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DR
PEMBANGUNAN SISTEM INFORMASI VS SOFTWARE
• REKAYASA SISTEM INFORMASI DAN REKAYASA PERANGKAT LUNAK (James Martin)
Rekayasa Perangkat Lunak
Rekayasa Sistem Informasi
Perancangan
PSI
Analisa
Implementasi
Karakteristik HardwareKarakteristik Hardware
Time
Fai
lure
rat
e
Infant mortalityWear out
Karakteristik SoftwareKarakteristik Software
Time
Fai
lure
rat
e
Idealized Curve
Increased failure rate due to side effects
Actual CurveChange
REKAYASA PERANGKAT LUNAKREKAYASA PERANGKAT LUNAK
• Mengapa Rekayasa Perangkat Lunak (Software Engineering) diperlukan ?
• Karena adanya Permasalahan didalam Perangkat Lunak dan Pengembangannya :– Krisis perangkat lunak.– Biaya perbaikan kesalahan yang meningkat
sejalan dengan tahapan pengembangan.– Biaya pemeliharaan perangkat lunak yang besar.– Keterlambatan dan kekurangan biaya.
Mengapa Rekayasa Perangkat Lunak Diperlukan ?
Keterlambatan penyampaian produk Tidak sesuai dengan spesifikasi , bahkan salah Menafikan aspek non teknis Software berukuran besar, dikembangkan oleh
team dari berbagai disiplin, secara terus menerus produk dapat mengalami perubahan sepanjang pengembangan dan setelah instalasi
REKAYASA PERANGKAT LUNAKREKAYASA PERANGKAT LUNAK
0
20
40
60
80
100
1960 1970 1980 1990
• Mengapa Rekayasa Perangkat Lunak diperlukan ?– Krisis Perangkat Lunak
Biaya perangkat lunak cenderung meningkat dan melebihi biaya perangkat keras
SOFTWARE COST
HARDWARE COST
Source : Electronic design, Jan 1981
REKAYASA PERANGKAT LUNAKREKAYASA PERANGKAT LUNAK• Mengapa Rekayasa Perangkat Lunak diperlukan ?
– Biaya perbaikan kesalahan yang meningkat sejalan dengan tahapan pengembanagan.
(Sumber : Boehm, software Engineering Economics 1981)
Perbaikan kesalahan pada tahap analisa memerlukan biaya 2 satuan. Perbaikan untuk kesalahan yang sama pada tahap operasi memelukan biaya 200 satuan
1000500200100502010521
RequirementAnalysis
Design Code DevelopmentTest
AcceptanceTest
Operation
Large software projects
IBM-SSD
GTE
80%Median (TRW survey) 20%
SAFEGUARD8
SMALLER SOFTWARE PROJECTS
(Boehm, 1980)
REKAYASA PERANGKAT LUNAKREKAYASA PERANGKAT LUNAK• Mengapa Rekayasa Perangkat Lunak Diperlukan ?
– Survei tentang kelambatan dan kekurangan biaya serta beberapa penyebabnya. ( Blum, GAO Report FGMSD 80-4 Revisited, ACM Sigsoft Software Engineering Notes, No. 1 Jan 1987 )
VeryCommon
FairlyCommon
Not VeryCommon
VeryRate
NeverOccurs
Dont”tKnow
Software development has dollaroverrun 21.2 29.2 25.7 9.7 6.2 3.0
Software development has calendaroverrun 30.1 31.9 25.7 8.0 1.8 2.7
The delivered software must becorrected or modified by in-houseprogrammer before it is usable
8.8 34.5 35.4 13.3 6.2 1.8
The software is paid for but never used - 3.6 16.1 57.1 20.5 2.7The delivered software is difficult tomodify 5.3 37.2 38.1 11.5 4.4 3.5
The contractor”s programming practicesare such that sofware is easilyunderstood by agency program
14.2 62.8 15.0 6.2 - 1.8
CAUSE Case Number
1 2 3 4 5 6 7 8 9Agency estimated its own state of progress when it let the contract X X X XIncorrect agency management action, such as using inapporapriatecontract X X X X
Agency failed to specify requirement adequtely X X X X X X XAgency overcommited it selt X Xagency failed to manage during execution, including executivechanges X X X X X
Agency failed to adequately inspect and test X X X X X
REKAYASA PERANGKAT LUNAKREKAYASA PERANGKAT LUNAK
• Mengapa Rekayasa Perangkat Lunak diperlukan ?
– Biaya pemeliharaan perangkat lunak yang besar. Corrective (21%), adaptive (25%), preventive (4%) dan perfective (50%)
49 43
8
(Sumber : Boehm, Software Engineering Economic 1982)
Biaya pemeliharaan lebih besar dari biaya pengembangan perangkat lunak.
Pemeliharaan
Pengembangan
Lain-lain49%
43%
8%
Aktivitas perawatan software
50%
21%
25%
4%
P erfec tiveC orrec tiveA daptiveP reventive
KUALITAS SOFTWARE: IS0 9126Karakteristik Sub karakteristik
Functionality: software untuk menjalankan fungsinya sebagaimana kebutuhan sistemnya
Suitability, Accuracy, Interoperability,Security
Reliability:Kemampuan software untuk dapat tetap tampil sesuai dengan fungsinya ketika digunakan
Maturity, Fault tolerance, Recoverability
Usability:Kemampuan software untuk mudah dimengerti, dipelajari, digunakan dan disukai pengguna
Understandability, Learnability, Operability, Attractiveness
Efficiency: Kemampuan software untuk menampilkan performans relatif terhadap penggunaan sumberdaya
Time Behavior, Resource Utilization
Maintainability: Kemampuan software untuk dimodifikasi (koreksi,adaptasi,perbaikan)
Analyzability, Changeability, Stability, Testability
Portability: Kemampuan software untuk ditransfer dari satu lingkungan ke lingkungan lain
Adaptability, Installability
K
REKAYASA PERANGKAT LUNAKREKAYASA PERANGKAT LUNAK
• Usaha untuk mengatasi permasalahan dalam perangkat lunak dilakukan melalui Rekayasa Perangkat Lunak atau Software Engineering.
• Rekayasa Perangkat lunak didefinisikan sebagai penerapan pengetahuan keilmuan secara praktis dalam perancangan dan pengembangan program dan dokumentasi terkait yang diperlukan untuk mengsembangkan, mengoperasikan dan memelihara program-program tersebut.
(Boehm ‘Software Engineering’ IEEE Trans on Computer).
REKAYASA PERANGKAT LUNAKREKAYASA PERANGKAT LUNAK
AKTIVITAS– REKAYASA PERANGKAT LUNAK
• Pengembangan perangkat lunak (software development).
• Manajemen proyek (project management).
• Metrik perangkat lunak (software metric).
• Pemeliharaan perangkat lunak (software maintenance).
• Jaminan kualitas perangkat lunak (software quality assurance).
• Manajemen konfigurasi perangkat lunak (software configuration management).
– PENGEMBANGAN PERANGKAT LUNAK
• Proses perangkat lunak (software process)
• Metodologi perangkat lunak (software methodology).
PROSES PERANGKAT LUNAK PROSES PERANGKAT LUNAK
FUNGSI UTAMAFUNGSI UTAMA• Menentukan tahap-tahap yang diperlukan untuk
pengembangan perangkat lunak.• Menentukan urutan pelaksanaan dari tahap-tahap
tersebut dalam rangka pengembangan perangkat lunak.
• Menentukan kriteria transisi/perpindahan dari satu tahap ke tahap berikutnya.
MODEL– Code and Fix
– System Development Life Cycle (SDLC)
– Prototyping
– Spiral
– CASE (Computer Aided Software Engineering)
CODE AND FIX MODEL.• TAHAP-TAHAPNYA :
– CODE (PEMROGRAMAN).
– FIX (PERBAIKAN/PEMELIHARAAN).
• KRITERIA TRANSISI :
– CODE (PROGRAM).
• CATATAN :
–Proses pengembangan perangkat lunak pada awal era pengolahan data.
–Menggunakan 3GL atau lebih rendah.
–Biaya pemeliharaan yang besar.
PROSES PERANGKAT LUNAKPROSES PERANGKAT LUNAK SDLC (System Development Life Cycle) TAHAP-TAHAPNYA :
– Investigasi– Analisa.– Perancangan.– Pengkodean.– Pengoperasian.– Pemeliharaan.
KRITERIA TRANSISI :– Dokumentasi.
CATATAN :– Sering dikenal sebagai “Document Driven Software
Process”– Merupakan perbaikan dari code and fix, dan sampai saat
ini merupakan salah satu proses perangkat lunak yang paling banyak digunakan.
Bernhard Boar has defined prototyping as A specific strategy for performing requirements definitions wherein user needs are extracted, presented, and successively refined by building a working model ofthe ultimate system quickly and in its working context.
Connell and Shafer: “A software prototype is a dynamic visual model providing a communication tool for customer and developer that is far more effective than either narrativeprose or static visual models for portraying functionality.
It has been described as: • functional after a minimal amount of effort • a means for providing users of a proposed application with a physical representation of key parts of the system before system implementation • flexible modifications require minimal effort • not necessarily representative of a complete system.”
• PROTOTYPINGPROTOTYPING• TAHAPAN: Identifikasi kebutuhan awal, prototyping, penggunaan dan
evaluasi prototipe (feedback),Revisi Prototyping ( Iterasi 1…n), Penerimaan/Persetujuan End User, Implementasi Sistem, Operasionalisasi dan Pemeliharaan
KRITERIA TRANSISI :
– CODE (PROGRAM) CATATAN :
– Sering dikenal sebagai “Code Driven Software Process”
– Merupakan salah satu proses perangkat lunak yang mulai banyak digunakan saat ini.
– Banyak memanfaatkan 4GL dan Application Generator.
– Dibandingkan dengan SDLC :* Produktivitas lebih baik
* Kelengkapan fungsi dari sistem kurang baik
* Keterpaduan (integrasi) sistem kurang baik
– Alternatif STRUCTURED RAPID PROTOTYPING.STRUCTURED RAPID PROTOTYPING.
PROSES PERANGKAT LUNAKPROSES PERANGKAT LUNAK
IDENTIFIKASI KEBUTUHANAWAL PEMAKAI
MENGGUNAKAN DANMENGEVALUASI
PROTOTYPE
REVISI PROTOTYPE
MEMBUAT SEBUAHPROTOTYPE
CONTOH MODEL(PROTOTYPE)
SISTEM YANG
DISERAHKAN
• PROTOTYPING
– Tahap-tahap :
TidakSetujuImplementasi
Objectives
Feature Design and Coding
Integration
Stabilize
Input from User Feedback Full Release
Start Specifications Complete
Beta 0
Beta 1
Beta 2
Beta 3
Beta 4
Beta 5 Beta 6
Januari February March April May June July Agustus
PENGEMBANGAN PROTOTIPE SEBAGAI SUATU PROSES PENGEMBANGAN APLIKASI
SECARA CEPAT (contoh produk NETSCAPE)
8Design Derivation
6Prototyping Iteration
1Projek Plan
2Rapid Analysis
7User
Approval
5Functions
3DatabaseCreation
9Tuning
4Menus
10Operation & Maintenance
PROSES PERANGKAT LUNAKPROSES PERANGKAT LUNAK• PROTOTYPING - STRUCTURED RAPID PROTOTYPING
(Sumber : J.L. Connel, L.B. Shafer, Structured Rapid Prototyping, Prentice Hall, 1989)
CONTOH PENGEMBANGAN SISTEM DENGAN MENGGUNAKANPENDEKATAN PENGEMBANGAN PROTOTYPE
• Team. A few end users and IS developers form a team to develop a business application
• Schematic. The initial prototype schematic design is developed.• Prototype. The schematic is converted into a simple point-and-click
prototype using prototyping tools.• Presentation. A few screens and routine linkages are presented to users.• Feedback. After the team gets feedback from users, the prototype is
retaired.• Reiteration. Further presentations and reiteration are made.• Consultation. consultation are held with central IT developers/consultants
to identify potential improvements and conformance to existing standards of the organization.
• Completion. The prototype is converted into a finished application.• Acceptance. Users review and sign off on their acceptance of the new
system• Installation. The new application software is installed on network servers
PROSES PERANGKAT LUNAKPROSES PERANGKAT LUNAK
MODEL SPIRAL• KRITERIA TRANSISI :
– Dokumen hasil analisa resiko.
• CATATAN :– Sering dikenal sebagai : “Risk Driven Software
Process”
– Untuk pengembangan proyek yang berskala besar, dengan memperhatikan pengaruh resiko dilihat dari segi finansial maupun keamanan (jiwa manusia).
– Kombinasi SDLC, Prototyping dan Risk Analysis.
• MODEL SPIRAL– tahap-tahapnya :
DetermineObjectivesAlternativesConstraints
Cumulative Cost
Progress through steps
Evaluate alternativeIdentity resolve risk
Riskanalysis
Riskanalysis
Riskanalysis
Riskanalysis
Prototype PrototypePrototypePrototypeOperasional
Simulation, model, bencmarksSoftware requirements
Requirementsvalidation
Requirements planlike cycle plan
Concept ofoperation
Commitment
PartitionReview
Integration andtest plan Design validation &
velitication
Softwareproductdesign
Detailed design
Code
Unit testIntegra -tion andtest
AcceptancetestImplemen -
tationPlan next phases
Develop, verifynext - level productSpiral Model
PlanningToolset
COMPUTER AIDED SOFTWARE ENGINEERING (CASE)
AnalysisToolset
DesignToolset
InformationIntegrator
CodeGeneration
Toolset
DatabaseGeneration
ToolsetSystem
Interface
Work StationRepositories
• The planning Toolset begins the development processwith information strategyplanning from a high-levelbusiness vantage point
• The Analysis Toolsetfocuses on correctlycapturing detailed businessrequirements early indevelopment process
• The Design Toolsetprovides detailedspecifications of the systemsolution
• The Information Integratorintegrates systemspscifications, check themfor consistency andcompleteness, and recordsthem in the repositories
• Workstation repositoriesand a server repositorydocument informationabout systems beingdeveloped or in use
• The Code GenerationToolsetproducesprogramcode basedon systemspecification
• The DatabaseGenerationToolsetgeneratesinformationneeded fordata storageand access
• The System• Interface• provides for• file transfers• and query• resporting
Case Workstation
Case
Server Repository
ControlWhat controls needed toprotect against accidental loss or damage ?is there a needed to controlaccess to data us by theapplication ?
OutputWhat information is neededby end users and in whatform should the output bepresented ?
Input
What data are available, in what form
StorageDoes the application usepreviously stored data ?Does it create data that mustbe stored for future use by thisor other applications ?
ProcessingWhat operations on the inputsare needed to produce thedesired output ?What software can mosteffectively support thoseoperations ?
END USER DEVELOPMENT
• Define a problem or opportunity using systems thinking
• Develop and evaluate alternative system solutions
• Select the system solution that best meets your requirements
• Design the selected system solution to meet your requirements
• Implement and evaluate the success of the designed system
PERUMUSAN MASALAH
PENGEMBANGANBERBAGAI
ALTERNATIFSOLUSI
PEMILIHAN SOLUSI TERBAIK
DISAINSOLUSI TERBAIK
IMPLEMENTASISOLUSI
PEMBANGUNAN SISTEM INFORMASI : PENDEKATAN SISTEM
Investigate
Analyze
Des
ign
Implement
Maintain
SIKLUSSIKLUSPENGEMBANGANPENGEMBANGANSISTEM INFORMASISISTEM INFORMASI(SDLC)(SDLC)
Memahami Permasalahan danPeluangSistem
SIKLUSSIKLUSPENGEMBANGANPENGEMBANGAN
SISTEM INFORMASISISTEM INFORMASI
Pengembangan SolusiSistem Informasi
Implementasi SolusiSistem Informasi
Systems InvestigationProduct
FeasibillityStudy
Systems AnalysisProduct
FunctionalRequirements
Systems DesignProduct System
Specifications
Systems ImplementationProduct
Operational systems
Systems MaintenanceProduct
Improved system
(SDLC)(SDLC)
INVESTIGASI SISTEM PRODUK: TUJUAN, RUANG LINGKUP DAN PERUMUSAN MASALAH
TOOLS: MATRIK KOMPONEN SISTEM INFORMASI DLLNYA.
• Interviews with employees, costumers, and managers.
• Questionnaires to appropriate end users in the organization.
• Personal observation, videotaping, or involvement in end user work activities.
• Examination of documents, reports, procedures manuals, and other documentation.
• Development, simulation, and observation of model of the work activities.
PRODUK INVESTIGASI SISTEM: LAPORAN STUDI KELAYAKAN
• How well proposed system supports the strategic objectives of the organization
• Cost savings
• Increased revenue
• Decreased investment
• Increased profits
• End user acceptance
• Management support
• Customer, supplier, and government requirements
• Hardware, Software, and network capability, reliability and availability
Organizational Feasibility Economic Feasibility
Technical Feasibility Operational Feasibility
TAHAPAN ANALISISPRODUK: FUNCTIONAL REQUIREMENTS
• User interface requirements. The input/output needs of end users that must be supported by the information system, including sources, formats, content, volume, and frequency of each type of input and output.
• Processing requirements. Activities required to convert input into output. Includes calculations, decision rules, and other processing operations, and capacity, throughput, turnaround time, and response time needed for processing activities.
• Storage requirements. Organization, content, and size of databases, types and frequency of updating and inquiries, and the length and rationale for record retention.
• Control requirements. Accuracy, validity safety, security, and adaptability requirements for system inputs, processing, output and storage functions.
CONTOH SALAH SATU PENDEKATAN ANALISIS DAN DISAIN YANG MELIBATKAN TIM DAN PENGGUNAAN VIDEO
Open-endedinterviews
On-site, in-contextobservations
Design solutions embodied in sketches, mock-ups, simulations
Understanding User Needs
Codevelopment
Form SystemsDevelopment Team
FinalSystemDesign
DataAnalysis
Open-endedinterviews
Coview video withdevelopers
Identify keyissues
Verify findingswith users
Design workshops with users
Coview user`s reactionsto design concepts
User videotapelibrary and database
• video• transcripts• site maps• mock-ups
PRODUK: SYSTEM SPESIFICATIONS
• User interface specifications: The content, format, and sequence of user interface products and methods such as display screens, interactive dialogues, audio responses, forms, documents, and reports.
• Database specifications: Content, structure, distribution, and access, response, maintenance, and retention of databases.
• Software specifications: The required software package or programming specifications of the proposed system, including performance and control specifications.
• Hardware and facilities specifications: The physical and performance characteristics of the equipment and facilities required by the proposed system.
• Personal specifications: Job descriptions of persons who will operate the system.
Tahapan Disain
User InterfaceDesign
User InterfaceDesign
DataDesign
DataDesign
ProcessDesign
ProcessDesign
• Screen, Form, Report,and Dialog design
• Data Element structur Design
• Progam and Procedure design
TAHAPAN IMPLEMENTASI
ImplementationActivities
Conversion• Parallel• Pilot• Phased• Plunge
SoftwareDevelopment
orModification
Acquisition ofHardware,Software,
and Services
End UserTraining
SystemDocumentation
• Evaluate and acquire new hardware and software. Hardware includes computer systems, POS terminals, and telecommunications processors and network facilities. Software includes network management programs and POS transaction processing packages.
• Develop computer programs or make any necessary modifications to software packages that are acquired.
• Prepare training materials and documentation on how to operate the new POS system for managers and salespeople.
• Educate and train managers, salespeople, and information systems personnel to operate the new system.
• Test the system and make corrections until it operates properly• Convert to the new system on a phased store-by-store basis to minimize disruption.
Use the first store converted as a pilot installation to help with testing and training.• Perform a postimplementation audit within 30 days of each store's conversion to
determine if the new POS systems are achieving their expected advantages.
TAHAPAN IMPLEMENTASI
KONVERSI SISTEM• DIRECT CUT OVER
( IMMEDIATE CUT OVER)
• PHASED IN CUT OVER
• PARALELL CUT OVER
• PILOT PROJECT