1. Subject Name: SOFTWARE ENGINEERING Subject Code:10IS51
Prepared By: HARKIRANPREET, ALPNA
Department: ISE
Date: 25 September, 2014
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2. UNIT 4 PROJECT MANAGEMENT
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3. Management activities Project planning Project scheduling
CONTENTS
Management activities
Project planning
Project scheduling
Risk management
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4. SOFTWARE PROJECT MANAGEMENT
It is Concerned with activities involved in ensuring that software is delivered on time and on schedule and in accordance with the requirements of the organisations developing and procuring the software.
Project management is needed because software development is always subject to budget and schedule constraints that are set by the organisation developing the software.
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5. SOFTWARE MANAGEMENT DISTINCTIONS
The product is intangible.
The product is uniquely flexible.
Software engineering is not recognized as an engineering discipline with the sane status as mechanical, electrical engineering, etc.
The software development process is not standardised.
Many software projects are 'one-off' projects.
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6. MANAGEMENT ACTIVITIES
Proposal writing.
Project planning and scheduling.
Project costing.
Project monitoring and reviews.
Personnel selection and evaluation.
Report writing and presentations.
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7. MANAGEMENT COMMONALITIES
These activities are not peculiar to software management.
Many techniques of engineering project management are equally applicable to software project management.
Technically complex engineering systems tend to suffer from the same problems as software systems.
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8. May not be possible to appoint the ideal people to work on a project.
PROJECT STAFFING
May not be possible to appoint the ideal people to work on a project.
Project budget may not allow for the use of highly-paid staff.
Staff with the appropriate experience may not be available.
An organisation may wish to develop employee skills on a software project.
Managers have to work within these constraints especially when there are shortages of trained staff.
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9. PROJECT PLANNING
Probably the most time-consuming project management activity.
Continuous activity from initial concept through to system delivery.
Plans must be regularly revised as new information becomes available.
Various different types of plan may be developed to support the main software project plan that is concerned with schedule and budget.
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10. TYPES OF PROJECT PLAN
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11. PROJECT PLANNING PROCESS
Establish the project constraints
Make initial assessments of the project parameters
Define project milestones and deliverables
while project has not been completed or cancelled loop
Draw up project schedule
Initiate activities according to schedule
Wait ( for a while )
Review project progress
Revise estimates of project parameters
Update the project schedule
Re-negotiate project constraints and deliverables
if ( problems arise ) then
Initiate technical review and possible revision
end if
end loop
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12. PROJECT PLAN STRUCTURE
Introduction.
Project organisation.
Risk analysis.
Hardware and software resource requirements.
Work breakdown.
Project schedule.
Monitoring and reporting mechanisms.
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13. ACTIVITY ORGANIZATION
Activities in a project should be organised to produce tangible outputs for management to judge progress.
Milestones are the end-point of a process activity.
Deliverables are project results delivered to customers.
The waterfall process allows for the straightforward definition of progress milestones.
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14. MILESTONES IN THE RE PROCESS
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15. Organize tasks concurrently to make optimal use of workforce.
PROJECT SCHEDULING
Split project into tasks and estimate time and resources required to complete each task.
Organize tasks concurrently to make optimal use of workforce.
Minimize task dependencies to avoid delays caused by one task waiting for another to complete.
Dependent on project managers intuition and experience.
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16. THE PROJECT SCHEDULING PROCESS
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17. The unexpected always happens. Always allow contingency in planning.
SCHEDULING PROBLEMS
Estimating the difficulty of problems and hence the cost of developing a solution is hard.
Productivity is not proportional to the number of people working on a task.
Adding people to a late project makes it later because of communication overheads.
The unexpected always happens. Always allow contingency in planning.
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18. BAR CHARTS AND ACTIVITY NETWORKS
Graphical notations used to illustrate the project schedule.
Show project breakdown into tasks.
Tasks should not be too small. They should take about a week or two.
Activity charts show task dependencies and the critical path.
Bar charts show schedule against calendar time.
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19. TASK DURATIONS AND DEPENDENCIES
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20. ACTIVITY NETWORK
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21. ACTIVITY TIMELINE
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22. STAFF ALLOCATION
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23. RISK MANAGEMENT
Risk management is concerned with identifying risks and drawing up plans to minimise their effect on a project.
A risk is a probability that some adverse circumstance will occur
Project risks affect schedule or resources;
Product risks affect the quality or performance of the software being developed;
Business risks affect the organisation developing or procuring the software.
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24. SOFTWARE RISKS
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25. THE RISK MANAGEMENT PROCESS
Risk identification
Identify project, product and business risks;
Risk analysis
Assess the likelihood and consequences of these risks;
Risk planning
Draw up plans to avoid or minimise the effects of the risk;
Risk monitoring
Monitor the risks throughout the project;
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26. THE RISK MANAGEMENT PROCESS
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27. RISK IDENTIFICATION Technology risks. People risks.
Organisational risks.
Requirements risks.
Estimation risks.
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28. RISKS AND RISK TYPES
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29. RISK ANALYSIS Assess probability and seriousness of each risk.
Probability may be very low, low, moderate, high or very high.
Risk effects might be catastrophic, serious, tolerable or insignificant.
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30. RISK ANALYSIS (I)
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31. RISK ANALYSIS (II)
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32. Consider each risk and develop a strategy to manage that risk.
RISK PLANNING
Consider each risk and develop a strategy to manage that risk.
Avoidance strategies
The probability that the risk will arise is reduced;
Minimisation strategies
The impact of the risk on the project or product will be reduced;
Contingency plans
If the risk arises, contingency plans are plans to deal with that risk;
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33. RISK MANAGEMENT STRATEGIES (I)
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34. RISK MANAGEMENT STRATEGIES (II)
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35. RISK MONITORING
Assess each identified risks regularly to decide whether or not it is becoming less or more probable.
Also assess whether the effects of the risk have changed.
Each key risk should be discussed at management progress meetings.
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36. RISK INDICATORS
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37. SYSTEM MODELS
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38. CONTENTS Context models Behavioural models Data models Object models
CASE workbenches
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39. SYSTEM MODELLING
System modelling helps the analyst to understand the functionality of the system and models are used to communicate with customers.
Different models present the system from different perspectives
External perspective showing the system’s context or environment;
Behavioural perspective showing the behaviour of the system;
Structural perspective showing the system or data architecture.
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40. MODEL TYPES
Data processing model showing how the data is processed at different stages.
Composition model showing how entities are composed of other entities.
Architectural model showing principal sub-systems.
Classification model showing how entities have common characteristics.
Stimulus/response model showing the system’s reaction to events.
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41. CONTEXT MODELS
Context models are used to illustrate the operational context of a system - they show what lies outside the system boundaries.
Social and organisational concerns may affect the decision on where to position system boundaries.
Architectural models show the system and its relationship with other systems.
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42. THE CONTEXT OF AN ATM SYSTEM
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43. PROCESS MODELS
Process models show the overall process and the processes that are supported by the system.
Data flow models may be used to show the processes and the flow of information from one process to another.
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44. EQUIPMENT PROCUREMENT PROCESS
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45. Two types of behavioural model are:
BEHAVIOURAL MODELS
Behavioural models are used to describe the overall behaviour of a system.
Two types of behavioural model are:
Data processing models that show how data is processed as it moves through the system;
State machine models that show the systems response to events.
These models show different perspectives so both of them are required to describe the system’s behaviour.
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46. DATA-PROCESSING MODELS
Data flow diagrams (DFDs) may be used to model the system’s data processing.
These show the processing steps as data flows through a system.
DFDs are an intrinsic part of many analysis methods.
Simple and intuitive notation that customers can understand.
Show end-to-end processing of data.
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47. ORDER PROCESSING DFD
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48. DATA FLOW DIAGRAMS
DFDs model the system from a functional perspective.
Tracking and documenting how the data associated with a process is helpful to develop an overall understanding of the system.
Data flow diagrams may also be used in showing the data exchange between a system and other systems in its environment DFDs model the system from a functional perspective.
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49. INSULIN PUMP DFD
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50. STATE MACHINE MODELS
These model the behaviour of the system in response to external and internal events.
They show the system’s responses to stimuli so are often used for modelling real-time systems.
State machine models show system states as nodes and events as arcs between these nodes. When an event occurs, the system moves from one state to another.
State charts are an integral part of the UML and are used to represent state machine models.
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51. STATE CHARTS
Allow the decomposition of a model into sub-models (see following slide).
A brief description of the actions is included following the ‘do’ in each state.
Can be complemented by tables describing the states and the stimuli.
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52. MICROWAVE OVEN MODEL
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53. MICROWAVE OVEN STATE DESCRIPTION
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54. MICROWAVE OVEN STIMULI
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55. MICROWAVE OVEN OPERATION
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56. SEMANTIC DATA MODELS
Used to describe the logical structure of data processed by the system.
An entity-relation-attribute model sets out the entities in the system, the relationships between these entities and the entity attributes
Widely used in database design. Can readily be implemented using relational databases.
No specific notation provided in the UML but objects and associations can be used.
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57. LIBRARY SEMANTIC MODEL
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58. DATA DICTIONARIES
Data dictionaries are lists of all of the names used in the system models. Descriptions of the entities, relationships and attributes are also included.
Advantages
Support name management and avoid duplication;
Store of organisational knowledge linking analysis, design and implementation;
Many CASE workbenches support data dictionaries.
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59. DATA DICTIONARY ENTRIES
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60. OBJECT MODELS
Object models describe the system in terms of object classes and their associations.
An object class is an abstraction over a set of objects with common attributes and the services (operations) provided by each object.
Various object models may be produced
Inheritance models;
Aggregation models;
Interaction models.
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61. More abstract entities are more difficult to model using this approach
OBJECT MODELS
Natural ways of reflecting the real-world entities manipulated by the system
More abstract entities are more difficult to model using this approach
Object class identification is recognised as a difficult process requiring a deep understanding of the application domain
Object classes reflecting domain entities are reusable across systems
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62. INHERITANCE MODELS
Organise the domain object classes into a hierarchy.
Classes at the top of the hierarchy reflect the common features of all classes.
Object classes inherit their attributes and services from one or more super-classes. these may then be specialised as necessary.
Class hierarchy design can be a difficult process if duplication in different branches is to be avoided.
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63. OBJECT MODELS AND THE UML
The UML is a standard representation devised by the developers of widely used object-oriented analysis and design methods.
It has become an effective standard for object-oriented modelling.
Notation
Object classes are rectangles with the name at the top, attributes in the middle section and operations in the bottom section;
Relationships between object classes (known as associations) are shown as lines linking objects;
Inheritance is referred to as generalisation and is shown ‘upwards’ rather than ‘downwards’ in a hierarchy.
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64. LIBRARY CLASS HIERARCHY
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65. USER CLASS HIERARCHY
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66. MULTIPLE INHERITANCE
Rather than inheriting the attributes and services from a single parent class, a system which supports multiple inheritance allows object classes to inherit from several super-classes.
This can lead to semantic conflicts where attributes/services with the same name in different super-classes have different semantics.
Multiple inheritance makes class hierarchy reorganisation more complex.
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67. MULTIPLE INHERITANCE
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68. OBJECT AGGREGATION
An aggregation model shows how classes that are collections are composed of other classes.
Aggregation models are similar to the part-of relationship in semantic data models.
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69. OBJECT AGGREGATION
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70. OBJECT BEHAVIOUR MODELLING
A behavioural model shows the interactions between objects to produce some particular system behaviour that is specified as a use-case.
Sequence diagrams (or collaboration diagrams) in the UML are used to model interaction between objects.
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71. ISSUE OF ELECTRONIC ITEMS
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72. CASE tools support system modelling as part of a structured method.
STRUCTURED METHODS
Structured methods incorporate system modelling as an inherent part of the method.
Methods define a set of models, a process for deriving these models and rules and guidelines that should apply to the models.
CASE tools support system modelling as part of a structured method.
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73. They do not model non-functional system requirements.
METHOD WEAKNESSES
They do not model non-functional system requirements.
They do not usually include information about whether a method is appropriate for a given problem.
The may produce too much documentation.
The system models are sometimes too detailed and difficult for users to understand.
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74. CASE WORKBENCHES
A coherent set of tools that is designed to support related software process activities such as analysis, design or testing.
Analysis and design workbenches support system modelling during both requirements engineering and system design.
These workbenches may support a specific design method or may provide support for a creating several different types of system model.
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75. AN ANALYSIS AND DESIGN WORKBENCH
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76. ANALYSIS WORKBENCH COMPONENTS
Diagram editors
Model analysis and checking tools
Repository and associated query language
Data dictionary
Report definition and generation tools
Forms definition tools
Import/export translators
Code generation tools
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77. Thank you…..
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78. 25/9/2014