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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Martin Hamilton 3 INTERNET-DRAFT Loughborough University 4 Expires December 1997 Renato Iannella 5 DSTC Pty Ltd 6 Jon Knight 7 Loughborough University 8 June 1997 10 Representing the Dublin Core within X.500, LDAP and CLDAP 12 Filename: draft-hamilton-dcxl-01.txt 14 Status of this Memo 16 This document is an Internet-Draft. Internet-Drafts are working 17 documents of the Internet Engineering Task Force (IETF), its 18 areas, and its working groups. Note that other groups may also 19 distribute working documents as Internet-Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six 22 months and may be updated, replaced, or obsoleted by other 23 documents at any time. It is inappropriate to use Internet- 24 Drafts as reference material or to cite them other than as ``work 25 in progress.'' 27 To learn the current status of any Internet-Draft, please check 28 the ``1id-abstracts.txt'' listing contained in the Internet- 29 Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net 30 (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East 31 Coast), or ftp.isi.edu (US West Coast). 33 Distribution of this document is unlimited. 35 Abstract 37 The Dublin Core is a simple resource description format which arose 38 out of a loose grouping of "librarians, archivists, humanities 39 scholars and geographers, as well as standards makers in the 40 Internet, Z39.50 and Standard Generalized Markup Language (SGML) 41 communities" [1]. 43 This document describes a mapping from the abstract model of the 44 Dublin Core to the X.500 [2], LDAP [3], and CLDAP [4] directory 45 service protocols. 47 1. The Dublin Core in X.500, LDAP and CLDAP 49 We propose that each of the thirteen elements of the Dublin Core be 50 made into an X.500/[C]LDAP attribute, and that these attributes be 51 gathered together in an object class: 53 Name: dcObject 54 Description: object containing the Dublin Core attributes 55 OID: lutObjectClass.1 (1.3.6.1.4.1.1828.2.1) 56 SubclassOf: top 57 MustContain: 58 MayContain: dcSubject, dcDescription, dcTitle, dcAuthor, 59 dcPublisher, dcContributor, dcDate, 60 dcResourceType, dcForm, dcResourceIdentifer, 61 dcRelation, dcSource, dcLanguage, dcCoverage, 62 dcRightsManagement 64 Attribute definitions for the individual Dublin Core elements: 66 Name: dcSubject 67 Description: The topic addressed by the resource, or a 68 set of appropriate keywords 69 OID: lutAttributeType.1 (1.3.6.1.4.1.1828.1.1) 70 Syntax: DirectoryString 71 SizeRestriction: None 72 SingleValued: False 74 Name: dcDescription 75 Description: A plain text description or abstract about 76 the resource. 77 OID: lutAttributeType.2 (1.3.6.1.4.1.1828.1.2) 78 Syntax: DirectoryString 79 SizeRestriction: None 80 SingleValued: False 82 Name: dcTitle 83 Description: The name of the resource 84 OID: lutAttributeType.3 (1.3.6.1.4.1.1828.1.3) 85 Syntax: DirectoryString 86 SizeRestriction: None 87 SingleValued: False 89 Name: dcAuthor 90 Description: The person(s) primarily responsible for the 91 intellectual content of the resource 92 OID: lutAttributeType.4 (1.3.6.1.4.1.1828.1.4) 93 Syntax: DirectoryString 94 SizeRestriction: None 95 SingleValued: False 97 Name: dcPublisher 98 Description: The agent or agency responsible for making the 99 resource available 100 OID: lutAttributeType.5 (1.3.6.1.4.1.1828.1.5) 101 Syntax: DirectoryString 102 SizeRestriction: None 103 SingleValued: False 105 Name: dcContributor 106 Description: The person(s), such as editors and transcribers, who 107 have made other significant intellectual 108 contributions to the work 109 OID: lutAttributeType.6 (1.3.6.1.4.1.1828.1.6) 110 Syntax: DirectoryString 111 SizeRestriction: None 112 SingleValued: False 114 Name: dcDate 115 Description: The date of publication 116 OID: lutAttributeType.7 (1.3.6.1.4.1.1828.1.7) 117 Syntax: DirectoryString 118 SizeRestriction: None 119 SingleValued: False 121 Name: dcResourceType 122 Description: The genre of the resource, such as novel, poem, or 123 dictionary 124 OID: lutAttributeType.8 (1.3.6.1.4.1.1828.1.8) 125 Syntax: DirectoryString 126 SizeRestriction: None 127 SingleValued: False 129 Name: dcForm 130 Description: The physical manifestation of the resource, such as 131 Postscript file or Windows executable file 132 OID: lutAttributeType.9 (1.3.6.1.4.1.1828.1.9) 133 Syntax: DirectoryString 134 SizeRestriction: None 135 SingleValued: False 137 Name: dcResourceIdentifier 138 Description: String or number used to uniquely identify the 139 resource 140 OID: lutAttributeType.10 (1.3.6.1.4.1.1828.1.10) 141 Syntax: DirectoryString 142 SizeRestriction: None 143 SingleValued: False 145 Name: dcRelation 146 Description: Relationship to other resources 147 OID: lutAttributeType.11 (1.3.6.1.4.1.1828.1.11) 148 Syntax: DirectoryString 149 SizeRestriction: None 150 SingleValued: False 152 Name: dcSource 153 Description: Resources, either print or electronic, from which 154 this resource is derived, if applicable 155 OID: lutAttributeType.12 (1.3.6.1.4.1.1828.1.12) 156 Syntax: DirectoryString 157 SizeRestriction: None 158 SingleValued: False 160 Name: dcLanguage 161 Description: Language of the intellectual content 162 OID: lutAttributeType.13 (1.3.6.1.4.1.1828.1.13) 163 Syntax: DirectoryString 164 SizeRestriction: None 165 SingleValued: False 167 Name: dcCoverage 168 Description: The spatial locations and temporal durations 169 characteristic of the resource 170 OID: lutAttributeType.14 (1.3.6.1.4.1.1828.1.14) 171 Syntax: DirectoryString 172 SizeRestriction: None 173 SingleValued: False 175 Name: dcRightsManagement 176 Description: Information concerning the intellectual property 177 rights that are being exercised over the 178 resource (including access terms) 179 OID: lutAttributeType.15 (1.3.6.1.4.1.1828.1.15) 180 Syntax: DirectoryString 181 SizeRestriction: None 182 SingleValued: False 184 2. Examples and implementation considerations 186 For example, using Quipu [5] EDB notation, a Dublin Core "Title" 187 element which had the value "Cities of The Red Night" would be 188 represented as the attribute/value pair: 190 dcTitle= Cities of The Red Night 192 One aspect of the Dublin Core does not translate directly to X.500 193 and LDAP - each element may have additional qualifying information 194 attached to it. This gives the creator of the record a way of 195 indicating additional semantics, e.g. the classification scheme being 196 used in the "Subject" element. 198 Since X.500 and LDAP are, like most Internet based search and 199 retrieval protocols, attribute/value oriented, it is necessary to 200 find a place to put this extra information. We propose that, given 201 the difficulty of incorporating this model within the X.500/LDAP 202 paradigm, a simple but sub-optimal approach be taken - with any 203 qualifying information being placed at the beginning of the value 204 part of the attribute/value pair, delimited using round brackets, and 205 with any additional qualifiers following using comma separation. 207 For example, if the subject classification for the above book were 208 813 in the Dewey Decimal system, the resulting Dublin Core record 209 expressed as an X.500 EDB entry would look like this: 211 dcSubject= (scheme=DDC) 813 213 3. Extensibility 215 It is important to note that the Dublin Core element set is intended 216 for use in describing document-like objects, and not as a means of 217 describing arbitrary objects. Furthermore, the number of elements is 218 strictly limited in the interests of interoperability. 220 Work is ongoing on the Warwick Framework [6], which attempts to 221 provide a mechanism for packaging together collections of descriptive 222 information. It is envisaged that this would be used in cases where 223 the Dublin Core element set did not provide enough descriptive 224 capability. This is a subject for further study. 226 4. Security considerations 228 This proposal does not introduce any new security related issues. 230 One of the main uses to which the Dublin Core is expected to be put 231 is in the generation of author supplied cataloguing information for 232 on-line resources. Implementations which manipulate externally 233 produced data should treat it with caution - for example, to avoid 234 buffer overrun problems and unexpected evaluation of metacharacters. 236 5. Conclusions 238 This document has shown how the X.500 protocol, and the related LDAP 239 and CLDAP protocols, may be used as carriers for the abstract 240 resource descriptions of the Dublin Core proposal. 242 It should be apparent that a little care is necessary when delivering 243 this information via these protocols, but that this does not imply 244 any great additional implementation complexity. 246 6. Acknowledgements 248 Thanks to Hoylen Sue, CiTR Pty Ltd (Australia), Rachel Heery and 249 Lorcan Dempsey for their comments on draft versions of this document. 251 This work was supported by UK Electronic Libraries Programme (eLib) 252 grant 12/39/01, the European Commission's Telematics for Research 253 Programme, grant RE 1004, and the Cooperative Research Centres 254 Program, through the Department of the Prime Minister and Cabinet of 255 Australia. 257 7. References 259 [1] S. Weibel. "Metadata: The Foundations of Resource 260 Description", D-Lib Magazine, July 1995. 261 262 264 [2] C. Weider, J. Reynolds, S. Heker. "Technical Overview 265 of Directory Services Using the X.500 Protocol", RFC 266 1309. March 1992. 267 269 [3] W. Yeong, T. Howes & S. Kille. "Lightweight Directory 270 Access Protocol", RFC 1777. March 1995. 271 273 [4] A. Young. "Connection-less Lightweight Directory 274 Access Protocol", RFC 1798. June 1995. 275 277 [5] S.E. Kille. "Implementing X.400 and X.500: the PP and 278 QUIPU systems", Artech House, 1991. 280 [6] L. Dempsey, S. Weibel. "The Warwick Metadata Workshop: 281 A Framework for the Deployment of Resource 282 Description", D-Lib Magazine, July/August 1996. 283 284 286 8. Authors' addresses 288 Martin Hamilton 289 Department of Computer Studies 290 Loughborough University of Technology 291 Leics. LE11 3TU, UK 293 Email: m.t.hamilton@lut.ac.uk 295 Renato Iannella 296 Research Data Network CRC 297 DSTC Pty Ltd 298 Gehrmann Laboratories 299 University of Queensland 300 Australia 302 Email: renato@dstc.edu.au 304 Jon Knight 305 Department of Computer Studies 306 Loughborough University of Technology 307 Leics. LE11 3TU, UK 309 Email: j.p.knight@lut.ac.uk