Application modernization continued

 

This section of the article discusses a case study on the incremental code-migration strategy of large monolithic base used in supply system. The code migration strategy considers a set of factors that includes scaffolding code, balancing iterations, and grouping related functionality.

Incremental migration only works when it is progressive. Care must be taken to ensure that progress is measured by means of some key indicators. These include tests, percentage of code migration, signoffs and such other indicators. Correspondingly the backlog of the code in the legacy system that must be migrated must also decrease.

Since modernized components are being deployed prior to the completion of the entire system, it is necessary to combine elements from the legacy system with the modernized components to maintain the existing functionality during the development period. Adapters and other wrapping techniques may be needed to provide a communication mechanism between the legacy system and the modernized systems, when dependencies exist.

There is no downtime during the incremental modernization approach and this kind of modernization effort tries to always keep the system fully operational while reducing the amount of rework and technical risk during the modernization. One way to overcome challenges in this regard is to plan the efforts involved in the modernization. A modernization plan must also include the order in which the functionality is going to be modernized.

Another way to overcome challenges is to build and use adapters, bridges and other scaffolding code which represents an added expense, as this code must be designed, developed, tested and maintained during the development period but it eventually reduces the overall development and deployment costs.

Supporting an aggressive and yet predictable schedule also helps in this regard. The componentization strategy should seek to minimize the time required to develop and deploy the modernized system.

This does not necessarily have a tradeoff with quality as both the interim and final stages must be tested and the gates for release and progression towards revisions only helps with the overall predictability and timeline of the new system.

Risk occurs in different forms and some risk is acceptable if it is managed and mitigated properly. Due to the overall size and investment required to complete a system migration, it is important that the overall risk be kept low. The expectations around the system including its performance helps to mitigate these risks.