Software Applications and Models

Application Tier Models

Application architecture models arrange how users will access data within an organization.

Presentation Layer/Client Layer

layer the user sees and interacts with when using the software

Application Layer/Business Logic Layer

controls an application’s functionality with detailed processing

Database Layer

where all the data is stored

One-Tier Architecture model

user has direct access to data since data is stored in the local system

Advantages of a one-tier architecture model

Easy to implement, One machine model, No network connectivity is needed

Disadvantages of a one-tier architecture model

Usually does not support remote access to data resources, not commonly used due to lack of redundancy and security issues - not scalable

Two-tier architecture model

Communication occurs between the Client (machine one) and the Server (machine two). The client system sends requests to the server system, which processes the request and sends the data back to the client system.

Important characteristics of a two-tier architecture model

User logs into the computer to access database, the application layer is missing and shares space with client or database layers, requires network connectivity to LAN storage (database)- NAS or File Server

Three-tier architecture model

users log into their computers and connect to an application server. The application server then accesses information from the database, usually consisting of three steps: client (presentation), application (translates commands), and database tiers

Important characteristics of a three-tier architecture model

Reinforces scalability, Improves data integrity and security, Can be complex, Internet access is required