Teiid 8.0 has more or less has the same Admin API as it's 7.x releases. However the Admin connection ownership no longer held with the Teiid. i.e Teiid does not control which port the Admin connection nor the security that goes along, these are now core features from AS itself. However, usage for the purposes of the Teiid Designer is not changed.
Teiid Designer needs to be upgraded to use the 8.0 API and validate all the operations it provides.