International Business Machines Corporation

Andrew Henry Richter

Jeffrey Douglas Haggar

Edward Glen Britton

Barton Clark Vashaw

Michael G Fitzpatrick

Maurice Isrel

Thomas Donald Moore

Paul Anderson

Michael E Baskey

Wim De Pauw

Dilip Dinkar Kandlur

Grace Ann Richter

Rohit Dilip Kelapure

John Andrew Aiken, Jr

James L Hall

Belinda L Thompson

Techniques are disclosed for calculating large precision common logarithms. A common logarithm may be calculated using addition and/or subtraction of known logarithm values. Embodiments of the invention permit calculation of common logarithms of real numbers stored within character arrays, where each element of the array corresponds to a digit in the real number.

Calculating large precision common logarithms

Embodiments of the present invention address deficiencies of the art in respect to workload management of backend systems and provide a novel and non-obvious method, system and computer program product for limiting a request rate from a client based on a health state of a server system. In one embodiment of the invention, a computer-implemented method for limiting a request rate from a client based on a health state of a server system that includes monitoring a server system, determining a measure of health of the server system, sending the determined measure of health to a client submitting a request to the server system and receiving a subsequent request from the client that is delayed by a time period, wherein the time period is based at least in part upon the determined measure of health. The computer-implemented method can further include receiving server system CPU utilization, determining an approximate predicted real server response time of a transaction and sending the determined approximate predicted real server response time of a transaction to a client submitting a request to the server system.

Reducing workload on a backend system using client side request throttling

A method for enabling connectivity for protocol aware applications across different network topologies can include receiving frames passing between a first network having a first network topology and a second network having a second network topology; inspecting an incoming one of the frames to identify a remote resource in the second network and a device identifier corresponding to the remote resource, and an outgoing one of the frames to identify a socket assigned to a local resource in the first network and a device identifier for the local resource corresponding to the socket; and, transmitting data from a protocol-aware application in the first network to the remote resource in the second network in a protocol consistent with the second network topology, and further transmitting data from the remote resource in the second network to the protocol-aware application in the first network in a protocol consistent with the first network topology.

Dynamic translational topology layer for enabling connectivity for protocol aware applications

The invention ensures that a single and consistent reply is made to ARP request in a system of connected IP networks. When an adapter (A) becomes active, the owning host sends an ARP advertisement into the network over the adapter. If the advertisement is also received at the sending host over a different adapter B, then the host knows that adapter B is on in the same physical network as adapter A and B can be designated as a backup adapter for A and A can be designated as backup adapter for B. If adapter A fails or becomes inactive, the host resets the backup adapter field for any adapter it owns for which A is marked as the backup adapter. If a backup adapter B has been designated for A, the host also sends an ARP advertisement associating MAC-B with IP-A. This allows network connections originally served via adapter A to continue non-disruptively over adapter B and it also provides access to the host for subsequent new connections. When adapter A becomes active again, the host sends a gratuitous ARP advertisement that maps IP-A to MAC-A. This allows adapter A to re-assume responsibility for responding to ARP requests for IP-A.

Method and apparatus for generating replies to address resolution protocol requests

The invention ensures that a single and consistent reply is made to an ARP request in a system of connected IP networks. When an adapter becomes active, the relative network on which it resides is determined by transmitting control packets over it and all other adapters known to the host and observing if and where responses are returned to the adapters. One adapter on a network is designated as active. If the same network contains other adapters, they are marked as standby adapters for the purpose of responding to ARP messages. Special processing is provided for offload adapters that perform there own ARP processing.

Method and apparatus for generating replies to address resolution protocol requests for virtual IP addresses

The invention ensures that a single and consistent reply is made to ARP requests in a system of connected IP networks in which each host can contain combinations of host adapters, offload adapters and virtual IP addresses.

Methods, systems and computer program products are provided for transferring a Virtual IP Address (VIPA) from a first application instance to a second application instance executing on a cluster of data processing systems having a plurality of communication protocol stacks. A list of dynamic VIPAs is distributed among the protocol stacks and a hierarchy of backup communication protocol stacks for the dynamic VIPAs is determined based on the list of dynamic VIPAs. Upon receiving notification of failure of the first stack the second stack evaluates the hierarchy of backup stacks to determine if it is the next stack in the hierarchy for the VIPA associated with the first application instance. If so, then the VIPA associated with the first application instance is transferred to the second communication protocol stack associated with the second application instance.

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Raleigh, NC, United States of America

Andrew Henry Richter