Pinpointing patch impact test targets of web server systems

The greatest bottleneck in the updating of software programs (i.e. patching) is the time required to test a patched subset of systems for stability before rolling out the patch to all systems. For web servers, comprehensive tests are required for all web content. Even if we knew which modules would be updated by a patch, these tests would be unavoidable because we could not necessarily know the relationship between the web contents and web server modules. To reduce the test operation steps to perform, we propose a method of identifying the specific subset of web content and the web server modules that might be affected by a patch by identifying the relationship between the contents and modules. To estimate how much of a reduction could be made in the test operation steps, we conducted an evaluation using an actual web server system, which provides six web content groups. Our method identified that 23% of the web server modules were used by only one web content group. If we assume a patch would replaces these modules, the expected reduction in the test steps was 83% of the steps required to test all web content groups. The evaluation results implied that our method was effective in reducing the number of test steps.