以太合约之实时事件 Real-time Events

2023-10-07 13:23:46

Geth v1.4和更高版本支持使用JSON-RPC通知进行发布/订阅。这使客户端可以等待事件，而不是轮询事件。

它通过订阅特定事件来工作。该节点将返回订阅ID。对于与订阅匹配的每个事件，带有相关数据的通知将与订阅ID一起发送。

例子：

// create subscription
>> {"id": 1, "method": "eth_subscribe", "params": ["newHeads", {}]}
<< {"jsonrpc":"2.0","id":1,"result":"0xcd0c3e8af590364c09d0fa6a1210faf5"}

// incoming notifications
<< {"jsonrpc":"2.0","method":"eth_subscription","params":{"subscription":"0xcd0c3e8af590364c09d0fa6a1210faf5","result":{"difficulty":"0xd9263f42a87",<...>, "uncles":[]}}}
<< {"jsonrpc":"2.0","method":"eth_subscription","params":{"subscription":"0xcd0c3e8af590364c09d0fa6a1210faf5","result":{"difficulty":"0xd90b1a7ad02", <...>, "uncles":["0x80aacd1ea4c9da32efd8c2cc9ab38f8f70578fcd46a1a4ed73f82f3e0957f936"]}}}

// cancel subscription
>> {"id": 1, "method": "eth_unsubscribe", "params": ["0xcd0c3e8af590364c09d0fa6a1210faf5"]}
<< {"jsonrpc":"2.0","id":1,"result":true}

注意事项

通知是针对当前事件而不是针对过去事件发送的。如果您的用例要求您不要错过任何通知，那么订阅可能不是最佳选择。
订阅需要全双工连接。Geth以WebSocket和IPC的形式提供此类连接（默认情况下启用）。
订阅耦合到连接。如果连接已关闭，则将删除通过此连接创建的所有订阅。
通知存储在内部缓冲区中，并从该缓冲区发送到客户端。如果客户端无法跟上，并且缓冲的通知数达到限制（当前为10k），则连接将关闭。请记住，订阅某些事件可能会导致大量通知，例如，在节点开始同步时侦听所有日志/块。

创建订阅

订阅是通过常规RPC调用创建的，其中RPCeth_subscribe作为方法，订阅名称为第一个参数。如果成功，则返回订阅ID。

参数

订阅名称
可选参数

例子

>> {"id": 1, "method": "eth_subscribe", "params": ["newHeads", {"includeTransactions": true}]}
<< {"id": 1, "jsonrpc": "2.0", "result": "0x9cef478923ff08bf67fde6c64013158d"}

取消订阅

使用常规的RPC调用（eth_unsubscribe作为方法，订阅ID作为第一个参数）取消订阅。它返回一个布尔值，指示是否成功取消了订阅。

参数

订阅编号

例子

>> {"id": 1, "method": "eth_unsubscribe", "params": ["0x9cef478923ff08bf67fde6c64013158d"]}
<< {"jsonrpc":"2.0","id":1,"result":true}

支持的订阅

newHeads

每次将新标头附加到链（包括链重组）时，都会触发通知。用户可以使用Bloom筛选器来确定该块是否包含对其感兴趣的日志。

如果发生链重组，则订阅将发出新链的所有新标头。因此，订阅可以在相同高度上发出多个标头。

例子

>> {"id": 1, "method": "eth_subscribe", "params": ["newHeads"]}
<< {"jsonrpc":"2.0","id":2,"result":"0x9ce59a13059e417087c02d3236a0b1cc"}

<< {
       "jsonrpc": "2.0",
       "method": "eth_subscription",
       "params": {
         "result": {
           "difficulty": "0x15d9223a23aa",
           "extraData": "0xd983010305844765746887676f312e342e328777696e646f7773",
           "gasLimit": "0x47e7c4",
           "gasUsed": "0x38658",
           "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
           "miner": "0xf8b483dba2c3b7176a3da549ad41a48bb3121069",
           "nonce": "0x084149998194cc5f",
           "number": "0x1348c9",
           "parentHash": "0x7736fab79e05dc611604d22470dadad26f56fe494421b5b333de816ce1f25701",
           "receiptRoot": "0x2fab35823ad00c7bb388595cb46652fe7886e00660a01e867824d3dceb1c8d36",
           "sha3Uncles": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
           "stateRoot": "0xb3346685172db67de536d8765c43c31009d0eb3bd9c501c9be3229203f15f378",
           "timestamp": "0x56ffeff8",
           "transactionsRoot": "0x0167ffa60e3ebc0b080cdb95f7c0087dd6c0e61413140e39d94d3468d7c9689f"
         },
         "subscription": "0x9ce59a13059e417087c02d3236a0b1cc"
       }
     }

日志

返回包含在新导入的块中并符合给定过滤条件的日志。

如果进行链重组，则将重新发送旧链上的先前发送的日志，并将removed属性设置为true。发出来自结束于新链中的事务的日志。因此，订阅可以多次发出同一事务的日志。

参数

object 具有以下（可选）字段
- address，一个地址或一个地址数组。仅返回从这些地址创建的日志（可选）
- topic，仅匹配指定主题的日志（可选）

例子

>> {"id": 1, "method": "eth_subscribe", "params": ["logs", {"address": "0x8320fe7702b96808f7bbc0d4a888ed1468216cfd", "topics": ["0xd78a0cb8bb633d06981248b816e7bd33c2a35a6089241d099fa519e361cab902"]}]}
<< {"jsonrpc":"2.0","id":2,"result":"0x4a8a4c0517381924f9838102c5a4dcb7"}

<< {"jsonrpc":"2.0","method":"eth_subscription","params": {"subscription":"0x4a8a4c0517381924f9838102c5a4dcb7","result":{"address":"0x8320fe7702b96808f7bbc0d4a888ed1468216cfd","blockHash":"0x61cdb2a09ab99abf791d474f20c2ea89bf8de2923a2d42bb49944c8c993cbf04","blockNumber":"0x29e87","data":"0x00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000003","logIndex":"0x0","topics":["0xd78a0cb8bb633d06981248b816e7bd33c2a35a6089241d099fa519e361cab902"],"transactionHash":"0xe044554a0a55067caafd07f8020ab9f2af60bdfe337e395ecd84b4877a3d1ab4","transactionIndex":"0x0"}}}

newPendingTransactions

返回添加到挂起状态并使用节点中可用密钥签名的所有事务的哈希。

如果重新定义后，以前属于规范链的交易不属于新规范链，则再次发出该交易。

参数

没有

例子

>> {"id": 1, "method": "eth_subscribe", "params": ["newPendingTransactions"]}
<< {"jsonrpc":"2.0","id":2,"result":"0xc3b33aa549fb9a60e95d21862596617c"}
<< {
        "jsonrpc":"2.0",
        "method":"eth_subscription",
        "params":{
            "subscription":"0xc3b33aa549fb9a60e95d21862596617c",
            "result":"0xd6fdc5cc41a9959e922f30cb772a9aef46f4daea279307bc5f7024edc4ccd7fa"
        }
   }

正在同步

指示节点何时开始或停止同步。结果可以是指示同步已开始（true），完成（false）的布尔值，也可以是具有各种进度指示器的对象。

参数

没有

例子

>> {"id": 1, "method": "eth_subscribe", "params": ["syncing"]}
<< {"jsonrpc":"2.0","id":2,"result":"0xe2ffeb2703bcf602d42922385829ce96"}

<< {"subscription":"0xe2ffeb2703bcf602d42922385829ce96","result":{"syncing":true,"status":{"startingBlock":674427,"currentBlock":67400,"highestBlock":674432,"pulledStates":0,"knownStates":0}}}}

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