# Events

Events are responsible to warn the user that an action has to be taken. Those actions can be signing a new payload, or that the transactions went through.

## Scheduling

Schedule new Vertices events. Make sure to process them afterward to have the SDK process the queued events.

### Parameters

* `evt` : event to be processed

```c
typedef struct
{
    vtc_evt_type_t type; ///< \see vtc_evt_type_t
    size_t bufid; ///< internal buffer ID, used to identify a pending transaction
} vtc_evt_t;


typedef enum
{
    VTC_EVT_TX_READY_TO_SIGN = 0, ///< transaction's payload must be signed: the user must provide the signing function and emit the \c VTC_EVT_TX_READY_TO_SEND event.
    VTC_EVT_TX_SENDING, ///< transaction is being sent to the blockchain API. When the user got the event, the transaction has probably been already sent.
    VTC_EVT_TX_SUCCESS, ///< transaction has been successfully sent and executed, after that event, the buffer is freed.
} vtc_evt_type_t;
```

### Return codes

* `VTC_SUCCESS` on success.
* `VTC_ERROR_NO_MEM` when event queue is full: either process events or increase `VTC_EVENTS_COUNT`.

## Processing

Call this function to have the Vertices SDK process pending events. Whenever calling a Vertices function, make sure to process all the events. To make sure all the events are processed, this function should be called from an infinite loop or OS thread/task. This function will call the user-defined callback if one has been passed when using  `vertices_new`

```
/// \param queue_size
/// \return \c VTC_SUCCESS if event has correctly been processed
ret_code_t
vertices_event_process(size_t *queue_size);

```

### Parameters

`queue_size` : Pointer to `size_t` value that will be replaced with the Vertices interval queue size defining the number of events to be processed.

### Return code

* `VTC_SUCCESS` when the event is correctly processed.&#x20;
* Error code from the event.