Coarse-grained vs fine-grained
In simple terms
- Coarse-grained - larger components than fine-grained, large subcomponents. Simply wraps one or more fine-grained services together into a more coarse-grained operation.
- Fine-grained - smaller components of which the larger ones are composed, lowerlevel service
It is better to have more coarse-grained service operations, which are composed by fine-grained operations
From Wikipedia (granularity):
Granularity is the extent to which a system is broken down into small parts, either the system itself or its description or observation. It is the extent to which a larger entity is subdivided. For example, a yard broken into inches has finer granularity than a yard broken into feet.
Coarse-grained systems consist of fewer, larger components than fine-grained systems; a coarse-grained description of a system regards large subcomponents while a fine-grained description regards smaller components of which the larger ones are composed.
Coarse-grained: A few ojects hold a lot of related data that's why services have broader scope in functionality. Example: A single "Account" object holds the customer name, address, account balance, opening date, last change date, etc. Thus: Increased design complexity, smaller number of cells to various operations
Fine-grained: More objects each holding less data that's why services have more narrow scope in functionality. Example: An Account object holds balance, a Customer object holds name and address, a AccountOpenings object holds opening date, etc. Thus: Decreased design complexity , higher number of cells to various service operations. These are relationships defined between these objects.