Client/Server Technology Two-Tier Architecture Three-Tier Architecture Josh Antonelli Jenn Lang Joe Schisselbauer Chad 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

Quiz Time! 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 own b. a Client/Server application c. 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, Manager b. Data, Logic, Design c. Presentation, Processing, Data 6.Three-Tier Architecture is the most secure.

Answers 1.False 2.True 3.B 4.False – it is expensive, but EASY to maintain 5.C 6.True