chainlink node setup[See Description] Connect any API to your smart contract Chainlink Engineering Tutorials

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chainlink node setup Monero XMR Price · Price Index,... [See Description] Connect any API to your smart contract Chainlink Engineering Tutorials
welcome back engineers in one of our earlier videos we showed how to make an api call through a chain link node in this video were going to go into number one how this actually works number two exactly what the code looks like and what you need to do with the code number three an introduction to adapters and number four a brief introduction into external adapters and to get help with any of this ask any other questions and join the community be sure to grab the discord link in the description below lets build remember that chain link oracles are blockchain middleware so we need something to programmatically tell them to make an api call or get this data put another way we need something to initiate them to post data through an external transaction onto the blockchain these instructions for telling a chain-link node to start getting data is called an initiator each chain-link node has specified initiators that theyre going to be listening for in addition they also have a specific set of instructions on what to do with that data once they start getting it this set of instructions defining what to do is called the adapters or tasks list the combination of initiators and adapters makes up a single job in a chain-link node chain-link nodes can define as many jobs as they like so in this way how they get data and what they do with that data is essentially limitless once a job is defined its given a specified job id one of the most common jobs that most nodes have functionality for is a run log initiator combined with a http get json parse multiply fun256 and ftx adapters well get what into this list of adapters does soon a job with a run lock initiator means that the chain link node will actually watch the blockchain for any events that have that job specific id once the chain link node finds an event it will execute whats specified in the adapters or list of instructions including posting the data onto the chain via an external transaction your smart contract will have to wait a little bit for the chain link node to post this data in an external transaction but once it does youll be able to pull the data right from that transaction lets see what this looks like in code form heres a subset of the code from the previous video where all we want to do is get the numerical price of ethereum to start making a request of the chain link node we will call the build chain link request function that is imported from the chainlink client.sol this function returns a chainlink.request struct that we need to populate to send and make the chainlink request in this function we need to pass the specific job id the callback address and the callback function signature in order to build this chain link request struct we can find a job id by heading over to a node listing service like and searching for the job that we want when we come to the node listing service there are two things that we want to get a job id and an oracle address node listing services are where independent nodes post their information about how to connect to their chain link node you can refer to them often for building your decentralized network of oracles you can search right here or browse jobs nodes feeds and a number of other things we want a job that can do an http get request and return a uint256 so lets look up get uint 256. oh we need to make sure were on the correct network first we want on robston so now we get a list of nodes that have a job for http get uint256 to make sure this job has the right adapters or set of instructions for the job lets find the actual job in its list of jobs here heres the get ui 256 job that we want and here are the tasks or adapters that it has it has the http get json parse multiply fun 256 and f transaction adapter so this job will work perfectly for us we can then copy the job id to use in our code you can see other nodes that have similar jobs and you can come back to this list when you make your contract decentralized but again for testing and developing we can just pull from a single node for now make sure you also grab the oracle address as youll need this later too for this demonstration were going to be hard coding all the variables but you may want to go back and refactor this code later to add these parameters to be passable to your function so that you dont have to add a new function for every oracle that you add the second parameter is the address of the contract to return the data to or the callback address with this were saying we want the data to be returned to this contract and the last parameter is the function that will process the data once collected or the callback function signature once the chain link node makes the external transaction posted on chain its transaction will actually perform the execution of the callback function in this case fulfill this is where you can customize what to do with the data once received we want to make sure we add this record chain link fulfillment to ensure only the requesting oracle can fulfill it it takes the request id and the data from the chain link node as you can see were just going to set the return value to our current price variable we can then add parameters to our adapter tasks remember how in this job we have this http get adapter here we can add the parameters of what to actually call with this adapter we can add it by saying get the name of the adapter and the api that we actually want to call since every piece of data we store on the chain costs ethereum and we only need the uint256 price we then add the path parameter to our jsonparse adapter to walk the path and get the specified value in this api call we can see that the mapping is from usd so we add this to a request with the path right.add path usd this way we will only be returning this value and finally the multiply or times adapter we do this because decimals dont work well on the blockchain and we need a whole number so were going to multiply this number by 100 which essentially will move the decimal place over two places so that our smart contract can understand the value the last two adapters convert the result into an avi encoded uint256 and creates the ethereum transaction on chain those we dont have to add any parameters to and now were done with the adapters you can see a list of all the adapters and how to use them in the chain link documentation links in the description now we use the send chain link request to method with the address of the oracle we got from the request itself and the oracle payment this will be how much link we want to send to this node we can see the cost of the job on as well for this job the cost is 0.1 link this will be the representation of point one link now lets run this contract compile inject to web3 approve connect deploy confirm copy the address send it some link and then request the price of eth here we actually have the chain link node and we can see the request come in and the chain link node go through the adapters once the request transaction actually goes through well be able to see the job show up on the chain link node here i have access to the gui of the chain link node and we can see created just now we have a new job run if we flip back to our code we still dont have the current price this is because the chain link node hasnt finished making the transaction back onto the chain with the data once its fully complete we can flip back to our code and once its complete that means this fulfill function has been called and we can see once we click current price we can see its actually been updated here oracles can define the parameters right in their job definition as well these are known as their job specs and you can just call a job without having to put any parameters in at all for example you can see here that the parameters are already defined what you could just do for this is copy the job id copy the address of the node and just have your code look like this you can see exactly what a job spec looks like by hitting the job spec tab on the node listing service this has been a pretty deep dive in exactly how chain link works from an engineering perspective but with this you now have a lot of the basic tools for building some amazing projects in blockchain yourself but lets say you want to do something a little bit more involved like the api that youre using requires authorization maybe you want to save some gas by doing some computation off chain or maybe theres just some functionality not covered in the adapters tasks list this is where jobs with external adapters come in external adapters are ways of building additional customized functionality into your jobs and we can find out exactly how those work in the next video ill see you there The Chainlink Fall 2021 Hackathon kicks off October 22. Sign up today: ️Update:️️️️️️ JSON parsing has moved from periods to commas, please see docs for details. ️️️️️️️️️️️ ---Updates--- The ropsten testnet is no longer supported. You can use this blog to get started instead. Smart contracts need to be able to connect to real-world data & APIs. Chainlink is the middleware that enables blockchain to be connected to the real world. This video describes how to get data from HTTP GET requests, HTTP POST requests, and a number of other methods into your smart contract. showing you exactly how it plays out on the Ethereum blockchain. Chainlink is a decentralized oracle network that enables smart contracts to securely access off-chain data feeds, web APIs, and traditional bank payments. Chainlink is critical to connecting the blockchain ecosystem to the rest of the world. Resources from the video: Note: Ropsten is currently broken, please use Kovan or other testnet: Remix Code from the video with notes: Node listing service: Learn more: Chainlink Documentation for this video: Connect any API to your smart contract : Adapters documentation: Initiators documentation: Learn more about Chainlink : Documentation: Discord: - Very active and developer focused! Website Building DeFi Applications: Twitter Telegram ChainlinkEngineeringTutorials,