Modeling Tools

1. Modeling Tools

2. TOPICS • Systems Concepts Why??? • Modeling Diagram Conventions The Rules of the Game • Modeling Diagrams Basic Principles Context Diagrams Decomposition Diagrams Data Flow Diagrams

3. Business Strategy Operating Environment Information System Information Environment INPUTS OUTPUTS Feedback and Control Loop Government Mandates Organization Policies Business Environment Systems Concepts Systems Thinking Application of formal Systems theory and concepts The Information Environment Constantly changing along with Social, Business and Organizational changes The Information System The Collection of inter-related systems/packages System Inputs Data from the Organization, external sources, other systems, or self-generated System Outputs Reports, Screens, Files, Data to other systems, etc. Feedback & Control Loop Self-Monitoring &Modification (Thermostatic Control)

4. Marketing IS Finance IS Accounting IS INPUTS INPUTS INPUTS INPUTS INPUTS INPUTS OUTPUTS OUTPUTS OUTPUTS OUTPUTS OUTPUTS Sales Production Marketing Finance Service Accounting Service IS Production IS Sales IS OUTPUTS Systems Concepts Systems Thinking Process Concepts Historically, IS were focused on individual business functions IS were developed for each functional Area Each IS was intended to process or transform the inputs to outputs

5. Marketing IS Finance IS Accounting IS INPUTS INPUTS Sales Marketing Finance Accounting Cross-Functional IS Sales IS INPUTS INPUTS Systems Concepts Systems Thinking Process Concepts It later became obvious that some functions were inter-related, and Cross-functional IS were needed to get input from each functional area, Process it, and return it to the individual functional systems as input

6. Information System Marketing IS Finance IS Accounting IS Sales Production Marketing Finance Service Accounting OUTPUTS INPUTS Service IS Production IS Sales IS Systems Concepts Systems Thinking Process Concepts The emphasis today is to have an Enterprise Model which will encompass the entire organization (individual functional Area IS Still in Existence)

7. Systems Concepts Systems Thinking Process Concepts The emphasis Corresponds to the idea of a system as a business A business operates within a constantly changing system A business has various actors who impact it (Customers, Suppliers, Competitors, Government) A business has various inputs (Raw Materials, Services, Equipment) A business Transforms goods (WIP, Value-Added Services) A business has various Outputs (Products, Services) A business operates in a synergistic manner The Change in System Processing reflects the trend in Business Process Redesign (BPR) The emphasis is in not merely improving on the existing system, but in re-inventing the manner in inputs are processed

8. Modeling Diagram Conventions Structured Methodology Goals Used for requirements specification, systems analysis and systems design Intended to structure a project into small, well-defined activities Specifies the sequence and interaction of these activities Use diagrammatic and other modeling techniques Give a precise (structured) definition Are understandable by both users (clients) and developers Structured Methodology (Intended) Advantages Reduce life cycle development costs through improved analysis and design Improve quality of systems delivered Improve project management, planning and control More effective use of inexperienced staff Improve communication User  Analyst Designer  Analyst Designer  User Self documenting

9. Process Name Process Name Process Name SSADM Gane & Sarson Demarco/Yourdan Modeling Diagram Conventions Available Methodologies Gane & Sarson (Chris Gane and Trish Sarson): Late 1970s Yourdan: Late 1970s Demarco: Late 1970s Merise (France): late 1970s Information Engineering (Finkelstein and Martin): Late 1970s/early 1980s Structured Systems Analysis and Design Method (SSADM): - 1980 ??? Which one will we Use ??? Gane & Sarson ??? Why ??? It is (perhaps) still the most common ??? Are there Differences ??? Some, but basically trivial: Process Representation:

10. Rectangle Supplier Supplier Supplier Supplier C.E.O Customer Customer Customer Customer Customer Customer Customer Customer ? ? ? Modeling Diagram Conventions Basic Symbols Source ORDestination of Information Sometimes, for the sake of clarity, an Information source/destination is duplicated In that case, a duplication symbol is associated with the source/destination If the source/destination appears more than once, a multiple duplication symbol is used A B B B Note also that Identifying notation may also be used

11. Rounded Rectangle Marketing IS Update Inventory Verify that an Order is valid Process Number Hierarchy/Activity Number Identification 35 4.2 Compute Monthly Sales Compute Monthly Sales Function/ Process/ Activity Description Physical Location IDS C:/CMS.exe Department Program Name Modeling Diagram Conventions Basic Symbols A Process/Activity which transforms/adds to data Processes are generally not duplicated, but can contain identifying notation

12. Open-ended Rectangle Database File Temp. Storage Supplier D1 D4 D3 D2 Accounts Receivable Customer Inventory Employee ? D2 D2 D2 Customer Customer Customer Modeling Diagram Conventions Basic Symbols A data store Data stores are generally annotated with a number and descriptive name As with processes, if data stores are duplicated in a diagram, extra lines are added Here, the store has 3 lines at the left to indicate it appears 3 times in the diagram

13. Customer Customer Employee D2 D2 Customer Customer ? ? Produce Paycheck Modeling Diagram Conventions Basic Symbols A data flow: Information of any sort (written or oral), Invoices, Receipts, Database data, etc. The direction of the arrow shows the direction of the flow The process receives a payment from a Customer After Processing, the Customer Database is updated Data flows are ALWAYS assigned names: Customer Payment Updated Cust. Data (Paycheck) Unless it is completely obvious: Data flow names should be unique (unless the same data flow is generated at multiple locations)

14. Customer Data Customer Data D2 D2 Customer Customer Updated Customer Data ? ? Customer Payment Customer Order Customer Complaint Customer Return ? ? Customer Customer Customer Transactions Modeling Diagram Conventions Basic Symbols A data flow: Information of any sort (written or oral), Invoices, Receipts, Database data, etc. If data flows in both directions, separate arrows should be used (Don’t use ) Sometimes, data flows can become unwieldy: In which case we might want to merge data flows

15. Analogous to our previous ‘Forest vs. Tree’ Idea Marketing IS Marketing IS Ka-Boom !!! ~~~ ~~~ ~~~ ~~ ~~ ~~ ~~ ~~~ ~~~ ~~~ ~~ ~~ ~~ ~~ Modeling Diagrams General Principles Analysis/design is still (essentially) a top-down approach When we need to, we can ‘explode’ processes We can continue until there is nothing left to ‘Explode’

16. Publishers Advertising Agreements Invoices Payments Title Announcements Customer Order Harpo’s Book Club Purchase Orders Invoice Suppliers Members Product Invoices Shipped Product List Payments Payments Club Promotion Subscription Order Potential Subscribers Modeling Diagrams Context Diagrams Identifies the system boundaries and responsibilities. Determines the boundaries, actors and interactions required. Identifies Primary Data Flows

17. Information System Marketing Systems Production Systems Accounting Systems Finance Systems Process Control System Inventory System Inventory Receipt System Inventory Ordering System Modeling Diagrams Decomposition Diagrams Intended to show all sub-processes and tasks and which can be ‘exploded’ Decomposition Diagrams (Hierarchy Chart)

18. Process Book Details Publisher Address D2 D2 D1 Publisher Books Customer Order Verify Order Publisher Customer Valid Gather Publisher Requisition Order Customer Credit Status D3 Pending Order Purchase Order Order Modeling Diagrams Data Flow Diagrams (DFDs) Exploded Context Diagrams Shows all Processes, sources/destinations of data, data stores, and data flows Intended to be top-down

19. ? ? Modeling Diagrams Data Flow Diagrams (DFDs) Basic DFD Guidelines 1. Identify External Entities involved 2. For Each Entity, Identify scheduled inputs and Outputs Note: Data Flows are Not Physical Products Book Invoices are shipped, not the Books themselves 3. For each Entity Input and Output, determine which process the receives the entity outputs and which process will generate the entity inputs 4. For Each Process, Identify what data stores need to be accessed for inputs and which data stores will be updated or given new outputs

20. ? ? ? Modeling Diagrams Data Flow Diagrams (DFDs) Basic DFD Guidelines Note: Data Flows MUST ALWAYS flow to or from a Process

21. ? ? Employee Address Bank Statement Generate Employee Banking Statement Employee Employee Data Modeling Diagrams Data Flow Diagrams (DFDs) Basic DFD Guidelines Note: Processes MUST ALWAYS have inputs AND Outputs A Black Hole A Miracle The inputs to a process must be sufficient to produce the output Where did the Accounting Information Come From ?? A Grey Hole

22. 1.0: Process Order 1.1 1.2 Assemble Publisher Requisition Verify Order 1.0 Process Order 1.5 1.4 1.3 Verify Shipment Assemble Customer Order Assign Shipment Modeling Diagrams Data Flow Diagrams (DFDs) Exploding DFDs Processes should be exploded according to the Decomposition Chart Notice that at this point in time, all we are doing is listing the activities Involved We should, however, be able to determine (approximately) the order of processing, and assign identifiers accordingling

23. 1.0: Process Order Book Details Publisher Address 1.1 1.2 Purchase Order Assemble Publisher Requisition Verify Order D2 D1 Books Customer Customer Order Process Order Valid Order PO Details Customer Credit Status D5 Publisher Orders Order Details Title Orders Publishers Consign. Note Ship. Note 1.5 D4 D3 Publisher Pending Order 1.4 1.3 Assign Shipment Verify Shipment Assemble Customer Order Order Details Title Quant. Customer Data Publisher Modeling Diagrams Data Flow Diagrams (DFDs) Exploding DFDs Of Course, we will have to add details

24. 1.2: Assemble Publisher Requisition 1.2.1. 1.2.4. Publisher Address Publisher Ordering Information Business Terms Assemble Publisher Requisition Retrieve Pub. Order Info. D4 Publisher 1.2.2 1.2.3. Unit Orders P.O Totals by Title Extract Publisher Orders Copies Total Number of Copies Pending Order Details Copy of PO Order Details 1.2.6. 1.2.5 Order Date, PO# Create PO in Progress Record P.O Publisher Orders Note Order Info. In Pending Orders D3 Details D3 Pending Order Publisher Modeling Diagrams Data Flow Diagrams (DFDs) Exploding DFDs We can now continue Exploding

25. Modeling Diagrams Data Flow Diagrams (DFDs) Exploding DFDs ??? When Do We Stop ??? When We are done