Abstract: Instructing a plurality of worker systems in a distributed computing system to perform a checkpoint. Instructing the worker systems includes receiving timing messages from the plurality of worker systems and determining, based on the received timing messages, a common checkpoint time indicating an estimated amount of time to be taken by the plurality of worker systems to write data to the persistent storage for a subsequent checkpoint. The common checkpoint time is used to determine a checkpoint threshold, and responsive to the determined checkpoint threshold, it is determined whether to perform the checkpoint. Responsive to determining to perform the checkpoint, messages are transmitted to the plurality of worker systems instructing the worker systems to perform the checkpoint.

Abstract: An exemplary device comprises a first and second protocol layer, and an information exchange service (IES) in communication with the first and the second protocol layers. The IES is configured to share control information between the protocol layers. A protocol layer is capable of adapting behavior based on the control information shared by the IES. An exemplary method is presented for communicating between publishing and subscribing layers in a protocol stack. The method comprises, in the publishing layer, specifying a selected attribute and an associated value to be shared with the subscribing layer. The method further comprises storing the specified attribute and associated value, and receiving a subscribe request from the requesting layer. The request specifies the published attribute. The method further comprises, in response to the request, providing the associated value to a subscribing layer, and in the subscribing layer, adapting behavior based on the shared control information.

Abstract: A circuit for producing an output pulse of predetermined amplitude and a width equal to the mid amplitude width of an input pulse from an electro-optical label reading system is provided. The present circuit comprises delay line means having a first output terminal and a second output terminal with the signal at the second output terminal being delayed twice the time of the delay at the first terminal. The first output terminal of the delay line is connected to an amplifier operative to double the amplitude of the signal applied thereto. The output of the amplifier is connected to one input of each of first and second comparators with the other input to the comparators respectively connected to the input signal source and the second terminal of the delay line. The output of the comparators is connected to the input to an AND gate with the output from the AND gate providing the desired pulse width information.