US 7,496,668 B2Granted

OPC server redirection manager

AssigneeHoneywell International Inc.

InventorsEllen B. Hawkinson, Timothy J. Fortin, Anuradha Vidyashankar

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Abstract

An OPC redirection manager maintains the information necessary for taking appropriate action when the target OPC server fails and for ensuring that no bad status is returned to the client. Any existing OPC client needing seamless failover between target OPC data access and/or alarm and event servers will connect to a uniquely configured instance of the redirection manager instead of connecting to the primary server. The client application continues to perform OPC related tasks as usual. Because each client connection is unique, the redirection manager itself is not a single point of failure. Each configured redirection manager instance monitors the health of the target server mode and the target server itself by subscribing to failure events.

A redirection management method for an OPC system in which first and second clients communicate with first and second OPO target servers that read and write data to a device, comprising:

operating an OPC redirection manager for communications between said first and second OPC clients and said first and second OPC target servers to respond to:
a first client connection request for said first OPO client by granting said first OPC client a first private connection to a first instance of said OPC redirection manager;
a second client connection request for said second OPC client by granting said second client a second private connection to a second instance of said OPC redirection manager, wherein said first and second instances execute in first and second unique address spaces such that if said second instance fails, only said second private connection for said second OPC client is lost and said first private connection is maintained for said first OPC client, and wherein at least one of said first and second OPC target servers is connected to said device;
connecting to said first target OPO server;
connecting to an OPC server status change provider for said first target OPC server;
connecting to at least one additional target OPC server, including said second target OPC server configured to backup said first target OPC server;
receiving an OPC add-group request from said first OPC client;
forwarding said OPC add-group request with add-group parameters to said first target OPC server to service said OPC add-group request;
upon receiving a request-complete event from said first target OPO server, implementing a plurality of add-group interfaces associated with said OPC add-group request by creating at least one group;
forwarding said OPC add-group request and said add-group parameters to each of said at least one additional target OPC server to store said at least one group as inactive;
and
storing information related to said OPC add-group request, including said at least one group.

9 more elements

Facts

Application

10/403,704Filed 31 Mar 2003 · us provisional application

Priority

28 Jun 2002

Published

US 2004/0006624 A18 Jan 2004

Granted

24 Feb 2009

Term ends

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Classification15 codes

H04L 67/1095
In which an application is distributed across nodes in the network: replication or mirroring of data, e.g. scheduling or transport for data…
H04L 67/1008
Server selection for load balancing: based on parameters of servers, e.g. available memory or workload
H04L 67/1029
For accessing one among a plurality of replicated servers: using data related to the state of servers by a load balancer
H04L 67/1034
For accessing one among a plurality of replicated servers: reaction to server failures by a load balancer

Abstract

Claims4