3-Tier Architecture

Question 1

What are the three tiers of a 3-tier architecture?

Answer 1

3-tier architecture = a client-server architecture,

• presentation layer (interface, top or surface layer)
• application layer (middle or business logic layer)
• database layer (core layer)

Question 2

Can those tiers be changed or upgraded independently?

Answer 2

Yes.

Question 3

When do you use a 3-tier architecture?

Answer 3

Web applications that
• have large databases
• many operational features that are demanded by the presentation layer

For:
SECURITY: A physically separation between tiers and the attack surface on the web server is reduced because there is a reduced amount of code, etc running on the web server. But it ADDS COMPLEXITY.

SCALABILITY: A 3-tier architecture is more scalable than a 2-tier architecture because the web-tier and middle-tier can be scaled differently if necessary.

PERFORMANCE: More specific work designation and therefore reduces the stress on the entire network.

REUSE AND MAINTENANCE: A single physical middle-tier can be shared by a number of clients, so reuse and maintenance is increased.