OPC server redirection manager

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.

Description

CROSS REFERENCE [0001] This application is a divisional application of U.S. patent application Ser. No. 10 / 403,704, filed on Mar. 31, 2003, which claims priority of U.S. Provisional Patent Application Ser. No. 60 / 392493, filed on Jun. 28, 2002, entitled “OPC Server Redirection Manager.”BACKGROUND [0002] 1. Field of the Invention [0003] The present invention generally relates to an OPC server redirection manager, which is an intermediate OPC server that forwards all OPC calls made by clients to actual OPC servers that communicate with data sources. In particular, the OPC server redirection manager maintains the information necessary to take appropriate action when a target OPC server fails and ensures that no bad status is returned to a client. [0004] 2. Description of the Related Art [0005] OLE FOR PROCESS CONTROL® (OPC®) is an emerging industry standard that facilitates integration by allowing automation systems to share information and interoperate with other industrial automation...

AI Technical Summary

Benefits of technology

[0017] A connection is made by the redirection manager to the primary target OPC server. Additional connections are made by the redirection manager to an OPC server status change provider for the primary target OPC server and to additional target OPC server(s). If it is determined that the primary target OPC server supports OPC alarms and events, an alarms-and-events module is loaded. At least one on-event request is provided to the OPC client from the primary target OPC server. Upon receiving an active-server-failed event from the OPC server status change provider for the primary target OPC server, a switchover to the secondary target OPC server is performed and the alarms-and-events module is notified of the switchover. A currently active event is synchronized with the secondary target OPC server to prevent loss of data and an OPC on-event request is provided to the OPC client from the secondary target OPC server. When notice from the OPC server status change provider is received that the primary target OPC server is now available, a connection is made to the primary target OPC server and it is established with the state information.

Problems solved by technology

If that service fails, then all connected clients are impacted.

If the private connection fails, then only the connected client is impacted.

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