Transcript Namespaces

Namespaces
cs3353
Namespace Domain
• A computer system namespace domain is
created and maintained to:
– standardize the policy for names
– prevent name collisions (same names with
different meanings)
Namespace
• The namespace is used to create names for
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User IDs
Individual computer systems
Other hardware
Other categories?
• Passwords
Namespace Policy
• Formula
• Theme
– All names fit a theme like planet names,
cartoon characters, star trek characters, etc.
• Function
– The name describes the function: disk_server,
main_printer, etc.
Namespace Policy
• Theme names for hardware are ok when
there are only a few systems:
– Server = hal9000
– Clients = uhura, checkov, sulu, spock, etc
Managing a large number of systems this way is
not advised.
Namespace Policy
• Function names: disk_server01,
disk_server02, etc.
• Function names have their own
maintenance problems: consider what
happens when the disk_server is reassigned
its role in the computing system to handle email.
Namespace Policy: Formula
• Formula names are not interesting or
personal, but are practical for large
namespaces.
• Divide the name into fields. Fixed length
fields make the names easier to learn.
• Keep the name to a reasonable length.
Namespace Policy: Formula
• Formula names can be used to obscure the
function of named entities in the domain.
• Keep the names to a reasonable length
unless long names serve a specific purpose.
– Longer names tend to be used less frequently
Formula Policy
• User IDs, Passwords
• Machine names: clients & servers
• Miscellaneous hardware:
– Printers, Fax-machine, etc
• Other?
Namespace Formula Policy
• Use any combination of:
– Prefix:
– Infix:
– Postfix
To construct a namespace.
Example: User ID Formula
(Prefix)
• Prefix (one letter field)
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Regular employee (e)
Consultant/Contractor (c)
Temp (t)
Vendor/Supplier (s | v)
Visitor/Guest (g)
Helpful for identification and access control
Example: User ID Formula
(Infix,Postfix)
• Infix (three character field)
– Three letters using name initials
• Postfix (two character field)
– 00 through 99 if two entities have the same first
four characters.
Example: Namespace Policy
(Hardware)
• Computer systems (6 to 8 characters)
– Postfix
– Infix
– Prefix
Example: Namespace Policy
(Hardware)
• Postfix
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Server (s)
Client (c)
Experimental (e)
Printer (p)
Backup device (b)
Etc.
Example: Formula Namespace
(Hardware)
• Infix – 3 character base-36 number: 000-zzz
• Postfix – 2 digits Year of purchase (09).
Most hardware is retired within 10 years.
User ID name space
• Possible choices
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Full name
Initials and digits
Anonymity of user IDs may be required.
Limit to 8 characters if possible.
User ID name space
• A centralized data base for User ID names
is needed.
• A single authentication data base can be
used to keep track of User ID name space.
Other Namespace Considerations
• Scope – what is the scope for your
namespace.
– What is the impact of growth or a merger?
• Security – do the names need to be obscure?
• Reuse – When is it appropriate to re-use a
name, if ever?
Changes in the Namespace
• A name change policy is needed.
• A central database with a record of all
names in the namespace is required for
managing the namespace.
Class Exercise
• Create a formula policy for:
– Hardware
– User IDs
– The formula method can be applied to
passwords