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<chapter id="tutorial">
<title>Tutorial</title>
<sect1 id="tutorial-oai">
<title>A first &acro.oai; indexing example</title>
<para>
In this section, we will test the system by indexing a small set of
sample &acro.oai; records that are included with the &zebra; distribution,
running a &zebra; server against the newly created database, and
searching the indexes with a client that connects to that server.
</para>
<para>
Go to the <literal>examples/oai-pmh</literal> subdirectory of the
distribution archive, or make a deep copy of the Debian installation
directory
<literal>/usr/share/idzebra-2.0-examples/oai-pmh</literal>.
An XML file containing multiple &acro.oai;
records is located in the sub
directory <literal>examples/oai-pmh/data</literal>.
</para>
<para>
Additional OAI test records can be downloaded by running a shell
script (you may want to abort the script when you have waited
longer than your coffee brews ..).
<screen>
cd data
./fetch_OAI_data.sh
cd ../
</screen>
</para>
<para>
To index these &acro.oai; records, type:
<screen>
zebraidx-2.0 -c conf/zebra.cfg init
zebraidx-2.0 -c conf/zebra.cfg update data
zebraidx-2.0 -c conf/zebra.cfg commit
</screen>
In case you have not installed zebra yet but have compiled the
binaries from this tarball, use the following command form:
<screen>
../../index/zebraidx -c conf/zebra.cfg this and that
</screen>
On some systems the &zebra; binaries are installed under the
generic names, you need to use the following command form:
<screen>
zebraidx -c conf/zebra.cfg this and that
</screen>
</para>
<para>
In this command, the word <literal>update</literal> is followed
by the name of a directory: <literal>zebraidx</literal> updates all
files in the hierarchy rooted at <literal>data</literal>.
The command option
<literal>-c conf/zebra.cfg</literal> points to the proper
configuration file.
</para>
<para>
You might ask yourself how &acro.xml; content is indexed using &acro.xslt;
stylesheets: to satisfy your curiosity, you might want to run the
indexing transformation on an example debugging &acro.oai; record.
<screen>
xsltproc conf/oai2index.xsl data/debug-record.xml
</screen>
Here you see the &acro.oai; record transformed into the indexing
&acro.xml; format. &zebra; is creating several inverted indexes,
and their name and type are clearly visible in the indexing
&acro.xml; format.
</para>
<para>
If your indexing command was successful, you are now ready to
fire up a server. To start a server on port 9999, type:
<screen>
zebrasrv-2.0 -c conf/zebra.cfg @:9999
</screen>
</para>
<para>
The &zebra; index that you have just created has a single database
named <literal>Default</literal>.
The database contains several &acro.oai; records, and the server will
return records in the &acro.xml; format only. The indexing machine
did the splitting into individual records just behind the scenes.
</para>
</sect1>
<sect1 id="tutorial-oai-sru-pqf">
<title>Searching the &acro.oai; database by web service</title>
<para>
&zebra; has a build-in web service, which is close to the
&acro.sru; standard web service. We use it to access our new
database using any &acro.xml; enabled web browser.
This service is using the &acro.pqf; query language.
In a later
section we show how to run a fully compliant &acro.sru; server,
including support for the query language &acro.cql;
</para>
<para>
Searching and retrieving &acro.xml; records is easy. For example,
you can point your browser to one of the following URLs to
search for the term <literal>the</literal>. Just point your
browser at this link:
<ulink
url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the</ulink>
</para>
<warning>
<para>
These URLs won't work unless you have indexed the example data
and started an &zebra; server as outlined in the previous section.
</para>
</warning>
<para>
In case we actually want to retrieve one record, we need to alter
our URL to the following
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=dc">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=dc
</ulink>
</para>
<para>
This way we can page through our result set in chunks of records,
for example, we access the 6th to the 10th record using the URL
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=6&maximumRecords=5&recordSchema=dc">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=6&maximumRecords=5&recordSchema=dc
</ulink>
</para>
<!--
relation tests:
<ulink url="">
http://localhost:9999/?version=1.1&operation=searchRetrieve
&x-pquery=title%3Cthe
-->
</sect1>
<sect1 id="tutorial-oai-sru-present">
<title>Presenting search results in different formats</title>
<para>
&zebra; uses &acro.xslt; stylesheets for both &acro.xml;record
indexing and
display retrieval. In this example installation, they are two
retrieval schema's defined in
<literal>conf/dom-conf.xml</literal>:
the <literal>dc</literal> schema implemented in
<literal>conf/oai2dc.xsl</literal>, and
the <literal>zebra</literal> schema implemented in
<literal>conf/oai2zebra.xsl</literal>.
The URLs for accessing both are the same, except for the different
value of the <literal>recordSchema</literal> parameter:
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=dc">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=dc
</ulink>
and
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra
</ulink>
For the curious, one can see that the &acro.xslt; transformations
really do the magic.
<screen>
xsltproc conf/oai2dc.xsl data/debug-record.xml
xsltproc conf/oai2zebra.xsl data/debug-record.xml
</screen>
Notice also that the &zebra; specific parameters are injected by
the engine when retrieving data, therefore some of the attributes
in the <literal>zebra</literal> retrieval schema are not filled
when running the transformation from the command line.
</para>
<para>
In addition to the user defined retrieval schema's one can always
choose from many build-in schema's. In case one is only
interested in the &zebra; internal metadata about a certain
record, one uses the <literal>zebra::meta</literal> schema.
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::meta">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::meta
</ulink>
</para>
<para>
The <literal>zebra::data</literal> schema is used to retrieve the
original stored &acro.oai; &acro.xml; record.
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::data">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::data
</ulink>
</para>
</sect1>
<sect1 id="tutorial-oai-sru-searches">
<title>More interesting searches</title>
<para>
The &acro.oai; indexing example defines many different index
names, a study of the <literal>conf/oai2index.xsl</literal>
stylesheet reveals the following word type indexes (i.e. those
with suffix <literal>:w</literal>):
<screen>
any:w
title:w
author:w
subject-heading:w
description:w
contributor:w
publisher:w
language:w
rights:w
</screen>
By default, searches do access the <literal>any:w</literal> index,
but we can direct searches to any access point by constructing the
correct &acro.pqf; query. For example, to search in titles only,
we use
<ulink
url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=@attr 1=title the&startRecord=1&maximumRecords=1&recordSchema=dc">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=@attr 1=title the&startRecord=1&maximumRecords=1&recordSchema=dc
</ulink>
</para>
<para>
Similar we can direct searches to the other indexes defined. Or we
can create boolean combinations of searches on different
indexes. In this case we search for <literal>the</literal> in
<literal>title</literal> and for <literal>fish</literal> in
<literal>description</literal> using the query
<literal>@and @attr 1=title the @attr 1=description fish</literal>.
<ulink
url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=@and @attr 1=title the @attr 1=description fish&startRecord=1&maximumRecords=1&recordSchema=dc">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=@and @attr 1=title the @attr 1=description fish&startRecord=1&maximumRecords=1&recordSchema=dc
</ulink>
</para>
</sect1>
<sect1 id="tutorial-oai-sru-zebra-indexes">
<title>Investigating the content of the indexes</title>
<para>
How does the magic work? What is inside the indexes? Why is a certain
record found by a search, and another not?. The answer is in the
inverted indexes. You can easily investigate them using the
special &zebra; schema
<literal>zebra::index::fieldname</literal>. In this example you
can see that the <literal>title</literal> index has both word
(type <literal>:w</literal>) and phrase (type
<literal>:p</literal>)
indexed fields,
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::index::title">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::index::title
</ulink>
</para>
<para>
But where in the indexes did the term match for the query occur?
Easily answered with the special &zebra; schema
<literal>zebra::snippet</literal>. The matching terms are
encapsulated by <literal><s></literal> tags.
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::snippet">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::snippet
</ulink>
</para>
<para>
How can I refine my search? Which interesting search terms are
found inside my hit set? Try the special &zebra; schema
<literal>zebra::facet::fieldname:type</literal>. In this case, we
investigate additional search terms for the
<literal>title:w</literal> index.
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::facet::title:w">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::facet::title:w
</ulink>
</para>
<para>
One can ask for multiple facets. Here, we want them from phrase
indexes of type
<literal>:p</literal>.
<ulink url="http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::facet::publisher:p,title:p">
http://localhost:9999/?version=1.1&operation=searchRetrieve&x-pquery=the&startRecord=1&maximumRecords=1&recordSchema=zebra::facet::publisher:p,title:p
</ulink>
</para>
</sect1>
<sect1 id="tutorial-oai-sru-yazfrontend">
<title>Setting up a correct &acro.sru; web service</title>
<para>
The &acro.sru; specification mandates that the &acro.cql; query
language is supported and properly configured. Also, the server
needs to be able to emit a proper &acro.explain; &acro.xml;
record, which is used to determine the capabilities of the
specific server instance.
</para>
<para>
In this example configuration we exploit the similarities between
the &acro.explain; record and the &acro.cql; query language
configuration, we generate the later from the former using an
&acro.xslt; transformation.
<screen>
xsltproc conf/explain2cqlpqftxt.xsl conf/explain.xml > conf/cql2pqf.txt
</screen>
</para>
<para>
We are all set to start the &acro.sru;/&acro.z3950; server including
&acro.pqf; and &acro.cql; query configuration. It uses the &yaz; frontend
server configuration - just type
<screen>
zebrasrv -f conf/yazserver.xml
</screen>
</para>
<para>
First, we'd like to be sure that we can see the &acro.explain;
&acro.xml; response correctly. You might use either of these equivalent
requests:
<ulink
url="http://localhost:9999">http://localhost:9999
</ulink>
or
<ulink
url="http://localhost:9999/?version=1.1&operation=explain">
http://localhost:9999/?version=1.1&operation=explain
</ulink>
</para>
<para>
Now we can issue true &acro.sru; requests. For example,
<literal>dc.title=the
and dc.description=fish</literal> results in the following page
<ulink
url="http://localhost:9999/?version=1.1&operation=searchRetrieve&query=dc.title=the and dc.description=fish&startRecord=1&maximumRecords=1&recordSchema=dc">
http://localhost:9999/?version=1.1&operation=searchRetrieve&query=dc.title=the and dc.description=fish &startRecord=1&maximumRecords=1&recordSchema=dc
</ulink>
</para>
<para>
Scan of indexes is a part of the &acro.sru; server business. For example,
scanning the <literal>dc.title</literal> index gives us an idea
what search terms are found there
<ulink
url="http://localhost:9999/?version=1.1&operation=scan&scanClause=dc.title=fish">
http://localhost:9999/?version=1.1&operation=scan&scanClause=dc.title=fish
</ulink>,
whereas
<ulink
url="http://localhost:9999/?version=1.1&operation=scan&scanClause=dc.identifier=fish">
http://localhost:9999/?version=1.1&operation=scan&scanClause=dc.identifier=fish
</ulink>
accesses the indexed identifiers.
</para>
<para>
In addition, all &zebra; internal special element sets or record
schema's of the form
<literal>zebra::</literal> just work right out of the box
<ulink
url="http://localhost:9999/?version=1.1&operation=searchRetrieve&query=dc.title=the and dc.description=fish&startRecord=1&maximumRecords=1&recordSchema=zebra::snippet">
http://localhost:9999/?version=1.1&operation=searchRetrieve&query=dc.title=the and dc.description=fish &startRecord=1&maximumRecords=1&recordSchema=zebra::snippet
</ulink>
</para>
</sect1>
<sect1 id="tutorial-oai-z3950">
<title>Searching the &acro.oai; database by &acro.z3950; protocol</title>
<para>
In this section we repeat the searches and presents we have done so
far using the binary &acro.z3950; protocol, you can use any
&acro.z3950; client.
For instance, you can use the demo command-line client that comes
with &yaz;.
</para>
<para>
Connecting to the server is done by the command
<screen>
yaz-client localhost:9999
</screen>
</para>
<para>
When the client has connected, you can type:
<screen>
Z> format xml
Z> querytype prefix
Z> elements oai
Z> find the
Z> show 1+1
</screen>
</para>
<para>
&acro.z3950; presents using presentation stylesheets:
<screen>
Z> elements dc
Z> show 2+1
Z> elements zebra
Z> show 3+1
</screen>
</para>
<para>
&acro.z3950; buildin Zebra presents (in this configuration only if
started without yaz-frontendserver):
<screen>
Z> elements zebra::meta
Z> show 4+1
Z> elements zebra::meta::sysno
Z> show 5+1
Z> format sutrs
Z> show 5+1
Z> format xml
Z> elements zebra::index
Z> show 6+1
Z> elements zebra::snippet
Z> show 7+1
Z> elements zebra::facet::any:w
Z> show 1+1
Z> elements zebra::facet::publisher:p,title:p
Z> show 1+1
</screen>
</para>
<para>
&acro.z3950; searches targeted at specific indexes and boolean
combinations of these can be issued as well.
<screen>
Z> elements dc
Z> find @attr 1=oai_identifier @attr 4=3 oai:caltechcstr.library.caltech.edu:4
Z> show 1+1
Z> find @attr 1=oai_datestamp @attr 4=3 2001-04-20
Z> show 1+1
Z> find @attr 1=oai_setspec @attr 4=3 7374617475733D756E707562
Z> show 1+1
Z> find @attr 1=title communication
Z> show 1+1
Z> find @attr 1=identifier @attr 4=3
http://resolver.caltech.edu/CaltechCSTR:1986.5228-tr-86
Z> show 1+1
</screen>
etc, etc.
</para>
<para>
&acro.z3950; scan:
<screen>
yaz-client localhost:9999
Z> format xml
Z> querytype prefix
Z> scan @attr 1=oai_identifier @attr 4=3 oai
Z> scan @attr 1=oai_datestamp @attr 4=3 1
Z> scan @attr 1=oai_setspec @attr 4=3 2000
Z>
Z> scan @attr 1=title communication
Z> scan @attr 1=identifier @attr 4=3 a
</screen>
</para>
<para>
&acro.z3950; search using server-side CQL conversion:
<screen>
Z> format xml
Z> querytype cql
Z> elements dc
Z>
Z> find harry
Z>
Z> find dc.creator = the
Z> find dc.creator = the
Z> find dc.title = the
Z>
Z> find dc.description < the
Z> find dc.title > some
Z>
Z> find dc.identifier="http://resolver.caltech.edu/CaltechCSTR:1978.2276-tr-78"
Z> find dc.relation = something
</screen>
</para>
<!--
etc, etc. Notice that all indexes defined by 'type="0"' in the
indexing style sheet must be searched using the 'eq'
relation.
Z> find title <> and
fails as well. ???
-->
<tip>
<para>
&acro.z3950; scan using server side CQL conversion -
unfortunately, this will _never_ work as it is not supported by the
&acro.z3950; standard.
If you want to use scan using server side CQL conversion, you need to
make an SRW connection using yaz-client, or a
SRU connection using REST Web Services - any browser will do.
</para>
</tip>
<tip>
<para>
All indexes defined by 'type="0"' in the
indexing style sheet must be searched using the '@attr 4=3'
structure attribute instruction.
</para>
</tip>
<para>
Notice that searching and scan on indexes
<literal>contributor</literal>, <literal>language</literal>,
<literal>rights</literal>, and <literal>source</literal>
might fail, simply because none of the records in the small example set
have these fields set, and consequently, these indexes might not
been created.
</para>
</sect1>
</chapter>
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