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1.1     ! root        1: %\documentstyle [11pt,ucl-rn-pic,tgrind,a4] {article}
        !             2: \documentstyle [11pt,ucl-rn,tgrind] {article}
        !             3: \author {S.E. Kille}
        !             4: \date {June 1990}
        !             5: \rnnumber{RN/90/29}
        !             6: \title {Using the OSI Directory to achieve \\  User Friendly Naming}
        !             7: \begin {document}
        !             8: \maketitle
        !             9: \begin {abstract}
        !            10: The OSI Directory has user friendly naming as a goal.  A simple minded usage
        !            11: of the directory does not achieve this.  Two aspects not achieved are:
        !            12: 
        !            13: \begin{itemize}
        !            14: \item A user oriented notation
        !            15: \item Guessability
        !            16: \end{itemize}
        !            17: 
        !            18: This proposal sets out some conventions for representing names in a friendly
        !            19: manner, and shows how this can be used to achieve really friendly naming.
        !            20: \end {abstract}
        !            21: 
        !            22: \tableofcontents
        !            23: \listoffigures
        !            24: \listoftables
        !            25: \pagebreak
        !            26: 
        !            27: \section {Why a notation is needed}
        !            28: 
        !            29: Many OSI Applications make use of Distinguished Names (DN) as defined in the
        !            30: OSI Directory \cite{CCITT.Directory}.
        !            31: The main reason for having a notation for
        !            32: is for interacting with a user
        !            33: interface.  This proposal is coming dangerously close to the sin of
        !            34: standardising interfaces.  However, there are aspects of presentation which
        !            35: it is desirable to standardise.
        !            36: 
        !            37: In very many cases, a user will be required to
        !            38: input a name.  This notation is designed to allow this to happen in a
        !            39: uniform manner across many user interfaces.    The intention is that
        !            40: the name can just be typed in.  There should not be any need to engage in
        !            41: form filling or complex dialogue.
        !            42: 
        !            43: A secondary goal, is to have a common
        !            44: format to be able to unambiguously refer to names.
        !            45: This notation should {\em not} be needed to write on business cards or in
        !            46: the minutes of meetings.  If this is the case, the directory has failed to a
        !            47: large extent.  It should be possible to take the ``human'' description given
        !            48: at the meeting, and use it directly.  The means in which this happens will
        !            49: become clear later.  In practice, it will often be useful to explicitly write
        !            50: down directory names, even though it is not strictly needed.
        !            51: 
        !            52: \section {A notation for Distinguished Name}
        !            53: 
        !            54: \subsection {Goals}
        !            55: 
        !            56: The following goals are laid out:
        !            57: 
        !            58: \begin {itemize}
        !            59: \item  It should be intuitive for the majority of names encountered
        !            60: \item It should be fully general
        !            61: \item It should be possible to lay it out in a number of ways
        !            62: \end {itemize}
        !            63: 
        !            64: \subsection {Informal definition}
        !            65: 
        !            66: This notation is designed to be convenient for common forms of name.
        !            67: Some examples are given. 
        !            68: My directory (distinguished) name would be written:
        !            69: 
        !            70: \begin{verbatim}
        !            71: Steve Kille, Computer Science, University College London, GB  
        !            72: \end{verbatim}
        !            73: 
        !            74: This may be folded, perhaps to display in multi-column format.
        !            75: For example:
        !            76: 
        !            77: \begin {verbatim}
        !            78: Steve Kille, 
        !            79: Computer Science, 
        !            80: University College London, 
        !            81: GB  
        !            82: \end{verbatim}
        !            83: 
        !            84: or 
        !            85: 
        !            86: \begin {verbatim}
        !            87: Steve Kille 
        !            88: Computer Science 
        !            89: University College London, GB  
        !            90: \end{verbatim}
        !            91: 
        !            92: Another name might be:
        !            93: 
        !            94: 
        !            95: \begin {verbatim}
        !            96: Christian Huitema, INRIA, FR
        !            97: \end{verbatim}
        !            98: 
        !            99: An example, showing how different attribute types are handled:
        !           100: 
        !           101: 
        !           102: \begin {verbatim}
        !           103: James Hacker 
        !           104: locality=Basingstoke 
        !           105: Widget Inc 
        !           106: GB 
        !           107: \end{verbatim}
        !           108: 
        !           109: An example showing quoting of a comma in an Organisation name:
        !           110: 
        !           111: \begin {verbatim}
        !           112: L. Eagle, "Sue, Grabbit and Runn", GB
        !           113: \end{verbatim}
        !           114: 
        !           115: 
        !           116: \subsection {Formal definition}
        !           117: 
        !           118: 
        !           119: The structure is specified in a BNF grammar in Figure~\ref{BNF}.
        !           120: 
        !           121: \begin{figure}
        !           122: \begin {verbatim}
        !           123: <name> ::= <name-component>
        !           124:        | <name-component> <spaced-separator> <name>
        !           125: 
        !           126: <spaced-separator> ::= <optional-space>  
        !           127:                 <separator>
        !           128:                 <optional-space>
        !           129: 
        !           130: <separator> ::= "," ( <CR> )
        !           131:               | <CR> 
        !           132: 
        !           133: <optional-space> ::= *( " " ) 
        !           134: 
        !           135: <name-component> ::= <attribute> 
        !           136:         | <attribute> <optional-space> "+" ( <CR> ) 
        !           137:           <optional-space> <name-component>
        !           138: 
        !           139: <attribute> ::= <string>
        !           140:         | <key> <optional-space> "=" <optional-space> <string>
        !           141: 
        !           142: <key> ::= 1*( <keychar> )
        !           143: <keychar> ::= letters, numbers, and space
        !           144: 
        !           145: <string> ::= *( <stringchar> | <pair> )
        !           146:          | '"' *( <stringchar> | "," | "+" | "=" | <CR> ) '"'
        !           147:          
        !           148: <special> ::= "," | "=" | '"' | <CR> | "\" | "+"
        !           149: <pair> ::= "\" <special> 
        !           150: <stringchar> ::= any char except <special>
        !           151: 
        !           152: \end{verbatim}
        !           153: \caption {BNF Grammar for Distinguished and Purported Name}
        !           154: \label {BNF}
        !           155: \end{figure}
        !           156: 
        !           157: 
        !           158: The quoting mechanism is used for the following cases:
        !           159: 
        !           160: \begin {itemize}
        !           161: \item Strings containing ``,'', ``+'', ``=''or ``\verb|"|''  or \verb|<CR>|
        !           162: \item Strings with leading or trailing spaces
        !           163: \item Strings containing consecutive spaces
        !           164: \end {itemize}
        !           165: 
        !           166: A list of valid keywords for well known attribute types used in naming is
        !           167: given in Table~\ref{keywords}.  This is a list of keywords which must be
        !           168: supported.  These are chosen because they appear in common forms of name,
        !           169: and can do so in a place which does not correspond to the default schema
        !           170: used.
        !           171: If other attributes are used for naming, this can always be
        !           172: extended locally.
        !           173: 
        !           174: \begin{table}
        !           175: \begin{center}
        !           176: \begin {tabular}{l l}
        !           177: Key & Attribute (X.520 keys) \\
        !           178: \hline
        !           179: Locality & LocalityName \\
        !           180: Area & LocalityName \\
        !           181: Organisation & OrganizationName \\
        !           182: Organization & OrganizationName \\
        !           183: \end {tabular}
        !           184: \end{center}
        !           185: \caption {Standardised Keywords}
        !           186: \label {keywords}
        !           187: \end{table}
        !           188: 
        !           189: 
        !           190: Only string type attributes are
        !           191: considered, but other attribute syntaxes could be supported locally.
        !           192: It is assumed that the interface will translate from the supplied string
        !           193: into PrintableString or T.61.
        !           194: 
        !           195: The \verb|"+"| notation is used to specify multi-component RDNs.  In this
        !           196: case, the types for attributes in the RDN must be explicit.
        !           197: 
        !           198: The name is presented/input in a little-endian order.  If no type are given,
        !           199: a type hierarchy (schema) is assumed as:
        !           200: 
        !           201: \begin {verbatim}
        !           202: Common Name, (((Organisational Unit)*,  Organisation,) Country)
        !           203: \end{verbatim}
        !           204: 
        !           205: Explicitly typed RDNs may be inserted into this hierarchy.  Two types of
        !           206: object are named.  They are distinguished by context in the application:
        !           207: 
        !           208: \begin{description}
        !           209: \item[Common Name Object] Typically a leaf object and a person.  In this
        !           210: case, the LHS RDN is assumed to be common name, and other RDNs follow the
        !           211: hierarchy.
        !           212: 
        !           213: \item[Other Object] Typically a non-leaf object.  
        !           214: \end{description}
        !           215: 
        !           216: 
        !           217: \section {Purported names}
        !           218: 
        !           219: 
        !           220: A purported name is what a user supplies to an interface for resolution
        !           221: into  one or more distinguished names.
        !           222: The same
        !           223: notation is used as for distinguished name.  
        !           224: A purported name may differ from a distinguished name in a number of ways
        !           225: which are itemised below.
        !           226: 
        !           227: Typically, an
        !           228: interface will display a distinguished name, using the distinguished name
        !           229: notation.  However, it may display a purported name, as this will be more
        !           230: pleasing to the user.  The most common example of this is where the higher
        !           231: components of the distinguished name are not displayed (abbreviation).
        !           232: 
        !           233: The ways in which a purported name may vary from a distinguished name are
        !           234: now described:
        !           235: 
        !           236: \begin {description}
        !           237: \item[Abbreviation] Some of the more significant components of the DN will
        !           238: be omitted, and then defaulted in some way (e.g., relative to a local
        !           239: context).  For example:
        !           240: 
        !           241: \begin {verbatim}
        !           242: Steve Kille
        !           243: \end{verbatim}
        !           244: 
        !           245: \item[Component Omission]
        !           246: An intermediate component of the name may be omitted.  Typically this will
        !           247: be an organisational unit.   For example:
        !           248: 
        !           249: \begin {verbatim}
        !           250: Steve Kille, University College London, GB
        !           251: \end{verbatim}
        !           252: 
        !           253: 
        !           254: In some cases, this can be combined with abbreviation.  For example:
        !           255: 
        !           256: \begin {verbatim}
        !           257: Steve Kille, University College London
        !           258: \end{verbatim}
        !           259: 
        !           260: \item[Approximation] Approximate renditions or alternate values
        !           261: of one or more of the components
        !           262: will be supplied. For example:
        !           263: 
        !           264: \begin {verbatim}
        !           265: Stephen Kille, CS, UCL, GB   
        !           266: \end{verbatim}
        !           267: 
        !           268: or
        !           269: 
        !           270: \begin{verbatim}
        !           271: Steve Keill, Comp Sci, Univarstiy College London, GB
        !           272: \end{verbatim}
        !           273: 
        !           274: 
        !           275: \item[Friendly Country] A ``friendly country name'' can be used instead of
        !           276: the ISO 3166 two letter code.  For example: UK; USA; France; Deutchland.  
        !           277: 
        !           278: \item[Type Changing] A type may be omitted, even where it does not follow
        !           279: the hierarchy.   Type variants can be explored.
        !           280: The previous distinguished name:
        !           281: \begin {verbatim}
        !           282: James Hacker 
        !           283: locality=Basingstoke 
        !           284: Widget Inc 
        !           285: GB 
        !           286: \end{verbatim}
        !           287: 
        !           288: Could be represented by the purported name:
        !           289: 
        !           290: \begin {verbatim}
        !           291: James Hacker 
        !           292: Basingstoke 
        !           293: Widget Inc 
        !           294: GB 
        !           295: \end{verbatim}
        !           296: 
        !           297: 
        !           298: \end {description}
        !           299: 
        !           300: 
        !           301: \section {Matching a purported name}
        !           302: 
        !           303: The major utility of the purported name is to provide the important ``user
        !           304: friendly'' characteristic of guessability.  A user will supply a purported
        !           305: name to a user interface, and this will be resolved onto a distinguished
        !           306: name.   
        !           307: When a user supplies a purported name there is a need to derive the DN.  In
        !           308: most cases, it should be possible to derive a single name from the purported
        !           309: name.  In some cases, ambiguities will arise and the user will be prompted
        !           310: to select from a multiple matches.  This should also be the case where a
        !           311: component of the name did not ``match very well''.   
        !           312: 
        !           313: There is an assumption that the user will simply enter the name correctly.
        !           314: The purported name variants are designed to make this happen!  There is no
        !           315: need for fancy window based interfaces or form filling for many applications
        !           316: of the directory.  Note that the fancy interfaces still have a role for
        !           317: browsing, and for more complex matching.  This type of naming is to deal
        !           318: with cases where information on a known user is desired and keyed on the
        !           319: user's name.
        !           320: 
        !           321: \subsection {Environment}
        !           322: 
        !           323: 
        !           324: 
        !           325: 
        !           326: All matches occur in the context of a local environment.
        !           327: The local environment defines a 
        !           328: sequence of name of a non-leaf objects in the DIT.   
        !           329: This environment effectively defines a list of acceptable name abbreviations
        !           330: where the DUA is employed.   It also defines an order in which to operate.
        !           331: 
        !           332: 
        !           333: This list is defined in the context of the number of name components
        !           334: supplied.  This allows varying heuristics, depending on the environment, to
        !           335: make the approach have the ``right'' behaviour.
        !           336: 
        !           337: 
        !           338: In most cases, the environment will start at a local point in the DIT, and
        !           339: move upwards.   Examples are given in Tables~\ref{e1} and~\ref{e2}.
        !           340: Table~\ref{e1} shows an example for a typical local DUA, which has the
        !           341: following characteristics:
        !           342: 
        !           343: \begin{description}
        !           344: \item[One component] Assumed first to be a user in the department, then a
        !           345: user or department within the university, the a national organisation, and
        !           346: finally a country.
        !           347: \item[Two components] Most significant component is first assumed to be a
        !           348: national organisation, then a department (this might be reversed in some
        !           349: organisations), and finally a country.
        !           350: \item[Three or more components] The most significant component is first
        !           351: assumed to be a country, then a national organisation, and finally a
        !           352: department. 
        !           353: \end{description}
        !           354: 
        !           355: 
        !           356: 
        !           357: \begin{table}
        !           358: \begin{center}
        !           359: \begin{tabular}{l l}
        !           360: Number of & Environment \\
        !           361: Components & \\
        !           362: \hline
        !           363: 1 & Physics, University College London, GB  \\
        !           364: & University College London, GB \\
        !           365: & GB  \\
        !           366: & -- \\
        !           367: \hline
        !           368: 2 & GB  \\
        !           369: & University College London, GB \\
        !           370: & -- \\
        !           371: \hline
        !           372: 3+  & -- \\
        !           373: & GB  \\
        !           374: & University College London, GB \\
        !           375: 
        !           376: \end{tabular}
        !           377: \end{center}
        !           378: \caption {Local environment for private DUA}
        !           379: \label{e1}
        !           380: \end{table}
        !           381: 
        !           382: \begin{table}
        !           383: \begin{center}
        !           384: \begin{tabular}{l l}
        !           385: Number of & Environment \\
        !           386: Components & \\
        !           387: \hline
        !           388: 1,2  & US  \\
        !           389: & CS \\
        !           390: & -- \\
        !           391: \hline
        !           392: 3+ & -- \\
        !           393: & US \\
        !           394: & CA \\
        !           395: \end{tabular}
        !           396: \end{center}
        !           397: \caption {Local environment for US Public DUA}
        !           398: \label{e2}
        !           399: \end{table}
        !           400: 
        !           401: 
        !           402: \subsection {Matching}
        !           403: 
        !           404: 
        !           405: A purported name will be supplied, usually with a small number of components.
        !           406: This will be matched in the context of an environment.
        !           407: 
        !           408: Where there are multiple components to be matched, these should be matched
        !           409: sequentially.  If an unambiguous DN is determined, the match continues as if
        !           410: the full DN had been supplied.  
        !           411: For example if 
        !           412: 
        !           413: \begin{quote}
        !           414: \begin{verbatim}
        !           415: Stephen Kille, UCL
        !           416: \end{verbatim}
        !           417: \end{quote}
        !           418: 
        !           419: is being matched in the context of environment \verb|GB|, first \verb|UCL|
        !           420: is resolved to the distinguished name:
        !           421: 
        !           422: \begin{quote}
        !           423: \begin{verbatim}
        !           424: University College London, GB
        !           425: \end{verbatim}
        !           426: \end{quote}
        !           427: 
        !           428: Then the next component of the purported name is taken to determine the
        !           429: final name. 
        !           430: If there is an ambiguity (e.g., if \verb|UCL| had made two matches,
        !           431: both paths are explored to see if the ambiguity can
        !           432: be resolved.  Eventually a set of names will be passed back to the user.
        !           433: 
        !           434: 
        !           435: Each component of the environment is taken in turn.
        !           436: If the purported name has more
        !           437: components than the maximum depth, the environment element is skipped.  
        !           438: The advantage of this will be seen in the example given later.
        !           439: 
        !           440: 
        !           441: 
        !           442: 
        !           443: 
        !           444: 
        !           445: A match of a name is considered to have three levels:
        !           446: 
        !           447: \begin{description}
        !           448: \item[Exact]  A DN is specified exactly
        !           449: \item[Good]
        !           450: Initially, a match should be considered good if
        !           451: it is unambiguous, and exactly matches an attribute value in the entry.
        !           452: For human names, a looser metric is probably desirable (e.g., \verb|S Kille|
        !           453: should be a good match of \verb|S. Kille|, \verb|S.E. Kille| or \verb|Steve
        !           454: Kille| even if these are not explicit alternate values).
        !           455: \item[Poor] Any other substring or approximate match
        !           456: \end{description}
        !           457: 
        !           458: Following a match, the reference can be followed, or the user prompted.
        !           459: If there are multiple matches, more than one path may be followed.
        !           460: There is also a shift/reduce type of choice: should any partial matches be
        !           461: followed or should the next element of the environment be tried.
        !           462: The following heuristics are suggested, which may be modified in the light
        !           463: of experience.  The overall aim is to resolve cleanly specified names with a
        !           464: minimum of fuss, but give sufficient user control to prevent undue searching
        !           465: and delay.   
        !           466: 
        !           467: \begin{enumerate}
        !           468: \item Always follow an exact match. 
        !           469: \item Follow all good matches if there are no exact matches.
        !           470: \item If there are only poor matches, prompt the user.  If the user accepts
        !           471: one or more match, they can be considered as good.  If all are rejected,
        !           472: this can be treated as no matches.
        !           473: \item Automatically move to the next element of the environment if no
        !           474: matches are found.   
        !           475: \end{enumerate}
        !           476: 
        !           477: When the final component is matched, a set of names will be identified.
        !           478: If none are identified, proceed to the next environment element.
        !           479: If the user rejects all of the names, processing of the next environment
        !           480: element should be confirmed.
        !           481: 
        !           482: The exact approach to matching will depend on the level of the tree at which
        !           483: matching is being done.  
        !           484: We can now consider how attributes are matched at various levels of the DIT.
        !           485: 
        !           486: 
        !           487: There is an issue of approximate matching.  Sometimes it helps, and
        !           488: sometimes just returns many spurious matches.  When a search is requested,
        !           489: all relevant attributes should be returned, so that distinguished and
        !           490: non-distinguished values can be looked at.  This will allow a distinction to
        !           491: be made between good and poor matches.  It is important that where, for
        !           492: example, an acronym exactly matches an organisation, that the user is not
        !           493: prompted about other organisations where it matches as a substring.
        !           494: 
        !           495: \subsection {Top Level}
        !           496: 
        !           497: In this case, a match is being done at the root of the DIT.   
        !           498: Three approaches are suggested, dependent on the length of supplied name.
        !           499: All lead to a single level search of the top level of the DIT. 
        !           500: 
        !           501: \begin{description}
        !           502: \item[Exactly 2] This is assumed to be a 3166 two letter country code, or an exact
        !           503: match on a friendly country or organisation (e.g., UK or UN).  
        !           504: Do exact match on country and friendly country.
        !           505: \item[Greater than 2] Make 
        !           506: an approximate and substring match on friendly country and organisation.
        !           507: 
        !           508: \end{description}
        !           509: 
        !           510: 
        !           511: 
        !           512: 
        !           513: 
        !           514: 
        !           515: \subsection {Intermediate Level}
        !           516: 
        !           517: Once the root level has been dealt with, intermediate levels will be looking
        !           518: for organisational components (Organisation, Locality, Org Unit). 
        !           519: In some cases, private schema control will allow the system to determine
        !           520: which is at the next level.  In general this will not be possible.
        !           521: In each case, make  a substring  and approximate match search of one level.
        !           522: The choice depends on the base object used in the search.
        !           523: 
        !           524: \begin {enumerate}
        !           525: \item If DN has no Organisation or Locality, filter on Organisation and
        !           526: Locality. 
        !           527: \item If DN has Org Unit, filter on Org Unit.
        !           528: \item If DN has Organisation, filter on Locality and Org Unit.
        !           529: \item If DN has Locality, filter on Organisation.
        !           530: \end {enumerate}
        !           531: 
        !           532: These allow some optimisation, based on legal choices of schema.  Keeping
        !           533: filters short is usually desirable to improve performance.   
        !           534: 
        !           535: A few examples of this, where a base object has been determined (either by
        !           536: being the environment or by partial resolution of a purported name), and the
        !           537: next element of a purported name is being considered.  This will generate a
        !           538: single level search.  What varies is the types being filtered against.
        !           539: If the DN is:
        !           540: 
        !           541: \begin{verbatim}
        !           542: University College London, GB
        !           543: \end{verbatim}
        !           544: 
        !           545: The search should be for Org Unit or Locality.  If the DN is:
        !           546: 
        !           547: \begin{verbatim}
        !           548: Organisation=UN
        !           549: \end{verbatim}
        !           550: 
        !           551: the search should be for Org Unit or Locality.
        !           552: 
        !           553: There may be some improvements with respect to very short keys.  Not making
        !           554: approximate or substring matches in these cases seems sensible\footnote{It
        !           555: might be desirable to allow ``\verb|*|'' as a part of the purported name
        !           556: notation}.
        !           557: 
        !           558: \subsection {Bottom level}
        !           559: 
        !           560: The ``Bottom Level'' is to deal with leaf entries in the DIT.  This will
        !           561: often be a person, but may also be a role, an application entity or
        !           562: something else.  
        !           563: 
        !           564: The last component of a purported name may either reference a leaf or
        !           565: non-leaf.  For this reason, {\em both} should be tested for.
        !           566: As a heuristic, if the base object for the search  has two or more
        !           567: components it should be tested first as a bottom level name and then
        !           568: intermediate.  Reverse this for shorter names.  This optimises for the
        !           569: (normal) case
        !           570: of non-leaves high up the tree and leaves low down the tree.
        !           571: 
        !           572: For bottom level names, make an
        !           573: approximate and substring match against Common Name, Surname, and User ID.
        !           574: Where common name is looked for, 
        !           575: A full subtree search will be used when at
        !           576: the second level of the DIT or lower, otherwise a single level search.
        !           577: 
        !           578: For example, if I have resolved a purported name to the distinguished name
        !           579: 
        !           580: \begin{verbatim}
        !           581: University College London, GB
        !           582: \end{verbatim}
        !           583: 
        !           584: and have a single component \verb|Bloggs|, this will generate a subtree
        !           585: search.
        !           586: 
        !           587: \section{Examples}
        !           588: 
        !           589: 
        !           590: This is all somewhat confusing, and a few examples are given.  These are all
        !           591: in the context of the environment shown in Table~\ref{e1} on
        !           592: Page~\pageref{e1}.
        !           593: 
        !           594: If ``Joe Bloggs'' is supplied, a subtree search of 
        !           595: 
        !           596: \begin{verbatim}
        !           597: Physics, University College London, GB
        !           598: \end{verbatim}
        !           599: 
        !           600: will be made, and the user prompted for ``Joseph Z. Bloggs'' as the only
        !           601: possible match.
        !           602: 
        !           603: If ``Computer Science'' is supplied, first 
        !           604: 
        !           605: \begin{verbatim}
        !           606: Physics, University College London, GB
        !           607: \end{verbatim}
        !           608: 
        !           609: will be searched, and the user will reject the approximate match of ``Colin
        !           610: Skin''.   Then a subtree search of
        !           611: 
        !           612: \begin{verbatim}
        !           613: University College London, GB
        !           614: \end{verbatim}
        !           615: 
        !           616: will be made, looking for a person.  Then a single level search will be made
        !           617: looking for Org Unit, and 
        !           618: 
        !           619: \begin{verbatim}
        !           620: Computer Science, University College London, GB
        !           621: \end{verbatim}
        !           622: 
        !           623: will be returned without prompting (exact match).   
        !           624: 
        !           625: 
        !           626: Supplying ``Steve Kille'' will lead to a failed subtree search of 
        !           627: 
        !           628: \begin{verbatim}
        !           629: Physics, University College London, GB
        !           630: \end{verbatim}
        !           631: 
        !           632: and lead straight to a subtree search of
        !           633: 
        !           634: \begin{verbatim}
        !           635: University College London, GB
        !           636: \end{verbatim}
        !           637: 
        !           638: This will lead to an exact value match, and so a single entry returned
        !           639: without prompting.
        !           640: 
        !           641: 
        !           642: If ``Andrew Findlay, Brunel'' is supplied, the first element of the
        !           643: environment will be skipped, single level search of ``Brunel'' under ``GB'
        !           644: will find:
        !           645: 
        !           646: \begin{verbatim}
        !           647: Brunel University, GB
        !           648: \end{verbatim}
        !           649: 
        !           650: and a subtree search for ``A Findlay'' initiated.   This will yield
        !           651: 
        !           652: \begin{verbatim}
        !           653: Andrew Findlay, Computing and Media Services, Brunel University, GB
        !           654: 
        !           655: Dr A J Findlay, Manufacturing and Engineering Systems, 
        !           656: Brunel University, GB
        !           657: \end{verbatim}
        !           658: 
        !           659: 
        !           660: and the user will be prompted with a choice.
        !           661: 
        !           662: 
        !           663: This approach shows how a simple format of this nature will ``do the right
        !           664: thing'' in many cases.   
        !           665: 
        !           666: \section {Support required from the standard}
        !           667: 
        !           668: Fortunately, all that is needed is there!  It would be useful to have
        !           669: ``friendly country name'' as a standard attribute.
        !           670: 
        !           671: 
        !           672: \section{Support of OSI Services}
        !           673: 
        !           674: The major focus of this work has been to provide a mechanism for identifying
        !           675: Organisations and Users.   A related function is to identify applications.
        !           676: Where the Application is identified by an AET (Application Entity Title)
        !           677: with an RDN of Common Name, this proposal leads to a natural usage.
        !           678: For example, if a filestore in named ``gannet'', then this could easily be
        !           679: identified by the name:
        !           680: 
        !           681: \begin{verbatim}
        !           682: Gannet, Computer Laboratory, Cambridge University, GB   
        !           683: \end{verbatim}
        !           684: 
        !           685: In normal usage, this might lead to access (using a purported name) of:
        !           686: 
        !           687: \begin{verbatim}
        !           688: FTAM gannet,cambridge
        !           689: \end{verbatim}
        !           690: 
        !           691: A second type of access is where the user identifies an Organisation
        !           692: (Organisational Unit), and expects to obtain a default service.   
        !           693: The service is implied by the application, and should not require any
        !           694: additional naming as far as the user is concerned.  It is proposed that this
        !           695: is supported by User Friendly Naming in the following way.  
        !           696: 
        !           697: \begin{enumerate}
        !           698: \item Determine that the purported name identifies a non-leaf object, which is
        !           699: of object class Organisation or Organistaional Unit or Locality.
        !           700: 
        !           701: \item Perform a {\em single level} search for Application Entities which
        !           702: support the required application contexts.  This assumes that all services
        !           703: which are supporting default access for the organisation are registred at
        !           704: one level below (possibly by the use of aliaes), and that other services
        !           705: (specific machines or parts of the organisation) are represented further
        !           706: down the tree.  This seems to be a reasonable layout, and its utility can be
        !           707: evaluated by experiment.
        !           708: 
        !           709: \end{enumerate}
        !           710: 
        !           711: \section {Experience}
        !           712: 
        !           713: An experimental implementation of this has been written by Colin Robbins.
        !           714: The example in Figure~\ref{usage} shows that it can be very effective at
        !           715: locating known individuals with a minimum of effort.
        !           716: 
        !           717: \begin{figure}
        !           718: \begin{small}
        !           719: \begin{verbatim}
        !           720: -> t hales, csiro, australia
        !           721: Found good match(es) for 'australia'
        !           722: Found exact match(es) for 'csiro'
        !           723: Please select from the following:
        !           724:    Trevor Hales, OC, HPCC, DIT, IICT, CSIRO, AU [y/n] ? y
        !           725: The following were matched...
        !           726:    Trevor Hales, OC, HPCC, DIT, IICT, CSIRO, AU
        !           727: 
        !           728: -> g michaelson, queensland, au
        !           729: Found exact match(es) for 'au'
        !           730: Please select from the following:
        !           731:    University of Queensland, AU [y/n] ? y
        !           732:    Axolotl, AU [y/n] ? n
        !           733: Please select from the following:
        !           734:    George Michaelson, Prentice Computer Centre, University of Queensland, AU
        !           735: [y/n] ? y
        !           736:    Manager, University of Queensland, AU [y/n] ? n
        !           737: The following were matched...
        !           738:    George Michaelson, Prentice Computer Centre, University of Queensland, AU
        !           739: 
        !           740: -> r needham, cambridge
        !           741: Found good match(es) for 'cambridge'
        !           742: Please select from the following:
        !           743:    Roger Needham, Computer Lab, Cambridge University [y/n] ? y
        !           744: The following were matched...
        !           745:    Roger Needham, Computer Lab, Cambridge University
        !           746: 
        !           747: -> kirstein
        !           748: Found good match(es) for 'kirstein'
        !           749: The following were matched...
        !           750:    Peter Kirstein
        !           751: 
        !           752: 
        !           753: \end{verbatim}
        !           754: \end{small}
        !           755: \caption {Example usage of User Friendly Naming}
        !           756: \label{usage}
        !           757: \end{figure}
        !           758: 
        !           759: 
        !           760: \section {Relationship to other work}
        !           761: 
        !           762: Colin Robbin's work on the interface ``Tom'' and implementation of a
        !           763: distribution list interface strongly influenced this proposal.
        !           764: 
        !           765: Some of the ideas used here originally came from a UK Proposal to the
        !           766: ISO/CCITT Directory Group on ``New Name Forms'' \cite{NNF}.  This defined,
        !           767: and showed how to implement, four different types of names:
        !           768: 
        !           769: \begin{description}
        !           770: \item[Typed and Ordered] The current Distinguished Name is a restricted
        !           771: example of this type of name.
        !           772: 
        !           773: \item[Untyped and Ordered] This is the type of name proposed here (with some
        !           774: extensions to allow optional typing).  It is seen as meeting the key user
        !           775: requirement of disliking typed names, and is efficient to implement.
        !           776: 
        !           777: \item[Typed and Unordered] This sort of name is proposed by others as the
        !           778: key basis for user friendly naming.  Neufeld shows how X.500 can be used to
        !           779: provide this \cite{Neufeld.Descr}, and Peterson proposes the Profile system
        !           780: to provide this \cite{Profile.2}.  The author contends that whilst typed
        !           781: naming is interesting for some types of searching (e.g., yellow page
        !           782: searching), it is less desirable for
        !           783: naming objects.  This is born out by operational experience with OSI
        !           784: Directories \cite{THORN.RARE.LSPX}.
        !           785: 
        !           786: \item[Untyped and Unordered] Surprisingly this form of name can be supported
        !           787: quite easily.  However, a considerably gain in efficiency can be achieved by
        !           788: requiring ordering.  In practice, users can supply this easily.  Therefore,
        !           789: this type of name is not proposed.   
        !           790: \end{description}
        !           791: 
        !           792: 
        !           793: \section {Proposal}
        !           794: 
        !           795: This approach should be tested out experimentally, with the QUIPU
        !           796: implementation.  This will involve:
        !           797: 
        !           798: \begin{itemize}
        !           799: \item An interface to generate strings in this form from DNs, with control over
        !           800: \begin{itemize}
        !           801: \item Folding (line, column, or max width)
        !           802: \item Presence of commas at EOL
        !           803: \item A DN to be abbreviated against
        !           804: \end{itemize}
        !           805: 
        !           806: \item A routine to resolve a purported name in the context of an environment.
        !           807: \end{itemize}
        !           808: 
        !           809: The Distribution List interface seems to be an ideal system to experiment
        !           810: with.
        !           811: 
        !           812: A specification should then be progressed, and made widely available.
        !           813: Perhaps as a RARE Document or RFC.
        !           814: 
        !           815: \bibliographystyle{alpha}
        !           816: \bibliography{../../bib/sek}
        !           817: 
        !           818: \pagebreak
        !           819: \appendix
        !           820: 
        !           821: \section{Pseudo-code for the matching algorithm}
        !           822: 
        !           823: The following pseudo-code is intended to clarify the matching algorithm.
        !           824: The language uses ASN.1 data types, with flow control `C'-like, but with
        !           825: keywords upper--cased.
        !           826: 
        !           827: \tagrindfile{algo}{Matching Algorithm}{algo}
        !           828: 
        !           829: 
        !           830: 
        !           831: \end {document}
        !           832: 

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