Java EE Modular Solutions

Web tier access EIS direct or though EJB

use of tiers

Decide on requirements

Based on:

• functionality
• complexity
• scalability

EJB tier

• security
• transactions
• distributed processing

Web tier use of JDBC implications

• ideal for small simple applications with few transaction requirements

• implements all core functionality
• implements transaction management - JTA

Implies:

• poor scaling with complexity
• monolithic

Using Web and EJB tier

• better for:
  • building large scale complex applications
  • complex security/transaction requirements
  • performance requirements
• implications
  • Splits business logic into EJB tier
  • web tier becomes mainly request processing and view

Use of distribution

Must be designed for distributed architecture Use of:

• service locator - to hide location/naming resolution
• business delegate - to hide remote nature
• composite entity/transfer object assembler - to reduce fine grained access

Local

• same virtual machine
• no network overhead
• no serialisation overhead
• low latency
• allows for fine grained control/access

Remote

• more modular
• more reusable
• lower dependency between components
• higher overheads - data copying, latency
• security considerations
• typically more scalable (horizontally) - can split and run on more machines
• more highly available - easier to migrate to different machine in the event of failures