# 개요

Web3.js와 호환되기 위해서 LoomProvider는 이더리움 JSON RPC 메소드와 완벽히 호환되는 몇 개의 메소드를 추가했습니다, 이 메소드들은 Loom QueryService나 LoomProvider에 의해서 직접 호출될 수 있습니다, 이번 튜토리얼에서 우리는 LoomProvider에 대해서 얘기할 것입니다

# JSON RPC 메서드를 호출 하는 LoomProvider

프로바이더는 클라이언트와 Loom DAppChain 사이의 다리역할이 되어야 합니다, 아래 코드는 LoomProvider 가 인스턴스화되어 eth_accounts로 계정을 얻기 위해서 JSON RPC를 호출하는 예제입니다

const privateKey = CryptoUtils.generatePrivateKey();
const publicKey = CryptoUtils.publicKeyFromPrivateKey(privateKey);

// 클라이언트 생성
const client = new Client(
  "default",
  "ws://127.0.0.1:46658/websocket",
  "ws://127.0.0.1:46658/queryws"
);

// 함수 호출자의 주소
const from = LocalAddress.fromPublicKey(publicKey).toString();

// loom provider 인스턴스화
const loomProvider = new LoomProvider(client, privateKey);

// eth_accounts JSON RPC 호출
const jsonRPCString = '{"id": 1,"jsonrpc": "2.0", "method": "eth_accounts", "params": []}'

// 보내기전에 JSON 파싱은 필수적인 과정
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// 반환값은 다음과 같음
// {
//   "id":1,
//   "jsonrpc": "2.0",
//   "result": ["0x407d73d8a49eeb85d32cf465507dd71d507100c1"]
// }

# eth_accounts

# 설명

LoomProvider가 소유하고 있는 주소의 리스트를 반환한다

# 파라미터

없음

# 반환값

데이터 배열, 20 Bytes - 클라이언트가 소유하고 있는 주소.

# 예제

// eth_accounts JSON RPC call
const jsonRPCString = '{"id": 1,"jsonrpc": "2.0", "method": "eth_accounts", "params": []}'

// 보내기전에 JSON 파싱은 필수적인 과정
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// 반환값은 다음과 같음
// {
//   "id":1,
//   "jsonrpc": "2.0",
//   "result": ["0x407d73d8a49eeb85d32cf465507dd71d507100c1"]
// }

# eth_blockNumber

# 설명

가장 최근에 완성된 블록 번호를 반환합니다.

# 파라미터

없음

# 반환값

수량 - 현재 클라이언트에 올라간 현재 블록 번호의 정수값.

# 예제

// eth_blockNumber JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":83}'

// 보내기전에 JSON 파싱은 필수적인 과정
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// 반환값은 다음과 같음
// {
//   "id":83,
//   "jsonrpc": "2.0",
//   "result": "0x4b7" // 1207
// }

# eth_call

# 설명

블록체인에 트랜잭션 생성없이 즉시 새로운 메시지를 실행합니다.

# 파라미터

1. 객체 - 트랜잭션 호출 객체

• from: 데이터, 20 Bytes - 트랜잭션을 보내는 주소.
• to: 데이터, 20 Bytes - 트랜잭션이 전달되는 주소.
• data: 데이터 - 메소드 인증 해쉬 및 인코딩된 파라미터. 더 자세한 내용은 이더리움 컨트랙트 ABI를 보세요

# 반환값

데이터 - 실행된 컨트랙트의 반환값.

# 예제

// eth_call JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_call","params":[{see above}],"id":1}'

// 보내기전에 JSON 파싱은 필수적인 과정
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// 반환값은 다음과 같음
// {
//   "id":1,
//   "jsonrpc": "2.0",
//   "result": "0x"
// }

# eth_getBlockByNumber

# 설명

블록 번호에 해당하는 블록정보를 반환합니다.

# 파라미터

1. 숫자|태그 -기본 블록 파라미터로 지정될 블록번호의 숫자값 혹은 문자열 "earliest", "latest", "pending".
2. Boolean - true면 전체 트랜잭션 객체를 반환하고, false면 트랜잭션 해쉬값 만을 반환한다.

# 반환값

객체 - 블록객체, 또는 블록을 못찾을 경우 null:

• number: 숫자 - 블록 번호. 보류중인 블록은 null.
• hash: 데이터, 32 Bytes - 블록해쉬값. 보류중인 블록은 null.
• parentHash: 데이터`, 32 Bytes - 부모 블록의 해쉬값.
• logsBloom: 데이터, 256 Bytes - 블록의 로그를 위한 bloom filter. 보류중인 블록은 null.
• timestamp: 숫자 - 블록이 대조되었을때의 unix 타임스탬프.
• transactions: 배열 - 트랜잭션 객체의 배열, 또는 마지막에 지정된 파라미터에 의존하는 32 Bytes 트랜잭션 해쉬값들.

# 예제

// eth_getBlockByNumber JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_getBlockByNumber","params":["0x1b4", true],"id":1}'

// 보내기전에 JSON 파싱은 필수적인 과정
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// 반환값은 다음과 같음
// {
// "id":1,
// "jsonrpc":"2.0",
// "result": {
//     "number": "0x1b4", // 436
//     "hash": "0xe670ec64341771606e55d6b4ca35a1a6b75ee3d5145a99d05921026d1527331",
//     "parentHash": "0x9646252be9520f6e71339a8df9c55e4d7619deeb018d2a3f2d21fc165dde5eb5",
//     "logsBloom": "0xe670ec64341771606e55d6b4ca35a1a6b75ee3d5145a99d05921026d1527331",
//     "timestamp": "0x54e34e8e" // 1424182926
//     "transactions": [{...},{ ... }]
//   }
// }

# eth_getBlockByHash

# 설명

해쉬값에 해당하는 블록정보를 반환합니다.

# 파라미터

1. 데이터 - 32 Bytes - 블록의 해쉬값.
2. Boolean - true이면 전체 트랜잭션 객체를 반환하고, false이면 트랜잭션 해쉬값만을 반환합니다.

# 반환값

객체 - 블록객체, 또는 블록을 못찾을 경우 null:

• number: 숫자 - 블록 번호. 보류중인 블록은 null.
• hash: 데이터, 32 Bytes - 블록해쉬값. 보류중인 블록은 null.
• parentHash: DATA, 32 Bytes - 부모 블록의 해쉬값.
• logsBloom: 데이터, 256 Bytes - 블록의 로그를 위한 bloom filter. 보류중인 블록은 null.
• timestamp: 숫자 - 블록이 대조되었을때의 unix 타임스탬프.
• transactions: 배열 - 트랜잭션 객체의 배열, 또는 마지막에 지정된 파라미터에 의존하는 32 Bytes 트랜잭션 해쉬값들.

# Example

// eth_getBlockByHash JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_getTransactionByHash","params":["0xb903239f8543d04b5dc1ba6579132b143087c68db1b2168786408fcbce568238"],"id":1}'

// 보내기전에 JSON 파싱은 필수적인 과정
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// 반환값은 다음과 같음
// {
// "id":1,
// "jsonrpc":"2.0",
// "result": {
//     "number": "0x1b4", // 436
//     "hash": "0xe670ec64341771606e55d6b4ca35a1a6b75ee3d5145a99d05921026d1527331",
//     "parentHash": "0x9646252be9520f6e71339a8df9c55e4d7619deeb018d2a3f2d21fc165dde5eb5",
//     "logsBloom": "0xe670ec64341771606e55d6b4ca35a1a6b75ee3d5145a99d05921026d1527331",
//     "timestamp": "0x54e34e8e" // 1424182926
//     "transactions": [{...},{ ... }]
//   }
// }

# eth_getCode

# 설명

주어진 주소의 코드를 반환합니다.

# 파라미터

1. 데이터, 20 Bytes - 주소

# 반환값

데이터 - 주어진 주소의 코드.

# 예제

// eth_getCode JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_getCode","params":["0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b", "0x2"],"id":1}'

// 보내기전에 JSON 파싱은 필수적인 과정
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// 반환값은 다음과 같음
// {
//   "id":1,
//   "jsonrpc": "2.0",
//   "result": "0x600160008035811a818181146012578301005b601b6001356025565b8060005260206000f25b600060078202905091905056"
// }

# eth_getFilterChanges

# 설명

Polling method for a filter, which returns an array of logs which occurred since last poll.

# Parameters

1. QUANTITY - the filter id.

# Returns

Array - Array of log objects, or an empty array if nothing has changed since last poll.

• For filters created with eth_newBlockFilter the return are block hashes (DATA, 32 Bytes), e.g. ["0x3454645634534..."].

• For filters created with eth_newPendingTransactionFilter the return are transaction hashes (DATA, 32 Bytes), e.g. ["0x6345343454645..."].

• For filters created with eth_newFilter logs are objects with following params:

  • removed: TAG - true when the log was removed, due to a chain reorganization. false if its a valid log.
  • logIndex: QUANTITY - integer of the log index position in the block. null when its pending log.
  • transactionIndex: QUANTITY - integer of the transactions index position log was created from. null when its pending log.
  • transactionHash: DATA, 32 Bytes - hash of the transactions this log was created from. null when its pending log.
  • blockHash: DATA, 32 Bytes - hash of the block where this log was in. null when its pending. null when its pending log.
  • blockNumber: QUANTITY - the block number where this log was in. null when its pending. null when its pending log.
  • address: DATA, 20 Bytes - address from which this log originated.
  • data: DATA - contains one or more 32 Bytes non-indexed arguments of the log.
  • topics: Array of DATA - Array of 0 to 4 32 Bytes DATA of indexed log arguments. (In solidity: The first topic is the hash of the signature of the event (e.g. Deposit(address,bytes32,uint256)), except you declared the event with the anonymous specifier.)

# Example

// eth_getFilterChanges JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_getFilterChanges","params":["0x16"],"id":73}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
//   "id":1,
//   "jsonrpc":"2.0",
//   "result": [{
//     "logIndex": "0x1", // 1
//     "blockNumber":"0x1b4", // 436
//     "blockHash": "0x8216c5785ac562ff41e2dcfdf5785ac562ff41e2dcfdf829c5a142f1fccd7d",
//     "transactionHash":  "0xdf829c5a142f1fccd7d8216c5785ac562ff41e2dcfdf5785ac562ff41e2dcf",
//     "transactionIndex": "0x0", // 0
//     "address": "0x16c5785ac562ff41e2dcfdf829c5a142f1fccd7d",
//     "data":"0x0000000000000000000000000000000000000000000000000000000000000000",
//     "topics": ["0x59ebeb90bc63057b6515673c3ecf9438e5058bca0f92585014eced636878c9a5"]
//     },{
//       ...
//     }]
// }

# eth_getLogs

# Description

Returns an array of all logs matching a given filter object.

# Parameters

1. Object - The filter options:

• fromBlock: QUANTITY|TAG - (optional, default: "latest") Integer block number, or "latest" for the last mined block or "pending", "earliest" for not yet mined transactions.
• toBlock: QUANTITY|TAG - (optional, default: "latest") Integer block number, or "latest" for the last mined block or "pending", "earliest" for not yet mined transactions.
• address: DATA|Array, 20 Bytes - (optional) Contract address or a list of addresses from which logs should originate.
• topics: Array of DATA, - (optional) Array of 32 Bytes DATA topics. Topics are order-dependent. Each topic can also be an array of DATA with "or" options.
• blockhash: DATA, 32 Bytes - (optional, future) With the addition of EIP-234, blockHash will be a new filter option which restricts the logs returned to the single block with the 32-byte hash blockHash. Using blockHash is equivalent to fromBlock = toBlock = the block number with hash blockHash. If blockHash is present in in the filter criteria, then neither fromBlock nor toBlock are allowed.

# Returns

See eth_getFilterChanges

# Example

// eth_getFilterChanges JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_getLogs","params":[{"topics":["0x000000000000000000000000a94f5374fce5edbc8e2a8697c15331677e6ebf0b"]}],"id":74}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

Result see eth_getFilterChanges

# eth_getTransactionReceipt

# Description

Returns the receipt of a transaction by transaction hash.

Note That the receipt is not available for pending transactions.

# Parameters

1. DATA, 32 Bytes - hash of a transaction

# Returns

Object - A transaction receipt object, or null when no receipt was found:

• transactionHash: DATA, 32 Bytes - hash of the transaction.
• transactionIndex: QUANTITY - integer of the transactions index position in the block.
• blockHash: DATA, 32 Bytes - hash of the block where this transaction was in.
• blockNumber: QUANTITY - block number where this transaction was in.
• from: DATA, 20 Bytes - address of the sender.
• to: DATA, 20 Bytes - address of the receiver. null when its a contract creation transaction.
• contractAddress: DATA, 20 Bytes - The contract address created, if the transaction was a contract creation, otherwise null.
• logs: Array - Array of log objects, which this transaction generated.
• status: QUANTITY either 1 (success) or 0 (failure)

# Example

// eth_getTransactionReceipt JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_getTransactionReceipt","params":["0xb903239f8543d04b5dc1ba6579132b143087c68db1b2168786408fcbce568238"],"id":1}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
// "id":1,
// "jsonrpc":"2.0",
// "result": {
//      transactionHash: '0xb903239f8543d04b5dc1ba6579132b143087c68db1b2168786408fcbce568238',
//      transactionIndex:  '0x1', // 1
//      blockNumber: '0xb', // 11
//      blockHash: '0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b',
//      contractAddress: '0xb60e8dd61c5d32be8058bb8eb970870f07233155', // or null, if none was created
//      logs: [{
//          // logs as returned by getFilterLogs, etc.
//      }, ...],
//      status: '0x1'
//   }
// }

# eth_newBlockFilter

# Description

Creates a filter in the node, to notify when new pending transactions arrive. To check if the state has changed, call eth_getFilterChanges.

# Parameters

None

# Returns

QUANTITY - A filter id.

# Example

// eth_newBlockFilter JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_newBlockFilter","params":[],"id":73}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
//   "id":1,
//   "jsonrpc":  "2.0",
//   "result": "0x1" // 1
// }

# eth_newFilter

# Description

Creates a filter object, based on filter options, to notify when the state changes (logs). To check if the state has changed, call eth_getFilterChanges.

# A note on specifying topic filters:

Topics are order-dependent. A transaction with a log with topics [A, B] will be matched by the following topic filters:

• [] "anything"
• [A] "A in first position (and anything after)"
• [null, B] "anything in first position AND B in second position (and anything after)"
• [A, B] "A in first position AND B in second position (and anything after)"
• [[A, B], [A, B]] "(A OR B) in first position AND (A OR B) in second position (and anything after)"

# Parameters

1. Object - The filter options:

• fromBlock: QUANTITY|TAG - (optional, default: "latest") Integer block number, or "latest" for the last mined block or "pending", "earliest" for not yet mined transactions.
• toBlock: QUANTITY|TAG - (optional, default: "latest") Integer block number, or "latest" for the last mined block or "pending", "earliest" for not yet mined transactions.
• address: DATA|Array, 20 Bytes - (optional) Contract address or a list of addresses from which logs should originate.
• topics: Array of DATA, - (optional) Array of 32 Bytes DATA topics. Topics are order-dependent. Each topic can also be an array of DATA with "or" options.

# Returns

QUANTITY - A filter id

# Example

// eth_newFilter JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_newFilter","params":[{"topics":["0x12341234"]}],"id":73}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
//   "id":1,
//   "jsonrpc": "2.0",
//   "result": "0x1" // 1
// }

# eth_sendTransaction

# Description

Creates new message call transaction or a contract creation, if the data field contains code.

# Parameters

1. Object - The transaction object

• from: DATA, 20 Bytes - The address the transaction is send from.
• to: DATA, 20 Bytes - (optional when creating new contract) The address the transaction is directed to.
• data: DATA - The compiled code of a contract OR the hash of the invoked method signature and encoded parameters. For details see Ethereum Contract ABI

# Returns

DATA, 32 Bytes - the transaction hash, or the zero hash if the transaction is not yet available.

Use eth_getTransactionReceipt to get the contract address, after the transaction was mined, when you created a contract.

# Example

// eth_sendTransaction JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_sendTransaction","params":[{see above}],"id":1}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
//   "id":1,
//   "jsonrpc": "2.0",
//   "result": "0xe670ec64341771606e55d6b4ca35a1a6b75ee3d5145a99d05921026d1527331"
// }

# eth_subscribe

# Description

It works by subscribing to particular events. The node will return a subscription id. For each event that matches the subscription a notification with relevant data is send together with the subscription id.

# Parameters

1. object with the following (optional) fields

• address, either an address or an array of addresses. Only logs that are created from these addresses are returned (optional)
• topics, only logs which match the specified topics (optional)

# Returns

Subscription id

# Example

// eth_subscribe JSON RPC call
const jsonRPCString = '{"id": 1, "method": "eth_subscribe", "params": ["logs", {"address": "0x8320fe7702b96808f7bbc0d4a888ed1468216cfd", "topics": ["0xd78a0cb8bb633d06981248b816e7bd33c2a35a6089241d099fa519e361cab902"]}]}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
//   "jsonrpc":"2.0",
//   "id":2,
//   "result":"0x4a8a4c0517381924f9838102c5a4dcb7"
// }

# eth_uninstallFilter

# Description

Uninstalls a filter with given id. Should always be called when watch is no longer needed. Additonally Filters timeout when they aren't requested with eth_getFilterChanges for a period of time.

# Parameters

1. QUANTITY - The filter id

# Returns

Boolean - true if the filter was successfully uninstalled, otherwise false.

# Example

// eth_uninstallFilter JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"eth_uninstallFilter","params":["0xb"],"id":73}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
//   "id":1,
//   "jsonrpc": "2.0",
//   "result": true
// }

# net_version

# Description

Returns the current network id.

# Parameters

None

# Returns

String - The current network id.

• "474747": Currently there's now network id defined, the number returned is simply 474747

# Example

// net_version JSON RPC call
const jsonRPCString = '{"jsonrpc":"2.0","method":"net_version","params":[],"id":67}'

// Parse JSON is a necessary step before send
await loomProvider.sendAsync(JSON.parse(jsonRPCString))

// Return should be something like
// {
//   "id":67,
//   "jsonrpc": "2.0",
//   "result": "474747"
// }