Structured Systems Analysis and Design Method - Essay Example

The practical difficulties involved in using the SSADM methodology for a practicing developer Structured Systems Analysis and Design Method (SSADM) is a system that provides the analysis and design of information systems. This set of standards developed in the early 1980s and widely used for government computing projects in the United Kingdom. Since 1981 SSADM has been improved and version 4 came into the world in 1990. SSADM is an open standard, i.e. it is freely available for use in industry and many companies offer support, training and Case tools for it. The terms "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. (1) SSADM uses a number of text and diagrams right through the whole life cycle of a system design, from the initial design idea to the actual physical design of the application. Structured Systems Analysis and Design Method are a discipline within the software development industry, seeking to provide a structure for capture and the activity, depot, dissemination of information aimed to make possible the economic development of computer systems that are suitable for aims and purpose (1) The major tolls for SSADM are: Logical Data Modeling - first of all this is the process of identifying. Also it is the process of modeling and documenting the data requirements of the system being designed. The data is separated into entities (things about which a business needs to record information) and relationships (the associations between the entities). (2) Data Flow Modeling - it is shows the process of identifying, modeling and documenting how data moves through a System of information. Data Flow Modeling examines processes (transform data from one form to another), data stores (the holding areas for data), external entities (sending data into a system or receives data from a system), and data flows (routes by which data can flow). (3) Entity Behavior Modeling - it is the process of identifying, modeling and documenting the events that affect on every entity and on the sequence where these events take place. All these three models gives us a different point of view on the same system, and each of it is required to form a ready model of the system being designed. This techniques are cross- concerned against each other to guarantee the readiness and exactness of the whole application. (4) SSADM projects are broken down into five modules which are divided in future into a nomber of stages, tasks, steps: Feasibility Study - Module 1 the feasibility study consists of only one stage. The business area is analyzed to determine whether a system can cost effectively support the business requirements. Requirements Analysis -- Module 2 consists of 2 stages. Stage 1 is called the Investigation of Current Environment and Stage 2 is the Business System Options (BSO). First the requirements of the system are determined and then starting the modeling of the current business environment in terms of the processes carried out and the data structures involved. During stage 2 more then 6 models are investigated and as a result one of these models ore a hybrid solution is chosen. During this part 2 it is stipulated to support each business system option and the final chosen option. The transition from Stage 1 to Stage 2 of Module 2 is the main part of SSADM, this is these part in which the movement from a logical model of the current system to a logical model of the required system is carried out. Requirements Specification -- Module 3 consists of a single stage. Here the future development of the work carried out, that was started in module 2. Detailed functional and non-functional requirements are determined and new techniques are presented to define the needed data structures and processing. Logical System Specification -- Module 4 consists of 2 stages; Stage 4 it is Technical System Options and Stage 5 is the Logical Design. Here we have options of technical systems which are produced, dialogues of the system and the logical design of update and enquiry processing. Physical Design -- Module 5 consists of a single stage. A physical database design and a number of program specifications which are created to use the specification of logical and technical systems. One of the main characteristics of SSADM is that it creates every step on the work that was described and ordered in the previous step with no deviation from the model. SSADM is ideal for control over projects and able to develop systems of better quality and characteristics because of the firmed structure of the methodology. (5) The creators of SSADM, Avison and Fitzgerald, summarized the problems of information systems community and showed their weaknesses and backlog. Their response was the development of structured methodologies for Information Systems Engineering. Their aims were to reduce the chances of misunderstanding the requirements and to create best practice techniques to the analysis and design process. So, their answer was SSADM. The Structured Systems Analysis and Design Method. But time showed that SSADM has several lacks and defects. SSADM don't really address the basic importance of corporate data management. SSADM takes a structured project led approach method to the development of data processes and structures. But the approach can't "understand" that many processes are dynamic and data structures are stable mostly. SSADM can make the chances of initial requirements smaller being misunderstood and of the systems functionality deviating from the requirements through the use of wrong design techniques and analysis. But the problem is that SSADM agrees that the requirements will not change during the development of a project. Following each step of SSADM exactly can take some time and it is possible a serious delay between inception and delivery then. The thing is, that the longer will the development time - the more chances we have that the system will meet with the requirements specification but not satisfying the business requirements at the time of delivery. (5) Here some examples of using SSADM : . References (1) SSADM Reference Manual,1986 (Version 3), 1999 (Version 4), NCC (2) SSADM Version 4:A Users Guide, (2nd Ed), Malcom Eva, McGraw-Hill,1994 (3) Practical SSADM V4, Philip L. Weaver, Pitman Publishing,1993 (4) SSADM, Application and Context, 1991(2nd Ed), by Downs, Clare&Coe, pub Prentice Hall (5) SSADM, Practical Approach,1990, (Version 4 book due 1995) by Ashworth/Slater&Goodland, pub McGraw-Hill Read More