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X.500 Part 2. Models and Objects. CNS 4650 Fall 2004 Rev. 2. X.500 Models. Models are used to snapshot certain function and operations Usually a distinct portion of the directory Abstracts the rest of the directory. Models Examined.
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X.500 Part 2 Models and Objects CNS 4650 Fall 2004 Rev. 2
X.500 Models • Models are used to snapshot certain function and operations • Usually a distinct portion of the directory • Abstracts the rest of the directory
Models Examined • 1988 X.500 only specified one model, the Directory Informational Model • 1993 X.501 (The Directory: Models) expanded the model definitions • There are a number of models that will not be discussed
Directory Functional Model • The directory is comprise of one or more DSAs with access to the DIB • DSAs can use information stored locally or query other DSAs for information • DSAs can also “refer” to other DSAs
User Informational Model • Directory is a logical tree to the user • The tree contains objects • Objects have attributes • Attributes must respect syntax rules • More discussion at end of lecture
Operational and Administrative Information Model • Directory from the Administator’s view • Objects not only contain “user” attributes, but also administrative attributes • Similar to the User Information Model as far as how the directory is viewed (DIT) • Two types of attributes • Operational • Subentries
Operational Attributes • Three types • Directory Operational • Apply to every DSA (access control) • DSA-shared Operational • Apply to replication between DSAs • DSA-specific Operational • Apply to a single DSA (time stamp of last replica)
Subentries • Used to define a subtree • Applies properties to the subtree • access control • subschema • global properties
DSA Information Model • DSA are organized into a DIT with naming contexts • The DIB may span across multiple DSAs • DSAs must be able access information, either through direct look up or referral • Replicas must be able to access original data at DUAs request • Knowledge Information • DSA-Specific Information
Knowledge Information • Describe relationships between DSAs • References hold information to portions of the DIB that are not local to the DSA • Four mandatory references • Superior • Subordinate • Suppiler • Consumer
Superior Reference • Non-first level DSA must contain one superior reference • References form path to the “root” • Book is incorrect, Immediate Superiors are an optional reference.
Subordinate Reference • References contain naming contexts (children) directly below current naming context • Contain RDN (Relative Distinguished Name) and access point for DSA
Suppiler Reference • Used for replication • Contains the agreement between the supplier and consumer for replication • Access point of Supplier DSA • States whether the Supplier is a master and if not it will contain the access point to the master DSA
Consumer Reference • Contains a copy of the agreement between the supplier and consumer • Access point for the consumer
DSA-Specific Entry • DSE are entries in the DIT that reflect how DSA views a certain object
Directory Distribution Model • A single master DSA will hold a authoritative copy of each object in the respective naming context • A DSA may contain a copy of the master, that DSA is referred to as a shadow • DIB fragment
Directory Administrative Authority Model • Divides the DIT into subtrees • Subtrees allow for delegated management • Subtrees are attached to a container object and extend down to the next subtree • Subtrees are assigned a particular administrative area • Autonomous Administrative Area • Specific Administrative Area • Inner Administrative Area
Autonomous Authority Area • The AAA usually encompasses the entire organization’s DIT • The may be more than one AAA in a DIT
Specific Administrative Area (SAA) • Administrate the attributes that are part of the subtree being administrated
Inner Administrative Area (IAA) • Delegate administration to a local administrator • IAA can be nested, unlike SAAs • Boundaries are somewhat permable, permissions may cross boundaries
Security Model • Defined in the Directory Administrative Authority Model • Security divisions correspond exactly to the administrative divisions
Sources • X.500 Information Technology - Open Systems Interconnection- The Directory: Overview of Concepts, Models, and Services, first published in 1988 • X.501 Information Technology - Open Systems Interconnection- The Directory: Models, first published in 1993 • X.518 Information Technology - Open Systems Interconnection- The Directory: Procedures for Distributed Operation, first published in 1988