Event Query and Subscription

IOTA full nodes support publish/subscribe using JSON-RPC notifications via the WebSocket API. You can use this service with IOTA client to filter and subscribe to a real-time event stream generated from Move or from the IOTA network.

The client provides an event filter to limit the scope of events. IOTA returns a notification with the event data and subscription ID for each event that matches the filter.

Event types

An IOTA node emits the following types of events:

• Move event
• Publish event
• Transfer object event
• Delete object event
• New object event
• Epoch change event

Move event

Move calls emit Move events. You can define custom events in Move contracts.

Attributes

Move event attributes:

• packageId
• transactionModule
• sender
• type
• fields
• bcs

Example Move event

{
  "moveEvent": {
    "packageId": "<PACKAGE-ID>",
    "transactionModule": "nft",
    "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
    "type": "<PACKAGE-ID>::nft::MintNFTEvent",
    "fields": {
      "creator": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
      "name": "NFT",
      "object_id": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
    },
    "bcs": "SXkTpH3AAoqF8kxw2CWZG3HGAAFwYT9PF64TY/en5yUdqrXFsG9owQtFeGFtcGxlIE5GVA=="
  }
}

Publish event

Publish events occur when you publish a package to the network.

Attributes

Publish event attributes:

• sender
• packageId

Example publish event

{
  "publish": {
    "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
    "packageId": "0x5f01a29887a1d95e5b548b616da63b0ce07d816e89ef7b9a382177b4422bbaa2"
  }
}

Transfer object event

Transfer object events occur when you transfer an object from one address to another.

Attributes

Transfer event attributes:

• packageId
• transactionModule
• sender
• recipient
• objectId
• version
• type

Example transfer object event

{
  "transferObject": {
    "packageId": "0x0000000000000000000000000000000000000000000000000000000000000002",
    "transactionModule": "native",
    "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
    "recipient": {
      "AddressOwner": "0xa3c00467938b392a12355397bdd3d319cea5c9b8f4fc9c51b46b8e15a807f030"
    },
    "objectId": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5",
    "version": 1,
    "type": "Coin"
  }
}

Delete object event

Delete object events occur when you delete an object.

Attributes

• packageId
• transactionModule
• sender
• objectId

Example delete object event

{
  "deleteObject": {
    "packageId": "0x5f01a29887a1d95e5b548b616da63b0ce07d816e89ef7b9a382177b4422bbaa2",
    "transactionModule": "discount_coupon",
    "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
    "objectId": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
  }
}

New object event

New object events occur when you create an object on the network.

Attributes

New object event attributes:

• packageId
• transactionModule
• sender
• recipient
• objectId

Example new object event

{
  "newObject": {
    "packageId": "<PACKAGE-ID>",
    "transactionModule": "nft",
    "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
    "recipient": {
      "AddressOwner": "0xa3c00467938b392a12355397bdd3d319cea5c9b8f4fc9c51b46b8e15a807f030"
    },
    "objectId": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
  }
}

Epoch change event

Epoch change events occur when an epoch ends and a new epoch starts.

Attributes

None, Epoch change events do not have any attributes. The event includes an Epoch ID associated with the epochChange.

Example epoch change event

{
  "epochChange": 20
}

Checkpoint event

A checkpoint event occurs for each checkpoint.

Attributes

None, Checkpoint events do not have any attributes. The event includes the Checkpoint sequence number associated with the checkpoint.

Example checkpoint event

{
  "checkpoint": 10
}

IOTA event query criteria

You can use the EventQuery criteria object to query an IOTA node and retrieve events that match query criteria.

Query	Description	JSON-RPC Parameter Example
All	All events	{"All"}
Transaction	Events emitted from the specified transaction.	{"Transaction":"DGUe2TXiJdN3FI6MH1FwghYbiHw+NKu8Nh579zdFtUk="}
MoveModule	Events emitted from the specified Move module	{"MoveModule":{"package":"<PACKAGE-ID>", "module":"nft"}}
MoveEvent	Move struct name of the event	{"MoveEvent":"<PACKAGE-ID>::nft::MintNFTEvent"}
EventType	Type of event described in Events section	{"EventType": "NewObject"}
Sender	Query by sender address	{"Sender":"0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106"}
Recipient	Query by recipient	{"Recipient":{"AddressOwner":"0xa3c00467938b392a12355397bdd3d319cea5c9b8f4fc9c51b46b8e15a807f030"}}
Object	Return events associated with the given object	{"Object":"0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"}
TimeRange	Return events emitted in [start_time, end_time] interval	{"TimeRange":{"startTime":1669039504014, "endTime":1669039604014}}

Pagination

The Event Query API provides cursor-based pagination to make it easier to work with large result sets. You can provide a cursor parameter in paginated query to indicate the starting position of the query. The query returns the number of results specified by limit, and returns the next_cursor value when there are additional results. The maximum limit is 1000 per query.

The following examples demonstrate how to create queries that use pagination for the results.

1. Get all events an nft module emits, in descending time order

Request

curl --location --request POST '127.0.0.1:9000' \
--header 'Content-Type: application/json' \
--data-raw '{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "iota_getEvents",
  "params": [
    {"MoveModule":{"package":"<PACKAGE-ID>", "module":"nft"}},
    null,
    null,
    true
  ]
}'

Response

{
  "jsonrpc": "2.0",
  "result": {
    "data": [
      {
        "timestamp": 1666699837426,
        "txDigest": "cZXsToU6r0Uia6HIAwvr1eMlGsrg6b9+2oYZAskJ0wc=",
        "id": {
          "txSeq": 1001,
          "eventSeq": 1
        },
        "event": {
          "moveEvent": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "type": "<PACKAGE-ID>::nft::MintNFTEvent",
            "fields": {
              "creator": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
              "name": "NFT",
              "object_id": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
            },
            "bcs": "LugLSi0gM2XfvWipCorZoNyhkVX+1JBtcbilg//9jpVnYCe2u4HXzwtFeGFtcGxlIE5GVA=="
          }
        }
      },
      {
        "timestamp": 1666699837426,
        "txDigest": "cZXsToU6r0Uia6HIAwvr1eMlGsrg6b9+2oYZAskJ0wc=",
        "id": {
          "txSeq": 1001,
          "eventSeq": 0
        },
        "event": {
          "newObject": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "recipient": {
              "AddressOwner": "0xa3c00467938b392a12355397bdd3d319cea5c9b8f4fc9c51b46b8e15a807f030"
            },
            "objectId": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
          }
        }
      },
      {
        "timestamp": 1666698739180,
        "txDigest": "WF2V6FM6y/kpAgRqzsQmR/osy4pmTgVVbE6qvSJxWh4=",
        "id": {
          "txSeq": 998,
          "eventSeq": 1
        },
        "event": {
          "moveEvent": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "type": "<PACKAGE-ID>::nft::MintNFTEvent",
            "fields": {
              "creator": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
              "name": "NFT",
              "object_id": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
            },
            "bcs": "1WV89qyrqVjFsB7AUW9PDax3x9L+1JBtcbilg//9jpVnYCe2u4HXzwtFeGFtcGxlIE5GVA=="
          }
        }
      },
      {
        "timestamp": 1666698739180,
        "txDigest": "WF2V6FM6y/kpAgRqzsQmR/osy4pmTgVVbE6qvSJxWh4=",
        "id": {
          "txSeq": 998,
          "eventSeq": 0
        },
        "event": {
          "newObject": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "recipient": {
              "AddressOwner": "0xa3c00467938b392a12355397bdd3d319cea5c9b8f4fc9c51b46b8e15a807f030"
            },
            "objectId": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
          }
        }
      }
    ],
    "nextCursor": null
  },
  "id": 1
}

2. Get all MintNFTEvent events

Request

curl --location --request POST '127.0.0.1:9000' \
--header 'Content-Type: application/json' \
--data-raw '{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "iota_getEvents",
  "params": [
    {"MoveEvent":"<PACKAGE-ID>::nft::MintNFTEvent"},
    null,
    null,
    "Ascending"
  ]
}'

Response

{
  "jsonrpc": "2.0",
  "result": {
    "data": [
      {
        "timestamp": 1666699837426,
        "txDigest": "cZXsToU6r0Uia6HIAwvr1eMlGsrg6b9+2oYZAskJ0wc=",
        "id": {
          "txSeq": 1001,
          "eventSeq": 1
        },
        "event": {
          "moveEvent": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "type": "<PACKAGE-ID>::nft::MintNFTEvent",
            "fields": {
              "creator": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
              "name": "NFT",
              "object_id": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
            },
            "bcs": "LugLSi0gM2XfvWipCorZoNyhkVX+1JBtcbilg//9jpVnYCe2u4HXzwtFeGFtcGxlIE5GVA=="
          }
        }
      },
      {
        "timestamp": 1666698739180,
        "txDigest": "WF2V6FM6y/kpAgRqzsQmR/osy4pmTgVVbE6qvSJxWh4=",
        "id": {
          "txSeq": 998,
          "eventSeq": 1
        },
        "event": {
          "moveEvent": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "type": "<PACKAGE-ID>::nft::MintNFTEvent",
            "fields": {
              "creator": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
              "name": "NFT",
              "object_id": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
            },
            "bcs": "1WV89qyrqVjFsB7AUW9PDax3x9L+1JBtcbilg//9jpVnYCe2u4HXzwtFeGFtcGxlIE5GVA=="
          }
        }
      }
    ],
    "nextCursor": null
  },
  "id": 1
}

3. Get all events and return 2 items per page in descending time order

Request

curl --location --request POST '127.0.0.1:9000' \
--header 'Content-Type: application/json' \
--data-raw '{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "iota_getEvents",
  "params": [
    "All",
    null,
    2,
    "Ascending"
  ]
}'

Response

{
  "jsonrpc": "2.0",
  "result": {
    "data": [
      {
        "timestamp": 1666698739180,
        "txDigest": "WF2V6FM6y/kpAgRqzsQmR/osy4pmTgVVbE6qvSJxWh4=",
        "id": {
          "txSeq": 998,
          "eventSeq": 0
        },
        "event": {
          "newObject": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "recipient": {
              "AddressOwner": "0xa3c00467938b392a12355397bdd3d319cea5c9b8f4fc9c51b46b8e15a807f030"
            },
            "objectId": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
          }
        }
      },
      {
        "timestamp": 1666698739180,
        "txDigest": "WF2V6FM6y/kpAgRqzsQmR/osy4pmTgVVbE6qvSJxWh4=",
        "id": {
          "txSeq": 998,
          "eventSeq": 1
        },
        "event": {
          "moveEvent": {
            "packageId": "<PACKAGE-ID>",
            "transactionModule": "nft",
            "sender": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
            "type": "<PACKAGE-ID>::nft::MintNFTEvent",
            "fields": {
              "creator": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106",
              "name": "NFT",
              "object_id": "0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"
            },
            "bcs": "1WV89qyrqVjFsB7AUW9PDax3x9L+1JBtcbilg//9jpVnYCe2u4HXzwtFeGFtcGxlIE5GVA=="
          }
        }
      }
    ],
    "nextCursor": 3
  },
  "id": 1
}

Subscribe to IOTA events

When you subscribe to the events described in the preceding sections, you can apply event filters to match the events you want to filter.

Event filters

You can use EventFilter to filter the events included in your subscription to the event stream. EventFilter supports filtering on one attribute or a combination of attributes.

List of attributes that support filters

Filter	Description	Applicable to Event Type	JSON-RPC Parameter Example
Package	Move package ID	MoveEvent Publish TransferObject DeleteObject NewObject	{"Package":"<PACKAGE-ID>"}
Module	Move module name	MoveEvent TransferObject DeleteObject NewObject	{"Module":"nft"}
MoveEventType	Move event type defined in the move code	MoveEvent	{"MoveEventType":"<PACKAGE-ID>::nft::MintNFTEvent"}
MoveEventField	Filter using the data fields in the move event object	MoveEvent	{"MoveEventField":{ "path":"/name", "value":"NFT"}}
SenderAddress	Address that started the transaction	MoveEvent Publish TransferObject DeleteObject NewObject	{"SenderAddress": "0x008e9c621f4fdb210b873aab59a1e5bf32ddb1d33ee85eb069b348c234465106"}
EventType	Type of event described in the Events section	MoveEvent Publish TransferObject DeleteObject NewObject EpochChange Checkpoint	{"EventType":"Publish"}
ObjectId	Object ID	TransferObject DeleteObject NewObject	{"ObjectId":"0x727b37454ab13d5c1dbb22e8741bff72b145d1e660f71b275c01f24e7860e5e5"}

Combining filters

IOTA provides a few operators for combining filters:

Operator	Description	JSON-RPC Parameter Example
And	Combine two filters; behaves the same as boolean And operator	{"And":[{"Package":"<PACKAGE-ID>"}, {"Module":"nft"}]}
Or	Combine two filters; behaves the same as boolean Or operator	{"Or":[{"Package":"<PACKAGE-ID>"}, {"Package":"0x1"}]}
All	Combine a list of filters; returns true if all filters match the event	{"All":[{"EventType":"MoveEvent"}, {"Package":"<PACKAGE-ID>"}, {"Module":"nft"}]}
Any	Combine a list of filters; returns true if any filter matches the event	{"Any":[{"EventType":"MoveEvent"}, {"EventType":"TransferObject"}, {"EventType":"DeleteObject"}]}

Example using a combined filter

The following example demonstrates how to subscribe to Move events (MoveEvent) that a <PACKAGE-ID>::nft package emits:

>> {"jsonrpc":"2.0", "id": 1, "method": "iota_subscribeEvent", "params": [{"All":[{"EventType":"MoveEvent"}, {"Package":"<PACKAGE-MODULE-ID>"}, {"Module":"nft"}]}]}
<< {"jsonrpc":"2.0","result":3121662727959200,"id":1}

To unsubscribe from this stream, use:

>> {"jsonrpc":"2.0", "id": 1, "method": "iota_unsubscribeEvent", "params": [3121662727959200]}
<< {"jsonrpc":"2.0","result":true,"id":1}

note

The subscribeEvent and subscribeTransaction methods are deprecated. Please use queryEvents and queryTransactionBlocks instead.