Jan 22 2008
Earlier today, while I was answering questions on OTN’s Oracle Call Interface forum, an inquiry came in regarding the usage of Transparent Application Failover (TAF) with dedicated server instances. In particular, it was questioning whether or not TAF would work in a non-RAC environment.
The basis of the question was that TAF is seemingly mentioned only in conjunction with RAC. While TAF can certainly be used without RAC, this blog entry is intended to discuss the history of TAF, how it works, and the types of environments it can be used in.
Transparent Application Failover: A Brief History
First introduced in 1997, TAF was released as part of Oracle 8.0 for use with Oracle Parallel Server (OPS). The design goal of TAF was to transparently handle OPS node failure by automatically reestablishing database connections and performing session migration to a remaining node. Contrary to what some information on the net says, TAF is a client-side feature built into Oracle Net.
How TAF Works
As mentioned in the brief history of TAF, it is a client-side feature of Oracle Net. As such, several layers of Oracle Net are responsible for signaling your application when a failure occurs. However, from a user standpoint, the method by which Oracle Net informs your program of a failure is through callbacks provided in OCI.
Use-Cases for TAF
Having now covered the history and basics of TAF operation,
How to use TAF
If you’ve read the above and are ready to play with TAF, here’s a brief intro.
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