Abstract: A call processing system, which may include multiple distributed call center sites, utilizes a local back-off approach to endpoint registration. The call processing system comprises a plurality of endpoints and at least a first server, wherein the endpoints register with the first server in order to send and receive calls in the call processing system. Responsive to an end-to-end connectivity failure or other designated event, a registration process is initiated in the call processing system for a given one of the endpoints. The issuance of at least one message of the sequence for the given endpoint is controlled so as to provide a local random back-off or other local back-off of the controlled message at that endpoint. For example, a second server implemented as an aggregation server may be operative to control the issuance of messages by the endpoints so as to provide a local random back-off for each of the plurality of endpoints by staggering the delivery of failure notifications to the endpoints.

Abstract: By checkpointing and restoring a user application process, that includes a volatile state and a persistent state, recovery of an application process from the checkpoint position is possible. Specifically, a volatile state is checkpointed in a checkpoint position. Next, the persistent state is monitored to detect a file operation following a checkpoint position that will modify the persistent state. Then, portions of the persistent state are checkpointed if a modification of the persistent state is about to be performed. Then, a recovery to the checkpoint position can be performed such that modifications to the persistent state since the checkpoint position are undone. This allows for resumption of the user application process from the checkpoint position.

Abstract: A checkpoint and restoration system is disclosed to provide checkpoint and restoration techniques for user application processes which save the process state, including the volatile state and desired portions of the persistent state, during normal execution, and thereafter restore the saved state. A lazy checkpoint technique is disclosed which delays the taking of the persistent state checkpoint until an inconsistency between the checkpointed volatile state and a portion of the persistent state is about to occur. The disclosed checkpoint and restoration system allows a user or a user application process to specify selected portions of the persistent state to be excluded from a checkpoint. A selected portion of the pre-restoring process state, such as a return value argument, may be protected before restoring the user application process to a checkpointed state, so that the pre-restoration values of the protected state are retained following restoration of the checkpoint.