IAD 2263: System Analysis and Design

1. IAD 2263: System Analysis and Design Chapter 7: Designing System Databases, Interfaces and Security

2. Content • Designing Databases • Designing the User Interface • Designing the System Interfaces, Controls and Security

3. Databases and Database Management Systems • Databases (DB) – integrated collections of stored data that are centrally managed and controlled • Database management system (DBMS) – system software that manages and controls access to database • Databases described by a schema – description of structure, content, and access controls

4. Database Models • Impacted by technology changes since 1960s • Model types • Hierarchical • Network • Relational • Object-oriented • Most current systems use relational or object-oriented data models

5. Relational Databases • Relational database management system (RDBMS) organizes data into tables or relations • Tables are two dimensional data structures • Tuples –rows or records • Fields –columns or attributes • Tables have primary key field(s) that can be used to identify unique records • Keys relate tables to each other

6. Partial Display of Relational Database Table

7. Designing Relational Databases • Create table for each entity type • Choose or invent primary key for each table • Add foreign keys to represent one-to-many relationships • Create new tables to represent many-to-many relationships

8. Designing Relational Databases (continued)‏ • Define referential integrity constraints • Evaluate schema quality and make necessary improvements • Choose appropriate data types and value restrictions (if necessary) for each field

9. Relationship Between Data in Two Tables

10. RMO Entity-Relationship Diagram

11. Representing Relationships • Relational databases use foreign keys to represent relationships • One-to-many relationship • Add primary key field of “one” entity type as foreign key in table that represents “many” entity type • Many-to-many relationship • Use the primary key field(s) of both entity types • Use (or create) an associative entity table to represent relationship

12. Entity Tables with Primary Keys

13. Database Normalization • Normal forms minimize data redundancy • First normal form (1NF) – no repeating fields or groups of fields • Functional dependency – one-to-one relationship between the values of two fields • 2NF – in 1NF and if each non-key element is functionally dependent on entire primary key • 3NF – in 2NF and if no non-key element is functionally dependent on any other non-key element

14. Object-Oriented Databases • Direct extension of OO design and programming paradigm • ODBMS stores data as objects • Direct support for method storage, inheritance, nested objects, object linking, and programmer-defined data types • Object Definition Language (ODL)‏ • Standard language for describing structure and content of an object database

15. Designing Object Databases • Determine which classes require persistent storage • Define persistent classes • Represent relationships among persistent classes • Choose appropriate data types and value restrictions (if necessary) for each field

16. RMO Domain Model Class Diagram

17. One-to-Many Relationship Between Customer and Order Classes

18. Views of Stored Data

19. Relationships • Relationships are represented with foreign keys • Foreign key values serve same purpose as object identifiers in ODBMS • 1:M relationship – add primary key field of class on “one” side of the relationship to table representing class on “many” side • M:M relationship – create new table that contains primary key fields of related class tables and attributes of the relationship itself

20. Systems Analysis and Design in a Changing World, 5th Edition Identifying System Interfaces • System interfaces are broadly defined as inputs or outputs with minimal or no human intervention • Inputs from other systems (messages, EDI)‏ • Highly automated input devices such as scanners • Inputs that are from data in external databases • Outputs to external databases • Outputs with minimal HCI • Outputs to other systems • Real-time connections (both input and output)‏

21. Systems Analysis and Design in a Changing World, 5th Edition Full Range of Inputs and Outputs Figure 15-1

22. Systems Analysis and Design in a Changing World, 5th Edition Designing System Outputs • Determine each type of output • Make list of specific system outputs required based on application design • Specify any necessary controls to protect information provided in output • Design and prototype output layout • Ad hoc reports – designed as needed by user

23. Systems Analysis and Design in a Changing World, 5th Edition Defining the Details of System Outputs • Type of reports • Printed reports • Electronic displays • Turnaround documents

24. Systems Analysis and Design in a Changing World, 5th Edition Sample Bar Chart and Pie Chart Reports Figure 15-17

25. Systems Analysis and Design in a Changing World, 5th Edition Formatting Reports • What is objective of report? • Who is the intended audience? • What is media for presentation? • Avoid information overload • Format considerations include meaningful headings, date of information, date report produced, page numbers

26. Systems Analysis and Design in a Changing World, 5th Edition Objectives of Integrity Controls • Ensure that only appropriate and correct business transactions occur • Ensure that transactions are recorded and processed correctly • Protect and safeguard assets of the organization • Software • Hardware • Information

27. Systems Analysis and Design in a Changing World, 5th Edition Points of Security and Integrity Controls Figure 15-18

28. Systems Analysis and Design in a Changing World, 5th Edition Input Integrity Controls • Used with all input mechanisms • Additional level of verification to help reduce input errors • Common control techniques • Field combination controls • Value limit controls • Completeness controls • Data validation controls

29. Systems Analysis and Design in a Changing World, 5th Edition Designing Security Controls • Security controls protect assets of organization from all threats • External threats such as hackers, viruses, worms, and message overload attacks • Security control objectives • Maintain stable, functioning operating environment for users and application systems (24 x 7)‏ • Protect information and transactions during transmission outside organization (public carriers)‏

30. Systems Analysis and Design in a Changing World, 5th Edition Security for Access to Systems • Used to control access to any resource managed by operating system or network • User categories • Unauthorized user – no authorization to access • Registered user – authorized to access system • Privileged user – authorized to administrate system • Organized so that all resources can be accessed with same unique ID/password combination

31. Systems Analysis and Design in a Changing World, 5th Edition Users and Access Roles to Computer Systems Figure 15-20

32. Systems Analysis and Design in a Changing World, 5th Edition Managing User Access • Most common technique is user ID / password • Authorization – Is user permitted to access? • Access control list – users with rights to access • Authentication – Is user who they claim to be? • Smart card – computer-readable plastic card with embedded security information • Biometric devices – keystroke patterns, fingerprinting, retinal scans, voice characteristics

33. Systems Analysis and Design in a Changing World, 5th Edition Data Security • Data and files themselves must be secure • Encryption – primary security method • Altering data so unauthorized users cannot view • Decryption • Altering encrypted data back to its original state • Symmetric key – same key encrypts and decrypts • Asymmetric key – different key decrypts • Public key – public encrypts; private decrypts

34. Systems Analysis and Design in a Changing World, 5th Edition Symmetric Key Encryption Figure 15-22

35. Systems Analysis and Design in a Changing World, 5th Edition Asymmetric Key Encryption Figure 15-23

36. Systems Analysis and Design in a Changing World, 5th Edition Digital Signatures and Certificates • Encryption of messages enables secure exchange of information between two entities with appropriate keys • Digital signature encrypts document with private key to verify document author • Digital certificate is institution’s name and public key that is encrypted and certified by third party • Certifying authority • VeriSign or Equifax

37. Systems Analysis and Design in a Changing World, 5th Edition Secure Transactions • Standard set of methods and protocols for authentication, authorization, privacy, integrity • Secure Sockets Layer (SSL) renamed as Transport Layer Security (TLS) – protocol for secure channel to send messages over Internet • IP Security (IPSec) – newer standard for transmitting Internet messages securely • Secure Hypertext Transport Protocol (HTTPS or HTTP-S) – standard for transmitting Web pages securely (encryption, digital signing, certificates)‏

38. Thanks