PHYSICAL ARCHITECTURE LAYER DESIGN

Physical Architecture Layer Design

Abstract

The design phase of software is the equivalent, in computer science; to the design phase in traditional engineering (mechanical, civil or electrical) this phase is to fully realize the product in an abstract form before the actual production. For cons, the intangible nature of software (modeled in information and not in the material), makes the boundary between architecture and the product far more blurred than in traditional engineering. The use of CASE tools (Computer-aided software engineering) or the production of architecture from the code itself and the documentation system used to highlight the close relationship between architecture and product. Physical Architecture Layer Design

Architecture Layer

The three-tier architecture are the application of more general model that is the multi-tier. The logical architecture of the system divided into three levels or layers:

Presentation Layer

Business layer

Data access layer

This is an extension of the model client / server.Definition and concepts

The three-tier architecture is a logical model of software architecture that aims to separate clearly three-layer software within a single application or system to model and present the application as a stack of three layers, floors, levels or strata whose role clearly defined:

Presentation of data: corresponding to display, the return on the workstation, the dialogue with the user;

Processing business data: corresponding to the implementation of all business rules and logic;

And finally the data access persistent: corresponding to the data which are to be maintained over time, even permanently.

In this approach, the layers communicate with each other through an exchange model, and each offers a range of services (Seltzer, 2008). The services of a layer made available to the upper layer. We refrain therefore, that invokes the service layer with a layer lower than the layer immediately below or higher than the next higher layer (each level communicates only with its nearest neighbors) (Leondes, 2002).

The role of each layer and the communication interface are well defined, the functionality of each may change without inducing changes in other layers. However, a new feature of the application may have an impact in several of them. It is ,therefore, essential to define an exchange model flexible enough to allow easy maintenance of the application (Aberer, 2011). This model of three-tier architecture intended to address the following concerns:

Relief of the workstation client (especially vis-à-vis conventional architectures client-server data - typical applications an an Oracle / Unix);

Taking into account the heterogeneity of platforms (servers, clients, languages, etc.).

Introduction of clients "light" (plus related ...