High availability (failure inner server)
The DMZ server is able to accept incoming data even if the inner server cannot be reached. A cause for this may be a disturbance in the network connection between the inner Integration Server and the DMZ server, maintenance in the network or a restart of the inner server. Per default, it is assumed that the maintenance window is no longer than two hours, but the standard setting can also be changed in the configuration (see parameter "lifeTime" in section Availability of CommunicationLogService (offline mode).
By using a DMZ cluster of at least two DMZ servers can guarantee an uninterrupted availability of the DMZ side.
The availability strategies of the AuthenticationService and the CommunicationLogService differ, due to different goals. For the AuthenticationService, a caching strategy is used, while with the CommunicationLogService the communication between DMZ server and the inner server is handled by using persistent messages if synchronous messages fail.