Structured systems analysis and design method: Difference between revisions

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{{Short description|Waterfall based systems analysis method}}

{{notability|date=October 2017}}

{{More footnotes|date=May 2010}}

'''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 [[Central Computer and Telecommunications Agency]], a [[UK government]] office concerned with the use of technology in government, from 1980 onwards.

== Overview ==

SSADM is a [[Waterfall model|waterfall method]] for the analysis and design of [[information systems]]. SSADM can be thought to represent a pinnacle of the rigorous document-led approach to system design, and contrasts with more contemporary [[Agile software development|agile]] methods such as [[Dynamic Systems Development Method|DSDM]] or [[Scrum (development)|Scrum]].

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 [[Edward_Yourdon#Yourdon_structured_method | 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 [[trademark|registered trademarks]] of the [[Office of Government Commerce]] (OGC), which is an office of the United Kingdom's Treasury.<ref>{{cite web

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== History ==

The principal stages of the development of SSADMStructured System Analysing And Design Method were:<ref>{{cite web |url = http://www.dcs.bbk.ac.uk/~steve/1/sld005.htm|archive-url=https://web.archive.org/web/20130219234253/http://www.dcs.bbk.ac.uk/~steve/1/sld001.htm|archive-date=2013-02-19 |url-status=dead|title = History of SSADM |work = SSADM – an Introduction |date = 20 January 1999 |author = Mike Goodland |author2 = Karel Riha |accessdate = 2010-12-17}}</ref>

* 1980: Central Computer and Telecommunications Agency (CCTA) evaluate analysis and design methods.

* 1981: Consultants working for Learmonth & Burchett Management Systems, led by John Hall, chosen to develop SSADM v1.

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* 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’'open' standard

* 1989: Moves towards [[Euromethod]], launch of CASE products certification scheme

* 1990: Version 4 launched

* 1993: SSADM V4 Standard and Tools Conformance Scheme

* 1995: SSADM V4+ announced, V4.2 launched

* 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://www.modelsys.com/msssadm.htm |title=Model Systems and SSADM |year=2002 |publisher=Model Systems Ltd |accessdate=2009-04-02 |deadurlurl-status=unfit |archiveurl=https://web.archive.org/web/20090402163313/http://www.modelsys.com/msssadm.htm |archivedate=April 2, 2009 }}</ref><ref>{{cite book |title= SSADM foundation |publisher= [[The Stationery Office]] |series= Business Systems Development with SSADM |year= 2000 |page= v |isbn= 0-11-330870-1 }}</ref>

== SSADM techniques ==

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

; Logical dataData modelingModelling

: The process of identifying, modelingmodelling and documenting the data requirements of the system being designed. The result is a data model containing entities (things about which a business needs to record information), attributes (facts about the entities) and relationships (associations between the entities).

; Data Flow ModelingModelling

: The process of identifying, modelingmodelling 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).

; Entity Event ModelingModelling

: A two-stranded process: Entity Behavior ModelingModelling, identifying, modelingmodelling and documenting the events that affect each entity and the sequence (or life history) in which these events occur, and Event ModelingModelling, designing for each event the process to coordinate entity life histories.

== Stages ==

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=== 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 notno time for a formal study or because the project is a “must"must-have”have" and will have to be done one way or the other. A data flow Diagram is used to describe how the current system works and to visualize the known problems.

When a feasibility study is carried out, there are four main areas of consideration:

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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 blowncomprehensive systems analysis and design. The requirements and usersusages 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 ===

The developers of SSADM understood that in almost all cases there is some form of current system even if it is entirely composed of people and paper. Through a combination of interviewing employees, circulating questionnaires, observations and existing documentation, the analyst comes to full understanding of the system as it is at the start of the project. This serves many purposes (Like examples?).

=== Stage 2 – Business system options ===

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:*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.

=== Stage 4 – Technical system options ===

This stage is the first towards a physical implementation of the new system application. Like the Business System Options, in this stage a large number of options for the implementation of the new system are generated. This is narrowed down to two or three to present to the user from which the final option is chosen or synthesized.

However, the considerations are quite different being:

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==References==

{{reflist}}

==Further reading==

{{refbegin |30em}}

* {{cite book

| last = Robinson

| first = Keith

| last2 = Berrisford

| first2 = Graham

| title = Object-oriented SSADM

| publisher = Prentice Hall International (UK)

| ___location = Hemel Hempstead

| date = 1994

| isbn = 0-13-309444-8

| url = https://books.google.com/books/about/Object_oriented_SSADM.html?id=8vIkAQAAIAAJ

| archive-url = https://web.archive.org/web/20230601000000/https://books.google.com/books/about/Object_oriented_SSADM.html?id=8vIkAQAAIAAJ

| archive-date = 2023-06-01

| url-status = live

}}

*{{cite book |last=Duncan |first=Joyce |last2=Rackley |first2=Lesley |last3=Walker |first3=Alexandria |title=SSADM in Practice: A Version 4 Text |publisher=Macmillan |year=1995 |isbn=9780333620670}}

*{{cite book |last=Downs |first=Ed |last2=Clare |first2=Peter |last3=Coe |first3=Ian |title=Structured Systems Analysis and Design Method: Application and Context |publisher=Prentice Hall |year=1992 |isbn=9780138536985}}

* {{cite book |last=Weaver |first=Philip L. |last2=Lambrou |first2=Nick |last3=Walkley |first3=Matthew |title=Practical SSADM Version 4+: A Complete Tutorial Guide |publisher=Pitman Publishing |year=2002 |edition=3rd|isbn=9780273655756}}

{{refend}}

{{Refimprove|date=November 2008}}

==External links==

{{subject bar|auto=y|d=y|Technology}}

* [http://www.webopedia.com/TERM/S/SSADM.html What is SSADM?] at webopedia.com

* [https://web.archive.org/web/20051202113000/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]

* [https://web.archive.org/web/20070203213944/http://www.yourdon.com/strucanalysis/wiki/index.php?title=Introduction Structured Analysis Wiki]

[[Category:Information systems]]