Address managing method and communication apparatus

A communication apparatus which establishes a one-way data connection utilized for one-way data transmission to another communication apparatus, and a connection to a network through which a message is transferred in two ways, said communication apparatus comprising:

• a one-way data connection status detecting unit operable to detect a connection validating request showing that data transmission, utilizing the one-way data connection, to the other communication apparatus is possible, and a connection invalidating request showing that the data transmission, utilizing the one-way data connection, to the other communication apparatus is impossible, the connection validating request and the connection invalidating request being outputted from the other communication apparatus;
• an apparatus address obtaining unit operable to obtain an apparatus address with the message via the network when a change from the connection invalidating request to the connection validating request is detected;
• an address holding unit which holds the apparatus address;
• and
• a message transmission continuing unit operable to respond to the message received via the network, based on the apparatus address held by said address holding unit regardless of whether or not said one-way data connection status detecting unit detects the connection invalidating request.