Connection Timeout

Clients choose their interval, but this may vary between differently configured clients. Clients are permitted to send requests more frequently in the case that their status has changed several times quickly, or in response to a server "clientAction" request. However, it is never expected that the client will poll significantly more slowly than requested.

Therefore, a long delay between polls can be considered as a warning that the printer has been powered off, or the network connection is lost. The server may then report this and take appropriate action (anything from displaying "offline/disconnected" to emailing a technician, this is server dependent).

The precise timeout is not always easy to calculate, especially while printing a job, which may take several seconds, or event minutes.
Therefore, it is recommended that a server calculate two timeouts for a particular job queue.

• Poll timeout recommended to be 2 * <poll interval> + 5s - this specified the time between polls before the server assumes that a device has gone offline or lost its connection.
• Print timeout recommended to be around 60s - this is the time allowed for a printer to accept and print a job before completing with a jobstate "restart"/"delete" before the server can assume that the printer has gone offline. The real time to print a document can vary significantly depending on the printer performance, job length and type of data, therefore it is recommended that a server considers its own usage scenario and adjusts this timeout accordingly.

Some devices will continue to send status poll requests during job printing, to verify that they are still online. In this case the Print Timeout is not essential, but not all clients can be guaranteed to do this. With firmware versions up to 1.3 the HI01X and HI02X interfaces will not issue POST requests after requesting a print job, until the job is complete or has failed, however version 1.4 and later will issue POST requests while printing is in progress.