Structured Systems Analysis and Design Methodology Contains 5 modules: Feasibility Study (Stage 0) Requirements Analysis (Stages 1 and 2) Requirements Specification (Stage 3) Logical System Specification (Stages 4 and 5) Physical Design (Stage 6)

Methodology: a definition A Methodology is a collection of procedures, techniques, tools and documentation which will help the systems developer to develop an information system.

SSADM Version 4 Stages of SSADM v4 annotated to show main uses of the three basic diagrammatic techniques. Notice how the diagrams carry forward from stage to stage becoming transformed from the existing physical system through a logical system and eventually to the required system. Key to abbreviations: c.p. = current physical diagram c.l. = current logical diagram r.s. = required system diagram DFD = dataflow diagram E.P.D. = elementary process description LDM = logical data model ELH = entity life history

SSADM Version 4 Stage 0: Feasibility Step 010 Prepare for feasibility study Step 040 Assemble feasibility report Step 030 Select feasibility options Step 020 Define the problem RJP/SSADM 0/PP overview LDS context diagram current physical level 1 DFD uses c.p.DFD and overview LDS subsets of DFD and LDS used for BSOs and TOs and for estimation of system size and complexity LDS included in environment descriptions

SSADM Version 4 Stage 1: Investigation of the current environment Step 160 Assemble investigation results Step 150 Derive logical view of current services Step 140 Investigate current data Step 130 Investigate the current processing Step 120 Investigate and define requirements Step 110 Establish analysis framework RJP/SSADM 1/PP level 1 current physical DFD (c.p. DFD) overview LDS in step 130 the c.p. DFD is updated from results of Step 120 c.p. DFD converted to current logical DFD (c.l. DFD) refine & validate LDM amend LDM to support c.l. DFD and EPDs as required

SSADM Version 4 Stage 2: Business System Options Step 220 Select business system options Step 210 Define business system options RJP/SSADM 2/PP DFDs and LDM may be used to support both these steps

SSADM Version 4 Stage 3: Definition of Requirements Step 310 Define required system processing Step 380 Assemble requirements specification Step 370 Confirm system objectives Step 360 Develop processing specification Step 350 Develop specification prototypes Step 340 Enhance required data model Step 330 Derive system functions Step 320 Develop required data model RJP/SSADM 3/PP amend c l DFD to agree with BSO and LDS (this gives required system DFD) use r.s. DFD to identify update & enquiry functions use r.s. DFD and LDM as inputs to entity/event modelling, creating ELHs, EAPs and ECDs use r.s. DFD and LDM for reference required system LDM prepared refer to r.s. LDM as necessary validate and enhance LDM from RDA update required system LDM as necessary cross check LDM against all other products

SSADM Version 4 Stage 4: Technical Options Step 410 Define technical system options Step 420 Select technical system options RJP/SSADM 4/PP LDM now part of requirements spec. which is input to this stage

SSADM Version 4 Stage 5: Logical Design Step 540 Assemble logical design Step 530 Define enquiry processes Step 520 Define update processes Step 510 Define user dialogues RJP/SSADM 5/PP update entity descriptions in LDM, include state indicators on ELHs and create update process models check LDM and other logical design products for consistency requirements spec. input to this stage create enquiry process models

SSADM Version 4 Stage 6: Physical Design Step 610 Prepare for physical design Step 630 Create function component implementation map Step 620 Create physical data design Step 640 Optimise physical data design Step 650 Complete function specification Step 660 Consolidate process data interface Step 670 Assemble physical design RJP/SSADM 6/PP LDM is main input LDM is used for reference

1.How many times in a project are the following diagrams worked on? –DFD –LDM (what is the LDM?) –ELH 2.What are the main artefacts output from each stage? –Stage 0 –Stage 1 –Stage 2 –Stage 3 –Stage 4 –Stage 5 –Stage 6 So…… Questions on the above structure: /Continued………..

3.On which life cycle is SSADM based? 4.What is meant by the following: Logical Design Physical Design 5.What does ‘Conceptual Model’ mean? 6.When is the code written? 7.When is the system tested? 8.When is the client/user trained to use the system? 9.Why is it advantageous to draw models? 10.What are the reasons for having all these three models: the Data Model (inc ERD/LDM), the Process Model (inc DFDs and process specifications) and the Behavioural Model (ELHs)? 11.Where and how does the Project Management happen? 12.Where and how does Quality Assurance happen? And…… Questions on the above structure (continued):