X-Git-Url: http://git.indexdata.com/?p=idzebra-moved-to-github.git;a=blobdiff_plain;f=doc%2Fintroduction.xml;h=d4b7e192aed509de57310873659c4ad16c5f0d69;hp=97780083479be61615791f98c8284b4f3c861f7f;hb=f3f20a205132c39c9434b10086422c6b49b47faf;hpb=ca4101c308ad8427fafba129a4f58a8b38ead63e diff --git a/doc/introduction.xml b/doc/introduction.xml index 9778008..d4b7e19 100644 --- a/doc/introduction.xml +++ b/doc/introduction.xml @@ -1,631 +1,699 @@ - - + Introduction - -
- Overview - - - &zebra; is a free, fast, friendly information management system. It can - index records in &xml;/&sgml;, &marc;, e-mail archives and many other - formats, and quickly find them using a combination of boolean - searching and relevance ranking. Search-and-retrieve applications can - be written using &api;s in a wide variety of languages, communicating - with the &zebra; server using industry-standard information-retrieval - protocols or web services. - - - &zebra; is licensed Open Source, and can be - deployed by anyone for any purpose without license fees. The C source - code is open to anybody to read and change under the GPL license. - - - &zebra; is a networked component which acts as a reliable &z3950; server - for both record/document search, presentation, insert, update and - delete operations. In addition, it understands the &sru; family of - webservices, which exist in &rest; &get;/&post; and truly &soap; flavors. - - - &zebra; is available as MS Windows 2003 Server (32 bit) self-extracting - package as well as GNU/Debian Linux (32 bit and 64 bit) precompiled - packages. It has been deployed successfully on other Unix systems, - including Sun Sparc, HP Unix, and many variants of Linux and BSD - based systems. - - - http://www.indexdata.com/zebra/ - http://ftp.indexdata.dk/pub/zebra/win32/ - http://ftp.indexdata.dk/pub/zebra/debian/ - - - &zebra; - is a high-performance, general-purpose structured text - indexing and retrieval engine. It reads records in a - variety of input formats (eg. email, &xml;, &marc;) and provides access - to them through a powerful combination of boolean search - expressions and relevance-ranked free-text queries. - - - - &zebra; supports large databases (tens of millions of records, - tens of gigabytes of data). It allows safe, incremental - database updates on live systems. Because &zebra; supports - the industry-standard information retrieval protocol, &z3950;, - you can search &zebra; databases using an enormous variety of - programs and toolkits, both commercial and free, which understand - this protocol. Application libraries are available to allow - bespoke clients to be written in Perl, C, C++, Java, Tcl, Visual - Basic, Python, &php; and more - see the - &zoom; web site - for more information on some of these client toolkits. - - - - This document is an introduction to the &zebra; system. It explains - how to compile the software, how to prepare your first database, - and how to configure the server to give you the - functionality that you need. - -
- -
- &zebra; Features Overview - - - - - - - &zebra; networked protocols - - - - Feature - Availability - Notes - Reference - - - - - Fundamental operation types - &z3950;/&sru; explain, search, and scan - - - - - &z3950; protocol support - yes - Protocol facilities supported are: - Init, Search, Present (retrieval), - Segmentation (support for very large records), Delete, Scan - (index browsing), Sort, Close and support for the ``update'' - Extended Service to add or replace an existing &xml; - record. Piggy-backed presents are honored in the search - request. Named result sets are supported. - - - - Web Service support - &sru_gps; - The protocol operations explain, - searchRetrieve and scan - are supported. &cql; to internal - query model &rpn; - conversion is supported. Extended RPN queries - for search/retrieve and scan are supported. - - - - -
- - - +
+ Overview + + &zebra; is a free, fast, friendly information management system. It can + index records in &acro.xml;/&acro.sgml;, &acro.marc;, e-mail archives and many other + formats, and quickly find them using a combination of boolean + searching and relevance ranking. Search-and-retrieve applications can + be written using &acro.api;s in a wide variety of languages, communicating + with the &zebra; server using industry-standard information-retrieval + protocols or web services. + + + &zebra; is licensed Open Source, and can be + deployed by anyone for any purpose without license fees. The C source + code is open to anybody to read and change under the GPL license. + + + &zebra; is a networked component which acts as a + reliable &acro.z3950; server + for both record/document search, presentation, insert, update and + delete operations. In addition, it understands the &acro.sru; family of + webservices, which exist in &acro.rest; &acro.get;/&acro.post; and truly + &acro.soap; flavors. + + + &zebra; is available as MS Windows 2003 Server (32 bit) self-extracting + package as well as GNU/Debian Linux (32 bit and 64 bit) precompiled + packages. It has been deployed successfully on other Unix systems, + including Sun Sparc, HP Unix, and many variants of Linux and BSD + based systems. + + + http://www.indexdata.com/zebra/ + http://ftp.indexdata.dk/pub/zebra/win32/ + http://ftp.indexdata.dk/pub/zebra/debian/ + + + + &zebra; + is a high-performance, general-purpose structured text + indexing and retrieval engine. It reads records in a + variety of input formats (e.g. email, &acro.xml;, &acro.marc;) and provides access + to them through a powerful combination of boolean search + expressions and relevance-ranked free-text queries. + + + + &zebra; supports large databases (tens of millions of records, + tens of gigabytes of data). It allows safe, incremental + database updates on live systems. Because &zebra; supports + the industry-standard information retrieval protocol, &acro.z3950;, + you can search &zebra; databases using an enormous variety of + programs and toolkits, both commercial and free, which understand + this protocol. Application libraries are available to allow + bespoke clients to be written in Perl, C, C++, Java, Tcl, Visual + Basic, Python, &acro.php; and more - see the + &acro.zoom; web site + for more information on some of these client toolkits. + + + + This document is an introduction to the &zebra; system. It explains + how to compile the software, how to prepare your first database, + and how to configure the server to give you the + functionality that you need. + +
+ +
+ &zebra; Features Overview + +
+ &zebra; Document Model + +
+ &zebra; document model + + + + + + + + Feature + Availability + Notes + Reference + + + + + Complex semi-structured Documents + &acro.xml; and &acro.grs1; Documents + Both &acro.xml; and &acro.grs1; documents exhibit a &acro.dom; like internal + representation allowing for complex indexing and display rules + and + + + + Input document formats + &acro.xml;, &acro.sgml;, Text, ISO2709 (&acro.marc;) + + A system of input filters driven by + regular expressions allows most ASCII-based + data formats to be easily processed. + &acro.sgml;, &acro.xml;, ISO2709 (&acro.marc;), and raw text are also + supported. + + + + Document storage + Index-only, Key storage, Document storage + Data can be, and usually is, imported + into &zebra;'s own storage, but &zebra; can also refer to + external files, building and maintaining indexes of "live" + collections. + + + + + +
+
+ + - + + + + + + + + Feature + Availability + Notes + Reference + + + + + Query languages + &acro.cql; and &acro.rpn;/&acro.pqf; + The type-1 Reverse Polish Notation (&acro.rpn;) + and its textual representation Prefix Query Format (&acro.pqf;) are + supported. The Common Query Language (&acro.cql;) can be configured as + a mapping from &acro.cql; to &acro.rpn;/&acro.pqf; + and + + + + Complex boolean query tree + &acro.cql; and &acro.rpn;/&acro.pqf; + Both &acro.cql; and &acro.rpn;/&acro.pqf; allow atomic query parts (&acro.apt;) to + be combined into complex boolean query trees + + + + Field search + user defined + Atomic query parts (&acro.apt;) are either general, or + directed at user-specified document fields + + , + , + , and + + + + Data normalization + user defined + Data normalization, text tokenization and character + mappings can be applied during indexing and searching + + + + Predefined field types + user defined + Data fields can be indexed as phrase, as into word + tokenized text, as numeric values, URLs, dates, and raw binary + data. + and + + + + + Regular expression matching + available + Full regular expression matching and "approximate + matching" (e.g. spelling mistake corrections) are handled. + + + + Term truncation + left, right, left-and-right + The truncation attribute specifies whether variations of + one or more characters are allowed between search term and hit + terms, or not. Using non-default truncation attributes will + broaden the document hit set of a search query. + + + + Fuzzy searches + Spelling correction + In addition, fuzzy searches are implemented, where one + spelling mistake in search terms is matched + + + + + + + +
+ &zebra; Index Scanning + + + &zebra; index scanning + + + + + + + + Feature + Availability + Notes + Reference + + + + + Scan + term suggestions + Scan on a given named index returns all the + indexed terms in lexicographical order near the given start + term. This can be used to create drop-down menus and search + suggestions. + and + + + + + Facetted browsing + available + Zebra 2.1 and allows retrieval of facets for + a result set. + + + + + Drill-down or refine-search + partially + scanning in result sets can be used to implement + drill-down in search clients + + + + +
+
+ +
+ &zebra; Document Presentation + + + &zebra; document presentation + + + + + + + + Feature + Availability + Notes + Reference + + + + + Hit count + yes + Search results include at any time the total hit count of a given + query, either exact computed, or approximative, in case that the + hit count exceeds a possible pre-defined hit set truncation + level. + + and + + + + + Paged result sets + yes + Paging of search requests and present/display request + can return any successive number of records from any start + position in the hit set, i.e. it is trivial to provide search + results in successive pages of any size. + + + + &acro.xml; document transformations + &acro.xslt; based + Record presentation can be performed in many + pre-defined &acro.xml; data + formats, where the original &acro.xml; records are on-the-fly transformed + through any preconfigured &acro.xslt; transformation. It is therefore + trivial to present records in short/full &acro.xml; views, transforming to + RSS, Dublin Core, or other &acro.xml; based data formats, or transform + records to XHTML snippets ready for inserting in XHTML pages. + + + + + Binary record transformations + &acro.marc;, &acro.usmarc;, &acro.marc21; and &acro.marcxml; + post-filter record transformations + + + + Record Syntaxes + + Multiple record syntaxes + for data retrieval: &acro.grs1;, &acro.sutrs;, + &acro.xml;, ISO2709 (&acro.marc;), etc. Records can be mapped between + record syntaxes and schemas on the fly. + + + + &zebra; internal metadata + yes + &zebra; internal document metadata can be fetched in + &acro.sutrs; and &acro.xml; record syntaxes. Those are useful in client + applications. + + + + &zebra; internal raw record data + yes + &zebra; internal raw, binary record data can be fetched in + &acro.sutrs; and &acro.xml; record syntaxes, leveraging %zebra; to a + binary storage system + + + + &zebra; internal record field data + yes + &zebra; internal record field data can be fetched in + &acro.sutrs; and &acro.xml; record syntaxes. This makes very fast minimal + record data displays possible. + + + + +
+
+ +
+ &zebra; Sorting and Ranking + + + &zebra; sorting and ranking + + + + + + + + Feature + Availability + Notes + Reference + + + + + Sort + numeric, lexicographic + Sorting on the basis of alpha-numeric and numeric data + is supported. Alphanumeric sorts can be configured for + different data encodings and locales for European languages. + and + + + + Combined sorting + yes + Sorting on the basis of combined sorts ­ e.g. combinations of + ascending/descending sorts of lexicographical/numeric/date field data + is supported + + + + Relevance ranking + TF-IDF like + Relevance-ranking of free-text queries is supported + using a TF-IDF like algorithm. + + + + Static pre-ranking + yes + Enables pre-index time ranking of documents where hit + lists are ordered first by ascending static rank, then by + ascending document ID. + + + + +
+
+ + +
+ &zebra; Live Updates + + + + &zebra; live updates + + + + + + + + Feature + Availability + Notes + Reference + + + + + Incremental and batch updates + + It is possible to schedule record inserts/updates/deletes in any + quantity, from single individual handled records to batch updates + in strikes of any size, as well as total re-indexing of all records + from file system. + + + + Remote updates + &acro.z3950; extended services + Updates can be performed from remote locations using the + &acro.z3950; extended services. Access to extended services can be + login-password protected. + and + + + + Live updates + transaction based + Data updates are transaction based and can be performed + on running &zebra; systems. Full searchability is preserved + during life data update due to use of shadow disk areas for + update operations. Multiple update transactions at the same + time are lined up, to be performed one after each other. Data + integrity is preserved. + + + + +
+
+ +
+ &zebra; Networked Protocols + + + &zebra; networked protocols + + + + + + + + Feature + Availability + Notes + Reference + + + + + Fundamental operations + &acro.z3950;/&acro.sru; explain, + search, scan, and + update + + + + + &acro.z3950; protocol support + yes + Protocol facilities supported are: + init, search, + present (retrieval), + Segmentation (support for very large records), + delete, scan + (index browsing), sort, + close and support for the update + Extended Service to add or replace an existing &acro.xml; + record. Piggy-backed presents are honored in the search + request. Named result sets are supported. + + + + Web Service support + &acro.sru; + The protocol operations explain, + searchRetrieve and scan + are supported. &acro.cql; to internal + query model &acro.rpn; + conversion is supported. Extended RPN queries + for search/retrieve and scan are supported. + + + + +
+
+ +
+ &zebra; Data Size and Scalability + + + &zebra; data size and scalability + + + + + + + + Feature + Availability + Notes + Reference + + + + + No of records + 40-60 million + + + + + Data size + 100 GB of record data + &zebra; based applications have successfully indexed up + to 100 GB of record data + + + + Scale out + multiple discs + + + + + Performance + O(n * log N) + &zebra; query speed and performance is affected roughly by + O(log N), + where N is the total database size, and by + O(n), where n is the + specific query hit set size. + + + + Average search times + + Even on very large size databases hit rates of 20 queries per + seconds with average query answering time of 1 second are possible, + provided that the boolean queries are constructed sufficiently + precise to result in hit sets of the order of 1000 to 5.000 + documents. + + + + Large databases + 64 bit file pointers + 64 file pointers assure that register files can extend + the 2 GB limit. Logical files can be + automatically partitioned over multiple disks, thus allowing for + large databases. + + + + +
+
+ +
+ &zebra; Supported Platforms + + + &zebra; supported platforms + + + + + + + + Feature + Availability + Notes + Reference + + + + + Linux + + GNU Linux (32 and 64bit), journaling Reiser or (better) + JFS file system + on disks. NFS file systems are not supported. + GNU/Debian Linux packages are available + + + + Unix + tar-ball + &zebra; is written in portable C, so it runs on most + Unix-like systems. + Usual tar-ball install possible on many major Unix systems + + + + Windows + NT/2000/2003/XP + &zebra; runs as well on Windows (NT/2000/2003/XP). + Windows installer packages available + + + + +
+
+ + + +
- References and &zebra; based Applications - - &zebra; has been deployed in numerous applications, in both the - academic and commercial worlds, in application domains as diverse - as bibliographic catalogues, geospatial information, structured - vocabulary browsing, government information locators, civic - information systems, environmental observations, museum information - and web indexes. - - - Notable applications include the following: - - - -
- Koha free open-source ILS + References and &zebra; based Applications + &zebra; has been deployed in numerous applications, in both the + academic and commercial worlds, in application domains as diverse + as bibliographic catalogues, Geo-spatial information, structured + vocabulary browsing, government information locators, civic + information systems, environmental observations, museum information + and web indexes. + + + Notable applications include the following: + + + +
+ Koha free open-source ILS + Koha is a full-featured - open-source ILS, initially developed in + open-source ILS, initially developed in New Zealand by Katipo Communications Ltd, and first deployed in January of 2000 for Horowhenua Library Trust. It is currently maintained by a team of software providers and library technology - staff from around the globe. + staff from around the globe. - LibLime, + LibLime, a company that is marketing and supporting Koha, adds in the new release of Koha 3.0 the &zebra; database server to drive its bibliographic database. In early 2005, the Koha project development team began looking at - ways to improve &marc; support and overcome scalability limitations + ways to improve &acro.marc; support and overcome scalability limitations in the Koha 2.x series. After extensive evaluations of the best of the Open Source textual database engines - including MySQL full-text searching, PostgreSQL, Lucene and Plucene - the team - selected &zebra;. + selected &zebra;. "&zebra; completely eliminates scalability limitations, because it @@ -633,72 +701,85 @@ Ferraro, LibLime's Technology President and Koha's Project Release Manager. "Our performance tests showed search results in under a second for databases with over 5 million records on a - modest i386 900Mhz test server." + modest i386 900Mhz test server." "&zebra; also includes support for true boolean search expressions and relevance-ranked free-text queries, both of which the Koha 2.x series lack. &zebra; also supports incremental and safe database updates, which allow on-the-fly record - management. Finally, since &zebra; has at its heart the &z3950; + management. Finally, since &zebra; has at its heart the &acro.z3950; protocol, it greatly improves Koha's support for that critical - library standard." + library standard." - + Although the bibliographic database will be moved to &zebra;, Koha 3.0 will continue to use a relational SQL-based database design for the 'factual' database. "Relational database managers have their strengths, in spite of their inability to handle large numbers of bibliographic records efficiently," summed up Ferraro, "We're taking the best from both worlds in our redesigned Koha - 3.0. - - + 3.0. + + See also LibLime's newsletter article - - Koha Earns its Stripes. - + + Koha Earns its Stripes. +
-
- Emilda open source ILS - - Emilda - is a complete Integrated Library System, released under the - GNU General Public License. It has a - full featured Web-OPAC, allowing comprehensive system management - from virtually any computer with an Internet connection, has - template based layout allowing anyone to alter the visual - appearance of Emilda, and is - &xml; based language for fast and easy portability to virtually any - language. - Currently, Emilda is used at three schools in Espoo, Finland. + +
+ Kete Open Source Digital Library and Archiving software + + Kete is a digital object + management repository, initially developed in + New Zealand. Initial development has + been a partnership between the Horowhenua Library Trust and + Katipo Communications Ltd. funded as part of the Community + Partnership Fund in 2006. + Kete is purpose built + software to enable communities to build their own digital + libraries, archives and repositories. + + + It is based on Ruby-on-Rails and MySQL, and integrates the &zebra; server + and the &yaz; toolkit for indexing and retrieval of it's content. + Zebra is run as separate computer process from the Kete + application. + See + how Kete manages + Zebra. - As a surplus, 100% &marc; compatibility has been achieved using the - &zebra; Server from Index Data as backend server. - + Why does Kete wants to use Zebra?? Speed, Scalability and easy + integration with Koha. Read their + detailed + reasoning here. +
-
- ReIndex.Net web based ILS +
+ ReIndex.Net web based ILS Reindex.net is a netbased library service offering all traditional functions on a very high level plus many new services. Reindex.net is a comprehensive and powerful WEB system - based on standards such as &xml; and &z3950;. - updates. Reindex supports &marc21;, dan&marc; eller Dublin Core with - UTF8-encoding. + based on standards such as &acro.xml; and &acro.z3950;. + updates. Reindex supports &acro.marc21;, dan&acro.marc; eller Dublin Core with + UTF8-encoding. Reindex.net runs on GNU/Debian Linux with &zebra; and Simpleserver - from Index + from Index Data for bibliographic data. The relational database system - Sybase 9 &xml; is used for - administrative data. - Internally &marcxml; is used for bibliographical records. Update - utilizes &z3950; extended services. + Sybase 9 &acro.xml; is used for + administrative data. + Internally &acro.marcxml; is used for bibliographical records. Update + utilizes &acro.z3950; extended services.
@@ -706,188 +787,114 @@ DADS - the DTV Article Database Service - DADS is a huge database of more than ten million records, totalling - over ten gigabytes of data. The records are metadata about academic - journal articles, primarily scientific; about 10% of these - metadata records link to the full text of the articles they - describe, a body of about a terabyte of information (although the - full text is not indexed.) - - - It allows students and researchers at DTU (Danmarks Tekniske - Universitet, the Technical College of Denmark) to find and order - articles from multiple databases in a single query. The database - contains literature on all engineering subjects. It's available - on-line through a web gateway, though currently only to registered - users. - - - More information can be found at - and - - -
- -
- Infonet Eprints - - The InfoNet Eprints service from the - - Technical Knowledge Center of Denmark - provides access to documents stored in - eprint/preprint servers and institutional research archives around - the world. The service is based on Open Archives Initiative metadata - harvesting of selected scientific archives around the world. These - open archives offer free and unrestricted access to their contents. + DADS is a huge database of more than ten million records, totalling + over ten gigabytes of data. The records are metadata about academic + journal articles, primarily scientific; about 10% of these + metadata records link to the full text of the articles they + describe, a body of about a terabyte of information (although the + full text is not indexed.) - - Infonet Eprints currently holds 1.4 million records from 16 archives. - The online search facility is found at - . - -
- -
- Alvis - - The Alvis EU - project run under the 6th Framework (IST-1-002068-STP) - is building a semantic-based peer-to-peer search engine. A - consortium of eleven partners from six different European - Community countries plus Switzerland and China contribute - with expertise in a broad range of specialties including network - topologies, routing algorithms, linguistic analysis and - bioinformatics. + + It allows students and researchers at DTU (Danmarks Tekniske + Universitet, the Technical College of Denmark) to find and order + articles from multiple databases in a single query. The database + contains literature on all engineering subjects. It's available + on-line through a web gateway, though currently only to registered + users. - The &zebra; information retrieval indexing machine is used inside - the Alvis framework to - manage huge collections of natural language processed and - enhanced &xml; data, coming from a topic relevant web crawl. - In this application, &zebra; swallows and manages 37GB of &xml; data - in about 4 hours, resulting in search times of fractions of - seconds. - + More information can be found at + and + +
+
+ ULS (Union List of Serials) + + The M25 Systems Team + has created a union catalogue for the periodicals of the + twenty-one constituent libraries of the University of London and + the University of Westminster + (). + They have achieved this using an + unusual architecture, which they describe as a + ``non-distributed virtual union catalogue''. + + + The member libraries send in data files representing their + periodicals, including both brief bibliographic data and summary + holdings. Then 21 individual &acro.z3950; targets are created, each + using &zebra;, and all mounted on the single hardware server. + The live service provides a web gateway allowing &acro.z3950; searching + of all of the targets or a selection of them. &zebra;'s small + footprint allows a relatively modest system to comfortably host + the 21 servers. + + + More information can be found at + + +
-
- ULS (Union List of Serials) - - The M25 Systems Team - has created a union catalogue for the periodicals of the - twenty-one constituent libraries of the University of London and - the University of Westminster - (). - They have achieved this using an - unusual architecture, which they describe as a - ``non-distributed virtual union catalogue''. - - - The member libraries send in data files representing their - periodicals, including both brief bibliographic data and summary - holdings. Then 21 individual &z3950; targets are created, each - using &zebra;, and all mounted on the single hardware server. - The live service provides a web gateway allowing &z3950; searching - of all of the targets or a selection of them. &zebra;'s small - footprint allows a relatively modest system to comfortably host - the 21 servers. - - - More information can be found at - - -
- -
- NLI-&z3950; - a Natural Language Interface for Libraries - - Fernuniversität Hagen in Germany have developed a natural - language interface for access to library databases. - - In order to evaluate this interface for recall and precision, they - chose &zebra; as the basis for retrieval effectiveness. The &zebra; - server contains a copy of the GIRT database, consisting of more - than 76000 records in &sgml; format (bibliographic records from - social science), which are mapped to &marc; for presentation. - - - (GIRT is the German Indexing and Retrieval Testdatabase. It is a - standard German-language test database for intelligent indexing - and retrieval systems. See - ) - - - Evaluation will take place as part of the TREC/CLEF campaign 2003 - . - - - - For more information, contact Johannes Leveling - Johannes.Leveling@FernUni-Hagen.De - +
+ Various web indexes + + &zebra; has been used by a variety of institutions to construct + indexes of large web sites, typically in the region of tens of + millions of pages. In this role, it functions somewhat similarly + to the engine of Google or AltaVista, but for a selected intranet + or a subset of the whole Web. + + + For example, Liverpool University's web-search facility (see on + the home page at + + and many sub-pages) works by relevance-searching a &zebra; database + which is populated by the Harvest-NG web-crawling software. + + + For more information on Liverpool university's intranet search + architecture, contact John Gilbertson + jgilbert@liverpool.ac.uk + + + Kang-Jin Lee + has recently modified the Harvest web indexer to use &zebra; as + its native repository engine. His comments on the switch over + from the old engine are revealing: +
+ + The first results after some testing with &zebra; are very + promising. The tests were done with around 220,000 SOIF files, + which occupies 1.6GB of disk space. + + + Building the index from scratch takes around one hour with &zebra; + where [old-engine] needs around five hours. While [old-engine] + blocks search requests when updating its index, &zebra; can still + answer search requests. + [...] + &zebra; supports incremental indexing which will speed up indexing + even further. + + + While the search time of [old-engine] varies from some seconds + to some minutes depending how expensive the query is, &zebra; + usually takes around one to three seconds, even for expensive + queries. + [...] + &zebra; can search more than 100 times faster than [old-engine] + and can process multiple search requests simultaneously + + + I am very happy to see such nice software available under GPL. + +
+ +
-
- Various web indexes - - &zebra; has been used by a variety of institutions to construct - indexes of large web sites, typically in the region of tens of - millions of pages. In this role, it functions somewhat similarly - to the engine of google or altavista, but for a selected intranet - or a subset of the whole Web. - - - For example, Liverpool University's web-search facility (see on - the home page at - - and many sub-pages) works by relevance-searching a &zebra; database - which is populated by the Harvest-NG web-crawling software. - - - For more information on Liverpool university's intranet search - architecture, contact John Gilbertson - jgilbert@liverpool.ac.uk - - - Kang-Jin Lee - has recently modified the Harvest web indexer to use &zebra; as - its native repository engine. His comments on the switch over - from the old engine are revealing: -
- - The first results after some testing with &zebra; are very - promising. The tests were done with around 220,000 SOIF files, - which occupies 1.6GB of disk space. - - - Building the index from scratch takes around one hour with &zebra; - where [old-engine] needs around five hours. While [old-engine] - blocks search requests when updating its index, &zebra; can still - answer search requests. - [...] - &zebra; supports incremental indexing which will speed up indexing - even further. - - - While the search time of [old-engine] varies from some seconds - to some minutes depending how expensive the query is, &zebra; - usually takes around one to three seconds, even for expensive - queries. - [...] - &zebra; can search more than 100 times faster than [old-engine] - and can process multiple search requests simultaneously - - - I am very happy to see such nice software available under GPL. - -
- -
-
- -
Support @@ -909,82 +916,8 @@ releases, bug fixes, etc.) and general discussion. You are welcome to seek support there. Join by filling the form on the list home page. - - Third, it's possible to buy a commercial support contract, with - well defined service levels and response times, from Index Data. - See - - for details. - -
- - -
- Future Directions - - - These are some of the plans that we have for the software in the near - and far future, ordered approximately as we expect to work on them. - - - - - - - - Improved support for &xml; in search and retrieval. Eventually, - the goal is for &zebra; to pull double duty as a flexible - information retrieval engine and high-performance &xml; - repository. The recent addition of XPath searching is one - example of the kind of enhancement we're working on. - - - There is also the experimental ALVIS &xslt; - &xml; input filter, which unleashes the full power of &dom; based - &xslt; transformations during indexing and record retrieval. Work - on this filter has been sponsored by the ALVIS EU project - . We expect this filter to - mature soon, as it is planned to be included in the version 2.0 - release of &zebra;. - - - - - - Finalisation and documentation of &zebra;'s C programming - &api;, allowing updates, database management and other functions - not readily expressed in &z3950;. We will also consider - exposing the &api; through &soap;. - - - - - - Improved free-text searching. We're first and foremost octet jockeys and - we're actively looking for organisations or people who'd like - to contribute experience in relevance ranking and text - searching. - - - - - - - - Programmers thrive on user feedback. If you are interested in a - facility that you don't see mentioned here, or if there's something - you think we could do better, please drop us a mail. Better still, - implement it and send us the patches. - - - If you think it's all really neat, you're welcome to drop us a line - saying that, too. You can email us on - info@indexdata.dk - or check the contact info at the end of this manual. - - -
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