**Source URL:** https://general.veevavault.dev/medical/mdl/component-types/queue.md

**Class: ** `metadata`

Spark messaging is a message notification system that allows for loosely coupled, asynchronous, near real-time integration between Vaults or external applications. Messages are processed by a queuing system to provide reliable delivery. Outbound messages are placed in an outbound queue, and delivered messages enter an inbound queue.

Learn about <a href="https://platform.veevavault.help/en/lr/53147" target="_blank">Creating & Managing Queues in Vault Help</a>.

| Attribute | Metadata | Description |
| --- | --- | --- |
| label | Type: StringMax length: 60 | UI-friendly string in the Vault's base language. |
| active | Type: Boolean | Indicates whether the field is active. |
| description | Type: StringMax length: 500 | The description of the queue. |
| message_delivery_event_handler | Type: ComponentReference | Specifies the optional Spark message delivery event handler to use for outbound queues. References the Messagedeliveryeventhandler component. |
| message_delivery_event_handler_user | Type: StringMax length: 1500 | Indicate the user who will process Spark message delivery event handler actions for the outbound queue. Applicable only when message_delivery_event_handler is configured. |
| message_processor | Type: ComponentReference | References the Messageprocessor component. |
| message_processor_user | Type: StringMax length: 1500 | Indicates the user who will process messages delivered to an Inbound queue. |
| rollback_on_error | Type: Boolean | Indicates whether this queue will continue the transaction when a message fails to enter the queue. If the type is job, Vault ignores this attribute. |
| sequential | Type: Boolean | Indicates if the messages intended for this queue must be processed sequentially, meaning one after another in the order they are received. If the type is job, Vault ignores this attribute. |
| type | Type: EnumRequiredAllowed values:inboundoutboundjob | Specifies whether the queue is Outbound (sends messages), or Inbound (receives messages). |

### Queueconnection {#queueconnection}

| Attribute | Metadata | Description |
| --- | --- | --- |
| label | Type: StringMax length: 60 | UI-friendly string in the Vault's base language. |
| active | Type: Boolean | Indicates whether the field is active. |
| connection_name | Type: StringRequiredMax length: 40 | The name of the connection. |
| connection_type | Type: StringMax length: 40 | The type of queue connection. |
| deliver_to_queue | Type: StringMax length: 1500 | The name of the connected queue. |

### Supported Operations {#supported-operations}

| Operation | Support |
| --- | --- |
| Create | Yes |
| Recreate | Yes |
| Alter | Yes |
| Drop | Yes |
| Rename | Yes |
| Describe | Yes |
| Generate Recreate | Yes |
| Queryable | Yes |


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