interface Factory
{
    public function sayHello();
}

class ParentClass implements Factory
{
    public function sayHello()
    {
        echo "hello\n";
    }
}

class ChildrenClass extends ParentClass
{

}

$reflect = new ReflectionClass('ParentClass');
var_dump($reflect->implementsInterface('Factory'));

$second_ref = new ReflectionClass('ChildrenClass');
var_dump($second_ref->isSubclassOf('ParentClass'));

$third_ref = new ReflectionClass('Factory');
var_dump($third_ref->isInterface());

//can not be called as static
var_dump(ReflectionClass::isInterface('Factory'));
die;
//#result
bool(true)
bool(true)
bool(true)
PHP Fatal error:  Non-static method ReflectionClass::isInterface() cannot be called statically