicleListing", "listingId": "LISTING_001", "reservePrice": 4000, "description": "Ford Mustang", "state": "FOR_SALE", "vehicle": "CAR_001" }