Five Phases of the Systems Development Life Cycle (SDLC)
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Transcript of Five Phases of the Systems Development Life Cycle (SDLC)
CHAPTER 20- INTRODUCTION TO SYSTEMS DEVELOPMENT AND SYSTEMS ANALYSIS
1. Five Phases of the Systems Development Life Cycle (SDLC)
Systems analysis- tahap ketika seluruh informasi yang dibutuhkan untuk membeli,
mengembangkan atau memodifikasi sistem dikumpulkan. Karena terbatasnya sumber daya yang
dimiliki, permintaan pengembangan harus disaring dan diprioritaskan. Jika tujuannya adalah untuk
membuat sistem lebih baik, maka:
o (initial investigation)
sifat dan ruang lingkup proyek yang diajukan harus diidentifikasi
o (systems survey)
lakukan survey terhadap sistem yang ada saat ini untuk mengidentifikasi keunggulan dan
kelemahan sistem
o (feasibility study)
tentukan apakah proyek tersebut feasible
o (information needs and system requirements)
jika proyek feasible, identifikasi dan dokumentasikan seluruh informasi yang dibutuhkan
untuk memilih atau mengembangkan sistem yang baru
o (deliver system requirement)
Siapkan laporan system analysis dan laporkan kepada information system steering
committee
Conceptual design – menentukan bagaimana memenuhi keinginan users.
o (design alternatives)
pilih antara membeli software, develop-in-house, outsource
o (design specifications)
sistem seperti apa yang ingin dibuat dan bagaimana pengendalian atas sistem tersebut
o (conceptual design requirements)
permintaan desain secara konseptual dilaporkan pada information system steering
committee
Physical design
o mengartikan permintaan desain konseptual lebih spesifik seperti detail sandi dan uji
program komputer, pembuatan dokumen input dan output, pembuatan file dan databases,
pembuatan prosedur dan pengendalian atas sistem yang baru.
o (developed system)
Hasil physical design kemudian dilaporkan kepada information system steering committee
Implementation and conversion – penggabungan seluruh sistem dan aktivitas pembangunan
sistem
o perencanaan dibuat dan dilaksanakan (planning),
o hardware dan software diinstal dan diuji
o pegawai direkrut, detraining atau direlokasi
o prosedur diuji dan dimodifikasi
o standar dan pengendalian telah terbentuk dan dokumen sudah siap
o organisasi menggunakan sistem baru, membuat beberapa penyesuaian, dan melakukan
evaluasid an koreksi atas implementasi sistem baru.
o membuat laporan operational system dan melaporkannya kepada information system
steering committee
operations and maintenance – sistem bar uterus direview dan dimodifikasi. Jika terjadi
modifikasi besar-besaran atau perubahan sistem dalam tahap ini, maka proses akan kembali ke
tahap pertama
2. People involved in systems development and the role they played
Management - menekan pentingnya keterlibatan users dalam proses pembuatan sistem,
mendukung dan mendorong proyek pengembangan sistem, menyelaraskan sostem dengan
tujuan perusahaan, menetapkan tujuan pembangunan sistem, memilih dan melakukan penilaian
atas kinerja dari pimpinan system department, menetapkan kebijakan atas proyek yang terpilih,
dan berpartisipasi dalam kepuntusan penting terkait sistem tersebut. User management
menentukan informasi yang dibutuhkan, mendampingi analis dengan pertimbangan cost dan
benefit, menempatkan staf dalam proyek pengembangan tersebut, dan mengalokasikan dana
untuk proyek terkait.
Accountants and other users
o sebagai pengguna : menentukan informasi yang dibutuhkan
o sebagai anggota tim proyek atau anggota steering committee : membantu pengembangan
sistem
o jika diminta, akuntan dapat membantu membuat, menguji dan mengaudit kontrol yang
memastikan keakuratan dan kelengkapan pemrosesan data
information system steering committee – membuat perencanaan dan mengawasi information
system function, membuat kebijakan AIS, memastikan keterlibatan, arahan dan kontrol dari top-
management memfasilitasi koordinasi dan integrasi aktivitas dalam sistem.
Project development team – mengarahkan pengembangan, merencanakan proyek, mengawasi
untuk memastikan ketepatan waktu dan efektifitas biaya penyelesaian, memastikan
pertimbangan yang tepat dalam pemilihan personel, mengkomunikasikan status proyek ke top
management dan steering committee dan memfasilitasi penerimaan pengguna atas sistem baru.
System analyst and programmers
o system analysts: mempelajari sistem yang ada, mendesain sistem baru, mempersiapkan
detail yang dibutuhkan programmer, menjembatani gap antara manusia dan teknologi
dengan sering berinteraksi dengan pegawai terkait pengembangan sistem, dan memastikan
bahwa sistem yang baru dapat memenuhi kebutuhan users.
o computer programmer: membuat program berdasarkan detail yang diberikan sistem analyst
dan memodifikasi atau menjaga program yang masih ada.
External players – pelanggan, vendor, auditor eksternal, dan pemerintah.
3. The importance of system developments planning and planning techniques
Kenapa harus ada planning?
memudahkan untuk menyelaraskan tujuan pembuatan atau pembangunan sistem dengan
tujuan perusahaan secara keseluruhan
sistem lebih efisisen, subsistem saling terhubung, dan terdapat dasar untuk memilih aplikasi
baru dalam pengembangan sistem
perusahaan update dengan perubahan terbaru dalam IT
sistem menjadi less costly dan lebih mudah digunakan
manajemen siap untuk sumber daya yang dibutuhkan dan pegawai siap atas perubahan yang
terjadi.
Bentuk planning:
Project development plan – disiapkan oleh tim proyek; berisikan analisis cost/benefit,
permintaan developmental dan operasional (orang, dana, hardware, software), dan jadwal
aktivitas untuk membangun dan mengoperasikan sistem yang baru.
Master plan – dibuat oleh steering committee, menspesifikasikan apa saja yang terdapat dalam
sistem, cara pengembangan, siapa yang mengembangkan, bagaimana mendapatkan sumber
daya yang dibutuhkan, dan tujuan AIS tersebut.
Teknik Perencanaan:
Program Evaluation and Review Techniques (PERT)
seluruh aktivitas dan hubungan antara aktivitas sebulum dan sesudahnya harus diidentifikasi
untuk menggambarka PERT diagram yang menunjukan mana aktivitas yang memerlukan
pengeluaran sumber daya dan waktu yang paling banyak, penyelesaian dan awal mula suatu
proyek. Setelah waktu penyelesaian ditentukan, tentukan pula critical path (proses yang
memerlukan waktu pengerjaan paling lama).
Gantt charts
diagram batang yang terdiri dari aktivitas di bagian kiri dan satuan waktu pada bagian atas.
Diagram batang digambarkan sepanjang waktu pengerjaan (starting-ending). Diagram batang
diiisi sepanjang pengerjaan proyek berdasarkan tingkat penyelesaiannya. Keuntungannya :
diagram ini memperlihatkan keseluruhan progress aktivitas. Kelemahannya : diagram ini tidak
dapat menunjukan hubungan antar aktivitas
4. Various types of feasibility analysis and calculate economic feasibility
Kenapa harus nalisis feasibility? untuk menentukan menghentikan proyek, melanjutkan proyek tanpa
syarat apapun atau melanjutkan proyek jika suatu masalah telah terselesaikan. Makin lama proyek
berjalan makin sulit untuk dibatalkan, sehingga keputusan ini harus ditetapkan sedini mungkin.
Jenis feasibility analysis:
economic feasibility – berapa waktu, uang dan sumber daya yang dibutuhkan untuk
implementasi sitem (bandingkan biaya dengan payback period, NPV dan IRR)
technical feasibility – apakah sistem dapat dikembangkan dan diimplementasikan dengan
teknologi yang ada saat ini
legal feasibility – apakah sistem telah mengikuti aturan yang berlaku
scheduling feasibility – apakah sistem dapat dikembangkan dan diimplementasikan dalam waktu
yang telah ditetapkan
operational feasibility – apakah organisasi memiliki akses terhadap orang yang mendesain,
mengimplementasikan dan mengoperasikan sistem ini? apakah sistem ini akan digunakan?
5. Why systems changes behavioral reactions, form of resistance and how to minimize the problem
Mengapa terjadi?
Fear- muncul mdar ketidak tahuan, ketakutan kehilangan pekerjaan, kehilangan status,
kegagalan, teknologi, dan ketidakpastian
top management support- ketika kurang dukungan top mmanagemenmt ats perubahan yang
dilakukan, mereka akan memopertanyakan mengapa mereka harus menyetujui perubahan
tersebut
experience with prior change – ketika mereka pernah memiliki pengalam buruk pada perubahan
sebelumnya
communication-pegawai tidak mau mendukung perubahan kecuali ada penjelasan mengapa
perubahan tersebut terjadi
disruptive nature of change – permintaan informasi dan interview membuat mereka menggangu
dan menambah beban bagi pegwai sehingga menimbulkan kesan negatif
manner in which chang is occurred – alasn perubahan yang diterma top management bisa jadi
tidak dpt diterima oleh lower level
biases and emotions – jika sisi emosional terpengaruh
personal characteristic and background – semakin muda dan semakin berpendidikan lebih
mudah menerima perubahan
Bentuk penolakan:
aggression
perilaku yang merusak, melumpuhkan dan melemahkan sistem, seperti meningkatnya kesalahan
atau sabotase.
projection
menyalahkan sistem jika suatu hal berjalan tidak sesuai.
avoidance
mengacuhkan sistem yang baru dengan harapan sistem tersebut tidak akan digunakan lagi.
Bagaimanan mencegah hal tersebut terjadi?
dapatkan dukungan manajer, penuhi kebutuhan users, libatkan users dalam proses pembuatan,
menekankan keuntungan sistem baru, bersikap loggis, megadakan training, evaluasi kinerja sistem baru,
selalu membuka komunikasi dengan users, menguji sistem, dan humanize sistem.
CHAPTER 21 – AIS DEVELOPMENT STRATEGIES
Purchasing software
canned software-djual pada pengguna yang memiliki kesamaan kebutuhan, turnkey software-software
yang dijual sepaket dengan hardware nya. ASP merupakan pnyedia jasa penyewaan software mellaui
internet.
Tahap :
pemilihan vendor-bisa mellaui konferensi, internet, majalah, buku telepon, dll.
acquiring hardware-software – untuk pembelian yang banyak dan complex maka gunakan RFP
agar: menghemat waktu )tanpa harus interview berulang), menyederhanakan proses
pembuatan keputusan (semua respons berdasarkan format dan info yang sama), mengurangi
eror (tidak perlu overlook), dan mengurangi kemungkinan ketidakcocokan (masing2 pihak sudah
memiliki ekspektasi tertentu). Kekurangannya : vendor tidak dapat menyarankan alternatif lain,
masalah teknis yang menjadi urusan vendor sulit dianalisa dan mnambah biaya yang dikenakan.
evaluating proposal and select system – proposal yang menyediakan informasi yang kurang,
tidak memenui permintaan dasar dan ambigu akan ditolak. Jika lolos dalam paper screening,
proposal dicocokan dengan sistem requirement. vendor kemudian diminta untuk
mendemonstrasikan sisrem tersebut. Membandingkan vendor dengan menggunakan point
scoring-dimana tiap-tiap kriteria diberikan berat brebeda berdasarkan tingkat kepentingannya.
Setelah itu membandingkan biaya yang dibutuhkan (purchasing cost + requirement cost)..
Development in house
End user developed software
end user computing – pengembangan, penggunaan dan pengendalian sistem dilakukan oleh users
Keuntungan:
user creation, control and implementation-user mengendalika proses pengembangan
system that meet user needs
timeliness- menghemat waktu
freeing up of system resources – sumberdaya dapat digunakan untuk pengembangan sistem
lain
versatility and ease of use – mudah dipahami, dapat dimodifikasi, dan dpat digunakan
diamana saja
Kelemahan :
logic and development error- user yang mengembangkan sistem tidak memiliki pengetahuan IS
yang baik, sehingga seringkali mereka banyak melakukan eror atau tidak menyadari adanya eror
tersebut
inadequately tested application – jarang dilakukan tes yang menyeluruh karene tidak
mengetahui kegunaan tes tersebut
inefficien systems
poorly controlled and documented system:
system incompatibilities
wasted resources – ada duplikasi sistem
increased cost- update
Cara mengatasi kelemahan : help desk (menyelesaikan masalah, evaluasi hardware software baru,
melakukan training, menyediakan bantuan teknis dan pendampingan dalam pembuatan aplikasi
OUTSOURCING
Merupakan kegiatan merekrut perusahaan luar untuk menangani seluruh aktivitas pemrosesan data
organisasi.
Keuntungan:
a business solution –agar perusahaan lebih fokus pada bisnis utamanya
asset utilization – menjual aset pada outsourcer
access to greater expertise and better technology – diserahkan pada ahlinya
lower cost – mengurangi biaya labor, instalasi, dll
less development time – perusahaan outsourcer yang baik dapat mengerjakan pengembangan
lebih cepat
elimination of peaks and valley usage – mengurangi penggunanaan untuk mengurangi
operational cost
facilitation of downsizing – merampingkan struktur
Kelemahan :
inflexibility – kontrak berkisar 10 tahun, jika ada ketidak[uasan dari pelnggan sangat sulit proses
untuk pembatalan kontrak tersebut
loss of control –terutama kontrol atas system dan data
reduce competitive advantage – karena tidak mengetahui proses
locked in system – pengeluaran cukup besar, sehingga harus tetap menggunakan sistem yang
dibangun
unfulfilled goals – banyak tujuan yang tidak terpenuhi
poor service – outsourcer kurang responsive terdapat perubahan yang terjadi
increased risk – ope, fin, tech, strategy , personnel, legal dan regulatory risk
BUSINESS PROCESS MANAGEMENT
Business process reengineering (BPR) is the analysis and redesign of business processes and information
systems to achieve significant performance improvements. Karena dinilai kurang efektif maka proses ini
dikembangkan menjadi BPM dengan pengembangan yang m=berkelanjutan untuk mengoptimalkan
proses bisnis dalam organisasi. Prinsip penting di bawah BPM :
Proses bisnis dapat menciptakan competitive advantage
Proses bisnis harus dikoordinasikan dan dikomunikasikan dengan baik.
business proses harus dapat beradaptasi mennyesuaikan perubahan yang terjadi
bisnis proses harus selaras dengan tujuan dan kebutuhan perusahaan
empat komponen utama BPM :
proses untuk membuat dan menjalankan aplikasi, termasuk peraturan dalam bisnis
analisa bisnis untuk mengidentifikasi isu, tren dan kesempatan
integrasi seluruh aktivitas
menyetorkan dan mengamankan dokumen dan file penting lainnya
PROTOTYPING
Four steps are involved in developing a prototype:
1. STEP ONE: Identify basic requirements
The first step is to identify basic requirements by meeting with users to agree on the size and scope of
the system and decide what it should include and exclude. Developer and users also determine decision-
making and transaction processing outputs and inputs and data needed to produce those outputs. The
emphasis is on what outputs should be produced rather than how. The developer must ensure user
expectations are realistic and their basic information requirements are met. The designer uses the
information requirements to develop cost, time, and feasibility estimates for alternative AIS solutions
2. STEP TWO: Develop an initial prototype
The second step involves developing an initial prototype that meets the agreed-on requirements. The
emphasis is on speed and low cost rather than efficiency of operation. The goal is to implement the
prototype within a short time period. Because of time constraints, some aspects are sacrificed. For
example, at this point, there is ignorance of non-essential functions, system controls, exception
handling, validation of input data, processing speed, and efficiency considerations. Users must see and
use tentative versions of data entry display screens, menus, input prompts, and source documents. They
must also respond to prompts, query the system, judge response times, and issue commands. When the
prototype is finished, the developer returns to the users and demonstrates the system. Users are
instructed to experiment and comment on what they do and do not like.
3. STEP THREE: Repeated iterations
The third step involves repeated iterations of users identifying changes, developers making the changes,
and the system being turned back to users for next round. This step continues until users are satisfied—
usually 4 to 6 iterations.
4. STEP FOUR: Use the system
The final step involves using the system approved by the users. An approved prototype is typically used
in one of two ways. Half of the prototypes are turned into fully functional systems referred to as
operational prototypes. To make them operational, the developer must add needed controls, improve
operational efficiency, provide backup and recovery, and integrate the prototype with the systems with
which it interfaces. Changes may be necessary to allow the program to accept real input, access real
data files, process data, make necessary computations and calculations, and produce real output. When
it’s not practical to modify the prototype to make a fully functional system, non-operational or
throwaway prototypes can be used in several ways. They may be discarded, and the systems
requirements identified in the process of building them can be used to develop a new system. If so, the
SDLC is followed to develop the system, and the prototype is a model. Alternately, they may be used as
the initial prototype for an expanded system designed to meet needs of many users. As a final
alternative, if users and developers decide the system is unsalvageable, the prototype can be discarded
completely.
There are some advantages of prototyping :
1. Better definition of user needs -- Because of intensive end-user involvement
2. Higher user involvement and satisfaction
3. Faster development time -- It may take days or weeks to get a prototype up vs. a year or
more for a traditional system
4. Fewer errors -- Errors are detected early because the users experiment with each
version. It’s also easy to identify and terminate an infeasible AIS early
5. More opportunity for changes
6. Less costly -- Some for 10–20% of the cost of traditional systems
Despite its advantage, prototype also has several disadvantages :
1. Significant user time
2. Less efficient use of system resources -- Shortcuts in developing the system may result in poor
performance and reliability and high maintenance and support costs
3. Incomplete system development
4. Inadequately tested and documented systems
5. Negative behavioral reactions -- If the prototype is discarded, users may be upset about using it
and losing it. Users may also be dissatisfied if all their suggestions are not incorporated or if they
have to go through too many iterations
6. Never-ending development -- If not managed properly, the development could get stuck in a
terminal loop
CASE TOOLS
Computer-aided software (or systems) engineering (CASE) tools are an integrated package of computer-
based tools that automate important aspects of the software development process. It is used to plan,
analyze, design, program, and maintain an information system. It is also used to enhance efforts of
managers, users, and programmers in understanding information needs.
There are several advantages of CASE technology :
1. Increased productivity -- Can generate bug-free code from system specifications and automate
repetitive tasks
2. Improved program quality -- Can simplify enforcement of structured development standards,
which improves quality of development and reduces threat of serious design errors; can check
internal accuracy of design and detect inconsistencies
3. Cost savings -- Cost savings of up to 80–90% are possible
4. Improved control procedures -- Encourages development early in the design process of system
controls, security measures, system auditability, and error handling procedures
5. Simplified documentation -- Automatically documents as the system development progresses
Despite its advantage, CASE technology also has several disadvantages :
1. Incompatibility -- Some tools don’t interact effectively with some systems
2. Cost -- Some packages > $360,000
3. Unmet expectations -- Only 37% of CIOs believe they achieved expected benefits
CHAPTER 22 – SYSTEM DESIGN, IMPLEMENTATION AND OPERATION
Conceptual Systems Design
In the conceptual systems design phase, a general framework is created for implementing user
requirements and solving the problems identified in the analysis phase. The three main steps are :
1. Evaluate design alternatives
The steering committee evaluates the alternatives. Following are some design considerations and
alternatives:
How should the communications channel be configured? -- Point-to-point, Multi-drop, or
Line-sharing
What type of communications channel should be used? -- Phone lines, Coaxial cable, Fiber
optics, Microwave, or Satellite
What type of communications network should be used? – Centralized, Decentralized,
Distributed, or Local area
What type of storage media should be used for data? – Tape, Disk, Diskette, Hard drive, CD,
or Paper
What type of data storage structure should be used? – Files or Database
How should files be organized and accessed? – Random, Sequential, orIndexed-sequential
access
What media should be used to input data? – Keying, OCR, MICR, POS, EDI, or Voice
What format will the input take? -- Source documents, Turnaround documents, Source data
automation, or Screen
How will the system be operated? -- In-house or Outsourcing
How frequently will outputs be produced? – Instantly, Hourly, Daily, Weekly, or Monthly
What media will be used for output? – Paper, Screen, Voice, Diskette, CD, or Microfilm
How will output be scheduled? -- On demand or at predetermined times
What format will the output take? – Narrative, Table, Graph, Electronic file or
communication
What form will printed output take? -- Pre-printed forms, Turnaround documents, or
System-generated forms
What processing mode will be used? – Manual, Batch, orReal time
What type of processor will be utilized? -- Personal computer, Minicomputer, or Mainframe
How will software be acquired? – Canned, Custom, or Modified
How will transactions be processed? -- By batch or Online
How frequently will updates occur? – Instantly, Hourly, Daily, Weekly, or Monthly
2. Prepare design specifications
Once a design has been selected, the project team develops the conceptual design specifications for the
following elements:
Output -- Because output is what goes to the user and the system must be designed to meet
user needs, the output specifications are prepared first
Data storage -- How will data be stored to produce the desired outputs?
Input -- What types of data must be entered to produce the desired outputs?
Processing procedures and operations -- How will data be processed and in what sequence
to produce the desired outputs?
3. Prepare the conceptual systems design report.
A conceptual systems design report is prepared at the end of the conceptual design phase to guide
physical system design activities, communicate how management and user information needs will be
met, and help the steering committee assess system feasibility.
Physical System Design
1. Output Design
The objective of output design is to determine the nature, format, content, and timing of printed
reports, documents, and screen displays. Important design considerations include :
Use of the output -- Who will use it and why?, when is it needed?, and what decisions will it
facilitate?
Output medium – Paper, Screen, Voice response, Diskette, Microfilm, and Other
Output format -- Should select the format that clearly conveys the most information. It could be
table, narrative, or graphic.
Pre-printed -- Should paper output be on preprinted form and/or turnaround document?
Location -- Where is the output to be sent?
Access -- Who should be able to access hard-copy and screen output?
Detail -- Lengthy output should be preceded by an executive summary and a table of contents.
Headings and legends organize data and highlight important items. Detailed info goes in an
appendix.
Timeliness -- How often should the output be produced?
Outputs usually fit into one of the following four categories:
Scheduled reports -- have pre-specified content and format, are prepared on a regular basis, for
examples: weekly sales analysis and monthly financial statements
Special-purpose analysis reports -- no pre-specified content and format, typically prepared in
response to a management request, for example: analysis of impact of a government mandate
on profitability
Triggered exception reports -- have pre-specified content and format, prepared only in response
to abnormal conditions, i.e., the “trigger”, for example: cost overruns
Demand reports -- have pre-specified content and format and prepared only on request.
2. File and database design
Important file and database design considerations include:
Storage medium -- Hard drive, Disk, Diskette, CD, Tape, or Paper
Processing mode – Manual, batch or real time
Maintenance -- What procedures are needed to effectively maintain the data?
Size -- How many records and how big are they? and how fast are they expected to grow?
Activity level -- What portion of records are added or deleted each year? and what portion
needs to be updated?
3. Input design
There are two principal types of data input, forms and computer screens. Considerations in input design
include:
Input medium – Keyboard, OCR, MICR, POS terminal, EDI, and Voice input
Input source – Computer, Customer, and Remote location
Input format -- Source or turnaround document, screen, and source data
automation
Input type -- What is the nature of the data?
Volume -- How much data are to be entered?
Personnel -- What functions and expertise do the data entry operators have? and is
additional training necessary?
Frequency -- How often is data to be entered?
Cost -- How can costs be minimized without adversely affecting efficiency and
accuracy?
Error detection and correction -- What errors are possible? and how can they be
detected and corrected?
4. Form design
Following are important principles for designing new forms and evaluating existing ones:
• General considerations -- Preprint as much data as possible; use appropriate weight and grade
of paper; use bold type, double-thick lines, and shading to highlight different parts of the form;
use a standard size and one that is consistent with requirements for filing, binding, or mailing; if
mailed to external parties, position the address for placement in a window envelope; have
copies of the form printed in different colors to facilitate accurate distribution; and include clear
instructions for completing the form.
• Introductory section of form -- Place the form name at the top in bold type; have the forms pre-
numbered consecutively; and if distributed to external parties, have company name and address
pre-printed on the form.
• Main body of form -- Group together logically related information (e.g., info about the customer,
info about the product); provide sufficient room to record each item; order the data items
consistent with the sequence in which the data is likely to be gathered; use codes and check-offs
in places where standardized explanations are likely.
• Conclusion section of form -- Provide space for recording final disposition of the form, approval
signatures, dates of approval and final disposition, and a dollar or numeric total ; clearly indicate
the distribution of each form.
Computer screens are most effective when the following principles are used:
Organize the screen for quick, accurate, and complete entry of the data -- Minimize input by
retrieving as much as possible from the system. Example: If the customer number is entered,
retrieve his name/address data from the system.
Enter data in the same order it appears on the document
Complete the screen from left to right and top to bottom, grouping logically related data together
Design the screen so users can jump from one data entry location to another or use a single key
to go directly to screen locations
Make it easy to correct mistakes -- Use clear and explicit error messages that are consistent on all
screens and provide a help feature for online assistance
Avoid clutter by restricting the amount of data on one screen -- Limit the number of menu
options on a single screen
5. Program design
The following slides discuss the eight steps for developing software and where these steps take place in
the SDLC.
STEP ONE: Determine user needs -- Occurs during the systems analysis stage of the SDLC.
STEP TWO: Develop and document a plan -- Occurs during the conceptual design phase and
the beginning of physical design.
STEP THREE: Write the program code -- Design in increasing levels of detail, known as
hierarchical program design. It begun during systems design and completed during systems
implementation.
STEP FOUR: Test the program code -- Debugging is discovering and eliminating program
errors. Desk checking happens after a program is coded and involves a visual and mental
review to discover programming errors. Programs are tested for logic errors using test data
that simulates both valid transactions and all possible error conditions. Large programs are
often tested in three stages, such as individual program modules, the linkages between the
module and the control module, and the interfaces between the program being tested and
other application programs. Errors need to be found as soon as possible in the development
process. Errors discovered late cost 80–1000% more to fix than those found early.
STEP FIVE: Document the program -- Documentation explains how programs work and helps
correct and resolve errors. It includes flowcharts, record layouts, E-R diagrams, REA data
models, narrative descriptions of the system, etc., organized in a manual.
STEP SIX: Train program users -- Often uses the program documentation.
STEP SEVEN: Install the system -- All components are brought together, and the company
begins to use the system.
STEP EIGHT: Use and modify the system -- Program maintenance is a response to any factors
that require program revision. It includes requests for new or revised reports; changes in
input, file content, or values such as tax rates; error detection and correction; and
conversion to new hardware.
6. Procedure design
Individuals who interact with a newly-designed AIS need procedures to cover input preparation,
transaction processing, error detection and correction, controls, reconciliation of balances, database
access, output preparation and distribution, and computer operator instructions. Procedures may take
the form of system manuals, user instruction classes, training materials, and online help screen. The
procedures may be written by development teams; users; or teams representing both groups.
7. Controls design
Improperly controlled input, processing, and database functions produce information of questionable
value. Controls must be built into an AIS to ensure its effectiveness, efficiency, and accuracy. These
controls should minimize errors and detect and correct errors when they do occur. Accountants play a
vital role in this area. Important control concerns that must be addressed include:
Validity -- Are all interactions valid?
Authorization -- Are input, processing, storage, and output activities authorized by
the appropriate managers?
Accuracy -- Is input verified to ensure accuracy? and what controls ensure that data
is not lost when passing between processing activities?
Security -- Is the system protected against unauthorized physical and logical access
to prevent improper use, alteration, destruction, or disclosure of information and
software and theft of system resources?
Numerical control -- Are documents pre-numbered to prevent errors or intentional
misuse and to detect when documents are missing or stolen?
Availability -- Is the system available as set forth in agreements? and can users
enter, update, and retrieve data during those times?
Maintainability -- Can the system be modified without affecting system availability,
security, and integrity?; Are only authorized, tested, and documented changes made
to the system and data?; Are resources available to manage, schedule, document,
and communicate changes to management and authorized users?
Integrity -- Is processing complete, accurate, timely, and authorized?; Is it free from
unauthorized or inadvertent manipulations?
Audit trail -- Can data be traced from source to output and vice versa?
8. Physical system design report
At the end of the physical design phase, a physical systems design report is prepared, summarizing what
was accomplished. This report serves as the basis for management’s decision whether to proceed to
implementation.
Systems Implementation and Conversion
Systems implementation is the process of installing hardware and software and getting the AIS up and
running. Phases include
1. Developing a plan
An implementation plan consists of implementation tasks, expected completion dates, cost estimates
and specification of the person(s) responsible for each task. The plan specifies when the project should
be complete and operational. The implementation team should identify risk factors that decrease the
likelihood of successful implementation, and the plan should contain a strategy for coping with each of
the risks. AIS changes may require adjustments to the company’s organizational structure, including
creation of new departments; elimination or downsizing of existing departments; and changes even in
the data processing department.
2. Preparing the site : Installing and testing hardware and software
A large computer may require changes such as new electrical outlets; data communications facilities;
raised floors; humidity controls; special lighting; air-conditioning; security measures, such as fire
protection and emergency power supply; space for equipment, storage, and offices. Site preparation is a
lengthy process and should begin well ahead of the installation date.
3. Selecting and training personnel
Employees can be hired from outside or transferred internally. Hiring from within is usually more
effective and less costly, because the employees already understand the business. Transferring displaced
employees can enhance loyalty and morale. Companies take training shortcuts because effective
training is time-consuming and expensive and those who understand the system are maintaining and
upgrading it. When training is insufficient, the company will not achieve the expected return on
investment. The hidden cost is that users will turn to their coworkers who have mastered the system for
help. It results in less productive coworkers and increased costs. Effective training includes hardware
and software skills and orientation to new policies and operations. The training should be scheduled just
before systems testing and conversion. Types of training include technical training from vendors, self-
study manuals, computer-aided instruction, videotape presentations, role-playing, case studies, and
experimenting with the AIS under the guidance of experienced users.
4. Completing documentation
Three types of documentation must be prepared for new systems:
Development documentation -- Describes the AIS and includes a system description;
copies of output, input, file, and database layouts; program flowcharts; test results;
and user acceptance forms.
Operations documentation – Includes operating schedules; files and databases
accessed; and equipment, security, and file retention requirements
User documentation -- Teaches users how to operate the AIS. and includes a
procedures manual and training materials.
5. Testing the system
Inadequate system testing has contributed to the failure of systems. Three common forms of testing
include:
Walk-throughs -- Step-by-step reviews of procedures or program logic : Attended by
the development team and users early in system design; focus is on organization
input, files, outputs, and data flows; subsequent walk-throughs are attended by
programmers; and address logical and structural aspects of program code.
Processing test transactions -- Determines whether the program operates as
designed; requires both valid and erroneous data; the correct response for each test
should be specified in advance.
Acceptance tests -- Uses copies of real transactions and files rather than
hypothetical ones; users develop acceptance criteria; and then make final decision
whether to accept.
Conversion is the process of changing from the old AIS to the new. Many elements must be converted,
including hardware, software, data files, and procedures. The process is complete when the new AIS has
become a routine, ongoing part of the system. Four conversion approaches are used to change from an
old to a new system:
1. Direct conversion
Immediately terminates the old AIS when the new one is introduced. Appropriate when the old AIS has
no value; or the new AIS is so different that comparisons between the two are meaningless. Main
advantage to direct conversion is inexpensive, but the main disadvantage is it provides no backup AIS.
There is a high risk of failure unless the new system has been very carefully developed and tested.
2. Parallel conversion
Operates the old and new systems simultaneously for a period of time. You can process transactions
with both systems, compare output, reconcile differences, and make corrections to the new AIS. Main
advantage to parallel conversion is it protects the company from errors but the main disadvantage is it is
costly and stressful for employees to process all transactions twice. Because companies often
experience problems during conversion, parallel processing has gained widespread popularity.
3. Phase-in conversion
Gradually replaces elements of the old AIS with the new one. The new system is often phased in a
module at a time. The main advantage is data processing resources can be acquired over time, but the
disadvantages are costs of creating temporary interfaces between old and new AIS and time required to
make the complete conversion.
4. Pilot conversion
Implements a system in just one part of the organization, e.g., a branch office or a single store. When
problems with the system are resolved, the new system could be implemented at the remaining
locations. The advantages of this conversion is it localizes conversion problems and allows training in a
live environment. But the disadvantages are long conversion time and need for interfaces between old
and new systems.
Data conversion can be time-consuming, tedious, and expense. The difficulty and magnitude is easy to
underestimate. Data files may need to be modified in three ways, there are files may be moved to a
different storage medium (e.g., tape to disk), data content may be changed (e.g., fields added or
deleted), and a file or database format may be changed. Steps in the data conversion process:
1. Decide which data files need to be converted.
2. Check files for completeness and data inaccuracies, and remove any
inconsistencies.
3. Do the actual data conversion.