Bab 9
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Transcript of Bab 9
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Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition
9C H A P T E R
PROCESS MODELING
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Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition
Chapter Map
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Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition
Models : Logical and Physical
Model Lojik – representasi non teknis (dalam bentuk gambar) yang menggambarkan tentang sistem atau proses. Disebut juga Model esensial, model konseptual, model bisnis
Physical model – representasi teknis yang menggambarkan tentang sistem atau proses dan bagaimana sistem diimplementasikan. Disebut juga model implementasi dan model teknis.
Model – representasi (grafik) dari dunia nyata.
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Process Modeling and DFDs
Process modeling – teknik yang digunakan untuk mengorganisasi dan mendokumentasi proses-proses sistem.
– Aliran data melalui proses– Lojik– Kebijaksanaan– Prosedur
Data flow diagram (DFD) – model proses yang digunakan untuk menggambarkan aliran data melalui proses dalam sistem. Disebut juga bubble chart, transformation graph, and process model.
DFD : tool populer untuk business process redesign (BPR)
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Simple Data Flow Diagram
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Differences Between DFDs and Flowcharts
• Proses pada DFD dapat dioperasikan secara paralel (pada saat yang bersamaan)– Proses pada flowchart dieksekusi pada satu waktu
• DFD memperlihatkan aliran data pada sistem– Flowchart memperlihatkan aliran kontrol (perpindahan
kontrol secara urut)
• Proses pada DFD dapat berlaku pada waktu yang berbeda-beda (daily, weekly, dll)– Proses pada flowchart merupakan bagian dari program
tunggal dengan waktu yang tertentu
• DFD dapat digunakan untuk memahami sistem secara keseluruhan (system thinking)
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Process Concepts
Proses – pekerjaan/aktivitas yang dikerjakan oleh sistem oleh karena adanya masukan data atau kondisi. Disebut juga dengan transformasi (transform).
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Process Decomposition
Dekomposisi – memecah sistem menjadi sub-sub komponen (sub-sub sistem) yang lebih detil.
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Decomposition Diagrams
Diagram Dekompisisi – tool yang digunakan untuk menggambarkan dekomposisi sistem. Disebut juga bagan berjenjang (hierarchy chart).
• Diagram dekomposisi dan DFD mrpk tool yg efektif untuk identifikasi proses, tetapi tidak bagus untuk menggambarkan logika proses.
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Common Process Errors on DFDs
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1. For each CUSTOMER NUMBER in the data store CUSTOMERS: a. For each LOAN in the data store LOANS that matches the above CUSTOMER NUMBER: 1) Keep a running total of NUMBER OF LOANS for the CUSTOMER NUMBER. 2) Keep a running total of the ORIGINAL LOAN PRINCIPAL for the CUSTOMER NUMBER. 3) Keep a running total of CURRENT LOAN BALANCE for the CUSTOMER NUMBER. 4) Keep a running total of AMOUNTS PAST DUE for the CUSTOMER NUMBER. b. If the TOTAL AMOUNTS PAST DUE for the CUSTOMER NUMBER is greater than $100.00 then: 1) Write the CUSTOMER NUMBER and all their data attributes as described in the data flow LOANS AT RISK. Else 1) Exclude the CUSTOMER NUMBER and data from the data flow LOANS AT RISK.
Structured English
Structured English – sintaks bahasa untuk mendefinisikan logika proses. Perpaduan antara bahasa inggris alami dengan struktur pemrograman
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Aliran data – data input ke atau output dari proses.
– Aliran data dapat digunakan untuk merepresentasikan : create, read, delete, update pada file atau database (disebut data store).
Aliran data komposit – aliran data yang memuat aliran data lain.
Aliran kontrol – kondisi atau nondata yang memicu terjadinya proses.
– Jarang digunakan pada DFD.
Data Flows & Control Flows
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Data Flow Packet Concept
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Composite and Elementary Data Flows
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Data Flows to and from Data Stores
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Illegal Data Flows
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A Data Structure for a Data FlowDATA STRUCTURE
ORDER=ORDER NUMBER +ORDER DATE+[ PERSONAL CUSTOMER NUMBER, CORPORATE ACCOUNT NUMBER]+SHIPPING ADDRESS=ADDRESS+(BILLING ADDRESS=ADDRESS)+1 {PRODUCT NUMBER+ PRODUCT DESCRIPTION+ QUANTITY ORDERED+ PRODUCT PRICE+ PRODUCT PRICE SOURCE+ EXTENDED PRICE } N+SUM OF EXTENDED PRICES+PREPAID AMOUNT+(CREDIT CARD NUMBER+EXPIRATION DATE)(QUOTE NUMBER)
ADDRESS=(POST OFFICE BOX NUMBER)+STREET ADDRESS+CITY+[STATE, MUNICIPALITY]+(COUNTRY)+POSTAL CODE
ENGLISH ENTERPRETATION
An instance of ORDER consists of:ORDER NUMBER andORDER DATE andEither PERSONAL CUSTOMER NUMBER
or CORPORATE ACCOUNT NUMBERand SHIPPING ADDRESS (which is equivalent
to ADDRESS)and optionally: BILLING ADDRESS (which is
equivalent to ADDRESS)and one or more instances of:
PRODUCT NUMBER andPRODUCT DESCRIPTION andQUANTITY ORDERED andPRODUCT PRICE andPRODUCT PRICE SOURCE andEXTENDED PRICE
and SUM OF EXTENDED PRICES andPREPAID AMOUNT andoptionally: both CREDIT CARD NUMBER and
EXPIRATION DATE
An instance of ADDRESS consists of:optionally: POST OFFICE BOX NUMBER andSTREET ADDRESS andCITY andEither STATE or MUNICIPALITYand optionally: COUNTRYand POSTAL CODE
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Data Structure Constructs
Data Structure Format by Example(relevant portion is boldfaced
English Interpretation(relevant portion is boldfaced)
Sequence of Attributes - The sequence data structure indicates one or more attributes that may (or must) be included in a data flow.
WAGE AND TAX STATEMENT= TAXPAYER IDENTIFICATION NUMBER+ TAXPAYER NAME+ TAXPAYER ADDRESS+ WAGES, TIPS, AND COMPENSATION+ FEDERAL TAX WITHHELD+…
An instance of WAGE AND TAX STATEMENTS consists of: TAXPAYER IDENTIFICATION NUMBER and TAXPAYER NAME and TAXPAYER ADDRESS and WAGES, TIPS AND COMPENSATION and FEDERAL TAX WITHHELD and…
Selection of Attributes - The selection data structure allows you to show situations where different sets of attributes describe different instances of the data flow.
ORDER= (PERSONAL CUSTOMER NUMBER, CORPORATE ACCOUNT NUMBER)+ ORDER DATE+…
An instance or ORDER consists of: Either PERSONAL CUSTOMER NUMBER or CORPORATE ACCOUNT NUMBER; and ORDER DATE and…
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Data Structure Constructs (continued)
Data Structure Format by Example(relevant portion is boldfaced
English Interpretation(relevant portion is boldfaced)
Repetition of Attributes - The repetition data structure is used to set off a data attribute or group of data attributes that may (or must) repeat themselves a specific number of time for a single instance of the data flow. The minimum number of repetitions is usually zero or one. The maximum number of repetitions may be specified as “n” meaning “many” where the actual number of instances varies for each instance of the data flow.
POLICY NUMBER+ POLICYHOLDER NAME+ POLICY HOLDER ADDRESS+ 0 {DEPENDENT NAME+ DEPENDENT’S RELATIONSHIP} N+ 1 {EXPENSE DESCRIPTION+ SERVICE PROVIDER+ EXPENSE AMOUNT} N
An instance of CLAIM consists of: POLICY NUMBER and POLICYHOLDER NAME and POLICYHOLDER ADDRESS and zero or more instance of: DEPENDENT NAME and DEPENDENT’S RELATIONSHIP and one or more instances of: EXPENSE DESCRIPTION and SERVICE PROVIDER and EXPENSE ACCOUNT
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Data Structure Constructs (concluded)
Data Structure Format by Example(relevant portion is boldfaced
English Interpretation(relevant portion is boldfaced)
Optional Attributes - The optional notation indicates that an attribute, or group of attributes in a sequence or selection date structure may not be included in all instances of a data flow.Note: For the repetition data structure, a minimum of “zero” is the same as making the entire repeating group “optional.”
CLAIM= POLICY NUMBER+ POLICYHOLDER NAME+ POLICYHOLDER ADDRESS+ ( SPOUSE NAME+ DATE OF BIRTH)+…
An instance of CLAIM consists of: POLICY NUMBER and POLICYHOLDER NAME and POLICYHOLDER ADDRESS and optionally, SPOUSE NAME and DATE OF BIRTH and…
Reusable Attributes - For groups of attributes that are contained in many data flows, it is desirable to create a separate data structure that can be reused in other data structures.
DATE= MONTH+ DAY+ YEAR+
Then, the reusable structures can be included in other data flow structures as follows: ORDER=ORDER NUMBER…+DATE INVOICE=INVOICE NUMBER…+DATE PAYMENT=CUSTOMER NUMBER…+DATE
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Data Types and Domains
Atribut data didefinisikan berdasarkan tipe data dan domainnya.
Tipe data – kelas yang disimpan pada atribut.– Character, integers, real numbers, dates, pictures, etc.
Domain – nilai yang diijinkan untuk atribut.
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Diverging and Converging Data Flows
Aliran data divergen – aliran data yang terpecah menjadi beberapa aliran data.– Aliran data yang berasal dari satu sumber yang
menuju ke beberapa tujuan.
Aliran data konvergen – gabungan dari beberapa aliran data yang menuju paket data tunggal.– Aliran data yang berasal dari beberapa sumber yang
secara bersamaan menyatu menjadi satu paket tunggal pada suatu proses.
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Diverging and Converging Data Flows
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External Agents
External agent – Orang, unit organisasi, sistem atau organisasi eksternal yang berinteraksi dengan sistem. Disebut juga eksternal entitas (external entity). – Entitas eksternal mendefinisikan scope atau batasan
sistem yang dimodelkan.– Dapat berupa :
• Kantor, departemen, divisi.• Organisasi eksternal atau agen.• Unit bisnis atau sistem informasi lain.• Manajer atau end-user
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Data Stores
Data store – penyimpanan data. – Sering diimplementasikan sebagai file atau
database.
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When to Draw Process Models
• Perencanaan sistem strategis– Model proses enterprise menggambarkan fungsi-fungsi bisnis
organisasi.
• Business process redesign• Analisis Sistem
– Model sistem saat ini termasuk batasan-2 nya– Model persyaratan lojik sistem baru (aliran data dan proses dari
sistem yang akan diimplementasikan)– Model solusi teknis yang diusulkan (DFD fisik)– Model solusi teknis yang dipilih (DFD fisik)
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Classical Structured Analysis
1. Gambarkan DFD fisik secara top-down yang merepresentasikan implementasi fisik sistem saat ini dengan batasan-batasannya.
2. Konversikan DFD fisik menjadi DFD lojik.
3. Gambarkan DFD lojik sistem yang diusulkan (diperbaiki).
4. Deskripsikan semua aliran data, data stores, kebijakan dan prosedur pada kamus data (data dictionary) atau ensiklopedi.
5. Gambarkan DFD fisik sistem baru yang diusulkan.
Metodologi analisis terstruktur klasik memerlukan waktu yang lama.
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Modern Structured Analysis
1. Gambarkan Konteks Diagram untuk merumuskan batasan sistem saat ini.
2. Gambarkan diagram dekomposisi sistem dengan memecah sistem menjadi sub-sub sistem.
3. Buat event-response atau use-case list sistem untuk mendefinisikan event-event yang harus direspon sistem.
4. Gambarkan DFD event untuk setiap event.5. Gabungkan DFD event menjadi diagram sistem yang lebih
besar.6. Gambarkan secara rinci, DFD utama untuk event-event yang
kompleks.7. Dokumentasikan aliran data dan proses pada kamus data (data
dictionary).
Metodologi di atas berbasis pemecahan sistem menjadi event-event, (barangkali) lebih praktis.
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Structured Analysis Diagram Progression (1 of 3)
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Structured Analysis Diagram Progression (2 of 3)
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Structured Analysis Diagram Progression (3 of 3)
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CASE for DFDs (Sample Screen) from System Architect 2001
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SoundStage Context DFD
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SoundStage Functional Decomposition Diagram
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Events
• External events ; dilakukan oleh entitas eksternal, menghasilkan transaksi input atau aliran data.
• Temporal events ; dipicu oleh waktu atau sesuatu yang mengharuskan terjadi, digambarkan dengan aliran kontrol.
• State events ; dipicu oleh perubahan sistem dari satu kondisi/keadaan ke kondisi/keadaan lainnya, digambarkan dengan aliran kontrol.
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Use Cases
Use case – tool untuk menemukan dan mengidentifikasi event bisnis dan responnye.
Actor – segala sesuatu yang berinteraksi dengan sistem.
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Use Case List
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Use Case List (continued)
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Event Decomposition Diagram (partial)
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External Event DFD
Event diagram – diagram aliran data yang menggambarkan konteks event tunggal.
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External Event DFD (more complex)
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Temporal Event DFD
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System DFD
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System DFD
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Primitive DFD (see book for more readable copy)
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Entering a Data Flow Using a CASE Tool
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Entering an Elementary Process Using a CASE Tool
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Sample Data to Process CRUD Matrix
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Sample Process to Location Association Matrix