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Thursday, May 13, 2010
Release It! - 17.2 Designing for Transparency
Transparency arises from deliberate design and architecture. “Adding transparency” late in development is about as effective as “adding quality.” Visibility inside one application or server is not enough. Strictly local visibility leads to strictly local optimization. Visibility into one application at a time can also mask problems with scaling effects. In designing for transparency, keep a close eye on coupling. It’s relatively easy for the monitoring framework to intrude on the internals of the system. The monitoring and reporting systems should be like an exoskeleton built around your system, not woven into it. In particular, decisions about what metrics should trigger alerts, where to set the thresholds, and how to “roll up” state variables into an overall system health status should all be left outside of the application itself. These are policy decisions that will change at a very different rate than the application code itself will.