X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=doc%2Fintroduction.xml;h=97780083479be61615791f98c8284b4f3c861f7f;hb=ca4101c308ad8427fafba129a4f58a8b38ead63e;hp=1fbb3aa43cea4802d5c2e68984b9674664b640af;hpb=a31f9b2d25006c89ae7e9fb5870c0d222ee88a3a;p=idzebra-moved-to-github.git diff --git a/doc/introduction.xml b/doc/introduction.xml index 1fbb3aa..9778008 100644 --- a/doc/introduction.xml +++ b/doc/introduction.xml @@ -1,293 +1,1001 @@ -Introduction - - -Overview - - -The Zebra system is a fielded free-text indexing and retrieval engine with a -Z39.50 frontend. You can use any commercial or freeware Z39.50 client -to access data stored in Zebra. - - - -The Zebra server is our first step towards the development of a fully -configurable, open information system. Eventually, it will be paired -off with a powerful Z39.50 client to support complex information -management tasks within almost any application domain. We're making -the server available now because it's no fun to be in the open -information retrieval business all by yourself. We want to allow -people with interesting data to make their things -available in interesting ways, without having to start out -by implementing yet another protocol stack from scratch. - - - -This document is an introduction to the Zebra system. It will tell you -how to compile the software, and how to prepare your first database. -It also explains how the server can be configured to give you the -functionality that you need. - - - -If you find the software interesting, you should join the support -mailing-list by sending email to zebra-request@indexdata.dk. - - - - - -Features - - -This is a list of some of the most important features of the -system. - - - - - - - - -Supports updating - records can be added and deleted without -rebuilding the index from scratch. -The update procedure is tolerant to crashes or hard interrupts -during register updating - registers can be reconstructed following a crash. -Registers can be safely updated even while users are accessing the server. - - - - - - -Supports large databases - files for indices, etc. can be -automatically partitioned over multiple disks. - - - - - - -Supports arbitrarily complex records - base input format is an -SGML-like syntax which allows nested (structured) data elements, as -well as variant forms of data. - - - - - - -Supports random storage formats. A system of input filters driven by -regular expressions allows you to easily process most ASCII-based -data formats. SGML, ISO2709 (MARC), and raw text are also supported. - - - - - - -Supports boolean queries as well as relevance-ranking (free-text) -searching. Right truncation and masking in terms are supported, as -well as full regular expressions. - - - - - - -Supports multiple concrete syntaxes -for record exchange (depending on the configuration): GRS-1, SUTRS, -ISO2709 (*MARC). Records can be mapped between record syntaxes and -schema on the fly. - - - - - - -Supports approximate matching in registers (ie. spelling mistakes, -etc). - - - - - - - - - -Protocol support: - - - - - - - - -Protocol facilities: Init, Search, Retrieve, Browse and Sort. - - - - - - -Piggy-backed presents are honored in the search-request. - - - - - - -Named result sets are supported. - - - - - - -Easily configured to support different application profiles, with -tables for attribute sets, tag sets, and abstract syntaxes. -Additional tables control facilities such as element mappings to -different schema (eg., GILS-to-USMARC). - - - - - - -Complex composition specifications using Espec-1 are partially -supported (simple element requests only). - - - - - - -Element Set Names are defined using the Espec-1 capability of the -system, and are given in configuration files as simple element -requests (and possibly variant requests). - - - - - - -Some variant support (not fully implemented yet). - - - - - - -Using the YAZ toolkit for the protocol implementation, the -server can utilise a plug-in XTI/mOSI implementation (not included) to -provide SR services over an OSI stack, as well as Z39.50 over TCP/IP. - - - - - - -Zebra runs on most Unix-like systems as well as Windows NT - a binary -distribution for Windows NT is forthcoming - so far, the installation -requires MSVC++ to compile the system (we use version 5.0). - - - - - - - - - - - -Future Work - - -This is a beta-release of the software, to allow you to look at -it - try it out, and assess whether it can be of use to you. - - - -These are some of the plans that we have for the software in the near -and far future, approximately ordered after their relative importance. -Items marked with an -asterisk will be implemented before the -last beta release. - - - - - - - - -*Complete the support for variants. - - - - - - -*Finalize the data element include facility -to support multimedia data elements in records. - - - - - - -Add more sophisticated relevance ranking mechanisms. Add support for soundex -and stemming. Add relevance feedback support. - - - - - - -Complete EXPLAIN support. - - - - - - -Add support for very large records by implementing segmentation and/or -variant pieces. - - - - - - -Support the Item Update extended service of the protocol. - - - - - - -We want to add a management system that allows you to -control your databases and configuration tables from a graphical -interface. We'll probably use Tcl/Tk to stay platform-independent. - - - - - - - - - -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. If you think it's all really -neat, you're welcome to drop us a line saying that, too. You'll find -contact info at the end of this file. - - - + + 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. + + + + +
+ + + + &zebra; search functionality + + + + Feature + Availability + Notes + Reference + + + + + Query languages + &cql; and &rpn;/&pqf; + The type-1 Reverse Polish Notation (&rpn;) + and it's textual representation Prefix Query Format (&pqf;) are + supported. The Common Query Language (&cql;) can be configured as + a mapping from &cql; to &rpn;/&pqf; + + + + + Complex boolean query tree + &cql; and &rpn;/&pqf; + Both &cql; and &rpn;/&pqf; allow atomic query parts (&apt;) to + be combined into complex boolean query trees + + + + Field search + user defined + Atomic query parts (&apt;) are either general, or + directed at user-specified document fields + + + + + Data normalization + + Data normalization, text tokenization and character mappings can be + applied during indexing and searching + + + + Predefined field types + + Data fields can be indexed as phrase, as into word tokenized text, + as numeric values, url's, dates, and raw binary data. + + + + Regular expression matching + Regexp + Full regular expression matching and "approximate + matching" (eg. spelling mistake corrections) are handled. + + + + Search truncation + + + + + + Fuzzy searches + + In addition, fuzzy searches are implemented, where one + spelling mistake in search terms is matched + + + + + + + + + &zebra; index scanning + + + + Feature + Availability + Notes + Reference + + + + + Scan + yes + Scan on a given named index returns all the + indexed terms in lexicographical order near the given start term. + + + + Facetted browsing + partial + &zebra; supports scan inside a hit + set from a previous search, thus reducing the listed + terms to the + subset of terms found in the documents/records of the hit set. + + + + Drill-down or refine-search + partially + scanning in result sets can be used to implement + drill-down in search clients + + + + +
+ + + + &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. + + + + + 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. + + + + &xml;ocument transformations + &xslt; based + Record presentation can be performed in many pre-defined &xml; data + formats, where the original &xml; records are on-the-fly transformed + through any preconfigured &xslt; transformation. It is therefore + trivial to present records in short/full &xml; views, transforming to + RSS, Dublin Core, or other &xml; based data formats, or transform + records to XHTML snippets ready for inserting in XHTML pages. + + + + Binary record transformations + &marc;, &usmarc;, &marc21; and &marcxml; + + + + + Record Syntaxes + + Multiple record syntaxes + for data retrieval: &grs1;, &sutrs;, + &xml;, ISO2709 (&marc;), etc. Records can be mapped between record syntaxes + and schemas on the fly. + + + + +
+ + + + &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. + + + + 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. + + + + Relevence ranking + TDF-IDF like + + + + + +
+ + + + + &zebra; document model + + + + Feature + Availability + Notes + Reference + + + + + Complex semi-structured Documents + &xml; and &grs1; Documents + Both &xml; and &grs1; documents exhibit a &dom; like internal + representation allowing for complex indexing and display rules + + + + Input document formats + &xml;, &sgml;, Text, ISO2709 (&marc;) + + A system of input filters driven by + regular expressions allows most ASCII-based + data formats to be easily processed. + &sgml;, &xml;, ISO2709 (&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. + + + + + +
+ + + + + &zebra; data size and scalability + + + + Feature + Availability + Notes + Reference + + + + + No of records + 40-60 million + + + + + Data size + 100 GB of record data + + + + + File pointers + 64 bit + + + + + 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 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; live updates + + + + Feature + Availability + Notes + Reference + + + + + 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. + + + + Incremental updates + + + + + + Remote updates + &z3950; extended services + + + + + Live updates + + 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. + + + + Database updates + live, incremental updates + Robust updating - records can be added and deleted ``on the fly'' + without rebuilding the index from scratch. + Records can be safely updated even while users are accessing + the server. + The update procedure is tolerant to crashes or hard interrupts + during database updating - data can be reconstructed following + a crash. + + + + +
+ + + &zebra; supported platforms + + + + Feature + Availability + Notes + Reference + + + + + Linux + + GNU Linux (32 and 64bit), journaling Reiser or (better) JFS filesystem + on disks. GNU/Debian Linux packages are available + + + + Unix + tarball + Usual tarball install possible on many major Unix systems + + + + Windows + + Windows installer packages available + + + + Supported Platforms + UNIX, Linux, Windows (NT/2000/2003/XP) + &zebra; is written in portable C, so it runs on most + Unix-like systems as well as Windows (NT/2000/2003/XP). Binary + distributions are + available for GNU/Debian Linux and Windows + + + + +
+ + + +
+ +
+ 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 + + Koha is a full-featured + 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. + + + 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 + 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;. + + + "&zebra; completely eliminates scalability limitations, because it + can support tens of millions of records." explained Joshua + 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." + + + "&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; + protocol, it greatly improves Koha's support for that critical + 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. + + + See also LibLime's newsletter article + + 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. + + + As a surplus, 100% &marc; compatibility has been achieved using the + &zebra; Server from Index Data as backend server. + +
+ +
+ 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. + + + Reindex.net runs on GNU/Debian Linux with &zebra; and Simpleserver + 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. + +
+ +
+ 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. + + + 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. + + + 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. + +
+ + +
+ 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. + +
+ +
+
+ + +
+ Support + + You can get support for &zebra; from at least three sources. + + + First, there's the &zebra; web site at + , + which always has the most recent version available for download. + If you have a problem with &zebra;, the first thing to do is see + whether it's fixed in the current release. + + + Second, there's the &zebra; mailing list. Its home page at + + includes a complete archive of all messages that have ever been + posted on the list. The &zebra; mailing list is used both for + announcements from the authors (new + 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. + + +
+