Structured Systems Analysis And Design Methods Information Technology Essay

The Object Oriented Methodology of Building Systems takes the object as the basic. Firstly, the system to be developed is observed and analyzed and the requirements are defined as in any other method of system development. Once this is done, the objects in the required system are identified. For example in case of a Banking System, a customer is an object, a chequebook is an object, and even an account is an object.

In simple terms, Object Modeling is based on identifying the objects in a system and their interrelationships. Once this is done, the coding of the system is done. Object Modeling is somewhat similar to the traditional approach of system designing, in that it also follows a sequential process of system designing but with a different approach. The basic steps of system designing using Object Modeling may be listed as:

System Analysis

System Design

Object Design

Implementation

Structured Systems Analysis and Design Method (SSADM) is a systems approach to the analysis and design of information systems. SSADM was produced for the Central Computer and Telecommunications Agency (now Office of Government Commerce), a UK governmentoffice concerned with the use of technology in government, from 1980 onwards.

SSADM is a waterfall method for the production of a Information System design. SSADM can be thought to represent a pinnacle of the rigorous document-led approach to system design, and contrasts with more contemporary Rapid Application Development methods such asDSDM.

SSADM is one particular implementation and builds on the work of different schools of structured analysis and development methods, such as Peter Checkland’s Soft Systems Methodology, Larry Constantine’s Structured Design, Edward Yourdon’s Yourdon Structured Method, Michael A. Jackson’s Jackson Structured Programming, and Tom DeMarco’s Structured Analysis.

The names “Structured Systems Analysis and Design Method” and “SSADM” are now Registered Trade Marks of the Office of Government Commerce (OGC), which is an Office of the United Kingdom’s Treasury.

The three most important techniques that are used in SSADM are:

Logical Data Modeling

This is the process of identifying, modeling and documenting the data requirements of the system being designed. The data are separated into entities (things about which a business needs to record information) and relationships (the associations between the entities).

Data Flow Modeling

This is the process of identifying, modeling and documenting how data moves around an information system. Data Flow Modeling examines processes (activities that transform data from one form to another), data stores (the holding areas for data), external entities (what sends data into a system or receives data from a system), and data flows (routes by which data can flow).

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Entity Behavior Modeling

This is the process of identifying, modeling and documenting the events that affect each entity and the sequence in which these events occur.

Benefits of Object-Oriented Approach 

Object-oriented databases make the promise of reduced maintenance, code reusability, real world modeling, and improved reliability and flexibility.  However, these are just promises and in the real world some users find that the object-oriented benefits are not as compelling as they originally believed.  For example, what is  code reusability?  Some will say that they can reuse much of the object-oriented code that is created for a system, but many say there is no more code reusability in object-oriented systems than in traditional systems.  Code reusability is a subjective thing, and depends heavily on how the system is defined.  The object-oriented approach does give the ability to reduce some of the major expenses associated with systems, such as maintenance and development of programming code.  Here are some of the benefits of the object-oriented approach:    

Reduced Maintenance:  The primary goal of object-oriented development is the assurance that the system will enjoy a longer life while having far smaller maintenance costs.  Because most of the processes within the system are encapsulated, the behaviors may be reused and incorporated into new behaviors.

Real-World Modeling:  Object-oriented system tend to model the real world in a more complete fashion than do traditional methods.  Objects are organized into classes of objects, and objects are associated with behaviors.  The model is based on objects, rather than on data and processing.

Improved Reliability and Flexibility:  Object-oriented system promise to be far more reliable than traditional systems, primarily because new behaviors can be “built” from existing objects. Because objects can be dynamically called and accessed, new objects may be created at any time.  The new objects may inherit data attributes from one, or many other objects.  Behaviors may be inherited from super-classes, and novel behaviors may be added without effecting existing systems functions.

High Code Reusability:  When a new object is created, it will automatically inherit the data attributes and characteristics of the class from which it was spawned.  The new object will also inherit the data and behaviors from all superclasses in which it participates.  When a user creates a new type of a widget, the new object behaves “wigitty”, while having new behaviors which are defined to the system.

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The downside of the Object Technology

There  are several major misconceptions which must be addressed when considering the use of an object-oriented method: 

Object-oriented Development is not a panacea – Object-oriented Development is best suited for dynamic, interactive environments, as evidenced by its widespread acceptance in CAD/CAM and engineering design systems.  Wide-scale object-oriented corporate systems are still unproved, and many bread-and-butter information systems applications (i.e. payroll, accounting), may not benefit from the object-oriented approach.

Object-oriented Development is not a technology – Although many advocates are religious in their fervor for object-oriented systems, remember that all the “HOOPLA” is directed at the object-oriented approach to problem solving, and not to any specific technology. 

Object-oriented Development is not yet completely accepted by major vendors – Object-oriented Development has gained some market respectability, and vendors have gone from catering to a “lunatic fringe” to a respected market.  Still, there are major reservations as to whether  Object-oriented development will become a major force, or fade into history, as in the 1980’s when Decision Support Systems made great promises, only to fade into obscurity. 

Cannot find qualified programmers and DBA’s

When one investigates the general acceptance of object-oriented systems in the commercial marketplace, you generally find that most managers would like to see an object technology approach, but they do not have the time to train their staffs in object-oriented methods.  Other will say that the object-oriented method is only for graphical workstation systems, and that there is no pressing need for object-oriented system within mainstream business systems. 

Even though commercial object-oriented programming languages have been on the market for several years, systems written with object-oriented languages comprise less than 1% of systems today.

Once a major vendor begins conforming to a standard, it can become impossible to retrofit their standard to conform to another standard.    When the American Standards Committee came out with a standard character set for computers (ASCII), IBM disregarded the standard and proceeded with their own character set, called the Extended Binary Character Data Interchange Code (EBCDIC).  Even thirty years later, there has still been no resolution between ASCII and EBCDIC, and data transfers between ASCII and EBCDIC machines continue to present problems.  For example, the EBCDIC character set has no characters for “[” and “]”, and ASCII has no character for the “cent” sign.   

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 Benefits of SSADM

Timelines: Theoretically, SSADM allows one to plan, manage and control a project well. These points are essential to deliver the product on time.

Usability: Within SSADM special emphasis is put on the analysis of user needs. Simultaneously, the systems model is developed and a comprehensive demand analysis is carried out. Both are tried to see if they are well suited to each other.6

Respond to changes in the business environment: As in SSADM documentation of the project′s progress is taken very seriously, issues like business objectives and business needs are considered while the project is being developed. This offers the possibility to tailor the planning of the project to the actual requirements of the business.

Effective use of skills: SSADM does not require very special skills and can easily be taught to the staff. Normally, common modelling and diagramming tools are used. Commercial CASE tools are also offered in order to be able to set up SSADM easily.

Better quality: SSADM reduces the error rate of IS by defining a certain quality level in the beginning and constantly checking the system.

Improvement of productivity: By encouraging on-time delivery, meeting business requirements, ensuring better quality, using human resources effectively as well as trying to avoid bureaucracy, SSADM improves the overall productivity of the specific project and the company.

Cuts costs: SSADM separates the logical and the physical systems design. So the system does not have to be implemented again with new hard -or software.

 Disadvantages of SSADM

But even for large companies, SSADM sometimes has some disadvantages: 

SSADM puts special emphasis on the analysis of the system and its documentation. This causes the danger of over-analysing, which can be very time and cost consuming.8 Due to various types of description methods, checks of consistence cannot be carried out. Especially with large systems, the outline diagram can become very unclear, because all relevant data flows have to be included.9 

However, large companies carrying out various projects, can profit from the fact that SSADM gives the possibility to reuse certain techniques and tools for other projects. This reduces cost and time spent enormously in the long run. So, the danger of spending too much money on analysis can be compensated by the reuse of the developed systems and experience gained.

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