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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

Midrange Concepts

Review for Test 2

security
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
security3
Security
  • Access Controls can be supplied by:
    • DB2/400
    • OS/400
    • Journaling Functions
  • Data Control Levels:
    • File
    • Record (journaling)
    • Field
security4
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
security5
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.
security6
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
physical files
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
physical files8
Physical Files
  • Data definition must include:
    • Field Names
    • Data Type
    • Length
  • Data can be defined:
    • Internally (using RPG or Cobol)
    • Externally (IDDU, DDS, SQL)
physical files9
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

physical files10
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.
physical files11
Physical Files
  • Physical files must have only one record level specification.
  • Keywords (all optional):
    • Text
    • Ref
    • Unique
physical files12
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
slide13

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
logical files
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
logical files15
Logical Files
  • Keywords:
    • PFILE
    • JFILE
      • JOIN
      • JFLD
commands
Commands
  • CRTPF
  • CRTLF
  • DSPDBR
  • FNDSTRPDM
commands17
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
creating cl programs
Creating CL Programs

Library

Programmer

PF-SRC

CRTMBR

*PGM

CLP

Compile

CL

Commands

SEU

CRTMBR

CLP

slide19

Creating a Data Physical File

Library

PF-SRC

Student

*FILE

PF-DTA

Machine Language

File Definition

Compile

Student

PF

Student

__

DDS

slide20

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)

slide21

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)