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Midrange Concepts

Midrange Concepts. Review for Test 2. Security. Security has two general purposes: Loss Prevention Objects - Data Access control Functions Controls should be exercised: At input time At update time When data is deleted. Security. Access Controls can be supplied by: DB2/400 OS/400

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Midrange Concepts

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  1. Midrange Concepts Review for Test 2

  2. Security • Security has two general purposes: • Loss Prevention • Objects - Data • Access control • Functions • Controls should be exercised: • At input time • At update time • When data is deleted

  3. Security • Access Controls can be supplied by: • DB2/400 • OS/400 • Journaling Functions • Data Control Levels: • File • Record (journaling) • Field

  4. Security • Object authority: the ability to provide access to object functions: • 2 users have object authority: • Owner of the object • System Security Officer • Also has authority to enter new users • Granting object authority: • EDTOBJAUT: Edit object Authority • GRTOBJAUT: Can use only against objects that you own. • WRKOBJ: Use options • EDTOBJAUT

  5. Security • Authorization List: • Identifies object owner and who has access. • Authorization Values: • *ALL • *USE • *EXCLUDE • *CHANGE • Group profiles • Everyone in the group will have the same authority.

  6. Security • System Level Security • Controlled at signon by the system value for security. • Range in value from 10 to 50 • 10: any user name and password will be given access • 20: User name and password must be valid to gain access but then have full capabilities • 30: User name and password with object authority • 40: all of 30 also security regarding machine interface objects. • 50: all of 40, highest level of security • Other means to assigning object security: • Adopted Authority • Alternative User Environments

  7. Physical Files • Character Representation • EBCDIC (Extended Binary Coded Decimal Interchange Code) • ASCII (American Standard Code for Information Interchange) • Numeric Representation • Zoned Decimal • Packed Decimal • Binary

  8. Physical Files • Data definition must include: • Field Names • Data Type • Length • Data can be defined: • Internally (using RPG or Cobol) • Externally (IDDU, DDS, SQL)

  9. Physical Files IDDU (Interactive Data Definition Utility) Came from the System 36 environment DDS (Data Definition Specifications) Define file structures Individual Field Characteristics Field edits

  10. Physical Files • Process of DDS: • Key definition into a member of source file with type pf. • Compile this member • Object created during compile will hold data. • DDS is a semi-positional language.

  11. Physical Files • Physical files must have only one record level specification. • Keywords (all optional): • Text • Ref • Unique

  12. Physical Files • Field Reference File • Physical files can have multiple members • Keyed Access Path (or Index to the data) • Keyed fields can be primary or secondary • Can use a combination of fields to specify key • Do not have to specify a key

  13. Keyed Sequence Access Paths • Allow access to records in both arrival sequence and keyed sequence • Allow individual records to be retrieved according to a specific key value • Utilities will default to either Arrival or Keyed sequence when accessing a keyed file • DSPPFM uses arrival sequence • CPYF uses keyed sequence

  14. Logical Files • Usually created to satisfy different user access requirements. • Offer a different view of physical file • DO NOT contain any data • Based on Physical file • Can not exist independently • Use DDS to define record layout • Can add/delete records of physical file and logical will see changes • Do not have the same key as the physical file

  15. Logical Files • Keywords: • PFILE • JFILE • JOIN • JFLD

  16. Commands • CRTPF • CRTLF • DSPDBR • FNDSTRPDM

  17. Commands • CPYF • Can copy from a PF, LF or a source file • Can copy to a PF, Printer, external devices • Can convert a source file to a physical file • Does not require DDS for new file • To file does not have to exist as object • Must specify create

  18. Creating CL Programs Library Programmer PF-SRC CRTMBR *PGM CLP Compile CL Commands SEU CRTMBR CLP

  19. Creating a Data Physical File Library PF-SRC Student *FILE PF-DTA Machine Language File Definition Compile Student PF Student __ DDS

  20. Ref Keyword Library PF-SRC FRF *FILE PF-DTA Student *FILE PF-DTA DDS Compile Machine Language File Definition Student PF Student __ DDS REF(FRF)

  21. Ref Keyword Library PF-SRC FRF *FILE PF-DTA Student *FILE PF-DTA DDS Compile Machine Language File Definition Student PF Student __ DDS REF(FRF)

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