In a Replacement project where the existing system is based around customer accounts.
Develop just enough features to be able to migrate a small number of customer accounts. Migrated accounts should be of the same type. More customers are migrated in increments as soon as any issues that arise with the first customers have been resolved. This pattern is often used together with the Product by product pattern.
- Risk of customer loss is reduced since the new system initially will have a small set of customers
- If there is a large variation in features that are needed for different types of customer this pattern reduces MRP significantly
- Customers will only interact with one system at any one time. Once they are migrated to the new system they will not interact with the old system. This reduces the risk of confusing customers.
- Migration can be performed in small increments
- Migration of the first sets of users can be done with a combination of automatic and manual operations.
- This pattern does not work well if a customer of one type suddenly can change into another type.
- Banking systems and insurance systems
Develop enough features to be able to support one type of customer. Migrate a few of these customers and arrange so that only a few customer representatives handle cases concerning these customers.