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Oracle Service Vendors

The opportunity of becoming an Oracle service vendor is open for any intrested party. Oracles can provide services to fetch public data, or can be limited to a certain Specialized domain that one has understanding of. A fixed amount of processing fee can be charged for each request to the Oracle. Details regarding becoming an Oracle service vendor have been provided below.

Deploying an Oracle Smart Contract

The first step ivolved in the process of becoming an Oracle service provider is deploying a custom Oracle contract. Please refer to this link for more information on the Oracle protocol.

A sample Oracle contract is available for reference, and can be found by following this link.

Downloading the Oracle Client

The following Git command can be used to directly clone Ontology's Oracle repository:

$ git clone https://github.com/ontio/ontology-oracle.git

Providing Specialized Data Services

The Oracle repository contains services that by default can fetch public data, and the data can be obtained without any extra permissions. The specialized data services from random.org can be fetched after applying for the key. The sample provided in the repository uses the Basic API version to fetch the development API key.

The data service provider can choose to add any kind of specialized data for the clients to access, or stick with the public data services, as shown in the sample.

The relevant data service files that can be found under the runners folder are as follows:

  1. The runner.go file defines the runner API and other runner routes.
  2. The http.go file provides some basic data retrieval services. The data is fetched using the HTTP methods.
  3. The json_parse.go file provides data analysis service.
  4. The random_org.go file provides specialized data retrieval services to fetch random numbers, including both ordinary random numbers and random numbers used for signature.

Data service vendors can refer to random_org.go to get an understanding of how to implement specialized data services.

Compiling the Oracle Client

go build main.go

Editing Configuration Files

The contents of the configuration file config.json are as follows:

{
  "WalletFile": "./wallet.dat",
  "LogLevel": 0,
  "ONTRPCAddress": "http://127.0.0.1:20336",
  "ScannerInterval": 10,
  "GasPrice": 0,
  "GasLimit": 20000,
  "ContractAddress": "b869eed573863f8efdb3ae39d4963a781e81d4b3",
  "RandomOrgKey": "c7511065-c88d-4f28-af4f-293c91ad20d9"
}
Field Description
WalletFile Wallet path, this wallet is used to pay the gas fees for data upload requests
LogLevel The selected log level
ONTRPCAddress The RPC address and port of the Ontology nodem, the transaction result of data upload request is transmitted to this node
ScannerInterval Time interval for scanning, the Oracle client scans request data from the Oracle contract in fixed time intervals
ContractAddress Contract address hash of the Oracle contract
RandomOrgKey The Basic API verion key fetched from random.org, permissions for fetching other specialized data can also be added

The different log levels supported are:

const (
	DebugLog = iota
	InfoLog
	WarnLog
	ErrorLog
	FatalLog
	MaxLevelLog
)

Starting the Oracle Client

The command used to start the Oracle client node is:

./main node

Please enter the password when prompted by the shell to start the node.

Making the Oracle Contract Address and Data Services Public

After deploying the Oracle contract and starting the Oracle client, the data service vendor can publicly share the Oracle contract address and fee structure along with the content being provided and the request format.