Ika Novita Dewi ikadewi@research.dinus.ac.id Rekayasa Sistem Ika Novita Dewi ikadewi@research.dinus.ac.id

1 2 3 4 Outline Sistem Berbasis Komputer Rekayasa Proses Bisnis Rekayasa Produk Rekayasa Kebutuhan

Sistem Berbasis Komputer Sistem berbasis komputer bertujuan untuk mendukung berbagai fungsi bisnis atau untuk mengembangkan suatu produk yang dapat dijual untuk menghasilkan keuntungan bisnis Contoh: Bagian pemasaran suatu perusahaan akan memanfaatkan data yang ada untuk mengetahui segmentasi pembeli dari suatu produk Elemen-elemen sistem berbasis komputer: Perangkat lunak (program komputer, struktur data, dan dokumen yang berhubungan) Perangkat keras (perangkat elektronik dan elektromekanik) Manusia (user yang memakai perangkat lunak dan perangkat keras) Basisdata (kumpulan informasi besar dan terorganisir yang diakses melalui perangkat lunak) Dokumentasi (manual, formulir, dan informasi deskriptif lainnya) Prosedur (langkah-langkah yang menentukan penggunaan elemen sistem) Sistem: kumpulan dari komponen yang saling berelasi Informasi

Pemodelan Sistem Karakteristik model yang dibuat Mendefinisikan proses yang dibutuhkan sesuai dengan permintaan Menggambarkan sifat suatu proses dan berasumsi tentang dasar dari proses itu Secara jelas menyebutkan bagaimana proses input kedalam model Menampilkan sistem secara keseluruhan ( termasuk output) yang memungkinkan engineer memahami keseluruhan proses

Faktor-faktor yang harus diperhatikan dalam pembuatan model Asumsi Membuat model sesuai dengan masalah yang akan diselesaikan Simplifikasi Model yang dibuat harus tepat waktu sesuai dengan yang telah ditentukan Batasan Model harus memiliki batasan yang jelas Kendala Digunakan sebagai pedoman dalam pembuatan model dan panduan jika model akan diterapkan Preferensi Panduan dalam pemilihan arsitektur data, fungsi, dan teknologi

Contoh pemodelan sistem context diagram establishes the information boundary between the system being implemented and the environment in which the system is to operate

Contoh Diagram Konteks

Rekayasa Proses Bisnis Untuk menentukan pemodelan sistem yang akan digunakan oleh suatu proses bisnis dalam penggunaan informasi Pemodelan sistem yang akan dibangun harus sesuai dengan sasaran dan tujuan bisnis

Rekayasa Produk The process of establishing the services that the customer requires from a system and the constraints under which it operates and is developed The requirements themselves are the descriptions of the system services and constraints that are generated during the requirements engineering process

Rekayasa Kebutuhan Dimana kebutuhan muncul dalam sistem? Ada dalam setiap Siklus hidup sistem

A statement of what the system must do A statement of characteristics the system must have Focus is on business user needs during analysis phase Requirements will change over time as project moves from analysis to design to implementation

Sebelum melakukan rekayasa kebutuhan Correctly understand and define problem Discover, understand, formulate, analyze and agree What problem should be solve Why such problem need to be solve Who should be involved in the responsibility of solving the problem

Kenapa diperlukan rekayasa kebutuhan

Laporan tentang kegagalan dalam pembangunan sistem (1995) 31.1% of projects will be canceled before they ever get completed. 52.7% of projects will cost over 189% of their original estimates. 1995 American companies and government agencies will spend $81 billion for canceled software projects. These same organizations will pay an additional $59 billion for software projects that will be completed, but will exceed their original time estimates.

Dimana letak kesalahannya Source : UK Health and Safety Executive, Out of Control: Why control systems go wrong and how to prevent failure. Health and Safety Guidance report 238, Bootle, UK, 2003

Kegaalan dalam proses rekayasa kebutuhan Lack of Stakeholder Involvement Incorrect of Environmental Assumptions Communication failures with development team Inadequate Conflict Management Lack of Contextual Detail

Contoh kegagalan rekayasa kebutuhan

Jenis Rekayasa Kebutuhan 1. User Requirement Statements in natural language plus diagrams of the services the system provides and its operational constraints. Written for customers 2. System Requirement A structured document setting out detailed descriptions of the system services. Written as a contract between client and contractor

Eliciting requirements Kegiatan dalam menentukan kebutuhan Eliciting requirements Modeling and analyzing requirements Communicating requirements Agreeing requirements Evolving requirements

Apakah dengan Rekayasa kebutuhan akan menjamin tidak ada kegagalan software? Hanya pengurangi jumlah kegagalan

Rekayasa kebutuhan sistem Descriptions and specifications of a system A well-written document that contains a set of precisely stated properties or constraints which a software system must satisfy

Rekayasa Kebutuhan Sistem What the software can do What the user can do with the software What the software must do

System Requirement Functional Requirement Non-Functional Requirement

Functional Requirement Statements of services the system should provide, how the system should react to particular inputs and how the system should behave in particular situations

Describe functionality or system services Depend on the type of software, expected users and the type of system where the software is used Functional user requirements may be high-level statements of what the system should do but functional system requirements should describe the system services in detail

example The user shall be able to search either all of the initial set of databases or select a subset from it The system shall provide appropriate viewers for the user to read documents in the document store Every order shall be allocated a unique identifier (ORDER_ID) which the user shall be able to copy to the account’s permanent storage area.

Non-Functional Requirement Behavioural properties the system must have; Operational Performance Security Cultural and political

Define system properties and constraints e. g Define system properties and constraints e.g. reliability, response time and storage requirements. Constraints are I/O device capability, system representations, etc. Non-functional requirements may be more critical than functional requirements. If these are not met, the system is useless

Non-functional classification Operational The physical and technical environments in which the system will operate. Product performance Requirements which specify that the delivered product must behave in a particular way e.g. execution speed, reliability, etc. Security Who has authorized access to the system under what circumstances. Cultural and political Requirements which are a consequence of organisational policies and procedures e.g. process standards used, implementation requirements, etc.

example Operational Performance Security Cultural and political The system should be able to fit in a pocket or purse Performance Any interaction between the user and the system should not exceed 2 seconds. Security Only direct managers can see personnel records of staff. Cultural and political Company policy says that we only buy computers from Dell.

Contoh dalam kasus peminjaman buku di perpustakaan Functional Requirement Pengguna bisa mencari semua informasi tentang buku atau bisa memilih salah satu dari informasi tentang buku Semua peminjam memiliki pengenal yang unik Sistem mampu catat transaksi peminjaman, pengembalian dan denda secara lengkap Hari libur bisa di-set sejak awal, dan bisa menerima perubahan dengan otoritas khusus Harus komplit (kebutuhan layanan jelas dan lengkap) dan konsisten (tidak kontradiksi dengan yang didefinisikan)

Non-Functional Requirement Kecepatan akses Keamanan data Besarnya kapasitas penyimpanan yang diperlukan Privasi masing-masing account Bahasa pemrograman yang digunakan Sistem operasi yang digunakan

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