Forces (which help to decide for or against a 3-tier architecture):

- Flexibility
- # of users
- # of UI (web, WAP)
- Legacy components
- time and $$
- hardware constraints
- system constraints (+ domain specific constraints)
    -> response time (network latency, WAN/LAN)
- legal issues, e.g. FDA approval
- physical environment, e.g. medical systems need to be
     geographically distributed -> influence on # of tiers

Expectations:

- vision of a book with problem/solution pairs
- interconnections/relationships between patterns
- categorize 3-tier architectures
- define paths through the PL
- differentiate between architectural and design patterns
- tool support?