System Analysis and Design

System
A collection of components that work together to realize some objective forms a system. Basically there are three major components in every system, namely input, processing and output.

                                              
System Life cycle
System life cycle is an organisational process of developing and maintaining systems. It helps in establishing a system project plan, because it gives overall list of processes and sub-processes required developing a system.
System development life cycle means combination of various activities. In other words we can say that various activities put together are referred as system development life cycle. In the System Analysis and Design terminology, the system development life cycle means software development life cycle.

Different phases of Software development Life Cycle

(a) System Study
System study is the first stage of system development life cycle. This gives a clear picture of what actually the physical system is? In practice, the system study is done in two phases. In the first phase, the preliminary survey of the system is done which helps in identifying the scope of the system. The second phase of the system study is more detailed and in-depth study in which the identification of user’s requirement and the limitations and problems of the present system are studied. After completing the system study, a system proposal is prepared by the System Analyst (who studies the system) and placed before the user. The proposed system contains the findings of the present system and recommendations to overcome the limitations and problems of the present system in the light of the user’s requirements.

(b) Feasibility Study
On the basis of result of the initial study, feasibility study takes place. The feasibility study is basically the test of the proposed system in the light of its workability, meeting user’s requirements, effective use of resources and .of course, the cost effectiveness. The main goal of feasibility study is not to solve the problem but to achieve the scope. In the process of feasibility study, the cost and benefits are estimated with greater accuracy.(c)

(c)System Analysis
Assuming that a new system is to be developed, the next phase is system analysis. Analysis involved a detailed study of the current system, leading to specifications of a new system. Analysis is a detailed study of various operations performed by a system and their relationships within and outside the system. During analysis, data are collected on the available files, decision points and transactions handled by the present system. Interviews, on-site observation and questionnaire are the tools used for system analysis.

(d) System Design
Based on the user requirements and the detailed analysis of a new system, the new system must be designed. This is the phase of system designing. It is a most crucial phase in the development of a system.

(e) Coding
After designing the new system, the whole system is required to be converted into computer understanding language. Coding the new system into computer programming language does this. It is an important stage where the defined procedure are transformed into control specifications by the help of a computer language. This is also called the programming phase in which the programmer converts the program specifications into computer instructions, which we refer as programs. The programs coordinate the data movements and control the entire process in a system.
It is generally felt that the programs must be modular in nature. This helps in fast development, maintenance and future change, if required.

(f) Testing
Before actually implementing the new system into operations, a test run of the system is done removing all the bugs, if any. It is an important phase of a successful system. After codifying the whole programs of the system, a test plan should be developed and run on a given set of test data. The output of the test run should match the expected results.

(g) Implementation
After having the user acceptance of the new system developed, the implementation phase begins. Implementation is the stage of a project during which theory is turned into practice. During this phase, all the programs of the system are loaded onto the user's computer. After loading the system, training of the users starts.
 
(h) Maintenance
Maintenance is necessary to eliminate errors in the system during its working life and to tune the system to any variations in its working environment. It has been seen that there are always some errors found in the system that must be noted and corrected. It also means the review of the system from time to time.  

From: http://www.laynetworks.com/cs05_SAD_4a.htm

How And When Database Helps Us?

The main advantages of using database is fast and efficient data retrieval. Database enable user to break data into specific parts to helps you rapidly query the data in the way you requested. We take the hypermarket sales as example, the marketing manager can store the sales details of every product in related databases, in such way, the question "What is the sales of product X for the last 3 months?" can be very easy and accurate to be answered. If all the information of the thousands of product available in the supermarket recorded into a large text file, its impossible to find out the data of specific product item.

Database also allows you to set up rules to ensure the data remains consistent and up-to-date when you modified it. You can set a unique ID for each of every product (unique identifier) so that all the product won't get mixed up, or else, telling the sales data of a product becomes impossible. A properly set-up database makes work efficiency and minimizes data redundancy.

Modified from : http://e-articles.info/e/a/title/Why-and-When-to-Use-a-Database/

How To Create Access Database Relationships?

http://www.youtube.com/watch?v=bBHewXpSgQQ

Physical & Logical Views of Data

A database management system provides the ability for many different users to share data and process resources. But as there can be many different users, there are many different database needs. The question now is: How can a single, unified database meet the differing requirement of so many users?


A DBMS minimizes these problems by providing two views of the database data: a logical (external) view and physical (internal) view. The logical view/user's view, of a database program represents data in a format that is meaningful to a user and to the software programs that process those data. That is, the logical view tells the user, in user terms, what is in the database. The physical view deals with the actual, physical arrangement and location of data in the direct access storage devices(DASDs). Database specialists use the physical view to make efficient use of storage and processing resources. With the logical view users can see data differently from how they are stored, and they do not want to know all the technical details of physical storage. After all, a business user is primarily interested in using the information, not in how it is stored.

One strength of a DBMS is that while there is only one physical view of the data, there can be an endless number of different logical views. This feature allows users to see database information in a more business-related way rather than from a technical, processing viewpoint. Thus the logical view refers to the way user views data, and the physical view to the way the data are physically stored.


http://astahost.com/info.php/logical-physical-view_t20654.html

What is Data???

In computing, data is information that has been translated into a form that is more convenient to move or process. Relative to today's computers and transmission media, data is information converted into binary digital form.

In computer
component interconnection and network communication, data is often distinguished from "control information," "control bits," and similar terms to identify the main content of a transmission unit.

In telecommunications, data sometimes means digital-encoded information to distinguish it from analog-encoded information such as conventional telephone voice calls. In general, "analog" or voice transmission requires a dedicated continual connection for the duration of a related series of transmissions. Data transmission can often be sent with intermittent connections in packets that arrive in piecemeal fashion.

Generally and in science, data is a gathered body of facts.
Some authorities and publishers, cognizant of the word's Latin origin and as the plural form of "datum," use plural verb forms with "data". Others take the view that since "datum" is rarely used, it is more natural to treat "data" as a singular form.


http://searchdatamanagement.techtarget.com/definition/data

Types of Decision Support Systems (DSS)

Decision Support Systems (DSS) are a class of computerized information system that support decision-making activities. DSS are interactive computer-based systems and subsystems intended to help decision makers use communications technologies, data, documents, knowledge and/or models to complete decision process tasks.

A decision support system may present information graphically and may include an expert system or artificial intelligence (AI). It may be aimed at business executives or some other group of knowledge workers.
Typical information that a decision support application might gather and present would be, (a) Accessing all information assets, including legacy and relational data sources; (b) Comparative data figures; (c) Projected figures based on new data or assumptions; (d) Consequences of different decision alternatives, given past experience in a specific context.
There are a number of Decision Support Systems. These can be categorized into five types:

• Communication-driven DSS Most communications-driven DSSs are targetted at internal teams, including partners. Its purpose are to help conduct a meeting, or for users to collaborate. The most common technology used to deploy the DSS is a web or client server. Examples: chats and instant messaging softwares, online collaboration and net-meeting systems.

• Data-driven DSS Most data-driven DSSs are targeted at managers, staff and also product/service suppliers. It is used to query a database or data warehouse to seek specific answers for specific purposes. It is deployed via a main frame system, client/server link, or via the web. Examples: computer-based databases that have a query system to check (including the incorporation of data to add value to existing databases.

• Document-driven DSS Document-driven DSSs are more common, targeted at a broad base of user groups. The purpose of such a DSS is to search web pages and find documents on a specific set of keywords or search terms. The usual technology used to set up such DSSs are via the web or a client/server system.

• Knowledge-driven DSS
  Knowledge-driven DSSs or 'knowledgebase' are they are known, are a catch-all category covering a broad range of systems covering users within the organization seting it up, but may also include others interacting with the organization - for example, consumers of a business. It is essentially used to provide management advice or to choose products/services. The typical deployment technology used to set up such systems could be slient/server systems, the web, or software runnung on stand-alone PCs.

• Model-driven DSS Model-driven DSSs are complex systems that help analyse decisions or choose between different options. These are used by managers and staff members of a business, or people who interact with the organization, for a number of purposes depending on how the model is set up - scheduling, decision analyses etc. These DSSs can be deployed via software/hardware in stand-alone PCs, client/server systems, or the web.

From: http://www.mis.cmich.edu/bis644/dss_01/sld001.htm

Transaction Processing System

Transaction processing

• supported by programs that are called transaction processing systems.
• provide three functional areas:

1.System runtime functions

 

Transaction processing systems provide an execution environment that ensures the integrity, availability, and security of data. It also ensures fast response time and high transaction throughput.

2.System administration functions

Transaction processing systems provide administrative support that lets users configure, monitor, and manage their transaction systems.

3.Application development functions

Transaction processing systems provide functions for use in custom business applications, including functions to access data, to perform intercomputer communications, and to design and manage the user interface.

The advantages of TPS

We have now seen the reasons why we need transaction processing systems. The advantages of three-tier applications in creating scalable and robust applications are made feasible by transaction processing systems. The ability to distribute the components that make up applications amongst separate servers without explicitly having to develop for that architecture is another advantage of transaction server processing. Transaction processing systems also ensure that transactions are atomic, consistent, isolated, and durable. This alleviates the developer from having to support these characteristics explicitly.

With all of these excellent reasons for developing an application that uses a transaction processing system, we now need a system that provides these features. We will now turn our attention to a transaction processing system that is part of the standard IIS 4.0 installation: Microsoft Transaction Server.

From:http://www.auditmypc.com/acronym/tps.asp