CONCLUSION
The chapter takes an end allowed us to highlight the shapes of
the subject of ours broadening our scope of knowledge of web applications and
the relationship between sustainable development and ICT. This means that the
subject is not ex nihilo and belongs to its time and the part that was so well
illustrated advantage will help us in refining our research methodology as well
as the selection of tools that will help us.
CHAPTER THREE:RESEARCH
METHODOLOGY AND MATERIALS USED
RESEARCH METHODOLOGY AND MATERIALS USED
INTRODUCTION
Any research necessarily involves several steps. This means
that once the preliminary investigations have been conducted, it is to choose a
methodology that will drive the project to completion. Thus, the abundance of
computer methods demands a rigorous examination of all possible choices. Also,
in the context of this application this chapter fits like a logical
continuation of the above will determine its content.
1. WEB APPLICATION ARCHITECTURE
In computing, the architecturerefers to the overall structure
inherent in a system, the organization of the different elements of the system
(software and/or hardware and/or humans and/or information) and relations
between elements. The Web architecture is the branch of the information system
architecture that is interested in web applications. There are currently a
large number of architectures used for the web.
1.1. The 2tiers architecture
It is composed of two parts, a client and a server. This
architecture can also be represented with a database server (DBMS).
In this type of architecture, the customer assumes
presentation tasks and communicates only with the application server. This type
of architecture can be developed very quickly depending on the complexity of
the project. There are a very large number of development languages and tools
for 2tiers architectures.
From the standpoint of convenience, the problem of
scalability, maintenance and implementation in complex projects must be taken
into account.
1.2. The 3-tiers architecture
Here the customer consists of a web browser and communicates
with the server.
This architecture consists of three elements or three
layers:
· The presentation layer (top level) often called HMI
(Human Machine Interface) is the visible and interactive part. This part is
designed for the Web in HTML usually with JavaScript, Flash.
· The business layer (second-level) is the functional
part of the application. The operations to be performed, the data access
functions and treatments are available to users and raised by their requests.
To provide these services, it sometimes relies on the data access layer and in
turn refers to the presentation layer the results it has calculated.
· The last layer (third level) manages access to system
data. These data can be stored on the same system (files, XML files, databases,
images ...) or other systems. Data access is transparent to the business layer
and is the only concern of the data access layer.
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