How to confirm a transaction

Irreversible block and irreversible transaction

On GXChain, the block confirmed by 2/3 or more trustnodes is defined as a reversible block, and all transactions in the irreversible block become irreversible transactions. Therefore, judging whether a transaction is irreversible is achieved by judging whether the transaction appears in an irreversible block.

The irreversible transaction is of great significance and can be used for scenarios such as transfer confirmation and exchange deposit confirmation. The main idea is to query related transactions by traversing irreversible blocks.

Step1: Get irreversible block height

Get dynamic global objects

request:

curl --data '{
    "jsonrpc": "2.0",
    "method": "call",
    "params": [0, "get_dynamic_global_properties", []],
    "id": 1
}' https://node1.gxb.io/rpc

response:

{
    "id":1,
    "jsonrpc":"2.0",
    "result":{
        "id":"2.1.0",
        "head_block_number":16757465, // Latest block number
        "head_block_id":"00ffb2d9f6e344f2190a8dfba58baaadd49e76c4", // Latest block id
        "time":"2019-01-28T06:08:00", // Block time
        "current_witness":"1.6.52",
        "next_maintenance_time":"2019-01-28T06:40:00",
        "last_budget_time":"2019-01-28T05:40:00",
        "witness_budget":3065824,
        "accounts_registered_this_interval":2,
        "recently_missed_count":0,
        "current_aslot":16958091,
        "recent_slots_filled":"340282366920938463463374607431768211455",
        "dynamic_flags":0,
        "last_irreversible_block_num":16757449 // Last irreversible block number
    }
}

Step2: Traversing irreversible blocks

For example: to determine whether a transaction with a txid of 9df2d2a2804c235bb16428c44f71de9468409ae7 is in an irreversible block, we will start query from the height of a block when sending the transaction, up to the height of the irreversible block, if this txid is found in the transaction_ids array, that proves that the transaction is irreversible, ie the transaction is finally confirmed by the network.

request:

curl --data '{
    "jsonrpc": "2.0",
    "method": "call",
    "params": [0, "get_block", [17136876]],
    "id": 1
}' https://node1.gxb.io/rpc

response:

{
  "previous": "01057cebdee3cf922d8fa54c2f6a7e0f01e4528a",
  "timestamp": "2019-02-10T18:25:42",
  "witness": "1.6.83",
  "transaction_merkle_root": "e8fdfcbd168ae9da64826d93c2fb88d19ac5f9fc",
  "extensions": [],
  "witness_signature": "1f4aa0526cf96d40f1b7c971b9bd39c72818b5dce421b3ec4e730d2f720e4a3a8e2f6dfe2696f8a52e221f4bfb4f828eff8488d6c6131933fc85a01437893564db",
  "transactions": [
    {
      "ref_block_num": 31978,
      "ref_block_prefix": 301877440,
      "expiration": "2019-02-10T18:26:08",
      "operations": [
        [
          73,
          {
            "proxy_memo": "QmcPwEMDdceMqzGNc7CCuffG7GvQnCFDJGteZMhTNtSYaA",
            "fee": {
              "amount": 1,
              "asset_id": "1.3.5"
            },
            "request_params": {
              "from": "1.2.17539",
              "to": "1.2.46",
              "proxy_account": "1.2.693712",
              "amount": {
                "amount": 10000,
                "asset_id": "1.3.5"
              },
              "percentage": 1000,
              "memo": "0ddad68dcb985a8031ff1a60c7984d36",
              "expiration": "2019-02-10T18:55:38",
              "signatures": [
                "2016918af85ee94ce72cf46f0dd8c0dec3e55eba9cf7b892e582f15b10f2949a3f7a6e4f9bdb1470414da2098032132c2ceb7725a9183fe2fe0eaa2b87c087ab88"
              ]
            },
            "extensions": []
          }
        ]
      ],
      "extensions": [],
      "signatures": [
        "1b0a289b4322ea6f522f7400bc368673a60aec7c28da463fcebf338a591cf7d8c8081ca39533a7ae28346cea503745804064f3d9f946f9bb2a13d5a04a3f751cfc"
      ],
      "operation_results": [
        [
          0,
          {}
        ]
      ]
    },
    {
      "ref_block_num": 31979,
      "ref_block_prefix": 2463097822,
      "expiration": "2019-02-10T18:26:09",
      "operations": [
        [
          0,
          {
            "fee": {
              "amount": 1000,
              "asset_id": "1.3.1"
            },
            "from": "1.2.19643",
            "to": "1.2.1061995",
            "amount": {
              "amount": "20916437581",
              "asset_id": "1.3.1"
            },
            "extensions": []
          }
        ]
      ],
      "extensions": [],
      "signatures": [
        "1f1918828badce7d0f0a05ee5890aba48dafe1e59f9ceb3a680f8abdaa17546c827f4302988d51857d1b89188bb2ba426410015c2d627cfa2dfa44c441348d3105"
      ],
      "operation_results": [
        [
          0,
          {}
        ]
      ]
    },
    {
      "ref_block_num": 31979,
      "ref_block_prefix": 2463097822,
      "expiration": "2019-02-10T18:26:09",
      "operations": [
        [
          73,
          {
            "proxy_memo": "QmTK6dHnEixSNoWgB14j1ZujKhT1RjEgXvUVJtcdWwJoTX",
            "fee": {
              "amount": 1,
              "asset_id": "1.3.5"
            },
            "request_params": {
              "from": "1.2.3840",
              "to": "1.2.46",
              "proxy_account": "1.2.693712",
              "amount": {
                "amount": 10000,
                "asset_id": "1.3.5"
              },
              "percentage": 1000,
              "memo": "5bfa26ee65ddc08558a8bf0f01dfe93a",
              "expiration": "2019-02-10T18:55:41",
              "signatures": [
                "2041dafb5c38ecc885f730af79cf741f5fc50c0f5b24c4f2d9fbfca7a34009394b3efea5ef426f4f7eb864431c8f9462b31a0e08af7fa6367b99d5673c502fe473"
              ]
            },
            "extensions": []
          }
        ]
      ],
      "extensions": [],
      "signatures": [
        "1b15649c701dad9aa38fc14ef85e28de849637a390fd46765c2960073f3993522d6d2a0e795f5c30005877cddafbcd926a9d94be6a763607d24b5fbf9e2b03fef2"
      ],
      "operation_results": [
        [
          0,
          {}
        ]
      ]
    }
  ],
  "block_id": "01057cecdc861a10a7c52052a1f681212fd99547",
  "signing_key": "GXC7iFA4ejkfbYQ8f7xR8rQ6dEANLqqFHKm3evo9NgCbtbx9aivXd",
  "transaction_ids": [
    "b53c8626bae9e17a07457fccca350c8edac42888",
    "9df2d2a2804c235bb16428c44f71de9468409ae7",
    "26a893ed6f6fd1b9781262c750dc8905a9af2add"
  ]
}