1. Rekayasa Perangkat Lunak
Kuliah 06

2. Outline of this presentation
The Generic Software Process Model
Prototyping Model
Incremental Model

3. Generic Software Process Model
Prototyping model
Prototyping is the rapid development of a system
Use if
Only general objectives available
Being unsure about
Software requirement
Efficiency of an algorithm
Human-computer interaction

4. Generic Software Process Model
Prototyping model
Uses of system prototypes
to help customers and developers understand the requirements for the system
Requirements elicitation.
Users can experiment with a prototype to see how the system supports their work
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5. Generic Software Process Model
Prototyping model
Uses of system prototypes
to help customers …
Requirements validation.
The prototype can reveal
errors and omissions in the Requirements
Prototyping can be considered as a risk reduction activity which reduces requirements risks

6. Generic Software Process Model
Prototyping model
Prototyping benefits
Misunderstandings between software users and developers are exposed
Missing services may be detected and confusing services may be identified
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7. Generic Software Process Model
Prototyping model
Prototyping benefits
A working system is available early in the process
The prototype may serve as a basis for deriving a system specification

8. Generic Software Process Model
Prototyping model
Other Prototyping benefits
The system can support user training and system testing
Improved system usability
Closer match to the system needed
Improved design quality
Improved maintainability
Reduced overall development effort

9. Generic Software Process Model
Prototyping model
Approaches to Prototyping
Evolutionary prototyping
Throw-away prototyping

10. Generic Software Process Model
Prototyping model
Approaches to Prototyping
Evolutionary prototyping
An approach to system development where an initial prototype is produced and refined through a number of stages to the final system

11. Generic Software Process Model
Prototyping model
Prototyping Objectives
The objective of evolutionary prototyping is to deliver a working system to end-users. The development starts with those requirements which are best understood.

12. Generic Software Process Model
Prototyping model
Approaches to Prototyping
Throw-away prototyping
A prototype which is usually a partial implementation of the system is produced to help discover requirements problems and then discarded. The system is then developed using some other development process

13. Generic Software Process Model
Prototyping model
Prototyping Objectives
The objective of throw-away prototyping is to validate or derive the system requirements. The prototyping process starts with those requirements which are poorly understood

14. Generic Software Process Model
Prototyping model
Evolutionary Prototyping
Must be used for systems where the specification cannot be developed in advance, e.g.
Artificial Intelligent Systems
and user interface systems
Based on techniques which allow rapid system iterations

15. Generic Software Process Model
Prototyping model
Evolutionary Prototyping
Verification is impossible as there is no separate specification.
Validation means demonstrating the adequacy of the system

16. Generic Software Process Model
Prototyping model
Evolutionary Prototyping

17. Generic Software Process Model
Prototyping model
Evolutionary Prototyping
Specification, design, and implementation are inter-twined
The system is developed as a series of increments that are delivered to the customer

18. Generic Software Process Model
Prototyping model
Evolutionary Prototyping
Techniques for rapid system development are used such as CASE tools and 4GLs
User interfaces are usually developed using a GUI development toolkit

19. Generic Software Process Model
Prototyping model
Evolutionary Prototyping Advantages
Accelerated delivery of the system
Rapid delivery and deployment are sometimes more important than functionality or long-term software maintainability

20. Generic Software Process Model
Prototyping model
Evolutionary Prototyping Advantages
User engagement with the system
Not only is the system more likely to meet user requirements, but users are more likely to commit to the use of the system

21. Generic Software Process Model
Prototyping model
Evolutionary Prototyping Problems
Management problems
Existing management processes assume a waterfall model of development
Specialist skills are required which may not be available in all development teams

22. Generic Software Process Model
Prototyping model
Evolutionary Prototyping Problems
Maintenance problems
Continual change tends to corrupt system structure so long-term maintenance is expensive
Contractual problems
No requirement document

23. Generic Software Process Model
Prototyping model
Throw-away Prototyping
Used to reduce requirements risk
The prototype is developed from an initial specification, delivered for experiment then discarded

24. Generic Software Process Model
Prototyping model
Throw-away Prototyping
The throw-away prototype should NOT be considered as a final system
Some system characteristics may have been left out
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25. Generic Software Process Model
Prototyping model
Throw-away Prototyping
The throw-away prototype should NOT be considered as a final system
There is no specification for long-term maintenance
The system will be poorly structured and difficult to maintain

26. Generic Software Process Model
Prototyping model
Throw-away Prototyping

27. Generic Software Process Model
Prototyping model
Throw-away Prototyping
Developers may be pressured to deliver a throw-away prototype as a final system

28. Generic Software Process Model
Prototyping model
Throw-away Prototyping
This is not recommended
It may be impossible to tune the prototype to meet non-functional requirements
The prototype is inevitably undocumented
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29. Generic Software Process Model
Prototyping model
Throw-away Prototyping
This is not recommended
The system structure will be degraded through changes made during development
Normal organisational quality standards may not have been applied

30. Generic Software Process Model
Prototyping Techniques
Various techniques may be used for rapid development
Paper Prototyping
- Scratch Art Work
Presentation Software Prototyping
- Power Point (Microsoft)
- Freelance Graphics (Lotus)
- etc

31. Generic Software Process Model
Prototyping Techniques
Various techniques may be used for rapid development
Dynamic high-level language development
Database programming
- SQL
Component and application assembly

32. Generic Software Process Model
Prototyping Techniques
These are not mutually exclusive techniques – they are often used together
Visual programming is an inherent part of most prototype development systems

33. Generic Software Process Model
User interface prototyping
It is impossible to pre-specify the look and feel of a user interface in an effective way. Prototyping is essential
UI development consumes an increasing part of overall system development costs

34. Generic Software Process Model
User interface prototyping
User interface generators may be used to ‘draw’ the interface and simulate its functionality with components associated with interface entities
Web interfaces may be prototyped using a web site editor

35. Generic Software Process Model
Prototyping model
Key Point
A prototype can be used to give end-users a concrete impression of the system’s capabilities
Prototyping is becoming increasingly used for system development where rapid development is essential
Continue…

36. Generic Software Process Model
Prototyping model
Key Point
Throw-away prototyping is used to understand the system requirements
In evolutionary prototyping, the system is developed by evolving an initial version to the final version
Continued …

37. Generic Software Process Model
Prototyping model
Key Point
Rapid development of prototypes is essential. This may require leaving out functionality or relaxing non-functional constraints
Prototyping techniques include the use of very high-level languages, database programming and prototype construction from reusable components

38. Generic Software Process Model
Prototyping model
Key Point
Prototyping is essential for parts of the system such as the user interface which cannot be effectively pre-specified. Users must be involved in prototype evaluation

39. Prototyping Model
Pendekatan prototyping model digunakan jika pemakai hanya mendefinisikan objektif umum dari perangkat lunak tanpa merinci kebutuhan input, pemrosesan dan outputnya,
sementara pengembang tidak begitu yakin akan efisiensi algoritma, adaptasi sistem operasi, atau bentuk interaksi manusia-mesin yang harus diambil.
Cakupan aktivitas prototyping model terdiri dari:
Mendefinisikan objetif secara keseluruhan dan mengidentifikasi kebutuhan yang sudah diketahui.
Melakukan perancangan secara cepat sebagai dasar untuk membuat prototype
Menguji coba dan mengevaluasi prototype dan kemudian melakukan penambahan dan perbaikan-perbaikan terhadap prototype yang sudah dibuat.

40. Kelemahan prototyping model:
Walaupun pemakai melihat berbagai perbaikan dari setiap versi prototype, tetapi pemakai mungkin tidak menyadari bahwa versi tersebut dibuat tanpa memperhatikan kualitas dan pemeliharaan jangka panjang.
Pengembang kadang-kadang membuat kompromi implementasi dengan menggunakan sistem operasi yang tidak relevan dan algoritma yang tidak efisien.

41. Generic Software Process Model
Incremental Model
Fact: Software evolves over time
Straight path to an end product is unrealistic
Tight market deadlines
Deliver limited version
Core product requirements well understood
Need for extensions foreseeable

42. Generic Software Process Model
Incremental Model
Requirements
design
code
test
integrate
O&M
Release 1
release 2
release 3
release 4
Incremental development
(each release adds more functionality)

43. Generic Software Process Model
Incremental Model
design
code
test
integrate
O&M
reqts
version 1
version 2
version 3
lessons learnt
Evolutionary development
(each version incorporates new requirements)

44. Generic Software Process Model
Incremental Model
Combines elements of the linear model and prototyping
Produces “deliverable” increments
First increment often core product
Focuses on operational product
(not throw-away prototype)

45. Generic Software Process Model
Incremental Model
Used when not enough resources are available to deliver the complete product in time
Increments help to manage technical risks
(e.g. currently unavailable hardware)

46. Generic Software Process Model
Incremental Model
Focuses attention on reuse options
Focuses attention on early error elimination
Puts quality objectives up front
Integrates development and maintenance
Provides a framework for hardware/software development

47. Generic Software Process Model
Incremental Model
Contractual development often specifies process model and deliverables in advance
Requires risk assessment expertise
Needs refinement for general use

48. Incremental Model
Merupakan kombinasi linear sequential model (diaplikasikan secara berulang) dan filosofi pengulangan dari prototyping model.
Setiap tahapan linear sequential menghasilkan deliverable increment bagi perangkat lunak, dimana increment pertamanya merupakan sebuah produk inti yang mewakili kebutuhan dasar sistem.
Produk inti ini nantinya dikembangkan menjadi increment-increment selanjutnya setelah digunakan dan dievaluasi sampai didapat produk yang lengkap dan memenuhi kebutuhan pemakai.

49. Kelemahan incremental model:
1. Hanya akan berhasil jika tidak ada staffing untuk penerapan secara menyeluruh.
2. Penambahan staf dilakukan jika hasil incremental akan dikembangkan lebih lanjut.

50. Finished,
Questions?