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'SASL' -- No information found for draft-ietf-ldapbis-syntaxes-xx - is the name correct? -- Possible downref: Normative reference to a draft: ref. 'Syntaxes' -- No information found for draft-ietf-ldapbis-user-schema-xx - is the name correct? -- Possible downref: Normative reference to a draft: ref. 'Schema' -- Possible downref: Non-RFC (?) normative reference: ref. 'Unicode' Summary: 7 errors (**), 0 flaws (~~), 5 warnings (==), 30 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 INTERNET-DRAFT Editor: Kurt D. Zeilenga 3 Intended Category: Standard Track OpenLDAP Foundation 4 Expires in six months 9 February 2005 5 Obsoletes: RFC 2251, RFC 2252, RFC 2256 7 LDAP: Directory Information Models 8 10 Status of this Memo 12 This document is intended to be published as a Standard Track RFC. 13 Distribution of this memo is unlimited. Technical discussion of this 14 document will take place on the IETF LDAP Revision Working Group 15 mailing list . Please send editorial 16 comments directly to the editor . 18 By submitting this Internet-Draft, I accept the provisions of Section 19 4 of RFC 3667. By submitting this Internet-Draft, I certify that any 20 applicable patent or other IPR claims of which I am aware have been 21 disclosed, or will be disclosed, and any of which I become aware will 22 be disclosed, in accordance with RFC 3668. 24 Internet-Drafts are working documents of the Internet Engineering Task 25 Force (IETF), its areas, and its working groups. Note that other 26 groups may also distribute working documents as Internet-Drafts. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference material 31 or to cite them other than as "work in progress." 33 The list of current Internet-Drafts can be accessed at 34 http://www.ietf.org/1id-abstracts.html 36 The list of Internet-Draft Shadow Directories can be accessed at 37 http://www.ietf.org/shadow.html 39 Copyright (C) The Internet Society (2005). All Rights Reserved. 41 Please see the Full Copyright section near the end of this document 42 for more information. 44 Abstract 46 The Lightweight Directory Access Protocol (LDAP) is an Internet 47 protocol for accessing distributed directory services which act in 48 accordance with X.500 data and service models. This document 49 describes the X.500 Directory Information Models, as used in LDAP. 51 Table of Contents 53 Status of this Memo 1 54 Abstract 2 55 Table of Contents 56 1. Introduction 3 57 1.1. Relationship to Other LDAP Specifications 58 1.2. Relationship to X.501 4 59 1.3. Conventions 60 1.4. Common ABNF Productions 61 2. Model of Directory User Information 6 62 2.1. The Directory Information Tree 7 63 2.2. Structure of an Entry 64 2.3. Naming of Entries 8 65 2.4. Object Classes 9 66 2.5. Attribute Descriptions 12 67 2.6. Alias Entries 15 68 3. Directory Administrative and Operational Information 17 69 3.1. Subtrees 70 3.2. Subentries 71 3.3. The 'objectClass' attribute 18 72 3.4. Operational attributes 19 73 4. Directory Schema 20 74 4.1. Schema Definitions 23 75 4.2. Subschema Subentries 30 76 4.3. 'extensibleObject' 35 77 4.4. Subschema Discovery 78 5. DSA (Server) Informational Model 36 79 5.1. Server-specific Data Requirements 80 6. Other Considerations 39 81 6.1. Preservation of User Information 40 82 6.2. Short Names 83 6.3. Cache and Shadowing 41 84 7. Implementation Guidelines 85 7.1. Server Guidelines 86 7.2. Client Guidelines 87 8. Security Considerations 42 88 9. IANA Considerations 89 10. Acknowledgments 43 90 11. Editor's Address 91 12. References 44 92 12.1. Normative References 93 12.2. Informative References 45 94 Appendix A. Changes 95 Intellectual Property Rights 50 96 Full Copyright 98 1. Introduction 100 This document discusses the X.500 Directory Information Models 101 [X.501], as used by the Lightweight Directory Access Protocol (LDAP) 102 [Roadmap]. 104 The Directory is "a collection of open systems cooperating to provide 105 directory services" [X.500]. The information held in the Directory is 106 collectively known as the Directory Information Base (DIB). A 107 Directory user, which may be a human or other entity, accesses the 108 Directory through a client (or Directory User Agent (DUA)). The 109 client, on behalf of the directory user, interacts with one or more 110 servers (or Directory System Agents (DSA)). A server holds a fragment 111 of the DIB. 113 The DIB contains two classes of information: 115 1) user information (e.g., information provided and administrated 116 by users). Section 2 describes the Model of User Information. 118 2) administrative and operational information (e.g., information 119 used to administer and/or operate the directory). Section 3 120 describes the model of Directory Administrative and Operational 121 Information. 123 These two models, referred to as the generic Directory Information 124 Models, describe how information is represented in the Directory. 125 These generic models provide a framework for other information models. 126 Section 4 discusses the subschema information model and subschema 127 discovery. Section 5 discusses the DSA (Server) Informational Model. 129 Other X.500 information models, such as access control distribution 130 knowledge, and replication knowledge information models, may be 131 adapted for use in LDAP. Specification of how these models apply to 132 LDAP is left to future documents. 134 1.1. Relationship to Other LDAP Specifications 136 This document is a integral part of the LDAP technical specification 137 [Roadmap] which obsoletes the previously defined LDAP technical 138 specification, RFC 3377, in its entirety. 140 This document obsoletes RFC 2251 sections 3.2 and 3.4, as well as 141 portions of sections 4 and 6. Appendix A.1 summaries changes to these 142 sections. The remainder of RFC 2251 is obsoleted by the [Protocol], 143 [AuthMeth], and [Roadmap] documents. 145 This document obsoletes RFC 2252 sections 4, 5 and 7. Appendix A.2 146 summaries changes to these sections. The remainder of RFC 2252 is 147 obsoleted by [Syntaxes]. 149 This document obsoletes RFC 2256 sections 5.1, 5.2, 7.1 and 7.2. 150 Appendix A.3 summarizes changes to these sections. The remainder of 151 RFC 2256 is obsoleted by [Schema] and [Syntaxes]. 153 1.2. Relationship to X.501 155 This document includes material, with and without adaptation, from 156 [X.501] as necessary to describe this protocol. These adaptations 157 (and any other differences herein) apply to this protocol, and only 158 this protocol. 160 1.3. Conventions 162 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 163 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 164 document are to be interpreted as described in BCP 14 [RFC2119]. 166 Schema definitions are provided using LDAP description formats (as 167 defined in Section 4.1). Definitions provided here are formatted 168 (line wrapped) for readability. Matching rules and LDAP syntaxes 169 referenced in these definitions are specified in [Syntaxes]. 171 1.4. Common ABNF Productions 173 A number of syntaxes in this document are described using Augmented 174 Backus-Naur Form (ABNF) [RFC2234]. These syntaxes (as well as a 175 number of syntaxes defined in other documents) rely on the following 176 common productions: 178 keystring = leadkeychar *keychar 179 leadkeychar = ALPHA 180 keychar = ALPHA / DIGIT / HYPHEN 181 number = DIGIT / ( LDIGIT 1*DIGIT ) 182 ALPHA = %x41-5A / %x61-7A ; "A"-"Z" / "a"-"z" 183 DIGIT = %x30 / LDIGIT ; "0"-"9" 184 LDIGIT = %x31-39 ; "1"-"9" 185 HEX = DIGIT / %x41-46 / %x61-66 ; "0"-"9" / "A"-"F" / "a"-"f" 187 SP = 1*SPACE ; one or more " " 188 WSP = 0*SPACE ; zero or more " " 190 NULL = %x00 ; null (0) 191 SPACE = %x20 ; space (" ") 192 DQUOTE = %x22 ; quote (""") 193 SHARP = %x23 ; octothorpe (or sharp sign) ("#") 194 DOLLAR = %x24 ; dollar sign ("$") 195 SQUOTE = %x27 ; single quote ("'") 196 LPAREN = %x28 ; left paren ("(") 197 RPAREN = %x29 ; right paren (")") 198 PLUS = %x2B ; plus sign ("+") 199 COMMA = %x2C ; comma (",") 200 HYPHEN = %x2D ; hyphen ("-") 201 DOT = %x2E ; period (".") 202 SEMI = %x3B ; semicolon (";") 203 LANGLE = %x3C ; left angle bracket ("<") 204 EQUALS = %x3D ; equals sign ("=") 205 RANGLE = %x3E ; right angle bracket (">") 206 ESC = %x5C ; backslash ("\") 207 USCORE = %x5F ; underscore ("_") 208 LCURLY = %x7B ; left curly brace "{" 209 RCURLY = %x7D ; right curly brace "}" 211 ; Any UTF-8 [UTF-8] encoded Unicode [Unicode] character 212 UTF8 = UTF1 / UTFMB 213 UTFMB = UTF2 / UTF3 / UTF4 214 UTF0 = %x80-BF 215 UTF1 = %x00-7F 216 UTF2 = %xC2-DF UTF0 217 UTF3 = %xE0 %xA0-BF UTF0 / %xE1-EC 2(UTF0) / 218 %xED %x80-9F UTF0 / %xEE-EF 2(UTF0) 219 UTF4 = %xF0 %x90-BF 2(UTF0) / %xF1-F3 3(UTF0) / 220 %xF4 %x80-8F 2(UTF0) 222 OCTET = %x00-FF ; Any octet (8-bit data unit) 224 Object identifiers (OIDs) [X.680] are represented in LDAP using a 225 dot-decimal format conforming to the ABNF: 227 numericoid = number 1*( DOT number ) 229 Short names, also known as descriptors, are used as more readable 230 aliases for object identifiers. Short names are case insensitive and 231 conform to the ABNF: 233 descr = keystring 235 Where either an object identifier or a short name may be specified, 236 the following production is used: 238 oid = descr / numericoid 240 While the form is generally preferred when the usage is 241 restricted to short names referring to object identifiers which 242 identify like kinds of objects (e.g., attribute type descriptions, 243 matching rule descriptions, object class descriptions), the 244 form should be used when the object identifiers may 245 identify multiple kinds of objects or when an unambiguous short name 246 (descriptor) is not available. 248 Implementations SHOULD treat short names (descriptors) used in an 249 ambiguous manner (as discussed above) as unrecognized. 251 Short Names (descriptors) are discussed further in Section 6.2. 253 2. Model of Directory User Information 255 As [X.501] states: 257 The purpose of the Directory is to hold, and provide access to, 258 information about objects of interest (objects) in some 'world'. 259 An object can be anything which is identifiable (can be named). 261 An object class is an identified family of objects, or conceivable 262 objects, which share certain characteristics. Every object belongs 263 to at least one class. An object class may be a subclass of other 264 object classes, in which case the members of the former class, the 265 subclass, are also considered to be members of the latter classes, 266 the superclasses. There may be subclasses of subclasses, etc., to 267 an arbitrary depth. 269 A directory entry, a named collection of information, is the basic 270 unit of information held in the Directory. There are multiple kinds 271 of directory entries. 273 An object entry represents a particular object. An alias entry 274 provides alternative naming. A subentry holds administrative and/or 275 operational information. 277 The set of entries representing the DIB are organized hierarchically 278 in a tree structure known as the Directory Information Tree (DIT). 280 Section 2.1 describes the Directory Information Tree 281 Section 2.2 discusses the structure of entries. 282 Section 2.3 discusses naming of entries. 283 Section 2.4 discusses object classes. 284 Section 2.5 discusses attribute descriptions. 285 Section 2.6 discusses alias entries. 287 2.1. The Directory Information Tree 289 As noted above, the DIB is composed of a set of entries organized 290 hierarchically in a tree structure known as the Directory Information 291 Tree (DIT). Specifically, a tree where vertices are the entries. 293 The arcs between vertices define relations between entries. If an arc 294 exists from X to Y, then the entry at X is the immediate superior of Y 295 and Y is the immediate subordinate of X. An entry's superiors are the 296 entry's immediate superior and its superiors. An entry's subordinates 297 are all of its immediate subordinates and their subordinates. 299 Similarly, the superior/subordinate relationship between object 300 entries can be used to derive a relation between the objects they 301 represent. DIT structure rules can be used to govern relationships 302 between objects. 304 Note: An entry's immediate superior is also known as the entry's 305 parent and an entry's immediate subordinate is also known as the 306 entry's child. Entries which have the same parent are known as 307 siblings. 309 2.2. Structure of an Entry 311 An entry consists of a set of attributes which hold information about 312 the object which the entry represents. Some attributes represent user 313 information and are called user attributes. Other attributes 314 represent operational and/or administrative information and are called 315 operational attributes. 317 An attribute is an attribute description (a type and zero or more 318 options) with one or more associated values. An attribute is often 319 referred to by its attribute description. For example, the 320 'givenName' attribute is the attribute which consists of the attribute 321 description 'givenName' (the 'givenName' attribute type [Schema] and 322 zero options) and one or more associated values. 324 The attribute type governs whether the attribute can have multiple 325 values, the syntax and matching rules used to construct and compare 326 values of that attribute, and other functions. Options indicate 327 subtypes and other functions. 329 Attribute values conform to the defined syntax of the attribute type. 331 No two values of an attribute may be equivalent. Two values are 332 considered equivalent only if they would match according to the 333 equality matching rule of the attribute type. If the attribute type 334 is defined with no equality matching rule, two values are equivalent 335 if and only if they are identical. (See 2.5.1 for other 336 restrictions.) 338 For example, a 'givenName' attribute can have more than one value, 339 they must be Directory Strings, and they are case insensitive. A 340 'givenName' attribute cannot hold both "John" and "JOHN" as these are 341 equivalent values per the equality matching rule of the attribute 342 type. 344 When an attribute is used for naming of the entry, one and only one 345 value of the attribute is used in forming the Relative Distinguished 346 Name. This value is known as a distinguished value. 348 2.3. Naming of Entries 350 2.3.1. Relative Distinguished Names 352 Each entry is named relative to its immediate superior. This relative 353 name, known as its Relative Distinguished Name (RDN) [X.501], is 354 composed of an unordered set of one or more attribute value assertions 355 (AVA) consisting of an attribute description with zero options and an 356 attribute value. These AVAs are chosen to match attribute values 357 (each a distinguished value) of the entry. 359 An entry's relative distinguished name must be unique among all 360 immediate subordinates of the entry's immediate superior (i.e., all 361 siblings). 363 The following are examples of string representations of RDNs [LDAPDN]: 365 UID=12345 366 OU=Engineering 367 CN=Kurt Zeilenga+L=Redwood Shores 369 The last is an example of a multi-valued RDN. That is, an RDN 370 composed of multiple AVAs. 372 2.3.2. Distinguished Names 374 An entry's fully qualified name, known as its Distinguished Name (DN) 375 [X.501], is the concatenation of its RDN and its immediate superior's 376 DN. A Distinguished Name unambiguously refers to an entry in the 377 tree. The following are examples of string representations of DNs 378 [LDAPDN]: 380 UID=nobody@example.com,DC=example,DC=com 381 CN=John Smith,OU=Sales,O=ACME Limited,L=Moab,ST=Utah,C=US 383 2.3.3. Alias Names 385 An alias, or alias name, is "an name for an object, provided by the 386 use of alias entries" [X.501]. Alias entries are described in Section 387 2.6. 389 2.4. Object Classes 391 An object class is "an identified family of objects (or conceivable 392 objects) which share certain characteristics" [X.501]. 394 As defined in [X.501]: 396 Object classes are used in the Directory for a number of purposes: 398 - describing and categorising objects and the entries that 399 correspond to these objects; 401 - where appropriate, controlling the operation of the Directory; 403 - regulating, in conjunction with DIT structure rule 404 specifications, the position of entries in the DIT; 406 - regulating, in conjunction with DIT content rule 407 specifications, the attributes that are contained in entries; 409 - identifying classes of entry that are to be associated with a 410 particular policy by the appropriate administrative authority. 412 An object class (a subclass) may be derived from an object class 413 (its direct superclass) which is itself derived from an even more 414 generic object class. For structural object classes, this process 415 stops at the most generic object class, 'top' (defined in Section 416 2.4.1). An ordered set of superclasses up to the most superior 417 object class of an object class is its superclass chain. 419 An object class may be derived from two or more direct 420 superclasses (superclasses not part of the same superclass chain). 421 This feature of subclassing is termed multiple inheritance. 423 Each object class identifies the set of attributes required to be 424 present in entries belonging to the class and the set of attributes 425 allowed to be present in entries belonging to the class. As an entry 426 of a class must meet the requirements of each class it belongs to, it 427 can be said that an object class inherits the sets of allowed and 428 required attributes from its superclasses. A subclass can identify an 429 attribute allowed by its superclass as being required. If an 430 attribute is a member of both sets, it is required to be present. 432 Each object class is defined to be one of three kinds of object 433 classes: Abstract, Structural, or Auxiliary. 435 Each object class is identified by an object identifier (OID) and, 436 optionally, one or more short names (descriptors). 438 2.4.1. Abstract Object Classes 440 An abstract object class, as the name implies, provides a base of 441 characteristics from which other object classes can be defined to 442 inherit from. An entry cannot belong to an abstract object class 443 unless it belongs to a structural or auxiliary class which inherits 444 from that abstract class. 446 Abstract object classes can not derive from structural nor auxiliary 447 object classes. 449 All structural object classes derive (directly or indirectly) from the 450 'top' abstract object class. Auxiliary object classes do not 451 necessarily derive from 'top'. 453 The following is the object class definition (see Section 4.1.1) for 454 the 'top' object class: 456 ( 2.5.6.0 NAME 'top' ABSTRACT MUST objectClass ) 458 All entries belong to the 'top' abstract object class. 460 2.4.2. Structural Object Classes 462 As stated in [X.501]: 464 An object class defined for use in the structural specification of 465 the DIT is termed a structural object class. Structural object 466 classes are used in the definition of the structure of the names 467 of the objects for compliant entries. 469 An object or alias entry is characterised by precisely one 470 structural object class superclass chain which has a single 471 structural object class as the most subordinate object class. 472 This structural object class is referred to as the structural 473 object class of the entry. 475 Structural object classes are related to associated entries: 477 - an entry conforming to a structural object class shall 478 represent the real-world object constrained by the object 479 class; 481 - DIT structure rules only refer to structural object classes; 482 the structural object class of an entry is used to specify the 483 position of the entry in the DIT; 485 - the structural object class of an entry is used, along with an 486 associated DIT content rule, to control the content of an 487 entry. 489 The structural object class of an entry shall not be changed. 491 Each structural object class is a (direct or indirect) subclass of the 492 'top' abstract object class. 494 Structural object classes cannot subclass auxiliary object classes. 496 Each entry is said to belong to its structural object class as well as 497 all classes in its structural object class's superclass chain. 499 2.4.3. Auxiliary Object Classes 501 Auxiliary object classes are used to augment the characteristics of 502 entries. They are commonly used to augment the sets of attributes 503 required and allowed to be present in an entry. They can be used to 504 describe entries or classes of entries. 506 Auxiliary object classes cannot subclass structural object classes. 508 An entry can belong to any subset of the set of auxiliary object 509 classes allowed by the DIT content rule associated with the structural 510 object class of the entry. If no DIT content rule is associated with 511 the structural object class of the entry, the entry cannot belong to 512 any auxiliary object class. 514 The set of auxiliary object classes which an entry belongs to can 515 change over time. 517 2.5. Attribute Descriptions 519 An attribute description is composed of an attribute type (see Section 520 2.5.1) and a set of zero or more attribute options (see Section 521 2.5.2). 523 An attribute description is represented by the ABNF: 525 attributedescription = attributetype options 526 attributetype = oid 527 options = *( SEMI option ) 528 option = 1*keychar 530 where identifies the attribute type and each