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Tier architecture
Designing robust system architecture it is critical for the success of the application. All the interconnections between components, their divisions in layers must be the focus of the architecting process.
A short history over the application architectures sounds like this: first there were the standalone applications (if they wanted however to manipulate data, they were doing this by acce ... Continuare
Logic levels in a software system
A well-designed software application based on the Client/Server model is divided into separate logical parts called layers or levels. Each layer has a different responsibility in the overall architecture. These layers are purely abstractions, and do not correspond to physical distribution. The logic levels and the interconnection between them represent the most common design of a transaction pr ... Continuare
Identifying the Software Technology for a System architecture
After identifying the objectives and the principle targets of the system, the wide array of potential technologies available on the market must be taken into analysis for the best usable technology; the evaluation of the technology that can be used while designing the architecture of a system must include a matrix that identifies the technology, the benefits of the technology, and the potentia ... Continuare
Fulfill requirements: functional and not-functional
Along with the architecture goals, there also must be taken into consideration non functional requirements, which are critical success factors in developing the architecture.
The nonfunctional requirements of the system identify what the system must achieve for itself in order for it to be considered successful. Those requirements differ from the architecture system goals by the fact they a ... Continuare
Objectives of the System Architecture
There are some general principles that are usually applied during the architectural process. These principles described bellow, guide the analysis and decision taking that must be performed during the process. The principle is to conceive an architecture that has follows the features described below:
. Has clarity - the objective is to create a system that can be easily understood. Even thou ... Continuare
Defining the System Architecture concept
The official definition of architecture is the study of design; the differences between design and an architecture is that design can be performed individually, while the architecture is a module, framework that can be applied in general situations with specific features. Architecting something means arrangements of parts or structure in a proper order. This is no difference to the case of comput ... Continuare
TCP/IP protocol - communication protocol
The term TCP/IP stands for Transmission Control Protocol / Internet Protocol, otherwise translated as the communication protocol for communication between computers connected to the Internet.
The standard TCP/IP-a communication protocol- is a package of rules descriptions regarding the communication between computers, how should they be connected to the Internet and how should data be transmitt ... Continuare
HTTP Response
. Protocol + Status code + Description
Ex: HTTP/1.1 200 OK
o the first line (or initial line) in the response output the HTTP protocol name/version, the response status code and the reason phrase describing the status code
. Response headers
o The headers are similar to the response headers, containg information about the content of the message body(Content-type, Content-Length) and may ... Continuare
HTTP Request
. Request Method + URI + Protocol/Version
Ex: GET /stone/index.jsp HTTP/1.1
o many request methods can be used in the header of a request: GET, HEAD, POST, OPTIONS, PUT, DELETE, TRACE
GET is the most simple and used method that retrieves data identified in the URL; if the URL refers to a script (CGI, servlet, etc) it returns the data produced by the script.
o The URI specifie ... Continuare
HTTP protocol
The name of HTTP protocol comes from Hyper Text Transfer protocol and basically is the protocol that allows servers and browser to exchange data on the Internet. Being a protocol that is used in client/server model system architecture, it is designed for treating and managing the requests and replies from clients, respective servers. It is the standard protocol that is used on the World-Wide-Web ... Continuare
Models in distributed Systems
The basic models for distributed system are Message Passing and Client/Server. Message Passing is the basic Distributed System paradigm for building distributed systems and refers to the communication methods between processes located on different hosts. For their communication, a specific protocol is need. The steps in this communication are that the sender process sends a request and the rec ... Continuare
Distributed Systems
A more concrete definition of a Distributed System is the following: a distributed system is a collection of computing resources autonomous, interconnected via a network, like Internet World-Wide-Web whose distribution is transparent to the user that sees the system as a single coherent one. The system appears as one local machine functionality, being in a contrast to a specific network, in wh ... Continuare
E-learning categories
Taking into consideration all these factors that directly influence the context in which the e-learning is being more and more developed, I will present next the categories of the E-Learning, taken by the inter-relation perspective.
In few words, the terms found in the scheme are explained below:
a) Courses: The main manifestation focus of the E-Learning; courses are subject modules, in which ... Continuare
E-Learning characteristics
Why is the E-learning form of school so useful and what could be the reasons for someone to join this kind of learning? In the next paragraphs the main points and benefits will be enchased.
Another way of putting into words the term of E-learning System (or Virtual Education System) consists in a planned activity and experience two-dimensional of learning-teaching, organized by an institution or ... Continuare
E-Learning history
Thus, E-earning domain directly resulted from the development of communication techniques and started its popularity since 1980'. E-Learning is an approach to facilitate and enhance learning through both computer and communications technology. The term covers a wide set of applications and processes underneath the domains of Web-based learning, computer-based learning, On-line Learning and Distanc ... Continuare
Specific view: ELRN project
The problem statement which the ELRN project is based upon is the following: the problem of necessity of continuously improving one\ s knowledge affects all individuals that wish to learn and/or develop their present abilities but the impact of which is due to everyday activities they are unable to attend classic forms of learning, a successful solution would be an alternative form of teaching/ ... Continuare
Java Script
E un limbaj de scripting la nivel de client, suportat de majoritatea browserelor actuale si este folosit pentru a realiza interactiunea cu utilizatorul prin afisare de mesaje si interogarea in vederea alegerii unei decizii, pentru validarea anumitor campuri si verificarea valorilor, imbunatatirea designului,crearea de cookiuri si multe altele[5.
In ceea ce priveste asemanarea intre Java si JavaSc ... Continuare
HTML (HyperText Markup Language)
HTML este un limbaj de formatare a textului de tip static. In esenta un document HTML-ul este un fisier text cate contine numai si numai text. Cand un browser deschide un fisier HTML, acesta se uita la codul HTML din text si il foloseste pentru a schimba layout-ul, sa insereze imagini sau sa creeze linkuri spre alte pagini. Intrucat HTML-ul este doar un fisier text el poate fi scris chiar si de ed ... Continuare
Arhitectura 3-tier
Arhitectura 3-tier a aparut ca o imbunatatire a arhitecturii pe doua nivele care s-a dovedit ineficienta in timp pentru aplicatii mai mari. Prin introducerea unui nivel intermediar intre aplicatia client si baza de date se poate spori performanta, imbunatatind disponibilitatea aplicatiei, ea devenind mai robusta.
Acest nivel de mijloc contine elemente de logica a aplicatiei, putand fiind constitu ... Continuare
Modele de arhitectura
Conceptul de nivele de arhitectura ofera un mod convenabil de a grupa diferite clase, de a modela structura unei aplicatii intr-un mod cand mai unitar.
Voi prezenta in cele ce urmeaza diferite modele de arhitecturi software, care se bazeaza pe cele trei nivele:
. Nivelul de prezentare (presentation tier ) - care reprezinta interfata cu utilizatorul si care se afla deasupra celorlalte nivele
. ... Continuare
