A guide to demoing the [[energy]] contract¶
Prerequisites¶
This documentation has been intended for readers with a basic understanding on the Solidity smart contract programming language and on basic web developing tools. In order to run, the demo requires the following software to be installed. For verified functionality, the specified versions are recommended:
Ubuntu 16.04.2 LTS
TestRPC, version 3.0.4
Truffle, version 3.2.1
Node.js, version 7.9.0
Running an [[Ethereum]] client
Install dependencies¶
Before the first run, dependencies need to be installed for the test scripts and the status viewer.
Run a deterministic TestRPC session¶
For demoing purposes, TestRPC is a good choice for a client, for a number of reasons. Firstly, TestRPC creates a new blockchain instance and transactions can be paid with tokens of the said blockchain. The creator of the TestRPC session gains access to the tokens for free and therefore transactions can be made without a cost. Secondly, by default, TestRPC is configured in such a way that there is no block time—instead, blocks are created on demand, whenever transactions occur. This type of a configuration is well suited for quick testing and demoing. Finally, TestRPC can be run in deterministic mode. This means that a smart contract’s address, for example, can be known already before deploying it in the blockchain. This makes it possible to reference the address in scripts made for testing or demoing purposes.
Deploy the contract¶
The smart contracts written in Solidity need to be compiled and deployed to the blockchain. This can be achieved by using a development environment for Ethereum called Truffle. A simple migration script needs to be created for Truffle, after which the contracts can be deployed using the following command:
Run the issuer script that issues smart meter ownerships¶
For the demo, a seller and a buyer of electricity are needed. Furthermore, the ownership of a smart meter needs to be assigned to both of these parties. In our demo, we utilize an approach where a master key holder has the power to establish ownerships to the system participants. We establish a master key holder of smart meters for the electricity marketplace and have the key holder assign ownership to the smart meters.
Open the status view in browser¶
Without a graphical user interface, none of the process steps can be visually observed in any way. Therefore, a simple web-browser-based status viewer has been added to the demo appli cation. It shows the changes in the status of the different entities as a crude HTML table. The status viewer can be accessed by opening the web page index.html in any web browser.
Open scripts/status/index.html in browser.
Create sell offers¶
For the purposes of the demo, the market should be populated with sell offers of energy. The script offer.js is used for this purpose. The script’s optional command line parameter index can be used to create different pre-populated sell offers. Change the optional index argument to create different pre-populated offers. The default behavior is to choose the offer at index 0 so the index must be within range 0 to 9. When omitting the index parameter, the script defaults to using index 0.
Accept offers as a buyer¶
Any sell offers created earlier can be accepted by the buyer. The script acceptoffer.js can be used to do so. The optional index parameter of the script works similarly as the parameter earlier specified for the offer.js script and can be used to accept offers. For example, if an offer was created using the command node offer 4, then running the command node acceptoffer 4 will make the buyer accept it.
Send reports from smart meters (or wait until the report deadline)¶
Once an offer has been created and accepted, and the scheduled transfer of electricity is due, both the seller’s and the buyer’s smart meters are expected to report on the successfulness of the transfer. The Ethereum transactions submitting these reports can be created using the scripts sellerreport.js and buyerreport.js. The optional index parameter can be used to refer to different sell offers exactly the same way as in the scripts described earlier. Both scripts, sellerreport.js and buyerreport.js need to be run in order to move an instance of electricity transfer to its next state in the smart contract. The reports have a deadline before which they need to be submitted. According to the deadline, the reports must be submitted and written into the blockchain no later than 30 minutes after the transfer is completed. In the case a transacting party fails to report within the allocated time frame, the smart contract will assume the worst possible economic outcome for the abstinent party.
Withdraw money¶
Once both smart meters have submitted their reports (or the deadline has expired), the assets stored in the contract can be withdrawn. The withdrawal can be initiated by anyone, in which case the assets are sent to their rightful owner, as determined by the logic of the smart contract. The script withdraw.js can be used to execute the withdrawal. The optional index parameter can be used to refer to different instances of electricity transfer.
- A part of this project was got from an article
Smart Contracts¶
The logic of the electricity market smart contract is defined in the Solidity file ElectricityMarket.sol. The contract defines the public methods for creating sell offers, accepting them, sending smart meter reports and withdrawing assets.
GUI¶
The status viewer is a web page which is useful for observing changes in the blockchain while running the demo. It shows the status of all the created sell offers and the account balances of the buyer, the seller and the electricity market smart contract. The status viewer can be run by opening the file index.html in any web browser.
Sourcecode¶
Armanriazi-Github-Energy-Sample Project
nodejs #metamask #rpc¶
[[Ethereum_Ecosystem_Research]]
[[smart-contract]]