Replace
Overview
Replace has the same objective as “rebuild,” i.e., the entire application is replaced, but the difference is that you don’t build the application; you replace it with a pre-built application. The application could be a COTS application running in the public cloud, but more recently, it is more common that the replacement is a SaaS service.
The replace pattern is the reverse of the previous options in that there is a very significant impact on the business. The impact on IT is significantly less than the rebuild pattern. IT still needs to execute the migration, build integrations and probably change their operating model to include SaaS. Still, these are well-defined low-risk activities compared to the much greater risk of a rebuild or a reimagine.
Benefits
| Time to migrate |  |
| Technical difficulty |  |
| Strategic Value |  |
Moving to SaaS has the broadest set of benefits of all the options in this analysis. The non-functional capabilities of SaaS applications are already high and improving all the time. As there is no IT development project (although there is, of course, IT integration work), the speed of deployment can be extremely fast indeed. Most SaaS applications can be made available by the vendor either on-demand or in just a few days.
Challenges
The challenges of replacing with SaaS are most significant on the business side. In many situations, there is a need for significant business process change. This may include revisiting end-to-end business processes with a concomitant impact on other existing systems where an integration exists.
The impact on users is also very high. Extensive retraining might be required, existing contracts with business process outsourcing might need renegotiating, and information systems (e.g., data warehouses) might also need significant work to use the new data from the SaaS system.