DIA-NEAR-adapter

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

Requests sent to contract.dia-test.testnet 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-test-client.dia-test.testnet, asking for a DIA 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-test.testnet 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-test.testnet 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-test.testnet 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:

• Run npm install and npm run build
• 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-test.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/diadata-org/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.