1 <chapter id="introduction">
2 <!-- $Id: introduction.xml,v 1.44 2007-02-02 14:34:20 marc Exp $ -->
3 <title>Introduction</title>
5 <section id="overview">
6 <title>Overview</title>
9 &zebra; is a free, fast, friendly information management system. It can
10 index records in &xml;/&sgml;, &marc;, e-mail archives and many other
11 formats, and quickly find them using a combination of boolean
12 searching and relevance ranking. Search-and-retrieve applications can
13 be written using &api;s in a wide variety of languages, communicating
14 with the &zebra; server using industry-standard information-retrieval
15 protocols or web services.
18 &zebra; is licensed Open Source, and can be
19 deployed by anyone for any purpose without license fees. The C source
20 code is open to anybody to read and change under the GPL license.
23 &zebra; is a networked component which acts as a reliable &z3950; server
24 for both record/document search, presentation, insert, update and
25 delete operations. In addition, it understands the &sru; family of
26 webservices, which exist in &rest; &get;/&post; and truly &soap; flavors.
29 &zebra; is available as MS Windows 2003 Server (32 bit) self-extracting
30 package as well as GNU/Debian Linux (32 bit and 64 bit) precompiled
31 packages. It has been deployed successfully on other Unix systems,
32 including Sun Sparc, HP Unix, and many variants of Linux and BSD
36 <ulink url="http://www.indexdata.com/zebra/">http://www.indexdata.com/zebra/</ulink>
37 <ulink url="http://ftp.indexdata.dk/pub/zebra/win32/">http://ftp.indexdata.dk/pub/zebra/win32/</ulink>
38 <ulink url="http://ftp.indexdata.dk/pub/zebra/debian/">http://ftp.indexdata.dk/pub/zebra/debian/</ulink>
42 <ulink url="http://indexdata.dk/zebra/">&zebra;</ulink>
43 is a high-performance, general-purpose structured text
44 indexing and retrieval engine. It reads records in a
45 variety of input formats (eg. email, &xml;, &marc;) and provides access
46 to them through a powerful combination of boolean search
47 expressions and relevance-ranked free-text queries.
51 &zebra; supports large databases (tens of millions of records,
52 tens of gigabytes of data). It allows safe, incremental
53 database updates on live systems. Because &zebra; supports
54 the industry-standard information retrieval protocol, &z3950;,
55 you can search &zebra; databases using an enormous variety of
56 programs and toolkits, both commercial and free, which understand
57 this protocol. Application libraries are available to allow
58 bespoke clients to be written in Perl, C, C++, Java, Tcl, Visual
59 Basic, Python, &php; and more - see the
60 <ulink url="&url.zoom;">&zoom; web site</ulink>
61 for more information on some of these client toolkits.
65 This document is an introduction to the &zebra; system. It explains
66 how to compile the software, how to prepare your first database,
67 and how to configure the server to give you the
68 functionality that you need.
72 <section id="features">
73 <title>&zebra; Features Overview</title>
81 <entry><xref linkend=""/></entry>
87 <entry><xref linkend=""/></entry>
93 <entry><xref linkend=""/></entry>
98 <table id="table-features-protocol" frame="top">
99 <title>&zebra; networked protocols</title>
103 <entry>Feature</entry>
104 <entry>Availability</entry>
106 <entry>Reference</entry>
111 <entry>Operation types</entry>
112 <entry> &z3950;/&sru; explain, search, and scan</entry>
114 <entry><xref linkend="querymodel-operation-types"/></entry>
117 <entry>Remote update</entry>
118 <entry>&z3950; extended services</entry>
120 <entry><xref linkend=""/></entry>
123 <entry>&z3950;</entry>
124 <entry>&z3950; protocol support</entry>
125 <entry> Protocol facilities: Init, Search, Present (retrieval),
126 Segmentation (support for very large records), Delete, Scan
127 (index browsing), Sort, Close and support for the ``update''
128 Extended Service to add or replace an existing &xml;
129 record. Piggy-backed presents are honored in the search
130 request. Named result sets are supported.</entry>
131 <entry><xref linkend=""/></entry>
134 <entry>Web Service support</entry>
135 <entry>&sru_gps;</entry>
136 <entry> The protocol operations <literal>explain</literal>,
137 <literal>searchRetrieve</literal> and <literal>scan</literal>
138 are supported. <ulink url="&url.cql;">&cql;</ulink> to internal
139 query model &rpn; conversion is supported. Extended RPN queries
140 for search/retrieve and scan are supported.</entry>
141 <entry><xref linkend=""/></entry>
148 <table id="table-features-search" frame="top">
149 <title>&zebra; search functionality</title>
153 <entry>Feature</entry>
154 <entry>Availability</entry>
156 <entry>Reference</entry>
161 <entry>Query languages</entry>
162 <entry>&cql; and &rpn;/&pqf;</entry>
163 <entry>The type-1 Reverse Polish Notation (&rpn;)
164 and it's textual representation Prefix Query Format (&pqf;) are
165 supported. The Common Query Language (&cql;) can be configured as
166 a mapping from &cql; to &rpn;/&pqf;</entry>
167 <entry><xref linkend="querymodel-query-languages-pqf"/>
168 <xref linkend="querymodel-cql-to-pqf"/></entry>
171 <entry>Complex boolean query tree</entry>
172 <entry>&cql; and &rpn;/&pqf;</entry>
173 <entry>Both &cql; and &rpn;/&pqf; allow atomic query parts (&apt;) to
174 be combined into complex boolean query trees</entry>
175 <entry><xref linkend="querymodel-rpn-tree"/></entry>
178 <entry>Field search</entry>
179 <entry>user defined</entry>
180 <entry>Atomic query parts (&apt;) are either general, or
181 directed at user-specified document fields
183 <entry><xref linkend=""/></entry>
186 <entry>Data normalization</entry>
188 <entry>Data normalization, text tokenization and character mappings can be
189 applied during indexing and searching</entry>
190 <entry><xref linkend=""/></entry>
193 <entry>Predefined field types</entry>
195 <entry>Data fields can be indexed as phrase, as into word tokenized text,
196 as numeric values, url's, dates, and raw binary data.</entry>
197 <entry><xref linkend=""/></entry>
200 <entry>Regular expression matching</entry>
201 <entry>Regexp </entry>
202 <entry>Full regular expression matching and "approximate
203 matching" (eg. spelling mistake corrections) are handled.</entry>
204 <entry><xref linkend=""/></entry>
207 <entry>Search truncation</entry>
210 <entry><xref linkend=""/></entry>
213 <entry>Fuzzy searches</entry>
215 <entry>In addition, fuzzy searches are implemented, where one
216 spelling mistake in search terms is matched</entry>
217 <entry><xref linkend=""/></entry>
224 <table id="table-features-scan" frame="top">
225 <title>&zebra; index scanning</title>
229 <entry>Feature</entry>
230 <entry>Availability</entry>
232 <entry>Reference</entry>
239 <entry><literal>Scan</literal> on a given named index returns all the
240 indexed terms in lexicographical order near the given start term.</entry>
241 <entry><xref linkend=""/></entry>
244 <entry>Facetted browsing</entry>
245 <entry>partial</entry>
246 <entry>&zebra; supports <literal>scan inside a hit
247 set</literal> from a previous search, thus reducing the listed
249 subset of terms found in the documents/records of the hit set.</entry>
250 <entry><xref linkend=""/></entry>
253 <entry>Drill-down or refine-search</entry>
254 <entry>partially</entry>
255 <entry>scanning in result sets can be used to implement
256 drill-down in search clients</entry>
257 <entry><xref linkend=""/></entry>
264 <table id="table-features-presentation" frame="top">
265 <title>&zebra; document presentation</title>
269 <entry>Feature</entry>
270 <entry>Availability</entry>
272 <entry>Reference</entry>
277 <entry>Hit count</entry>
279 <entry>Search results include at any time the total hit count of a given
280 query, either exact computed, or approximative, in case that the
281 hit count exceeds a possible pre-defined hit set truncation
284 <entry><xref linkend=""/></entry>
287 <entry>Paged result sets</entry>
289 <entry>Paging of search requests and present/display request can return any
290 successive number of records from any start position in the hit set,
291 i.e. it is trivial to provide search results in successive pages of
293 <entry><xref linkend=""/></entry>
296 <entry>&xml;ocument transformations</entry>
297 <entry>&xslt; based</entry>
298 <entry> Record presentation can be performed in many pre-defined &xml; data
299 formats, where the original &xml; records are on-the-fly transformed
300 through any preconfigured &xslt; transformation. It is therefore
301 trivial to present records in short/full &xml; views, transforming to
302 RSS, Dublin Core, or other &xml; based data formats, or transform
303 records to XHTML snippets ready for inserting in XHTML pages.</entry>
304 <entry><xref linkend=""/></entry>
307 <entry>Binary record transformations</entry>
308 <entry>&marc;, &usmarc;, &marc21; and &marcxml;</entry>
310 <entry><xref linkend=""/></entry>
313 <entry>Record Syntaxes</entry>
315 <entry> Multiple record syntaxes
316 for data retrieval: &grs1;, &sutrs;,
317 &xml;, ISO2709 (&marc;), etc. Records can be mapped between record syntaxes
318 and schemas on the fly.</entry>
319 <entry><xref linkend=""/></entry>
326 <table id="table-features-sort-rank" frame="top">
327 <title>&zebra; sorting and ranking</title>
331 <entry>Feature</entry>
332 <entry>Availability</entry>
334 <entry>Reference</entry>
340 <entry>numeric, lexicographic</entry>
341 <entry>Sorting on the basis of alpha-numeric and numeric data
342 is supported. Alphanumeric sorts can be configured for different data encodings
343 and locales for European languages. </entry>
344 <entry><xref linkend=""/></entry>
347 <entry>Combined sorting</entry>
349 <entry>Sorting on the basis of combined sorts  e.g. combinations of
350 ascending/descending sorts of lexicographical/numeric/date field data
352 <entry><xref linkend=""/></entry>
355 <entry>Relevance ranking</entry>
356 <entry>TF-IDF like</entry>
357 <entry>Relevance-ranking of free-text queries is supported
358 using a TF-IDF like algorithm.</entry>
359 <entry><xref linkend=""/></entry>
362 <entry>Relevence ranking</entry>
363 <entry>TDF-IDF like</entry>
365 <entry><xref linkend=""/></entry>
373 <table id="table-features-document" frame="top">
374 <title>&zebra; document model</title>
378 <entry>Feature</entry>
379 <entry>Availability</entry>
381 <entry>Reference</entry>
386 <entry>Complex semi-structured Documents</entry>
387 <entry>&xml; and &grs1; Documents</entry>
388 <entry>Both &xml; and &grs1; documents exhibit a &dom; like internal
389 representation allowing for complex indexing and display rules</entry>
390 <entry><xref linkend=""/></entry>
393 <entry>Input document formats</entry>
394 <entry>&xml;, &sgml;, Text, ISO2709 (&marc;)</entry>
396 A system of input filters driven by
397 regular expressions allows most ASCII-based
398 data formats to be easily processed.
399 &sgml;, &xml;, ISO2709 (&marc;), and raw text are also
401 <entry><xref linkend=""/></entry>
404 <entry>Document storage</entry>
405 <entry>Index-only, Key storage, Document storage</entry>
406 <entry>Data can be, and usually is, imported
407 into &zebra;'s own storage, but &zebra; can also refer to
408 external files, building and maintaining indexes of "live"
410 <entry><xref linkend=""/></entry>
419 <table id="table-features-scalability" frame="top">
420 <title>&zebra; data size and scalability</title>
424 <entry>Feature</entry>
425 <entry>Availability</entry>
427 <entry>Reference</entry>
432 <entry>No of records</entry>
433 <entry>40-60 million</entry>
435 <entry><xref linkend=""/></entry>
438 <entry>Data size</entry>
439 <entry>100 GB of record data</entry>
441 <entry><xref linkend=""/></entry>
444 <entry>File pointers</entry>
445 <entry>64 bit</entry>
447 <entry><xref linkend=""/></entry>
450 <entry>Scale out</entry>
451 <entry>multiple discs</entry>
453 <entry><xref linkend=""/></entry>
456 <entry>Performance</entry>
457 <entry><literal>O(n * log N)</literal></entry>
458 <entry> &zebra; query speed and performance is affected roughly by
459 <literal>O(log N)</literal>,
460 where <literal>N</literal> is the total database size, and by
461 <literal>O(n)</literal>, where <literal>n</literal> is the
462 specific query hit set size.</entry>
463 <entry><xref linkend=""/></entry>
466 <entry>Average search times</entry>
468 <entry> Even on very large size databases hit rates of 20 queries per
469 seconds with average query answering time of 1 second are possible,
470 provided that the boolean queries are constructed sufficiently
471 precise to result in hit sets of the order of 1000 to 5.000
473 <entry><xref linkend=""/></entry>
476 <entry>Large databases</entry>
477 <entry>64 file pointers assure that register files can extend
478 the 2 GB limit. Logical files can be
479 automatically partitioned over multiple disks, thus allowing for
480 large databases.</entry>
482 <entry><xref linkend=""/></entry>
489 <table id="table-features-updates" frame="top">
490 <title>&zebra; live updates</title>
494 <entry>Feature</entry>
495 <entry>Availability</entry>
497 <entry>Reference</entry>
502 <entry>Batch updates</entry>
504 <entry>It is possible to schedule record inserts/updates/deletes in any
505 quantity, from single individual handled records to batch updates
506 in strikes of any size, as well as total re-indexing of all records
507 from file system. </entry>
508 <entry><xref linkend=""/></entry>
511 <entry>Incremental updates</entry>
514 <entry><xref linkend=""/></entry>
517 <entry>Remote updates</entry>
518 <entry>&z3950; extended services</entry>
520 <entry><xref linkend=""/></entry>
523 <entry>Live updates</entry>
525 <entry> Data updates are transaction based and can be performed on running
526 &zebra; systems. Full searchability is preserved during life data update due to use
527 of shadow disk areas for update operations. Multiple update transactions at the same time are lined up, to be
528 performed one after each other. Data integrity is preserved.</entry>
529 <entry><xref linkend=""/></entry>
532 <entry>Database updates</entry>
533 <entry>live, incremental updates</entry>
534 <entry>Robust updating - records can be added and deleted ``on the fly''
535 without rebuilding the index from scratch.
536 Records can be safely updated even while users are accessing
538 The update procedure is tolerant to crashes or hard interrupts
539 during database updating - data can be reconstructed following
541 <entry><xref linkend=""/></entry>
547 <table id="table-features-platforms" frame="top">
548 <title>&zebra; supported platforms</title>
552 <entry>Feature</entry>
553 <entry>Availability</entry>
555 <entry>Reference</entry>
562 <entry>GNU Linux (32 and 64bit), journaling Reiser or (better) JFS filesystem
563 on disks. GNU/Debian Linux packages are available</entry>
564 <entry><xref linkend=""/></entry>
568 <entry>tarball</entry>
569 <entry>Usual tarball install possible on many major Unix systems</entry>
570 <entry><xref linkend=""/></entry>
573 <entry>Windows</entry>
575 <entry>Windows installer packages available</entry>
576 <entry><xref linkend=""/></entry>
579 <entry>Supported Platforms</entry>
580 <entry>UNIX, Linux, Windows (NT/2000/2003/XP)</entry>
581 <entry>&zebra; is written in portable C, so it runs on most
582 Unix-like systems as well as Windows (NT/2000/2003/XP). Binary
584 available for GNU/Debian Linux and Windows</entry>
585 <entry><xref linkend=""/></entry>
595 <section id="introduction-apps">
596 <title>References and &zebra; based Applications</title>
598 &zebra; has been deployed in numerous applications, in both the
599 academic and commercial worlds, in application domains as diverse
600 as bibliographic catalogues, geospatial information, structured
601 vocabulary browsing, government information locators, civic
602 information systems, environmental observations, museum information
606 Notable applications include the following:
610 <section id="koha-ils">
611 <title>Koha free open-source ILS</title>
613 <ulink url="http://www.koha.org/">Koha</ulink> is a full-featured
614 open-source ILS, initially developed in
615 New Zealand by Katipo Communications Ltd, and first deployed in
616 January of 2000 for Horowhenua Library Trust. It is currently
617 maintained by a team of software providers and library technology
618 staff from around the globe.
621 <ulink url="http://liblime.com/">LibLime</ulink>,
622 a company that is marketing and supporting Koha, adds in
623 the new release of Koha 3.0 the &zebra;
624 database server to drive its bibliographic database.
627 In early 2005, the Koha project development team began looking at
628 ways to improve &marc; support and overcome scalability limitations
629 in the Koha 2.x series. After extensive evaluations of the best
630 of the Open Source textual database engines - including MySQL
631 full-text searching, PostgreSQL, Lucene and Plucene - the team
635 "&zebra; completely eliminates scalability limitations, because it
636 can support tens of millions of records." explained Joshua
637 Ferraro, LibLime's Technology President and Koha's Project
638 Release Manager. "Our performance tests showed search results in
639 under a second for databases with over 5 million records on a
640 modest i386 900Mhz test server."
643 "&zebra; also includes support for true boolean search expressions
644 and relevance-ranked free-text queries, both of which the Koha
645 2.x series lack. &zebra; also supports incremental and safe
646 database updates, which allow on-the-fly record
647 management. Finally, since &zebra; has at its heart the &z3950;
648 protocol, it greatly improves Koha's support for that critical
652 Although the bibliographic database will be moved to &zebra;, Koha
653 3.0 will continue to use a relational SQL-based database design
654 for the 'factual' database. "Relational database managers have
655 their strengths, in spite of their inability to handle large
656 numbers of bibliographic records efficiently," summed up Ferraro,
657 "We're taking the best from both worlds in our redesigned Koha
661 See also LibLime's newsletter article
662 <ulink url="http://www.liblime.com/newsletter/2006/01/features/koha-earns-its-stripes/">
663 Koha Earns its Stripes</ulink>.
667 <section id="emilda-ils">
668 <title>Emilda open source ILS</title>
670 <ulink url="http://www.emilda.org/">Emilda</ulink>
671 is a complete Integrated Library System, released under the
672 GNU General Public License. It has a
673 full featured Web-OPAC, allowing comprehensive system management
674 from virtually any computer with an Internet connection, has
675 template based layout allowing anyone to alter the visual
676 appearance of Emilda, and is
677 &xml; based language for fast and easy portability to virtually any
679 Currently, Emilda is used at three schools in Espoo, Finland.
682 As a surplus, 100% &marc; compatibility has been achieved using the
683 &zebra; Server from Index Data as backend server.
687 <section id="reindex-ils">
688 <title>ReIndex.Net web based ILS</title>
690 <ulink url="http://www.reindex.net/index.php?lang=en">Reindex.net</ulink>
691 is a netbased library service offering all
692 traditional functions on a very high level plus many new
693 services. Reindex.net is a comprehensive and powerful WEB system
694 based on standards such as &xml; and &z3950;.
695 updates. Reindex supports &marc21;, dan&marc; eller Dublin Core with
699 Reindex.net runs on GNU/Debian Linux with &zebra; and Simpleserver
701 Data for bibliographic data. The relational database system
702 Sybase 9 &xml; is used for
704 Internally &marcxml; is used for bibliographical records. Update
705 utilizes &z3950; extended services.
709 <section id="dads-article-database">
710 <title>DADS - the DTV Article Database
713 DADS is a huge database of more than ten million records, totalling
714 over ten gigabytes of data. The records are metadata about academic
715 journal articles, primarily scientific; about 10% of these
716 metadata records link to the full text of the articles they
717 describe, a body of about a terabyte of information (although the
718 full text is not indexed.)
721 It allows students and researchers at DTU (Danmarks Tekniske
722 Universitet, the Technical College of Denmark) to find and order
723 articles from multiple databases in a single query. The database
724 contains literature on all engineering subjects. It's available
725 on-line through a web gateway, though currently only to registered
729 More information can be found at
730 <ulink url="http://www.dtv.dk/"/> and
731 <ulink url="http://dads.dtv.dk"/>
735 <section id="infonet-eprints">
736 <title>Infonet Eprints</title>
738 The InfoNet Eprints service from the
739 <ulink url="http://www.dtv.dk/">
740 Technical Knowledge Center of Denmark</ulink>
741 provides access to documents stored in
742 eprint/preprint servers and institutional research archives around
743 the world. The service is based on Open Archives Initiative metadata
744 harvesting of selected scientific archives around the world. These
745 open archives offer free and unrestricted access to their contents.
748 Infonet Eprints currently holds 1.4 million records from 16 archives.
749 The online search facility is found at
750 <ulink url="http://preprints.cvt.dk"/>.
754 <section id="alvis-project">
757 The <ulink url="http://www.alvis.info/alvis/">Alvis</ulink> EU
758 project run under the 6th Framework (IST-1-002068-STP)
759 is building a semantic-based peer-to-peer search engine. A
760 consortium of eleven partners from six different European
761 Community countries plus Switzerland and China contribute
762 with expertise in a broad range of specialties including network
763 topologies, routing algorithms, linguistic analysis and
767 The &zebra; information retrieval indexing machine is used inside
768 the Alvis framework to
769 manage huge collections of natural language processed and
770 enhanced &xml; data, coming from a topic relevant web crawl.
771 In this application, &zebra; swallows and manages 37GB of &xml; data
772 in about 4 hours, resulting in search times of fractions of
779 <title>ULS (Union List of Serials)</title>
782 has created a union catalogue for the periodicals of the
783 twenty-one constituent libraries of the University of London and
784 the University of Westminster
785 (<ulink url="http://www.m25lib.ac.uk/ULS/"/>).
786 They have achieved this using an
787 unusual architecture, which they describe as a
788 ``non-distributed virtual union catalogue''.
791 The member libraries send in data files representing their
792 periodicals, including both brief bibliographic data and summary
793 holdings. Then 21 individual &z3950; targets are created, each
794 using &zebra;, and all mounted on the single hardware server.
795 The live service provides a web gateway allowing &z3950; searching
796 of all of the targets or a selection of them. &zebra;'s small
797 footprint allows a relatively modest system to comfortably host
801 More information can be found at
802 <ulink url="http://www.m25lib.ac.uk/ULS/"/>
807 <title>NLI-&z3950; - a Natural Language Interface for Libraries</title>
809 Fernuniversität Hagen in Germany have developed a natural
810 language interface for access to library databases.
812 url="http://ki212.fernuni-hagen.de/nli/NLIintro.html"/> -->
813 In order to evaluate this interface for recall and precision, they
814 chose &zebra; as the basis for retrieval effectiveness. The &zebra;
815 server contains a copy of the GIRT database, consisting of more
816 than 76000 records in &sgml; format (bibliographic records from
817 social science), which are mapped to &marc; for presentation.
820 (GIRT is the German Indexing and Retrieval Testdatabase. It is a
821 standard German-language test database for intelligent indexing
822 and retrieval systems. See
823 <ulink url="http://www.gesis.org/forschung/informationstechnologie/clef-delos.htm"/>)
826 Evaluation will take place as part of the TREC/CLEF campaign 2003
827 <ulink url="http://clef.iei.pi.cnr.it"/>.
828 <!-- or <ulink url="http://www4.eurospider.ch/CLEF/"/> -->
831 For more information, contact Johannes Leveling
832 <email>Johannes.Leveling@FernUni-Hagen.De</email>
836 <section id="various-web-indexes">
837 <title>Various web indexes</title>
839 &zebra; has been used by a variety of institutions to construct
840 indexes of large web sites, typically in the region of tens of
841 millions of pages. In this role, it functions somewhat similarly
842 to the engine of google or altavista, but for a selected intranet
843 or a subset of the whole Web.
846 For example, Liverpool University's web-search facility (see on
848 <ulink url="http://www.liv.ac.uk/"/>
849 and many sub-pages) works by relevance-searching a &zebra; database
850 which is populated by the Harvest-NG web-crawling software.
853 For more information on Liverpool university's intranet search
854 architecture, contact John Gilbertson
855 <email>jgilbert@liverpool.ac.uk</email>
859 has recently modified the Harvest web indexer to use &zebra; as
860 its native repository engine. His comments on the switch over
861 from the old engine are revealing:
864 The first results after some testing with &zebra; are very
865 promising. The tests were done with around 220,000 SOIF files,
866 which occupies 1.6GB of disk space.
869 Building the index from scratch takes around one hour with &zebra;
870 where [old-engine] needs around five hours. While [old-engine]
871 blocks search requests when updating its index, &zebra; can still
872 answer search requests.
874 &zebra; supports incremental indexing which will speed up indexing
878 While the search time of [old-engine] varies from some seconds
879 to some minutes depending how expensive the query is, &zebra;
880 usually takes around one to three seconds, even for expensive
883 &zebra; can search more than 100 times faster than [old-engine]
884 and can process multiple search requests simultaneously
887 I am very happy to see such nice software available under GPL.
895 <section id="introduction-support">
896 <title>Support</title>
898 You can get support for &zebra; from at least three sources.
901 First, there's the &zebra; web site at
902 <ulink url="&url.idzebra;"/>,
903 which always has the most recent version available for download.
904 If you have a problem with &zebra;, the first thing to do is see
905 whether it's fixed in the current release.
908 Second, there's the &zebra; mailing list. Its home page at
909 <ulink url="&url.idzebra.mailinglist;"/>
910 includes a complete archive of all messages that have ever been
911 posted on the list. The &zebra; mailing list is used both for
912 announcements from the authors (new
913 releases, bug fixes, etc.) and general discussion. You are welcome
914 to seek support there. Join by filling the form on the list home page.
917 Third, it's possible to buy a commercial support contract, with
918 well defined service levels and response times, from Index Data.
920 <ulink url="&url.indexdata.support;"/>
926 <section id="future">
927 <title>Future Directions</title>
930 These are some of the plans that we have for the software in the near
931 and far future, ordered approximately as we expect to work on them.
939 Improved support for &xml; in search and retrieval. Eventually,
940 the goal is for &zebra; to pull double duty as a flexible
941 information retrieval engine and high-performance &xml;
942 repository. The recent addition of XPath searching is one
943 example of the kind of enhancement we're working on.
946 There is also the experimental <literal>ALVIS &xslt;</literal>
947 &xml; input filter, which unleashes the full power of &dom; based
948 &xslt; transformations during indexing and record retrieval. Work
949 on this filter has been sponsored by the ALVIS EU project
950 <ulink url="http://www.alvis.info/alvis/"/>. We expect this filter to
951 mature soon, as it is planned to be included in the version 2.0
958 Finalisation and documentation of &zebra;'s C programming
959 &api;, allowing updates, database management and other functions
960 not readily expressed in &z3950;. We will also consider
961 exposing the &api; through &soap;.
967 Improved free-text searching. We're first and foremost octet jockeys and
968 we're actively looking for organisations or people who'd like
969 to contribute experience in relevance ranking and text
978 Programmers thrive on user feedback. If you are interested in a
979 facility that you don't see mentioned here, or if there's something
980 you think we could do better, please drop us a mail. Better still,
981 implement it and send us the patches.
984 If you think it's all really neat, you're welcome to drop us a line
985 saying that, too. You can email us on
986 <email>info@indexdata.dk</email>
987 or check the contact info at the end of this manual.
992 <!-- Keep this comment at the end of the file
997 sgml-minimize-attributes:nil
998 sgml-always-quote-attributes:t
1001 sgml-parent-document: "zebra.xml"
1002 sgml-local-catalogs: nil
1003 sgml-namecase-general:t