Introduction To Software Engineering - Repository UNIKOM

  Citra Noviyasari, S.Si, MT

  What is software ?

_{Software is a set of items or objects}

_includes that form a “configuration” that _{• documents} • programs • data ...

  What is software? 

  Definitions: Computer programs, procedures, and possibly associated documentation and data pertaining to the operation of a computer system (IEEE

  Standard Glossary of Software

Engineering Terminology, 1990 ) What is software ? 

  Software is designed and built by software engineers.

  

Software is used by virtually everyone in

society.

   Software engineers have a moral obligation to build reliable software that does no harm to other people. What is software ? 

  Software is both a product and a vehicle for delivering a product (information).

  

Software is engineered not manufactured.



  Software does not wear out, but it does deteriorate.

   Currently, most software is still custom-built. Kurva Bahttube 

  Proses Umur 

  Proses Umur Perangkat Lunak W a k t u ^{T in gk at K eg ag al an K e m a t i a n s e g e r a U s a n g} eg ^{ag al an L a j u k e g a g a l a n m e n i n g k a t s e h u b u n g a n d e n g a n e f e k s a m p i n g}

  

Software Applications

Type 

  System software 

  Application software 

  Embedded software 

  Engineering/Scientific software 

  Product software 

  Web Applications 

  Artificial intelligence software

  

New Software Challenges



  Ubiquitous computing 

  Creating software to allow machines of all sizes to communicate with each other across vast networks 

  Netsourcing 

  Architecting simple and sophisticated applications that benefit targeted end-user markets worldwide 

  Open Source 

  Distributing source code for computing applications

so customers can make local modifications easily

and reliably

   New economy

   Building applications that facilitate mass Legacy Software 

  Many programs still provide a valuable business benefit, even though they are one or even two decades old.

   These programs must be maintained and this creates problems because their design is often not amenable to change. Legacy Software  must be adapted to meet the needs of new computing environments or technology

   must be enhanced to implement new business requirements

   must be extended to make it interoperable with more modern systems or databases

   must be re-architected to make it viable Software Evolution 

  Process by which programs change shape, adapt to the market place, and inherit characteristics from preexisting programs

   Unified theory for software evolution (Lehman):

  

  Law of continuing change

  

  Law of increasing complexity

  

  … The Cost of Change 1x ^{1.5-6x 60-100x}

  Important Questions for Software Engineers 

  Why does it take so long to get software finished? 

  Why are development costs so high? 

  Why can't we find all errors before we give the software to our customers? 

  Why do we continue to have difficulty in

measuring progress as software is being Software Myths 

  Still believed by many managers and practitioners 

  Insidious because they do have elements of truth 

  Every practitioner and manager should understand

the reality of the software

business.

  Software Myths: Clients’ point of view

  Myths:

  

  A general statement of objectives is enough to get going. Fill in the details later.

  

  Project requirements continually change, but change can be easily accommodated

  Reality: 

  Poor up-front definition of the requirements is THE major cause of poor and late software.

  

  Cost of the change to software in order to fix an error increases

  Software Myths: Developers’ point of view

  Reality:

  Myths: 

  50%-70% of the effort 

  Once a program is expended on a program written and works, the occurs after it is developer's job is done. delivered to the customer.

   Until a program is

   Software reviews can be running, there is no way more effective in finding to assess its quality. errors than testing for

   The only deliverable for a certain classes of errors. successful project is a

   A software configuration working program. includes documentation,

  Software Myths: Management’s point of view Reality:

  Myths:

  

  Books of standards

   Books may exist, but

  exist in-house so

  they are usually not up

  software will be to date and not used. developed _(**)

   CASE tools are needed satisfactorily. but are not usually obtained or used.

  

  Computers and software tools that are

   "Adding people to a late

  available in-house are

  software project makes What is Software Engineering ? 

  Software engineering is the establishment and sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machines (Fritz Bauer,1969)

   Software engineering is [1] the application

of a systematic, disciplined, quantifiable Why SE ? 

  To get the right software and to make the software right 

  Complexity of software 

  Domain problem: Business Rule

  

  Data size: Digital and Non Digital

  

  Solution: Algorithm

  

  Place or Sites Why SE ? (2) 

  Software must be correct

   Software correctness have to be maintained How should SE be applied ? 

  There are 2 things to be considered in SE: 

  Product = Software: _

  Programs _ Documents _ Data 

  Process of how the software is build: _

  Management process _ Technical process Product of SE 

  Product is obtained through stages of development = Software Development Life Cycle (SDLC)

   Examples of life cycles (SDLC):

  

  Waterfall model

  

  V model

  

  Spiral model

  

  Fountain model

   Process of SE 

  Management process includes: 

  Project management

  

  Configuration management

  

  Quality Assurance management Process of SE (2) 

  Technical process, described as methods to be applied in a particular stage of the s/w development life-cycle

  

  Analysis methods

  

  Design methods

  

  Programming methods

  

  Testing methods

   Technical methods are leading to When should SE be applied ? 

  Pre-project 

  Project Initiation 

  Project Realisation 

  Software Delivery & Maintenance Who is involved ? 

  Manager 

  Project Manager

  

  Configuration Manager

  

  Quality Assurance Manager

   Software Developer:

  

  Analyst

  

  Designer

   Who is involved ? 

  Support 

  Administration

  

  Technical Support for Customer

  

  Welfare What are the costs of software engineering? 

  Roughly 60% of costs are development

costs, 40% are testing costs. For custom

software, evolution costs often exceed development costs.

   Costs vary depending on the type of system being developed and the requirements of system attributes such as What are software engineering methods? 

  Structured approaches to software development which include system models, notations, rules, design advice and process guidance.

   Model descriptions _

  Descriptions of graphical models which should be produced; 

  Rules _ Constraints applied to system models;

   Recommendations _

  Advice on good design practice; 

  Process guidance What are the attributes of good software? 

  The software should deliver the required functionality and performance to the user and should be maintainable, dependable and acceptable.

  

  Maintainability

   Software must evolve to meet changing needs;

  

  Dependability

   Software must be trustworthy;

  

  Efficiency

   Software should not make wasteful use of system

  

What are the key challenges facing

software engineering? 

  Heterogeneity 

  Developing techniques for building software that can cope with heterogeneous platforms and execution environments;

   Delivery

  

  Developing techniques that lead to faster delivery of software;

   Trust Professional and ethical responsibility

   Software engineering involves wider responsibilities than simply the application of technical skills.

   Software engineers must behave in an honest and ethically responsible way if

they are to be respected as professionals.

   Ethical behaviour is more than simply Issues of professional responsibility 

  Confidentiality 

  Engineers should normally respect the confidentiality of their employers or clients irrespective of whether or not a formal confidentiality agreement has been signed.

   Competence

  

  Engineers should not misrepresent their level of competence. They should not knowingly accept work which is outwith Issues of professional responsibility 

  Intellectual property rights

   Engineers should be aware of local laws governing the use of intellectual property such as patents, copyright, etc. They should be careful to ensure that the intellectual property of employers and clients is protected.

  

  Computer misuse

   Software engineers should not use their technical skills to misuse other people’s computers. Computer misuse ranges from relatively trivial (game playing ACM/IEEE Code of Ethics 

  The professional societies in the US have

cooperated to produce a code of ethical

practice.

   Members of these organisations sign up to the code of practice when they join.

   The Code contains eight Principles related to the behaviour of and decisions made by professional software engineers,

  

Code of ethics - preamble



  Preamble 

  The short version of the code summarizes aspirations at a high level of the abstraction; the clauses that are included in the full version give examples and details of how these aspirations change the way we act as software engineering professionals. Without the aspirations, the details can become legalistic and tedious; without the details, the aspirations can become high sounding but empty; together, the aspirations and the details form a cohesive code.

   Software engineers shall commit themselves to making the analysis, specification, design, development, testing Code of ethics - principles 

  PUBLIC

   Software engineers shall act consistently with the public interest.

  

  CLIENT AND EMPLOYER

   Software engineers shall act in a manner that is in the best interests of their client and employer consistent with the public interest.

  

  PRODUCT

   Software engineers shall ensure that their products Code of ethics - principles 

  JUDGMENT

   Software engineers shall maintain integrity and

independence in their professional judgment.

  

  MANAGEMENT

   Software engineering managers and leaders shall subscribe to and promote an ethical approach to the management of software development and maintenance.

  

  PROFESSION

   Software engineers shall advance the integrity and Code of ethics - principles 

  COLLEAGUES 

  Software engineers shall be fair to and supportive of their colleagues.

   SELF

  

  Software engineers shall participate in lifelong learning regarding the practice of their profession and shall promote an ethical approach to the practice of the profession. Ethical dilemmas 

  Disagreement in principle with the policies of senior management.

   Your employer acts in an unethical way and releases a safety-critical system without finishing the testing of the system.

   Participation in the development of military weapons systems or nuclear systems.

  Atribut Produk 

  Kinerja 

  Reliability 

  Pelayanan 

  Maintanability 

  Garansi 

  Mudah digunakan 

  Penampilan 

  Merek Definisi 

  Rekayasa perangkat lunak adalah penetapan dan penggunaan prinsip-prinsip rekayasa yang tangguh/ teruji dalam upaya memperoleh perangkat lunak secara ekonomis, handal dan bekerja efisien di mesin nyata, dan berkaitan dengan metode dan kaidah yang diperlukan dalam mengembangkan perangkat lunak untuk computer.

   Sedangkan pengertian rekayasa perangkat lunak menurut IEEE : Rekayasa perangkat lunak adalah Prinsip Perangkat Lunak 

  Kekakuan ( Rigor ), Rekayasa yang dilakukan harus sesuai dengan keinginan user, walupun terkadang diperlukan kreativitas perekayasa untuk membuat perangkat lunak.

  

  Resmi (formal) Pemilihan salah satu metodologi/pendekatan perangkat lunak, berdampak pada harus Prinsip Perangkat Lunak 

  Pemisahan kepentingan Berkaitan dengan apek-aspek persoalan : melebarnya focus kerja, kompleksitas sistem.

   Abstraksi Menggambarkan keseluruhan sistem dalam bentuk yang sederhana

   Modularitas Mendekomposisikan persoalan menjadi modul- Karakteristik Perangkat Lunak 

  Perangkat lunak dibangun dan dikembangkan, tidak dibuat dalam bentuk yang klasik.

  Walaupun perkembangan antara perangkat keras dan perangkat lunak sangat ekuivalen, namun aktivitas diantara keduanya sangat berbeda.

   Perangkat lunak tidak pernah usang,

   Sebagian besar perangkat lunak dibuat secara Kurva Bahttube 

  Proses Umur 

  Proses Umur Perangkat Lunak W a k t u ^{T in gk at K eg ag al an K e m a t i a n s e g e r a U s a n g} eg ^{ag al an L a j u k e g a g a l a n m e n i n g k a t s e h u b u n g a n d e n g a n e f e k s a m p i n g} Tahapan Umur Perangkat Lunak Periode Simbolisasi Penyebab Solusi

  Pembuatan DFR (Decreasing Failure Rate)

  Defect, rendahnya control kualitas,

  Quality control, Pengujian penerimaan,

  Pemakaian CFR (Constant Failure Rate)

  Human error Redudancy, User friendly,

  Kadaluarsa IFR Peningkatan Teknologi,

  Pemodelan Sistem 

  Asumsi, digunakan untuk mengurangi jumlah kemungkinan (permutasi) dan variasi yang mungkin.

   Penyederhanaan, digunakan untuk menciptakan model dengan waktu yang tepat.

   Pembatasan ( Boundaries), digunakan untuk membatasi lingkup sistem.

   Batasan ( Constraint), digunakan untuk menunjukkan cara dimana model tersebut diciptakan dan pendekatan yang dilakukan pada saat model Ciri-ciri software yang baik 

  Maintainability (dapat dipelihara) 

  Software bisa menangani perubahan spek kebutuhan

   Dependability (dapat diandalkan)

  

  Aman, selamat, tidak menyebabkan keruksakan fisik

   Efficiency (Efisien)

  

  Software mampu mengoptimalkan resource