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'''Structured systems analysis and design method (SSADM)''' (originally released as ''methodology'') is a systems approach to the analysis and design of information systems. SSADM was produced for the [[Office of Government Commerce|Central Computer and Telecommunications Agency (now Office of Government Commerce)]], a [[UK government]] office concerned with the use of technology in government, from 1980 onwards.
== Overview ==
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* 1980: Central Computer and Telecommunications Agency (CCTA) evaluate analysis and design methods.
* 1981: Learmonth & Burchett Management Systems (LBMS) method chosen from shortlist of five.
* 1983: SSADM made mandatory for all new information system developments
* 1984: Version 2 of SSADM released
* 1986: Version 3 of SSADM released, adopted by NCC
* 1988: SSADM Certificate of Proficiency launched, SSADM promoted as ‘open’ standard
* 1989: Moves towards [[Euromethod]], launch of CASE products certification scheme
* 1990: Version 4 launched
* 1993: SSADM V4 Standard and Tools Conformance Scheme Launched
* 1995: SSADM V4+ announced, V4.2 launched
* 1998:PLATINUM TECHNOLOGY acquires LBMS
* 2000: CCTA renamed SSADM as "Business System Development". The method was repackaged into 15 modules and another 6 modules were added.<ref>{{cite web |url = http://web.archive.org/web/20090402163313/http://www.modelsys.com/msssadm.htm |title = Model Systems and SSADM |
== SSADM techniques ==
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== Stages ==
The SSADM method involves the application of a sequence of analysis, documentation and design tasks concerned with the following.
=== Stage 0 – Feasibility study ===
In order to determine whether or not a given project is feasible, there must be some form of investigation into the goals and implications of the project. For very small scale projects this may not be necessary at all as the scope of the project is easily understood. In larger projects, the feasibility may be done but in an informal sense, either because there is not time for a formal study or because the project is a “must-have” and will have to be done one way or the other.
When a feasibility study is carried out, there are four main areas of consideration:
Technical – is the project technically possible?<br />
Financial – can the business afford to carry out the project?<br />
Organizational – will the new system be compatible with existing practices?<br />
Ethical – is the impact of the new system socially acceptable?
To answer these questions, the feasibility study is effectively a condensed version of a fully blown systems analysis and design. The requirements and users are analyzed to some extent, some business options are drawn up and even some details of the technical implementation.
The product of this stage is a formal feasibility study document. SSADM specifies the sections that the study should contain including any preliminary models that have been constructed and also details of rejected options and the reasons for their rejection.
=== Stage 1 – Investigation of the current environment ===
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*the data model can be constructed
*the users become involved and learn the techniques and models of the analyst
*the boundaries of the system can be defined
The products of this stage are:
*Users Catalog describing all the users of the system and how they interact with it
*Requirements Catalogs detailing all the requirements of the new system
*Current Services Description further composed of
*Current environment logical data structure ([[Entity-relationship model|ERD]])
*Context diagram ([[Data flow diagram|DFD]])
*Leveled set of [[Data flow diagram|DFDs]] for current logical system
*Full data dictionary including relationship between data stores and entities
To produce the models, the analyst works through the construction of the models as we have described. However, the first set of data-flow diagrams ([[Data flow diagram|DFDs]]) are the current physical model, that is, with full details of how the old system is implemented. The final version is the current logical model which is essentially the same as the current physical but with all reference to implementation removed together with any redundancies such as repetition ofhe information that makes up the users and requirements catalogs.
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*the distribution of the system, for example, is it centralized to one office or spread out across several?
*cost/benefit
*impact of the new system
Where necessary, the option will be documented with a logical data structure and a level 1 data-flow diagram.
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*the updated data catalog
*the updated requirements catalog
*the processing specification which in turn is made up of
:*user role/function matrix
:*function definitions
:*required logical data model
:*entity life-histories
:*effect correspondence diagrams
'''
Though some of these items may be unfamiliar to you, it is beyond the scope of this unit to go into them in great detail.
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*the physical limitations such as a space occupied by the system
*the distribution including any networks which that may require
*the overall format of the human computer interface
All of these aspects must also conform to any constraints imposed by the business such as available money and standardization of hardware and software.
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*Separation of logical and physical aspects of the system
*Well-defined techniques and documentation
*User involvement
The size of SSADM is a hindrance to using it in some circumstances. There is an investment in cost and time in training people to use the techniques. The learning curve can be considerable if the full method is used, as not only are there several modeling techniques to come to terms with, but there are also a lot of standards for the preparation and presentation of documents.
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==External links==
* [http://www.webopedia.com/TERM/S/SSADM.html What is SSADM?] at webopedia.com
* [http://www.ogcio.gov.hk/eng/prodev/es3.htm SSADM Version 4.3 Structural Standards]
* [http://www.comp.glam.ac.uk/pages/staff/tdhutchings/chapter4.html Introduction to Methodologies and SSADM]
* [http://www.cilco.co.uk/briefing-studies/acme-fashion-supplies-feasibility-study/index.html Case study using pragmatic SSADM]
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