Linking electronic documents and standardisation of URL’s

Linking electronic documents and standardisation of URL’s

What can libraries do to enhance dynamic linking and bring related information within a distance of “only one click”?

Koninklijke Bibliotheek, Nationale bibliotheek van Nederland

Theo van Veen

Linking digital objects and standardisation of URL’s

What can libraries do? Standardisation and agreements Personal linking page (SFX and OpenUrl) Offer additional query responses in XML Conversion of references in electronic

documents to OpenUrl (DOI, CrossRef) Local resolution and redirection of

OpenUrl Disclosure of searchable sites (harvesting,

OAI-protocol and deep linking)



Request

Response

OpenUrl HTML, javascriptOpenUrl XML, javascript

XML XML, javascript

(dynamic) url’s HTML, javascript

telnet,VT100 ASCII

Z39.50 Z39.50

scripting screensteeling

http to Z39.50 Z39.50 to http

Trend

Aspects in standardisation What do we want ?

High degree of interoperability Low barrier implementation High level of automation

How (besides reaching agreements)? Extendibility: Do not reject a response with items that are not

(yet) in the standard Tolerance: Do not reject a response if items are missing if it is

not fatal Flexibility: Try to allow responses that are not requested Do not rely on negotiation between http server (“take it or

leave it”) and browser (“make the best of what it gets”) Keep it simple


Personal remark:

As interaction between systems becomes more complex and is moving all the time, standardisation of request and response might require a more non-conventional approach.

OpenUrl (simplified) OpenUrl=Base-url + query with standardised syntax

Example:Base-url: http://my.pc.com/request?

Query: issn=12345678&year=2000&vol=8&spage=123 Usage:

Dynamic and automatic generation of “just in case” links depending on “current” metadata and “user preferences”.

Link = request for service, search or object


Personal link page Metadata from anywhere link to any

system of the user’s choice Let the user set his own base-url (by

means of a cookie) Allow the user to set this base-url when

presenting the metadata (“only one click away”)

The personal link page can analyse the query-part of the OpenUrl in the user’s browser: no server needed!



Personal Link Page

Query


Personal Link Page

Response with javascript to allow setting the base url to personal link page.


Personal Link Page

Next responses will show personal link page as default for openURL link.

PLP

Personal, context dependent, dynamically generated links

Base-url points to plp

Record display with option to select personal link page


Example of personal link page for articles


Result obtained via PLP


Example of personal link page for books


HTML-page to create plp


HTML page with Javascript to get issn from openurl and present a link


<html>

<script>

srch=unescape(location.search);

srch=srch.substring(1,999);

sarray=srch.split("&");

issn="";

for (i=0 ; i<sarray.length ; i++)

{

ind_key=sarray[i].split("=");

if (ind_key[0] == "issn") issn=ind_key[1];

}

function search()

{

if (issn== "") alert("No issn");

else location="http://hognose.kb.nl/cgi-bin/gurl2url.pl?issn=" + issn

}

</script>

This is a very simple example of a personal link page. Click <a href="javascript:search()"> here </a>to search on issn.

</html>

Additonal XML-metadata


Query

ResponseNO HITSExample : Response with terms that are most alike (fuzzyness)

Fuzzy matching terms:

•Term 1•Term 2•Term 3•Term 4•Term 5

Additional responses

Related terms Results of fuzzy matching Index browse (z39.50 scan) Short title list Number of hits for each term Etc.


Additional data in XML


Query to different targetsResponses from different targetsFuzzy results

Short title listNo hits

Index browseIndex browseFuzzy resultsRelated terms

Integration of the results allows the user to improve his query and retry a distributed search

Example of additional responses XML

<response><number-of-hits>0</number-of-hits><fuzzy-list> <fuzzy-term>abc</fuzzy-term> <fuzzy-term>bcd</fuzzy-term></fuzzy-list><scan-list> <scan-term>abc</scan-term> <scan-term>acc</scan-term></scan-list></response>


For new tags that are not know to the client:

• Adapt XSL (and/or javascript) to display this item

• The user application may try to ask for this new tag (using the same name) in automatic generated urls.

Example of requesting URL:

http://www.demo.nl/query?keyword=test&request=<fuzzy-list>

Electronic references, DOI and Crossref

Author submits article Publisher resolves references Publisher submits metadata to DOI-agent and

receives DOI for referenced articles Publication is issued User requests publication User clicks on DOI of reference (link to DOI-

resolver) DOI-resolver presents DOI metadata User selects location from DOI metadata User requests article from that location


Remarks:

1. Not all references have a DOI

2. User may not have access to DOI-resolver

3. User may not have access to locations specified by the metadata from DOI-agent

4. The DOI identifies but does not localise objects

Retrieval of electronic references


Query ?

Article

Reference 1Reference 2Reference 3

Search for referenced article

Referenced articlePersonal

link pageresolvedbase-url(resolution)

Retrieval of electronic references


Electronic references: what can libraries do?

Convert references via XML or HTML to OpenUrl’s

Maintain a local list of journals with the base-url of their locations

Forward the user’s query to new base-url for journals that are on other locations.


Distributed query (Z39.50)


Distributed query to the “whole world”

user query

Central index (web search engines)


Harvesting of the “whole world”

user query

Selective query propagation


Distributed search to selected targets

user query

subject y geographicalownershipsubject x

Selective query propagation (hybride solution)


target selection for subject x

subject y geographicalownershipsubject x

Distributed query to selected targets

query to gateway or to selected targets directly

Central index (OAI-protocol ?)

Multi target search


1. Search for : dutchess art search*

2. Enter new search e.g. Rembrandt

3. Query will be send to all searchable targets

Metadata and digital objects

Separation of metadata and digital objects (different databases)

Metadata independent from digital objects (no hardcoded file names in bibliographic metadata)

Structure of digital objects not always known (e.g. subject to change e.g. due to preservation activities)

Digital objects can be anything (from single file to database of streaming objects)

Request is not always the whole digital object but a role: thumbnail, table of contents, title page etc.


Fields to be used in URL to request digital objects:

1. Identification of object (oid)

2. Role (standardised)

Examples:

http://dnep.kb.nl/openurl?oid=kb:1234&role=thumbnail http://dnep.kb.nl/openurl?oid=kb:1234&role=table-of-contents

Conclusions and recommendations

Make your services OpenUrl-compatible Focus on XML for the presented results

and as transfer format Implement the small piece of javascript

to allow setting of the plp Let’s come to agreements on extension

of OpenUrl to allow for fast and “low barrier” implementation of extra services and searches.


Linking electronic documents and standardisation of URL’s

Documents

Transcript of Linking electronic documents and standardisation of URL’s