Enum GattsEvent 

pub enum GattsEvent<'a> {
    Register(BleGattRegister),
    Read {
        conn_handle: ConnHandle,
        attr_handle: AttrHandle,
        offset: u16,
        reply: Mbuf<'a>,
    },
    Write {
        conn_handle: ConnHandle,
        attr_handle: AttrHandle,
        data: Mbuf<'a>,
    },
    SubscriptionChanged {
        conn_handle: ConnHandle,
        attr_handle: AttrHandle,
        reason: SubscribeReason,
        prev_notify: bool,
        cur_notify: bool,
        prev_indicate: bool,
        cur_indicate: bool,
    },
    NotifyComplete {
        conn_handle: ConnHandle,
        attr_handle: AttrHandle,
        indication: bool,
        status: i32,
    },
}

A GATT-server event, delivered on the host task to the single gatts_subscribe hook.

There are no per-characteristic callbacks: NimBLE dispatches every characteristic read and write through one shared trampoline, and they arrive here as Read / Write, keyed by the globally-unique attr_handle. The Register variants fire as the service table is registered (at start). SubscriptionChanged and NotifyComplete are server-role connection events that NimBLE delivers on the GAP callback and we demux here.

The hook returns the ATT status (0 on success) for Read/Write; the return is ignored for the others.

Variants

Register(BleGattRegister)

Read

A peer is reading one of our characteristics; append the value to reply.

This covers every ATT read (Read Request, Read Blob Request, Read By Type Request, Read Multiple Request) — NimBLE reports them all the same way — as well as local reads, which carry CONN_HANDLE_NONE instead of a real connection.

Fields

conn_handle: ConnHandle

attr_handle: AttrHandle

offset: u16

Non-zero only for a long read (ATT Read Blob Request), where it is the offset the peer is asking to continue from.

Always append the whole value regardless of this field: NimBLE hands a long read a scratch buffer and slices [offset..] out of it itself. The offset is informational — use it to tell a continuation from a fresh read (e.g. to snapshot the value at offset 0 so a multi-blob read stays coherent).

Always 0 on ESP-IDF < 5.3, where NimBLE does not report the offset at all.

reply: Mbuf<'a>

Write

A peer wrote one of our characteristics.

This covers every ATT write — Write Request, Write Command (write-without-response), Signed Write Command, and a completed Prepare/Execute long write (NimBLE coalesces the queued fragments into one event) — as NimBLE does not report which opcode carried the write. It need not be distinguished: for a Write Request the status returned by the hook becomes the ATT error response, and for a Write Command (which has no response) it is discarded. Local writes arrive here too, with CONN_HANDLE_NONE.

Fields

conn_handle: ConnHandle

attr_handle: AttrHandle

data: Mbuf<'a>

SubscriptionChanged

A peer’s subscription state for one of our characteristics changed: it wrote the CCCD, the connection is going down, or a bond was restored — see reason. The prev_* / cur_* pairs give the edge, so no shadow state is needed to tell a subscribe from an unsubscribe.

Fields

conn_handle: ConnHandle

attr_handle: AttrHandle

reason: SubscribeReason

prev_notify: bool

cur_notify: bool

prev_indicate: bool

cur_indicate: bool

NotifyComplete

An indication/notification we sent completed (for an indication, status is the peer’s confirmation result).

Fields

conn_handle: ConnHandle

attr_handle: AttrHandle

indication: bool

status: i32