SCEA Study Notes

COMMON ARCHITECTURES

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.

• Single tired architecture:
  • one PC involved
  • business logic and data stored in one place
  • not distributed
  • limited in scalability
  • not easier to be integrated with other system
  • single access control
  • less code reusability
  • more secure
• Two tier architecture:
  • client/server, two more PC involved typically
  • small user base
  • distributable
  • data & business logic integrated on the server side
  • user interface may contain part of business logic
  • not easier to maintain
  • less code reusability
  • hard to debug
  • hard to upgrade
  • less higher availability
  • fat client
  • fat server
  • less manageable
  • more secure
• Three- and n-Tier architectures
  • larger user base
  • server or client may have several tiers
  • business logic is moduled and separated
  • task is moduled and separately integrated
  • thin client
  • high code reusability
  • high scalability
  • high maintainability
  • higher availability
  • easier to deploy
  • easier to upgrade
  • easily extendible
  • more manageable
  • less secure
  • strong authentication and encryptions
• Other architectures:
  • Publish/Subscribe
  • Synchronous/Asynchronous
  • Internet/Intranet/Extranet

Recognize the effect of each of the following characteristics on J2EE technology: scalability maintainability, reliability, availability, extensibility, performance, manageability, and security.

• scalability
  Provides a quality service and capacity without changing the system as the system load is increased. Measurement includes response time and transaction volume.
• maintainability
  Corrects flaws in the existing functionality without impacting other components of the system.
• reliability
  Ensures the integrity and consistancy of the application and all its transactions as the system load is increased.
• availability
  Ensures the service and resource are always accessible even if some components fail.
• extensibility
  Adds or modifies the functionality without impacting existing system functionality.
• performance
  Has a good response time and transaction volume in a given time period.
• manageability
  Manages the system to ensure the continued health of a system with respect to performance, scalablity, reliability, availability and security.
• security
  Ensures the system cannot be compromised, including confidentiality and integrity.

Given an architecture described in terms of network layout, list benefits and potential weaknesses associated with it.

• one tiered
  • benefit:
  • weakness:
• two tiered
  • benefit:
  • weakness:
• three & n tiered
  • benefit:
  • weakness: