With the NodeJS support from Fabric you can use external packages from NPM and other into your smart contract code. Don't limit yourself to the ones Convector provides or just vanilla JavaScript.
Be careful
The code running in a chaincode container (smart contracts) has to be deterministic. This means that everywhere and anywhere it is executed with the same inputs should return the same outputs.
This is because your code will be executed distributely amongst computers (nodes) running in different contexts. Avoid using date based calculations, randoms, external sources, or any other input of data that you are not sure will be avilable for all the participants.
In some cases, the rol of Oracles is needed, what these special participants do is put data in the blockchain that can be used as inputs for chaincode operations. Since the data is put in the blockchain it now becomes a deterministic source. A common example is an exchange rate or weather information.
Tip 2: debugging and testing
Unit testing is a best practice in modern software development. Blockchain with Convector is not an exception. You can use the built in Mock Controller Adapter @worldsibu/convector-adapter-mock to simulate that your code is executed in the blockchain.
Users and admins are not created by Convector, unlike other frameworks Convector doesn't get in the middle of that to avoid extra errors or security issues.
So the pattern that Convector follows is:
Users and admins are created as regular users in the Fabric model, whether it's a CA or not
In your "business chaincode" (the one that is not for participants) you receive a tx, you get the this.sender and compare it against text fields that previously were set with a fingerprint of the expected user to do a task
Tips and tricks
Tip 1: use external packages, but be careful
With the NodeJS support from Fabric you can use external packages from NPM and other into your smart contract code. Don't limit yourself to the ones Convector provides or just vanilla JavaScript.
Be careful
The code running in a chaincode container (smart contracts) has to be deterministic. This means that everywhere and anywhere it is executed with the same inputs should return the same outputs.
This is because your code will be executed distributely amongst computers (nodes) running in different contexts. Avoid using date based calculations, randoms, external sources, or any other input of data that you are not sure will be avilable for all the participants.
In some cases, the rol of Oracles is needed, what these special participants do is put data in the blockchain that can be used as inputs for chaincode operations. Since the data is put in the blockchain it now becomes a deterministic source. A common example is an exchange rate or weather information.
Tip 2: debugging and testing
Unit testing is a best practice in modern software development. Blockchain with Convector is not an exception. You can use the built in Mock Controller Adapter
@worldsibu/convector-adapter-mockto simulate that your code is executed in the blockchain.You can find an easy example here: https://github.com/worldsibu/convector-example-drug-supply-chain/blob/master/%40worldsibu/chaincodes/cc-drug/tests/drug.spec.ts
Automate your tests and integrate them with your build processes for best results.
For debugging, you can just connect your debugger to your unit tests https://stackoverflow.com/questions/30023736/mocha-breakpoints-using-visual-studio-code or put a lot of
console.logaround. Doesn't matter on which team you are. 😁Tip 3: Users in the blockchain
Users and admins are not created by Convector, unlike other frameworks Convector doesn't get in the middle of that to avoid extra errors or security issues.
So the pattern that Convector follows is:
x509-fingerprint in the chaincode. I.e.: https://github.com/worldsibu/convector-example-drug-supply-chain/blob/master/package.json#L26this.senderand compare it against text fields that previously were set with a fingerprint of the expected user to do a taskThe full practical example can be found here: https://github.com/worldsibu/convector-example-drug-supply-chain
Convector CLI has been recently released! Get familiar with the new way to create Enterprise Smart Contract Systems.
Star Follow