You aren't showing how the callbacks are called. If they are called as methods (i.e.:

$method = $self->{server}->getcallback("data");
$self->$method();
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), you can just look up a coderef by method name for an object using can:

...setcallback(
   data => $self->can("gotdata"),
   connect => $self->can("connected"),
   disconnect => $self->can("disconnect")
)
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If a method isn't available for an object, can will return undef.

If the callbacks are expected to remember what object they belong (i.e. they are called like &{...getcallback("data")}()), use an anonymous sub:

...setcallback(
   data => sub { $obj->gotdata },
   ...
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