| 摘要 |
A publish/subscribe interface is used to enable a non-publish/subscribe first system (such as an IP network device) to obtain status information about a publish/subscribe device that cannot be pinged by the first system. The first system sends a status request to a domain name server associated with a system known to include the publish/subscribe device. The status request includes a domain name for the publish/subscribe device. Topic space maintained by a message broker in the publish/subscribe system includes status topics associated with publish/subscribe devices. The status topics contents reflect the current availability of the associated publish/subscribe device. The domain name is mapped to a status topic associated to the publish/subscribe device identified in the status request and the contents of that status topic are retrieved. If the contents have a first value, a "good" IP address is returned to the first system. If the contents have the second value, a "bad" IP address is returned. The return address is used in ping messages. If the ping operation succeeds, it is concluded the publish/subscribe device is online. If the ping operation fails, it is concluded that the publish/subscribe device is off-line.
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