Evergreen applications are business applications that continue to evolve as the business changes and therefore provide constant value year after year. At OutSystems, virtually any solution that is deployed using Agile methodologies is required to stay evergreen and subject to a continuous Agile Evolutionary Maintenance process. Part 1 of this article explores the main phases of Agile Evolutionary Maintenance while Part 2 identifies some key technology challenges you must overcome to deliver on the promise of Evergreen Applications.

Setting the Stage

Once your application goes live, it immediately enters the Agile Evolutionary Maintenance phase and will stay in this phase in order to keep up with changing business needs and to address application inefficiencies that are only identified with "real life" demand and conditions. To successfully deliver on this concept, the Agile Maintenance team schedules regular sprint releases focused on delivering the "next most valuable features" for the business.

Through this sequence of regular Evolutionary Maintenance releases, the application will keep up with business needs while minimizing the impact of change on the business. The underlying principle is the same as for general Agile development - fast deployment of the most valuable features, delivered on time and aligned with the business.

The Agile Evolutionary Maintenance Cycle

The Agile Evolutionary Maintenance process is a continuous cycle of application releases. Each cycle includes the following steps:

  1. Gather defects, user feedback and new business needs for the live application. This step is actually a continuous process that normally occurs in parallel with the applications' release process;
  2. Classify and prioritize all the feedback collected;
  3. Convert the classified feedback into project backlog items, agreeing on the next release content. The focus should be on the most critical defects and highest value change requests;
  4. Develop and deploy the Backlog agreed for the next release.

Evolutionary Maintenance using Agile Methods

Evolutionary Maintenance releases depend on the volume and type of change required. In my experience these releases fall into one of the following three categories:

  • Hot Fixes - quick intervention required to fix a critical defect that is dramatically affecting business operation, and deploy it immediately. These interventions are required to be completed in less than 24 hours and in some cases during the next couple of business hours.
  • Sprint Releases - made up of one sprint, lasting one or two weeks. In Agile Evolutionary Maintenance it's common to set regular short releases to keep answering accumulated user feedback and correct non critical defects.
  • Evolutionary Projects - When there is a more substantial business change, then a specific evolutionary maintenance cycle may be extended to a small/medium project with several 2 week sprints. This is a common approach to deploy a very large application: incrementally release extra functionality that has not made it into the initial agile project. Experience has proven time and time again that waiting for the perfect and complete solution leads to a less than expected return on investment due to constant changes in business scope and delayed benefit from the new application features.

The Agile Evolutionary Maintenance cycle is critical to keeping your applications evergreen. Following this approach will dramatically improve overall return on investment over the life of your application.

In Part 2 of this article I will identify some key technology challenges and how you can overcome them to deliver on the promise of evergreen applications.