NCI maintains several groups of servers, also referred to as "tiers," to facilitate development, QA, User Acceptance Testing (UAT), UML Model loading, etc. Following are explanations for each tier.
Once the development team has completed a set of enhancements, the source is extracted for the Source Control Management (SCM) system, built and deployed onto QA for the purpose of qualifying the product changes. Development team unit testing is completed prior to QA deployments to guarantee the QA team is using stable software. Bugs found during QA testing are opened as formal trackers. In some cases a Subject Matter Expert (SME) may be asked to certify a requested feature on the QA tier. However, this tier is only accessible behind the NIH firewall and SME verification of the product may wait until Stage or the SME will be given an NIH account.
Once QA testing is complete the product is promoted to the Stage tier for UAT. QA will perform a few more broad tests using the Stage tier prior to announcing the UAT is open. This guarantees the deployment was completed correctly and nothing was forgotten. During the UAT a group of users will certify the bug fixes and features documented in the product Release Notes. Stage is also used by the Development team to recreate bugs found on Production. Sometimes, caDSR curators use this tier for training.
Once UAT is complete the product is promoted to Production. This is the master copy of the caDSR database and tools. The content on all other tiers is periodically updated using Production.