Methods and systems for cross cluster replication are provided. Exemplary methods include: periodically requesting by a follower cluster history from a leader cluster, the history including at least one operation and sequence number pair, the operation having changed data in a primary shard of the leader cluster; receiving history and a first global checkpoint from the leader cluster; when a difference between the first global checkpoint and a second global checkpoint exceeds a user-defined value, concurrently making multiple additional requests for history from the leader cluster; and when a difference between the first global checkpoint and the second global checkpoint is less than a user-defined value, executing the at least one operation, the at least one operation changing data in a primary shard of the follower cluster, such that an index of the follower cluster replicates an index of the leader cluster.

Methods and systems for cross cluster replication are provided. Exemplary methods include: periodically requesting by a follower cluster history from a leader cluster, the history including at least one operation and sequence number pair, the operation having changed data in a primary shard of the leader cluster; receiving history and a first global checkpoint from the leader cluster; when a difference between the first global checkpoint and a second global checkpoint exceeds a user-defined value, concurrently making multiple additional requests for history from the leader cluster; and when a difference between the first global checkpoint and the second global checkpoint is less than a user-defined value, executing the at least one operation, the at least one operation changing data in a primary shard of the follower cluster, such that an index of the follower cluster replicates an index of the leader cluster.

In one example, a method includes allocating separate portions of memory for a control stack and a data stack. The method also includes, upon detecting a call instruction, storing a first return address in the control stack and a second return address in the data stack; and upon detecting a return instruction, popping the first return address from the control stack and the second return address from the data stack and raising an exception if the two return addresses do not match. Otherwise, the return instruction returns the first return address. Additionally, the method includes executing an exception handler in response to the return instruction detecting an exception, wherein the exception handler is to pop one or more return addresses from the control stack until the return address on a top of the control stack matches the return address on a top of the data stack.

In general, embodiments relate to a method for providing solutions to hardware component failures, comprising: creating a device state chain using a device state path, a current device state, and a next device state for a device; identifying root cause of a hardware component failure in the device using the device state chain; performing a context-aware search in a shared storage using the root cause of the hardware component failure; and obtaining, in response to the context-aware search, a result specifying a proposed solution for the hardware component failure.

Techniques for processing a request may include: providing tasks to a state machine framework, wherein the tasks perform processing of a workflow for servicing the request; generating, by the state machine framework, a state machine for processing the request, wherein the state machine includes states associated with the tasks, wherein generating the state machine may include automatically determining a first state transition of the state machine between a first and a second of the states; receiving the request; and responsive to receiving the request, performing first processing using the state machine to service the request. The framework may automatically generate triggers that drive the state machine to determine subsequent states in accordance with defined state transitions. State machine internal state information may be persistently stored and used in restoring the state machine to one of its states in connection processing of the command.

Techniques for processing a request may include: providing tasks to a state machine framework, wherein the tasks perform processing of a workflow for servicing the request; generating, by the state machine framework, a state machine for processing the request, wherein the state machine includes states associated with the tasks, wherein generating the state machine may include automatically determining a first state transition of the state machine between a first and a second of the states; receiving the request; and responsive to receiving the request, performing first processing using the state machine to service the request. The framework may automatically generate triggers that drive the state machine to determine subsequent states in accordance with defined state transitions. State machine internal state information may be persistently stored and used in restoring the state machine to one of its states in connection processing of the command.

There is disclosed a circuit for monitoring the security of a processor, wherein the circuit is configured to access a memory configured to store execution context data of a software program executed by the processor; to determine one or more signatures from said execution context data; and to compare said signatures with predefined signatures to monitor the security of the processor (110). Developments describe that context data can comprise control flow data, that a signature can comprise a hash value or a similarity signature, or that the integrity of signatures can be verified for example by using a secret key (e.g. obtained by random, or by using a physically unclonable function). Further developments describe various controls or retroactions on the processor, as well as various countermeasures if cyber attacks are determined.

There is disclosed a circuit for monitoring the security of a processor, wherein the circuit is configured to access a memory configured to store execution context data of a software program executed by the processor; to determine one or more signatures from said execution context data; and to compare said signatures with predefined signatures to monitor the security of the processor (110). Developments describe that context data can comprise control flow data, that a signature can comprise a hash value or a similarity signature, or that the integrity of signatures can be verified for example by using a secret key (e.g. obtained by random, or by using a physically unclonable function). Further developments describe various controls or retroactions on the processor, as well as various countermeasures if cyber attacks are determined.

Systems and techniques are provided for Byzantine agreement in open networks. An indication to change a validation network for an open network from a current validation network to a next validation network may be broadcast. An agreement to change to the validation network to the next validation network may be. An instance of external validity multi-valued Byzantine agreement may be run to determine a continuing sequence number to be used by the next validation network based on the sequence numbers of amendments applied to decentralized database copies stored node computing devices of the open network. The next validation network may be switched to as the validation network for the open network after the continuing sequence number is determined. An amendment validated by the next validation network may be applied to a decentralized database copy. The amendment may include a sequence number that is higher than the continuing sequence number.

Systems and techniques are provided for Byzantine agreement in open networks. An indication to change a validation network for an open network from a current validation network to a next validation network may be broadcast. An agreement to change to the validation network to the next validation network may be. An instance of external validity multi-valued Byzantine agreement may be run to determine a continuing sequence number to be used by the next validation network based on the sequence numbers of amendments applied to decentralized database copies stored node computing devices of the open network. The next validation network may be switched to as the validation network for the open network after the continuing sequence number is determined. An amendment validated by the next validation network may be applied to a decentralized database copy. The amendment may include a sequence number that is higher than the continuing sequence number.