2. Selecting Software Alternatives Planning Analysis Make, build Purchase In house system Commercial software package Implementation Customized software
3. Selecting Software Alternatives Decision will effect remaining SDLC phases Systems Analysts involvement depends on which alternative is selected
4. Evaluating Software Alternatives In-house developed software In-house customization of a software package In-house software developed by contract personnel End-user computing Outsource a customized software package Software vendor customizes its software package Software vendor enhances its software package Software package used without modification High Low
5. 1. 犖犖犖犢犖犖犖犖萎犖犖犖迦 (Application Design) 1.1 System interfaces Defining the interfaces Supporting clerical systems Man-machine interfaces (screens, forms, type and number of terminals, locations) Machine-machine interfaces 1.2 Program and their design 2. 犖犖犖犢犖犖犖犖迦犖犢犖犖÷弦犖 (Data Base Design) Systems Design : 犖犖迦牽犖犖犖犢犖犖犖犖萎犖
6. Systems Design Activities 1. Review the system requirements 2. Design the system user interface - dialogues, screens, forms, reports input process - sources documents, audit trails, system security data - how data will be organized, tables, ER diagram program specification system architecture - processing method, network config uration. 3. Present the design
7. Systems Design Considerations User Considerations Consider points where users interact with the system (e.g. where users receive output or provide input to the system. Make the system user-friendly. Anticipate future user, system and organization needs Processing Considerations Use a modular design Design independent modules that perform a single function Data Considerations Enter data where and when it occurs Verify data where it is input Use automated data-entry methods whenever possible Control access for data entry Report every instance of entry and change to data Entry data only once
8. Design tradeoffs Design goals often conflict with each other Easier use might create more complex programming requirements More flexibility might increase maintenance needed Meeting one users requirements might make it harder to satisfy anothers needs A major issue is quality versus cost
9. System Modeling Current Physical Model 犢犖犖犖犖犖迦牽犖犖橿犖迦犖犖犖犖犖萎犖犖犖園犖犖伍犖園 Current Logical Model 犖犖犖園 current physical model 犢犖犢 犖÷元犢犖犖犖迦鍵 犖犖園犖犢犖犖園犖犖犖迦犖犖朽犖犖橿犖犢犖 犢犖犖÷顕犖萎肩犖÷犖犢犢犖犖犖園犖犖迦犖朽 犢犖犖巌犖犖謹犖犢犖犢 New Logical Model 犖犖犖園 犢犖犖巌犖÷犖園犖犢犖犖園犖 犖犖迦検犖犖о顕犖÷犢犖犖犖犖迦牽犖犖犖犖犖項犢犖犢 犢犖ム鍵犖犖迦検犖犢犖犢犖犖犖犢犖犖萎犖犖犖犖園犖о鹸犢犖犖犖迦鍵犖犢犖犖萎犖 犖犖謹犖犖犖о検犖犖迦牽犖犖犖園犢犖犢犖犖犖園犖 process, data store 犢犖ム鍵 data flow 犖犖朽犖÷元犖犢犖о犖犖犖萎犖 New Physical Model 犖犖犖園 logical model 犖犖犖犖犖萎犖犖犖迦犢犖犖÷犢犖犢犖犢犖犖犖犖犖о顕犖÷犖犢犖犢犖犢犖犢犢犖犖犖迦牽犢犖犢犖犖迦犖犖犖巌 犖犖巌犖迦牽犖犖迦犖犖犢犖о犖犖犖犖犢犖犖犖橿犖園犢犖犖犖迦牽犖犖園犖犖 犖犖犖園犖∇顕犖犖犖犖朽犖犢犖犖犢犖犢犢犖ム鍵犖犖迦牽犢犖犢犖犖犢犖о犖犖園犖犖犖犖犖犖迦牽犖犖橿犖迦 clerical procedure 犢犖ム鍵 computer procedure
10. 犖犖 System Modeling : 犖犖迦 DFDs 犖犖犖犖犖萎犖犖犖迦犢犖犖÷ (New Physical Model) 犖犖園犖о鹸犢犖犖犖迦鍵犖犢犖犖萎犖犖犖迦検犖迦牽犖 犖犖犖犢犖犖犖犖園犖犢犖犖園犖 犖ム験犖僅険犖犖犖迦犢犖ム鍵犖犖迦牽犖犖犖萎検犖о献犖犖 犢犖犖∇犖犖朽権犖犢犖犢犖 Hierarchical chart 犖犖犖犢犖犖 犖犖犖犖迦 , 犖犖迦権犖犖迦 , user interface, dialogue design, input data control 犢犖犖∇犖犢犢犖犖犖犖巌犖犢犖迦犢犖犖朽犖犖萎犖犢犖犖謹犖犖迦犖犖犖犖犢犖犢犖犢犖犖∇権犖謹犖犖迦検犖犖園犖犢犖犖園犖犖犖朽犖÷元犢犖 Hierarchical chart 犖о犖迦犖犢犖ム鍵犖犖園犖犢犖犖園犖犖犖迦犖犖園犖犢犖犖о牽犖÷元犖犖犖犖迦 , 犖犖迦権犖犖迦 犖犖犖劇賢 犢犖犖犖犖犖犢犖÷犖犢犖ム犖о犖園犖犖 sequence dialogue diagram 犢犖о犖犢犖о権 犖犖犖犢犖犖 data base 犖犖園犖犖橿犖犖犖犖迦牽犢犖犖犢犖犖犖 - Program Specification 犖犖謹犖犢犖犖犖 process logic 犖犖犖犢犖犢犖ム鍵犢犖犖犢犖犖犖 犢犖ム鍵犖犖迦犖犢犖犖犖÷元犖犖迦牽犖犖犖犖о screen design 犢犖ム鍵 data base design 犖犖朽犢犖犢犖犖橿犖о犖犢犖迦犢犖ム犖о犖犖犢犖 2 犢犖ム鍵 犖犢犖 3 犖犖 犖 犖犖犖犖犖迦犖犖園犖犖犖園犖о鹸犢犖犖犖迦鍵犖犢犖犖萎犖犖∇険犖犖犢犖犖犖犖犖犢犖犖犢犖犖犢犖о犖犖犖 犖犖園犖犖犖犖犖犖迦牽犖犖蹩巌犖園犖巌犖迦 (procedure), network, hardware architecture 犖犖園犖犖犖犖犖犖迦牽犖犖犖犢犖犖犖犖犖犢犖犖犖犖萎犖犖犖迦 (Design the System)
16. Designing and using codes 犖犖迦牽犖犖園犖犖橿牽犖犖園肩犢犖犖巌犖犖謹犖犢犖÷厳犢犖 a new system is being introduced an existing code is outgrown more than one organizations with different coding system merge
17. Designing and using codes Unique identification to replace a name of an item to give information to give security / confidentiality 犖犖伍犖犖犖萎肩犖犖犢犖犖迦牽犢犖犢犖犖犖園肩犖犢犖犖÷弦犖
27. Significant code - Collating code 2. Soundex code : e.g. Use first letter ignore vowels and H, W and Y and replace the next three by 1 for B,F,P,V Lawrance L652 2 for C,G,J,K,Q,S,X,Z Lawrence L652 3 for D,T Laurence L652 4 for L Laurent L653 5 for M,N 6 for R
28. Significant code - Collating code 3. Classification codes 犖犖園犖犖犖園肩犖犖迦検 categories 3.1 Decimal : 3 Social science 37 Education in 372 Elementary 372.2 Kindergarten 372.21 Method 372.215 Songs and games
29. Significant code - Collating code 3. Classification codes 犖犖園犖犖犖園肩犖犖迦検 categories 3.2 Faceted : face 1 = type, face 2 = sex, face 3 = size, face 4 = style, face 5 = material SU M 38L 17 384 Suit male size 38long style 17 material 384
30. Significant code - Collating code 3.3 Significant digit codes : 犢犖犢犖犖伍犖犖犖犖犖園硯犢犖ム犢犖犢犖犢犖犢犖 group, subgroup 犢犖犢犖ム鍵 subgroup 犖÷元犖犖о顕犖÷見犖÷顕犖 99 99 99 999 Warehouse location section Part Type Serial number
31. Significant code - Abbreviation 1. Mnemonic cm centimeter m meter 2. Acronyms RADAR - Radio Detecting And Ranging
32. Significant code - Other codes 1. Cipher codes 犢犖犢犖犖犖迦牽 encode 犖犢犖犖÷弦犖 2. Action codes 犢犖犢犖犖犖園肩犢犖犖犖犖迦牽犖犖犖萎犖橿犖朽犖犢犖犖犖犖迦牽 犢犖犢犖 A 犖犖÷顕犖∇犖謹 Add X 犖犖÷顕犖∇犖謹 eXit 犖犖迦 program
33. Non - Significant code 1. Sequential code Block sequential code 2. Random codes
34. 1) Discussion Data Code 犖犖橿犖園犖犖萎犖犖朽権犖 2) Class Exercise 犖犖迦牽犖犖犖犢犖犖犖犖園犖犢犖犖園犖 犖ム験犖犖園犖犖迦 犢犖ム鍵犖犖迦牽犖犖犖萎検犖о献犖犖 - 犖犢犖犖犢犖о権
