Objective 2.1: Recognize the effect on each of the following characteristics of two tier, three tier and multi-tier architectures: scalability, maintainability, reliability, availability, extensibility, performance, manageability, and security
Objective 2.2: Recognize the effect of each of the following characteristics on J2EE technology: scalability, maintainability, reliability, availability, extensibility, performance, manageability, and security
Manageability
Manageability is the ability to monitor the system with respect to the other QoS requirements and to perform preventive maintenance on the system,
in order to ensure its health.
Although less flexible, single tier systems are usually more manageable than multi tier systems.
Effects
1 tier:
Relatively easy.
2 tier:
Poor. Updates have to be applied to all clients in turn.
n tier:
Mixed. Due to the distributed nature, multi tiered system can be hard to manage. Having
multiple instances allows day to day maintenance and the centralized business logic allows easy updates.
J2EE:
The component based architecture of J2EE, if used properly, can decrease the managereal problems caused by multi tiered systems.