Internet Draft Wang Liang
Document: draft-liang-irpdl-00.txt hust
Expires: March 2003 September 2003
Information Retrieval Protocol for Digital Library
draft-liang-irpdl-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document specifies an information retrieval protocol for digital
library. This protocol has two parts: standard search Webservice for
heterogeneous databases and the method to find and select such search
Webservice. By using this protocol, all the databases including web
page database, digital issue database, and video database, can
release the uniform search Webservice, though these databases may
have different metadata standards and architecture. And these
Webservice can be easily found and visited by search systems. This
very protocol makes it possible that users can obtain all kinds of
information on the Internet in single search engine, but not visit
lots of different search engines one by one.
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1. Introduction
Hundreds of databases have been introduced in many libraries, and
there are many more free information resources on the Internet. It
has become a kind of acrobatics for us to find the complete and
precise results about our query in so many databases. Everyone hopes
to obtain all kinds of information in one search engine, such as web
pages, Videos, but does not care where the information lies in.
Webservice [1] give us a good method to realize this desire. As long
as these databases can provide Webservice, it will be an easy mission
to integrate all kinds of information resources in one search engine.
Now Google [2] and some other databases have provided search
Webservice. But standard protocol for these searches Webservice does
not exist. Even different web search engines Webservice have
distinct formats of queries and search results, needless to mention
the Webservice of many other kinds of databases. Thus, a uniform
Webservice applicable for all the information resources and an
efficient method to find such Webservice should be established. This
document just achieves these two goals. The protocol comprises of two
interacting parts, Standard Search Webservice (SSW) which can be
applied to all databases and Search Webservice Description, Discovery
and Integration (SDDI) which provides an efficient way to find the
appropriate search Webservice.
2 Standard Searches Webservice
Information Retrieval Protocol defines a standard search Webservice
with its classes and functions. Most of databases can distribute the
uniform search Webservice by using this definition.
2.1 data encoding
In order to support searching documents in multiple languages, all
requests and responses should be in accordance with the UTF-8
encoding.
2.2. The format of query words
Query words are applied to present request.
The query words can include the logical operator
Boolean OR: "OR"
A OR B: A or B must appear in the results
Boolean AND: "AND"
A AND B: A and B must appear in the results
Boolean NOT: "NOT"
NOT A: the word A can't appear in the results
The logical operator can be used together.
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For example: (A AND B) AND (NOT C) means the results must include A
and B but can't have C.
The character "("and ")" in the query words will be treated as word
separators.
2.3 class and function
The standard Webservice with its class structures and functions are
detailed here and also presented in the form of WSDL [3].
There are three function components in a search Webservice.1 receive
the query words and return results.2 analyze and explain the results.
3 depict every recorder of the results. All these functions are
implemented with three classes of Webservice.
2.3.1 Class Search
Main function of this class is to submit a query string and a set of
parameters to the search service and receive in return a set of
search results.
There are three levels of search function in this class: basic search,
advanced search, full search.
a. Basic search
basicSearch(title.start,maxResults)
title: query words; represent the basic description of a recorder.
Field "title" is available in all the metadata and databases. Book,
video, webpage database all can provide the search in "title"
start: Zero-based index of the first desired result.
maxResults: Number of results desired per query. The maximum value
per query set to 100, and the minimum is defined as 10. If you make a
query that doesn't have many matching items, the actual number of
results you get may be smaller than that of you request.
b. Advanced search
advanceSearch(title,keywords,author,abstract,
dateStart,dateEnd,start,maxResults,order)
the meaning of title start maxResult is just the same as those in
Basic search. The reason to select the keywords, author, and date as
the search fields is that these fields are normally available in most
databases and metadata.
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keywords: query words, keywords for recorder
author : query words, author of the recorder.
abstract: the basic description of the recorder.
dateStart,dateEnd: present date range. If you want to limit your
results to document that are published within a specific date range,
you can use this query term to accomplish this.
Order: the sort order of the results. It can be "date" which means
sorting by date or "correlativity" which means sorting by
correlativity, or some other orders else.
c. Full search
fullSearch(" ", start, maxResults)
Full search will provides all the query formats of one database. They
will be confirmed by the database owners.
2.3.2 Class SearchResponse
Each time you issue a search request to the search service, a
response is returned back to you. This class describes the meanings
of the values returned to you. The character of this class is
described as follows.
TotalResultsCount: The estimated total number of results that exist
for the query.
resultElements: An array of "resultElement" items. This corresponds
to the actual list of search results.
startIndex:Indicates the index (1-based) of the first search result
in "resultElements".
endIndex: Indicates the index (1-based) of the last search result in
"resultElements".
searchTime :Text, floating-point number indicating the total server
time to return the search results, which measured in seconds.
2.3.3 Class ResultElement
This class describes every record in return results. This Class has
three characters as follows.
Sourcename: name of the information source.
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Title: title of the recorder.
URL: The URL of the recorder, returned as text, with an absolute URL
path.
Otherinformation: some information such as a snippet of a webpage,
author of the recorder. This character will be defined according to
different search Webservice.
2.3.4 WSDL of standard search Webservice
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......
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3 the description of the search Webservice
To describe the search Webservice, we refer to the UDDI[4]. Search
Webservice Description, Discovery and Integration (SDDI) is proposed
in this part. SDDI will help the search system find and select the
appropriate data sources.
3.1 The XML schema of the SDDI
We use the DC[5] standard to descript the character of the search
Webservice. 9 of 15 sub elements of DC are selected and divided into
three groups. The other basic information for a web service is also
added in the SDDI. Because all the search services use the uniform
standard Webservice, the business service, binding template and Model
in UDDI will be useless in SDDI. The information like BusinessEntity
in UDDI is enough to identify a search Webservice.
The elements and attributes to describe a search Webservice are
represented as follows.
1 content
Title: A name given to the resource.
Description: An account of the content of the resource.
Language: A language of the intellectual content of the resource.
2 copyright
Creator: An entity primarily responsible for making the content of
the resource.
Publisher: An entity responsible for making the resource available
Rights: Information about rights held in and over the resource.
3 characters
Date: A date of an event in the lifecycle of the resource
Format: The physical or digital manifestation of the resource.
Identifier: An unambiguous reference to the resource within a given
context.
4 UDDI: Key the UDDI content of this Webservice if available.
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5 categorybag: This is an optional list of name-value pairs that are
used to tag a search Webservice with specific taxonomy information.
Some classification methods according to subjects can be adopted,
such as (CLC) Chinese Library Classification (LCC) Library of
Congress Classification.
6 accesspoint: URL of this Webservice
The XML schema of SDDI as follow.
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3.2 The API of SDDI
3.2.1 Publish
When a library purchase a database, a SDDI of this database will be
authorized at the same time and saved at the local servers. The
library can revise the SDDI itself according to its own needs.
3.2.2 Inquiry API
Inquiry API will provide two simple functions that help the search
engine find the appreciate Webservice that matches the requirements
of users. The definition of element should refer the SDDI. Meanwhile,
the element can have complex structure.
1 find(element,value)
Return the accesspoint according to the element and its value. For
example:
find(copyright, "Tom", "publisher","right")
find(title, "ACM")
2 get(element1,value,element2)
Return the value of element2 according to the value of element1.For
example:
Get((title, "ACM", character)
Security Considerations
The security considerations should refer to those of Webservice.
There are no any additional security concerns in this protocol.
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References
[1] Webservice , http://www.w3.org/2002/ws/
[2] The web service of Google, http://www.google.com/apis/
[3] WSDL, http://www.w3.org/TR/wsdl
[4] UDDI, http://www.uddi.org
[5] S. Weibel, J. Kunze, "Dublin Core Metadata for Resource
Discovery", rfc2413, September 1998.
Author's Addresses
Wang liang
HUST
WUHAN 430074
China
Phone: 86-27-87553494
Email:wangliang_f@163.com
Guo YiPing
HUST
WUHAN 430074
China
Email:wangliang_f@163.com
Fang Ming
HUST
WUHAN 430074
China
Email:fangming_w@263.net
Xu Yuedong
HUST
WUHAN 430074
China
Email: xuyaodong2000@yahoo.com.cn
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