Minggu 4,5,6,7Materi Analisa Perancangan System

Apa itu sistem?

Sistem informasi?

Sistem analis?

Metodologi

Pendekatan ssadm

Ssadm stages

sdlc

Current system

Case study

steps1. Gambarkan sistem secara umum

(general) Dalam penggambaran sistem

tersebut, sebutkan siapa saja user/actor/sistem lain yang berperan di dalamnya.

Simpulkan permasalahan apa saja yang terjadi dalam sistem tersebut.

(see General Background.docx)

2. Investigasi lingkungan sistem

Fact-finding techniques Interview clarification. Forms and files users’ agreement,

Investigasi proses yang ada

DFDs

Elements of dfd

Process & Data Flow

External Entities & Data Stores

Partial DFD example

DFD rules Data flow diagram rulesThe analyst needs to be aware of some rules which apply to DFDs. These rules

exist not to make life difficult, but to ensure consistency in diagramming.

Process rules Processes must have both inputs and outputs. If there is no input, but there is

an output, then the output has been created from thin air. Sadly, this does not happen. If there is an input but no output, then the process is a waste of everyone’s time and should be scrapped.

Data flow rules Data flows must go through a process box. It is not allowed to have a data flow

going directly from an external entity to a data store, for example.

External entity rules The label must be a noun, e.g. SUPPLIER.

Data store rules A data flow into a data store means update the data store. A data flow from a data store means retrieve data from the data store.

See – Materi APS – Pengenalan DFD.pptx

Simple steps in data flow modelling The main tasks to be completed, in order,

are:1 Draw a context diagram.2 Draw a document flow diagram.3 Draw a top-level data flow diagram.4 Draw lower level data flow diagrams.

Context Diagram & Document Flow Diagram

Splitting the Steps – Study Case

2. Draw context diagram

3. Identify internal areas/departments

4. Draw Document Flow Diagram

5. Convert to top-level Data Flow Diagram

Level 1 Current Physical DFD

6. Fungsional decomposition

Cont…

Limitation of DFD Our current physical DFDs are now complete. They should give us a

picture of what the Medical Centre currently does. They should be understandable and be useful as a communications tool with the user. However,

there are limitations with DFDs. They don’t do everything (which is why we need other techniques). Here are a few limitations:

They don’t show us how the data is structured. They don’t show the effect of time or sequence. They may not help communicate with the user – they may be too

complex. They take a long time to draw and redraw. They may never be complete

While these limitations are real enough, the experienced analyst can use DFDs as a useful tool and not allow the limitations to become a problem.

Tugas1. Buat General Background dari sistem

yang anda pilih.2. Buat Problem/Requirements Catalouge3. Buat Daftar External Entiti4. Gambar Context Diagram5. Buat Daftar Internal Entiti6. Gambar Dokumen Flow Diagram7. Gambar Top Level Data Flow Diagram8. Gambar DFD Level 1 dan DFD level 2

masing – masing proses.

Pemodelan Struktur Data

Pemodelan Entitas/ Entity Entitas

Things/ Sesuatu tempat informasi berada▪ People, customer, member, student▪ Object, product, recipes,

Entity

Atribut

Bits of Data yang menerangkan Entitas Entitas MEMBER Atribut

Atribut

Keys

Cara untuk mengidentifikasi sesuatu Contoh orang, untuk

mengidentifikasi digunakan NAMA Primary Key, Key yang unik

MEMBER, MEMBERSHIP NUMBER STUDENT, NRP PATIENT, PATIENT NUMBER

Relationship

Hubungan antar Entitas

Relationship Type

Datastore - Entity

For Further study please read :System Analysis A Beginners Guide

Analisa Data System1.Data entitas yang ada pada sistem2.Masing-masing entitas dibuatkan atributnya dan contoh isiannya3. Memilih Key4. Menentukan relasi dan Tipe relasinya5. Mencocokkan datastore DFD dengan diagram entitas6. Membuat ERD.

Logicalization List Data Stores Produce the logical data store/entity cross-reference Remove time dependencies Remove names and departments from the process

boxes Change processes so that they describe what is

done to the data Remove any physical references from the process

box Make sure that the data flows refer to logical items

of data Data flows between processes should be removed

Business System Options

1. Identifikasi alternative solusi untuk menjawab hasil analisis2. Menentukan alternative solusi yang dipilih

Requirements Specification

Software Design

Elementery Process Description

Structured english and Decision Trees

Decision Tree

Decision Table

INPUT/ OUTPUT DESIGN

INPUT/ OUTPUT DESIGN

Tugas

1. Buat Analisa Data System2. Logikalisasi 3. Buat Business System Options4. Buat Elementary process descriptions5. Buat Decision Tree / Pseudo-Code /

Structured English6. Buat Design Input / Output