%local; %entities; %idcommon; ]> zebra &version; Index Data zebrasrv 8 Commands zebrasrv Zebra Server &zebrasrv-synopsis; DESCRIPTION Zebra is a high-performance, general-purpose structured text indexing and retrieval engine. It reads structured records in a variety of input formats (e.g. email, &acro.xml;, &acro.marc;) and allows access to them through exact boolean search expressions and relevance-ranked free-text queries. zebrasrv is the &acro.z3950; and &acro.sru; frontend server for the Zebra search engine and indexer. On Unix you can run the zebrasrv server from the command line - and put it in the background. It may also operate under the inet daemon. On WIN32 you can run the server as a console application or as a WIN32 Service. OPTIONS The options for zebrasrv are the same as those for &yaz;' yaz-ztest. Option -c specifies a Zebra configuration file - if omitted zebra.cfg is read. &zebrasrv-options; &acro.z3950; Protocol Support and Behavior &acro.z3950; Initialization During initialization, the server will negotiate to version 3 of the &acro.z3950; protocol, and the option bits for Search, Present, Scan, NamedResultSets, and concurrentOperations will be set, if requested by the client. The maximum PDU size is negotiated down to a maximum of 1 MB by default. &acro.z3950; Search The supported query type are 1 and 101. All operators are currently supported with the restriction that only proximity units of type "word" are supported for the proximity operator. Queries can be arbitrarily complex. Named result sets are supported, and result sets can be used as operands without limitations. Searches may span multiple databases. The server has full support for piggy-backed retrieval (see also the following section). &acro.z3950; Present The present facility is supported in a standard fashion. The requested record syntax is matched against the ones supported by the profile of each record retrieved. If no record syntax is given, &acro.sutrs; is the default. The requested element set name, again, is matched against any provided by the relevant record profiles. &acro.z3950; Scan The attribute combinations provided with the termListAndStartPoint are processed in the same way as operands in a query (see above). Currently, only the term and the globalOccurrences are returned with the termInfo structure. &acro.z3950; Sort &acro.z3950; specifies three different types of sort criteria. Of these Zebra supports the attribute specification type in which case the use attribute specifies the "Sort register". Sort registers are created for those fields that are of type "sort" in the default.idx file. The corresponding character mapping file in default.idx specifies the ordinal of each character used in the actual sort. &acro.z3950; allows the client to specify sorting on one or more input result sets and one output result set. Zebra supports sorting on one result set only which may or may not be the same as the output result set. &acro.z3950; Close If a Close PDU is received, the server will respond with a Close PDU with reason=FINISHED, no matter which protocol version was negotiated during initialization. If the protocol version is 3 or more, the server will generate a Close PDU under certain circumstances, including a session timeout (60 minutes by default), and certain kinds of protocol errors. Once a Close PDU has been sent, the protocol association is considered broken, and the transport connection will be closed immediately upon receipt of further data, or following a short timeout. &acro.z3950; Explain Zebra maintains a "classic" &acro.z3950; Explain database on the side. This database is called IR-Explain-1 and can be searched using the attribute set exp-1. The records in the explain database are of type grs.sgml. The root element for the Explain grs.sgml records is explain, thus explain.abs is used for indexing. Zebra must be able to locate explain.abs in order to index the Explain records properly. Zebra will work without it but the information will not be searchable. The &acro.sru; Server In addition to &acro.z3950;, Zebra supports the more recent and web-friendly IR protocol &acro.sru;. &acro.sru; can be carried over &acro.soap; or a &acro.rest;-like protocol that uses HTTP &acro.get; or &acro.post; to request search responses. The request itself is made of parameters such as query, startRecord, maximumRecords and recordSchema; the response is an &acro.xml; document containing hit-count, result-set records, diagnostics, etc. &acro.sru; can be thought of as a re-casting of &acro.z3950; semantics in web-friendly terms; or as a standardisation of the ad-hoc query parameters used by search engines such as Google and AltaVista; or as a superset of A9's OpenSearch (which it predates). Zebra supports &acro.z3950;, &acro.sru; &acro.get;, SRU &acro.post;, SRU &acro.soap; (&acro.srw;) - on the same port, recognising what protocol is used by each incoming requests and handling them accordingly. This is a achieved through the use of Deep Magic; civilians are warned not to stand too close. Running zebrasrv as an &acro.sru; Server Because Zebra supports all protocols on one port, it would seem to follow that the &acro.sru; server is run in the same way as the &acro.z3950; server, as described above. This is true, but only in an uninterestingly vacuous way: a Zebra server run in this manner will indeed recognise and accept &acro.sru; requests; but since it doesn't know how to handle the &acro.cql; queries that these protocols use, all it can do is send failure responses. It is possible to cheat, by having &acro.sru; search Zebra with a &acro.pqf; query instead of &acro.cql;, using the x-pquery parameter instead of query. This is a non-standard extension of &acro.cql;, and a very naughty thing to do, but it does give you a way to see Zebra serving &acro.sru; ``right out of the box''. If you start your favourite Zebra server in the usual way, on port 9999, then you can send your web browser to: http://localhost:9999/Default?version=1.1 &operation=searchRetrieve &x-pquery=mineral &startRecord=1 &maximumRecords=1 This will display the &acro.xml;-formatted &acro.sru; response that includes the first record in the result-set found by the query mineral. (For clarity, the &acro.sru; URL is shown here broken across lines, but the lines should be joined together to make single-line URL for the browser to submit.) In order to turn on Zebra's support for &acro.cql; queries, it's necessary to have the &yaz; generic front-end (which Zebra uses) translate them into the &acro.z3950; Type-1 query format that is used internally. And to do this, the generic front-end's own configuration file must be used. See ; the salient point for &acro.sru; support is that zebrasrv must be started with the -f frontendConfigFile option rather than the -c zebraConfigFile option, and that the front-end configuration file must include both a reference to the Zebra configuration file and the &acro.cql;-to-&acro.pqf; translator configuration file. A minimal front-end configuration file that does this would read as follows: zebra.cfg ../../tab/pqf.properties ]]> The <config> element contains the name of the Zebra configuration file that was previously specified by the -c command-line argument, and the <cql2rpn> element contains the name of the &acro.cql; properties file specifying how various &acro.cql; indexes, relations, etc. are translated into Type-1 queries. A zebra server running with such a configuration can then be queried using proper, conformant &acro.sru; URLs with &acro.cql; queries: http://localhost:9999/Default?version=1.1 &operation=searchRetrieve &query=title=utah and description=epicent* &startRecord=1 &maximumRecords=1 &acro.sru; Protocol Support and Behavior Zebra running as an &acro.sru; server supports SRU version 1.1, including &acro.cql; version 1.1. In particular, it provides support for the following elements of the protocol. &acro.sru; Search and Retrieval Zebra supports the &acro.sru; searchRetrieve operation. One of the great strengths of &acro.sru; is that it mandates a standard query language, &acro.cql;, and that all conforming implementations can therefore be trusted to correctly interpret the same queries. It is with some shame, then, that we admit that Zebra also supports an additional query language, our own Prefix Query Format (&acro.pqf;). A &acro.pqf; query is submitted by using the extension parameter x-pquery, in which case the query parameter must be omitted, which makes the request not valid &acro.sru;. Please feel free to use this facility within your own applications; but be aware that it is not only non-standard &acro.sru; but not even syntactically valid, since it omits the mandatory query parameter. &acro.sru; Scan Zebra supports &acro.sru; scan operation. Scanning using &acro.cql; syntax is the default, where the standard scanClause parameter is used. In addition, a mutant form of &acro.sru; scan is supported, using the non-standard x-pScanClause parameter in place of the standard scanClause to scan on a &acro.pqf; query clause. &acro.sru; Explain Zebra supports &acro.sru; explain. The ZeeRex record explaining a database may be requested either with a fully fledged &acro.sru; request (with operation=explain and version-number specified) or with a simple HTTP &acro.get; at the server's basename. The ZeeRex record returned in response is the one embedded in the &yaz; Frontend Server configuration file that is described in the . Unfortunately, the data found in the &acro.cql;-to-&acro.pqf; text file must be added by hand-craft into the explain section of the &yaz; Frontend Server configuration file to be able to provide a suitable explain record. Too bad, but this is all extreme new alpha stuff, and a lot of work has yet to be done .. There is no linkage whatsoever between the &acro.z3950; explain model and the &acro.sru; explain response (well, at least not implemented in Zebra, that is ..). Zebra does not provide a means using &acro.z3950; to obtain the ZeeRex record. Other &acro.sru; operations In the &acro.z3950; protocol, Initialization, Present, Sort and Close are separate operations. In &acro.sru;, however, these operations do not exist. &acro.sru; has no explicit initialization handshake phase, but commences immediately with searching, scanning and explain operations. Neither does &acro.sru; have a close operation, since the protocol is stateless and each request is self-contained. (It is true that multiple &acro.sru; request/response pairs may be implemented as multiple HTTP request/response pairs over a single persistent TCP/IP connection; but the closure of that connection is not a protocol-level operation.) Retrieval in &acro.sru; is part of the searchRetrieve operation, in which a search is submitted and the response includes a subset of the records in the result set. There is no direct analogue of &acro.z3950;'s Present operation which requests records from an established result set. In &acro.sru;, this is achieved by sending a subsequent searchRetrieve request with the query cql.resultSetId=id where id is the identifier of the previously generated result-set. Sorting in &acro.cql; is done within the searchRetrieve operation - in v1.1, by an explicit sort parameter, but the forthcoming v1.2 or v2.0 will most likely use an extension of the query language, &acro.cql; sorting. It can be seen, then, that while Zebra operating as an &acro.sru; server does not provide the same set of operations as when operating as a &acro.z3950; server, it does provide equivalent functionality. &acro.sru; Examples Surf into http://localhost:9999 to get an explain response, or use See number of hits for a query Fetch record 5-7 in Dublin Core format Even search using &acro.pqf; queries using the extended naughty parameter x-pquery Or scan indexes using the extended extremely naughty parameter x-pScanClause Don't do this in production code! But it's a great fast debugging aid. &yaz; server virtual hosts &zebrasrv-virtual; SEE ALSO zebraidx 1