DIA-NEAR-adapter

The dia-near adapter is a server process dedicated to fulfill requests posted on the smart contract contract.dia.oracles.near in the NEAR blockchain

Requests sent to contract.dia.oracles.near within the NEAR blockchain, are periodically polled, the data retrieved from DIA endpoints, and then sent back to the contract requesting the data by a call to the specified callback function. e.g. near call [requestring-contract-account-id] [callback-method] { "err":"", "data":[dia-api-call-result] }

Example

server up and resolving request_id 104 and 105 from quote-client.dia-oracles.testnet, asking for a BTC quote. Image shows incoming request and NEAR callback to originating contract

Technical details

This nodejs server is written in typescript.

It polls requests by periodically calling get_pending_requests_count() and get_pending_requests()

The requests to process have the following information:

• originating contract account id (String)
• request id (U128)
• requested data-key (String)
• data-item (String)
• callback method (String)

Request cycle

The dia-adapter server is periodically polling the contract.dia.oracles.near smart contract by using get_pending_requests() and will react to requests by:

• Query the corresponding DIA API endpoint for the data
• Prepare and execute a NEAR transaction with a function call to the originating contract’s callback method, including the the contract-specific request ID, the data-key, data-item and the data information retrieved from the DIA API endpoint
• The transaction will be signed by dia.oracles.near so the originating contract can verify the data source by controlling env::signer_account_id in the callback
• dia-adapter records the request contract+ID as serviced and calls remove() to remove the request from the pending requests list

Stats report

Bedisdes servicig contract.dia.oracles.near in the NEAR blockchain, this server also exposes an HTTP endpoint (default port 7001) to:

• show server stats (requests retrieved, serviced, with data, with error)
• show server log
• keep-alive response for the process watchdog
• shutdown the process (will be restarted by pm2)

Testnet Deployment Instructions

• You must deploy the main contract and client-test contracts in testnet
• make sure the dia-adapter server code is referencing your NEAR master account (see MASTER_ACCOUNT & GATEWAY_CONTRACT_ID at main.ts)

Integration Test Instructions

You need to have the server running and processing requests and also you need to simulate a client contract making a request. We will have two terminals one for each function:

• Start node dist/main in terminal 1.

• Start node dist/test/quote-make-request in terminal 2.

Terminal 1 has the server running in test mode.

Terminal 2 asks a test contract to send a request to contract.dia-oracles.testnet, the server in terminal 1 gets the request by polling, gets the data via dia-API call and then callbacks the requsting contract with the data.

You can navigate to localhost:8000 to check stats on the polling server in terminal 1.

Production Deployment Instructions

• You must deploy the main contract in NEAR mainnet
• You need to have pm2 installed in your server
• git clone/pull this repo in your server
• make sure the dia-adapter server code is referencing your NEAR master account (see MASTER_ACCOUNT & GATEWAY_CONTRACT_ID at main.ts)
• make sure the server has the MASTER_ACCOUNT credentials (check ~/.near-credentials/default. You can use near login to get the credentials file generated)
• in the repo dir type: npm start

> git clone https://github.com/Narwallets/dia-adapter.git
> cd dia-adapter
dia-adapter> npm install
dia-adapter> npm start

The dia-adapter process will be run, and restarted when necessary by pm2.
The pm2 configuration is at ecosystem.config.js
Use http://localhost:7001 to check the dia-adapter process status.