The DTAP-Street : a phased approach to a development / deployment cycle

The acronym DTAP finds its origin in the words Development, Testing, Acceptance and Production. The DTAP-street is a commonly accepted method to have a phased approach to software development / deployment.

A typical flow works as follows :

• Development – This environment is where the software is developed. It is the first environment that is used. Changes are very frequent here, as this is the first area where creativity is forged into a product.
• Test – A developer is (hopefully) not alone. In the test environment, the complete code base is merged and forged into one single product. The first attempts at standardization and alignment towards the future production environment are made here.
• Acceptation – Once the development team feels that the product is ready, it will be deployed to acceptance. This is a look-alike of the production and used by operations as a staging environment for production releases.
• Production – The real deal… Here the product surely needs to be ready for prime-time.

Sometimes the following are also added ;

• Education / Training – Sometimes a dedicated environment is needed where people can test drive the software in a safe sand box. Due to efficiency reasons, this environment is often time shared with acceptation.
• Backup / Disaster Recovery – Disasters can happen… Therefore some disaster recovery plans may rely on a dedicated backup / disaster recovery location.
• Integration – An environment that is sometimes located between “Test” & “Acceptance” as an intermediate step to test certain partner integrations. Just as with the “eduction” environment, this environment is often time shared with acceptation.

What are the most commonly used formations?

• Live – Production – Many companies rely solely on a production environment. The risk reduction is often neglected in favor of the cost benefit of having one environment.
• Staging – Production/Test – If no real customization are done to the implemented software, then two environments may suffice.
• DTAP – Development/Test/Acceptation/Production – Once customization hit… then a full DTAP-street is needed to reduce the amount of risks involved with software development.
• DTAPB – Development/Test/Acceptation/Production/Backup – This is an enhanced DTAP-street that is capable of doing a disaster recovery. (Sidenote ; The Test/Development environment is often shared with the backup location. This provides the advantage that the resources of the Test/Development can be sacrificed during a disaster.)

What Code / Data flows occur between the environments?

• Software Versions – Software releases go from Development to Test to Acceptation to Production… The timing varies from the chose release management cycle, though typical times are as follows ; Development (Continuous Builds), Test (Daily Build), Acceptation (Once per quarter, three weeks before production), Production (Once per quarter)
• Data – Data flows in the opposite direction as software versions. Data is taken from production and copied to Acceptance / Test / Development. Depending on the environment (and relative security compliancy), the data may be anonymized or even reduced to have a representative production workload of a limited size.