Java Enterprise Best Practices

Use a Client Simulation Tool

The client simulation tool, often referred to as a benchmark harness or load-testing tool, exercises the application as though one or more users are performing the expected business activity. Some projects adapt their quality assessment testing toolset to create a benchmark harness, other projects build a dedicated harness to exercise the server-side components directly, and others use an off-the-shelf web loading or GUI capture-and-playback tool.

The following three factors are imperative when deciding on a client simulation tool:

• The tool must effectively simulate client activity, including variable pauses in activity such as the time users would take to fill out fields or make selections at decision points.

• The tool should make and record timed measurements of simulated activity between arbitrary points, such as from a simulated user click on a browser to complete page display.

• The tool should not interfere with timing measurements—i.e., it should not add any significant overhead that would measurably affect the times being recorded.

From the J2SE world, here are some tips to keep in mind:

• Build or buy a benchmark harness, which is a tool dedicated to performance measurements and not robustness testing.

• Specify benchmarks based on real user behavior.

• Run benchmarks simulating user behavior across all expected scales.