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1.1 root 1: \chapter {Overview}
2:
3: \section {Introduction}
4:
5: QUIPU is a Public Domain implementation of the OSI Directory as
6: specified in CCITT X.500 Recommendations /
7: ISO DIS 9594 for Directory Services \cite{ISO.Directory}
8: \cite{CCITT.Directory}.
9: It is intended to provide an environment for experimentation and for early
10: pilots using Standardised Directory Services. QUIPU is currently aligned to
11: the CCITT X.500 Recommendations (unofficial version). This is expected to
12: be technically identical to the ISO IS. The latest available ISO version is
13: the DIS.
14:
15: This document describes the design of QUIPU 5.0, and looks at some
16: extensions which are planned for QUIPU 6.0.
17: The reader who is only interested in the first aspect, should be careful to
18: note those aspects (clearly marked) which are not yet implemented.
19: This document is intended to complement
20: the ISODE Manual \cite{QUIPU.Manual}, which describes how to operate QUIPU, and how
21: to interface applications to it.
22: Familiarity with the OSI
23: Directory specifications is assumed \cite{CCITT.Directory}.
24:
25:
26: QUIPU fully implements both of the OSI Directory Protocols, and a number of
27: extensions.
28: The highlights of the QUIPU Directory Service
29: Implementation are:
30:
31: \begin {itemize}
32: \item
33: Use of memory structures to provide fast access, without use of
34: complex keying techniques.
35: \item
36: Activity scheduling within the DSA to allow for multiple accesses.
37: \item
38: General and flexible searching capabilities.
39: \item
40: A mechanism to provide non-local access control.
41: \item
42: A mechanism to provide external schema management.
43: \item
44: A sophisticated approach for management of distributed operations and
45: replication.
46: \end {itemize}
47:
48: The current implementation provides a DSA, and a procedural interface to the
49: Directory Abstract Service and the associated Directory Access Protocol
50: (DAP), which will enable other applications to use the Directory.
51:
52: \section {General Aims}
53:
54: To understand the rationale behind some of the decisions, it is
55: useful to consider the original aims of the QUIPU project.
56: These
57: can then be mapped onto a number
58: of more technical considerations:
59:
60: \begin {itemize}
61: \item To produce an implementation which followed the
62: emerging standards. This is an aim in itself.
63:
64: \item Flexibility, to enable the system to be used
65: for experimentation and research into problems relating to directory
66: services.
67:
68: \item To provide a vehicle for experimentation in the area of
69: distribution and replication.
70:
71: \item To provide some level of real usage.
72: This sort of work is useless if entirely confined to the laboratory.
73: It is important that it is capable of use for some level of experimental
74: service. However, it is not consciously designed to evolve into a full
75: fledged product.
76: \end {itemize}
77:
78: As the work has evolved, the following goals have emerged as
79: additional to the original ones listed above:
80:
81: \begin {itemize}
82: \item To provide a public domain the OSI Directory implementation as a part of
83: the ISODE package.
84:
85: \item To provide integrated support for the ISODE Applications.
86:
87: \item To be used as a part of the initial pilot Directory Service in
88: the UK Academic Community and in other pilots.
89: \end {itemize}
90:
91:
92: \section {Technical Goals}
93:
94: The major goals of the QUIPU Directory Service are:
95:
96: \begin {itemize}
97: \item Full support of the Directory Access Protocol and Directory System
98: Protocols \cite{CCITT.Directory}.
99: \item
100: Support of the majority of the service elements specified in the OSI Directory.
101: \item
102: Full interworking with other OSI Directory implementations.
103: \item
104: Very full searching and matching capabilities, beyond the minimum
105: required by the OSI Directory.
106: \item
107: Provision of a system which has potential for very high distribution.
108:
109: \item Support of distributed operations in a manner which is full
110: conformant with respect to non-QUIPU systems, and provides additional
111: functionality for QUIPU systems.
112:
113: \end {itemize}
114:
115: The following areas were not intended as goals in the initial system.
116: Some discussion is given as to how these areas might be tackled in
117: future versions.
118:
119: \begin {itemize}
120: \item
121: The QUIPU Directory is not intended for very large scale
122: systems (i.e., Millions and tens of Millions of entries per DSA or hundreds
123: of megabytes of data per DSA).
124:
125: \item
126: Substantial data robustness is not required: there is no need to employ
127: complex data backup techniques, such as replicated hardware.
128: \item
129: The security aspects of the OSI Directory were initially omitted, as not
130: required by the general aims.
131: At this point, there is no reason why this aspect should not be
132: integrated.
133:
134: \end {itemize}
135:
136: \section {Further QUIPU documents}
137:
138:
139: The following documents are available:
140:
141: \begin {itemize}
142: \item This document, which describes the design of QUIPU \cite{QUIPU.Design}.
143:
144: \item The QUIPU Manual, which describes how to use QUIPU \cite{QUIPU.Manual}.
145:
146: \item A paper on the original design, which is mainly of historical interest
147: \cite{ECW87.INCA}.
148:
149: \item A paper presented at the 1988 IFIP 6.5 conference, which gives a
150: general overview \cite{QUIPU.IFIP}.
151:
152: \item A paper presented at Esprit Conference Week 1988, which describes the
153: distributed operations \cite{QUIPU.Distributed}.
154: \end {itemize}
155:
156: All of these papers, except the third, are distributed online with QUIPU.
157:
158: \section {Acknowledgements}
159:
160: QUIPU was developed in the Department of Computer Science at University
161: College London, under the {\ae}gis of the INCA (Integrated Network
162: Communication Architecture) project, which was project~395
163: of Esprit (European Strategic Programme for Research into
164: Information Technology).
165: The partners of INCA (GEC plc, Olivetti,
166: Nixdorf AG, and Modcomp GmbH) are acknowledged for releasing the first
167: version of this
168: software into the Public Domain.
169:
170: Continued funding of QUIPU as Openly Available Software is provided by the
171: Joint Network Team.
172:
173: Colin Robbins, Alan Turland, Alastair Hickling, Marshall Rose, Stella Page,
174: and Mike Roe have all made useful comments on this document.
175:
176: QUIPU 5.0 was implemented
177: primarily by Colin Robbins and Alan Turland. Additional acknowledgements
178: for implementation efforts
179: are given in the manual \cite{QUIPU.Manual}.
180:
181: \section {Pronouncing QUIPU}
182:
183: It is clearly important to distinguish QUIPU verbally as well as in writing.
184: The official pronunciation of QUIPU is {\em kwip --- ooo}.
185:
186: \section {Why QUIPU}
187:
188: QUIPU was originally developed as a part of the INCA project.
189: The Inca of Peru did not have writing. Instead, they stored information on
190: strings, carefully knotted in a specific manner and with coloured thread, and
191: attached to a larger rope.
192: These devices were known as ``Quipus''.
193: The encoding was obscure, and could only be read by selected trained people:
194: the Quipucamayocs.
195: The Quipu was a key component of Inca society, as it contained information
196: about property and locations throughout the extensive Inca empire.
197:
198:
199:
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