single subscriber/publisher subscribes/publishes multi topics

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Hi guys,

I have noticed that the description of DDS, subscriber/publisher could have multiple readers/writers, which means one subscriber/publisher can sub/pub different topics. But in the ROS2 demo,

publisher_ = this->create_publisher<std_msgs::msg::string>("topic", 10);

publisher_ can only publish messages to "/topic".

Is it possible for publisher_ to publish messages to both "/topic" and "/topic2"? Thanks.