C l i e n t / S e r v e r Te c h n o l o g yTw o - T i e r A r c h i t e c t u r e

T h r e e - T i e r A r c h i t e c t u r e

Josh AntonelliJenn Lang

Joe SchisselbauerChad Williams

Client/Server Technology• A computational

architecture that involves client processes (service consumers) requesting service from server processes (service providers).

• Client/server applications provide a reasonable mechanism for organizations to design applications that fit their business needs.

Features of Client/Server Model

1. Clients and Servers are functional modules with well defined interfaces, i.e., they hide internal information.

2. Each client/server relationship is established between two functional modules. One module initiates service requests and the other module responds to these requests.

3. Information exchange between clients and servers , i.e., requests and responses, are strictly through messages.

4. Message exchange is typically interactive.5. Clients and servers may run on separate dedicated machines

connected through a network.

Two Tier Architecture

• Divided into two parts:– Client Tier – where requests are sent from the client to the

database– Data Tier – consists of the database, where requests are

processed and data is sent back to the client.

Two Tier Architecture

• Characteristics:– Is a Client Server Application– Runs very fast because there is no intermediary

(Application Server)– Easy to Maintain

Two Tier Architecture

• Negatives:– Scalability Problems, where performance weakens

as the number of users increases.– Limited Interoperability.– Expensive maintenance costs.

• Definition: An application partitioned into three logical tiers: the presentation tier, the processing tier, and the data tier.

• Presentation tier (Tier 1): responsible for the graphical user interface layer.

• Processing tier (Tier 2): contains the business logic and is responsible for the processing associated with the applications supported.

• Data tier (Tier 3): Holds the permanent data associated with the applications supported.

Three-Tier Architecture

• Benefits of three-tier architecture:– Provides a greater degree of flexibility – Provides increased security, as security can be

defined at each level – Tasks are shared between servers, which leads to

increased performance– Has easy scalability as each tier can scale

horizontally

Three-Tier Architecture Cont’d

Q u i z T i m e !

1. Client/Server technology involves a client requesting an update only from one server.

2. Client/server technology is based upon two modules. One to initiate service requests, another to respond to these requests.

3. Two-Tier Architecture is:a. a function all on it’s ownb. a Client/Server applicationc. very slow

4. Two-Tier Architecture is both expensive and difficult to maintain.

5. Three-Tier Architecture has three tiers. They are:

a. Client, Processor, Managerb. Data, Logic, Designc. Presentation, Processing, Data

6. Three-Tier Architecture is the most secure.

A n s w e r s

1. False2. True3. B4. False – it is expensive, but EASY to maintain5. C6. True