Relevant data
Background
The bank intends to provide customers with various banking products such as Saving account, Personal Loan, Overdraft, Cards, BNPL, number of free transactions/ATM withdrawals, and other similar products. The bank also offers customers various “subscription packages” with different pricing and parameters for these products (e.g. number of free transactions, cards available, …).
The product design hence suggests a centralized component managing the subscription packages, their mapping to product parameters, and also the relationship between customer and their selected subscription package.
Having such centralized component would also allow us to apply “loyalty mission bonuses” simply by temporarily modifying the product parameters of a customer.
The objective of this document is to define the responsibilities of such component and its communication patterns to respective domain services owning each specific product.
Basic responsibilities of product manager:
Source of truth (SoT) for product parameters per customer, which include (but are not limited to):
Number of cards available
Number of free:
transactions
top-ups
ATM withdrawals
cash-ins
Availability of products (implies feature flags):
BNPL
Personal loan
Overdraft
Interest rates in saving account (pocket / main acc)
Interest rate in personal loan
Price of subscription
…
SoT for base parameters per subscription package
SoT for subscription package selected per customer
Options considered
The additional possible responsibilities of the service are explained in the options below with their benefits and issues briefly described
Synchronization via event choreography | Domain services always synchronously ask before applying the rule | Product manager as SoT for all product rules | |
|---|---|---|---|
Description | Upon changing the product parameter, an event is emitted and the domain microservices owning the specific product synchronize and apply the change. | Domain services do not sync the values upon changing product parameters in product manager, but rather always ask the product manager for the most up to date value whenever needed. However, the product manager does contain the parameters, and does not track the "progress" of parameters (e.g. how many free transactions were already used). | Domain services do not sync the values, but rather always ask the product service whether or not such action is allowed (e.g. creating another card), what's the cost of such action (e.g. issuing a new transaction), or what’s the current parameter set for a product (e.g. current interest rate for saving acct) |
Pros and cons |
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Estimated cost | LOW | MEDIUM | MEDIUM |
Product manager does not need to know about the business logic which has to be applied to individual services. Decoupled from the domain business logic.
Does not fit into the architectural principles of choreography. The process is initiated upon changing the parameters and is not finished for the initiator until the change is applied. The initiator needs visibility over the full e2e process
The above issue could be possibly solved by orchestrating the changes from product manager to downstream for these specific use-cases
Action items
Outcome
The chosen approach is Product manager as SoT for all product rules
Centralizing the product definitions with their progress within a single service gives the service great power to define its own business logic for deciding the product behavior. This allows the service to answer questions such as “If the customer has made 7 transactions this month, has 5 free each month, and on top of that has 10 additional transactions for 50% of the price because of a mission bonus, what is the price of the next transaction?”
Proposed responsibilities of Product manager
On top of the basic responsibilities, the product manager will:
maintain the current “progress” per parameters where it makes sense
expose endpoints to be able to respond to specific questions related to product offering. E.g.:
What’s the cost of next transaction?
What’s the cost of creating another card?
Can the customer use BNPL?
What’s the cost of next ATM withdrawal?
expose endpoints for consumers to notify the product manager of:
an action to be taken
result of the action (done / reverse required)