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Software Project Management (SPM)

Lecture 12Selection Of Appropriate

Software Project Approach

Dr. Daniel Keret

Reading Assignment

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Quality Software Project Management, R. Futrell, D. Shafer, L. Shafer, Prentice-Hall PTR 2002.•Chapter 4

Software Project Management, Bob Hughes and Mike Cotterell, McGraw-Hill, 3rd Edition.•Chapter 4

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Selection Of Appropriate Software Project Approach.

Process Domains:– Consumer– Business, Industrial– Real Time, Really Timely– Scientific

Classes of Product Systems– New Products, Re-Engineering of Existing Products– Component Integration, Heroic Maintenance

Software Development Life Cycle Models– Agile Programming: Extreme Programming (XP), Dynamic

Systems Development Method (DSDM), Rapid Application Development (RAD)

– Waterfall and V-Process Models– Prototyping, Spiral and Incremental Deliveries.

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Software Development Processes Development Processes

– Project Level: Implementation, Software Installation, Software Acceptance & Support

– System Level: System Requirement Analysis, System Architectural Design, System Integration, System Qualification Testing

– Software Level: Software Requirement Analysis, Software Architectural Design, Software Detailed Design, Software Coding & Testing, Software Integration, Software Qualification Testing

Reasons for choosing a standard software development process– Quality Improvement & Guarantee – Cost monitoring– Communication Improvement

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Project Characteristic Data/Process Oriented

– Data: Information Systems, Substantial Database, Relational Model

– Process: Scientific, Embedded control systems. Object Oriented

– Hybrid: Both Data & Process Characteristic Product/Application Specific

– Product: General Tool, Remote Updates/Helpdesk, Well Structures

– Application Specific: Niche, Sector, Business Knowledge is required. Integration, Open Interfaces

Special Characteristics– Special Hardware/software requirements– Safety Critical Application– Specific tool is required (graphics, expert system, etc.)

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Project Risks that Impacts the

Software Development Approach Product Uncertainty

– Requirements are not well defined/Fully documented– The users do not understand what the software system will do

( potential gap between the users requirements and the software detailed design)

– Undefined workflows and interrelations among sub applications Process Uncertainty

– Introducing new methods/processes to the project team– New Application Building Tools

Resource Uncertainty– Availability of staff– Availability of knowledge/experience

Project type risks– Availability of funding through the final stage of the project– Availability & knowledge level of the users– Clear definition of interfaces, conversion & implementation

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The Waterfall Model Stable Product Definition & Well Known Technical Tools Sequence of activities executed top to bottom. Each activity is validated/tested before moving to the next

activity Activities:Feasibility study, users requirements, system analysis,

system design, program design, coding, testing, installation, operations & support, maintenance, retirement

Strength of the Water fall Model– Easy to understand/implement– Good project control/milestones/utilization of staff

Weaknesses of the Model– Does not reflect problem-solving nature of software

development (iterations, solution preview, changes)– A lot of unknowns until the final stages (quality, budget,

schedule, functionality, ease of use, maintainability, etc) – All requirements should be known upfront

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The V-Shaped Model Stable Product Definition & Well Known Technical Tools

Emphasis on the Validation and Verification activities Testing/Acceptance tests are designed in parallel to

Requirements/Architecture Design. Project Requirements are defines in parallel to Product Operation

Strengths:– Emphasis on validation/testing/verification processes,

including all external and internal deliverables– Requirements before design before coding– Easy to track, easy to use

Weaknesses:– No iteration/dynamic changes concept– Risks and schedules delays can emerge too late in the life

cycle of the project

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System development models using multiple development

phases In most projects the first system build is

barely usable: too slow, too big, cumbersome First time development using New

Technology/System concept in most of the cases is a throwaway

The hardest single part of building a software system is to decide what to build (iterative extraction and refinement of the customer needs)

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The Incremental ModelNo upfront funding, Year+ Project, Requirements not totally defined,

Short market window implies basic functionality first, New technology, Limited staff availability

Constructing a partial implementation of a total system and slowly adding increased functionality/performance

Waterfall model in overlapping phases Complete up-front set of requirements implemented in a series of

small sub-projects, or general objectives that are refined and implemented in groups

The early phases of the project (planning, analysis, design) consider the entire system, prioritize requirements and define the groups to be implemented in a sub-project

Strength: – Funds can be allocated in parts– Early operational delivery that maximize the largest benefits– Improve knowledge and “lessons learned” – Reduce risks, easy to test– Small pieces are more manageable, can utilize smaller staff,

increase project momentum

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The Incremental Model (Cont.) Weaknesses:

– No iterations, difficult to change requirements of prior phases

– Requires good planning and users cooperation– Not fully defined requirements can be uncomfortable to

management– Costs can increase if the physical and the functional design

are not fully structured

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The Spiral Model

Medium to High Risk projects, New technology, Complex requirements, Large projects, Computation intensive system, Requirements are not final,

No commitment for full budget Support Management Processes, Risk analysis & management Allow Prototyping and Rapid Development Based on 4 major activities that repeats themselves until the delivery of

the product. Each repetition (spiral) increases the activity capacity– Determine objectives, alternatives and constrains– Evaluate alternatives, Identify and resolve risks (risk analysis and

prototyping)– Develop next layer of software (simulation, detailed design, code, unit

test, integration and acceptance) – Plan next phase (from project planning to transition plan, integration

and testing to operational and training) and review the last 4 quadrants The inner spirals deals with specifications and design The outers spirals deals with development, implementation, maintenance

and integration

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The Spiral Model (Cont.) Advantages:

– Rapid prototyping allow the users to see the system earlier

– Early indication of risks, Go-No-Go decision for each spiral

– Split large development to phases

– Flexible design Disadvantages:

– Too expensive for small, low risk projects

– Complex Model, No industry experience

– Good prototyping tools and reuse capabilities are a must Simplified versions were developed to overcome the

disadvantages.

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Samples for Partial Implementations of the Spiral Model

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The Structured Evolutionary Rapid Prototyping Model

Prototyping advantages– Learning by doing– Improve users involvement, communication, clarifications of

requirements and completion of requirements– Reduce needs for documentation, maintenance costs– Production of expected results

Prototyping disadvantages– Lack of control, Standards– Additional cost– Users can misunderstood the role of prototyping– Developers and users should be located on the same site

Types of prototyping– Mocks ups– Simulated interaction– Partial working prototype (vertical or horizontal)– Evolutionary prototyping

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Structured Evolutionary Rapid Prototyping ModelRequirements are unstable, not known upfront, changing rapidly

Analysis and design portion of Object Oriented developmentProof of concept, In combination with other models for parts of the

systemNew developed systems, Interfaces, Technical high risk systems

Short lived systems Requirement Phase – A quick partial

implementation of the system– Rapid analysis, Database creation, User interface,

Functions

Prototyping Iterations (until users signs – off that the requirements are met)

Production Version – Meet full workload and response time constrains, stress test, tuning

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Other Agile Models Rapid Application Development (RAD)

– Users are involved through all the stages of the development

– Utilize graphic user’s interface development tools Dynamic Systems Development Methods (DSDM)

– Four major iterative parts: Feasibility, Functional, Design/Build, Implementation

– MuSCoW prioritization: Must have, Should have, Could have, Won’t have

Extreme Programming (XP)– Code should be developed to meet current requirements– Emphasis on testing– After each software increment the full set of tests is

executed in order to verify that the last phase did not corrupted the previous stages