NAME Wais - access to freeWAIS-sf libraries SYNOPSIS `use Wais;' DESCRIPTION The interface is divided in four major parts. SFgate 4.0 For backward compatibility the functions used in SFgate up to version 4 are still present. Their use is deprecated and they are not documented here. These functions may no be supported in following versions of this module. Protocol XS functions which provide a low-level access to the WAIS protocol. E.g. `generate_search_apdu()' constructs a request message. SFgate 5.0 Perl functions that implement high-level access to WAIS servers. E.g. parallel searching is supported. dictionary A bunch of XS functions useful for inspecting local databases. We will start with the SFgate 5.0 functions. USAGE The main high-level interface are the functions `Wais::Search' and `Wais::Retrieve'. Both return a reference to an object of the class `Wais::Result'. Wais::Search Arguments of `Wais::Search' are hash references, one for each database to search. The keys of the hashes should be: query The query to submit. database The database which should be searched. host host is optional. It defaults to `'localhost''. port port is optional. It defaults to `210'. tag A tag by which individual results can be associated to a database/host/port triple. If omitted defaults to the database name. relevant If present must be a reference to an array containing alternating document id's and types. Document id's must be of type `Wais:Docid'. Here is a complete example: $result = Wais::Search({'query' => 'pfeifer', 'database' => $db1, 'host' => 'ls6', 'relevant' => [$id, 'TEXT']}, {'query' => 'pfeifer', 'database' => $db2}); If *host* is `'localhost'' and *database*`.src' exists, local search is performed instead of connecting a server. `Wais::Search' will open `$Wais::maxnumfd' connections in parallel at most. Wais::Retrieve `Wais::Retrieve' should be called with named parameters (i.e. a hash). Valid parameters are database, host, port, docid, and type. $result = Wais::Retrieve('database' => $db, 'docid' => $id, 'host' => 'ls6', 'type' => 'TEXT'); Defaults are the same as for `Wais::Search'. In addition type defaults to `'TEXT''. `Wais:Result' The functions `Wais::Search' and `Wais::Retrieve' return references to objects blessed into `Wais:Result'. The following methods are available: diagnostics Returns and array of diagnostic messages. Each element (if any) is a reference to an array consisting of tag The tag of the corresponding search request or `'document'' if the request was a retrieve request. code The WAIS diagnostic code. message A textual diagnostic message. header Returns and array of WAIS document headers. Each element (if any) is a reference to an array consisting of tag The tag of the corresponding search request or `'document'' if the request was a retrieve request. score lines Length of the corresponding dcoument in lines. length Length of the corresponding document in bytes. headline types A reference to an array of types valid for docid. docid A reference to the WAIS identifier blessed into `Wais::Docid'. text Returns the text fetched by `Wais::Retrieve'. Dictionary There are a couple of functions to inspect local databases. See the inspect script in the distribution. You need the Curses module to run it. Also adapt the directory settings in the top part. Wais::dictionary %frequency = Wais::dictionary($database); %frequency = Wais::dictionary($database, $field); %frequency = Wais::dictionary($database, 'foo*'); %frequency = Wais::dictionary($database, $field, 'foo*'); The function returns an array containing alternating the matching words in the global or field dictionary matching the prefix if given and the freqence of the preceding word. In a sclar context, the number of matching word is returned. Wais::list_offset The function takes the same arguments as Wais::dictionary. It returns the same array rsp. wordcount with the word frequencies replaced by the offset of the postinglist in the inverted file. Wais::postings %postings = Wais::postings($database, 'foo'); %postings = Wais::postings($database, $field, 'foo'); Returns and an array containing alternating numeric document id's and a reference to an array whichs first element is the internal weight if the word with respect to the document. The other elements are the word/character positions of the occurances of the word in the document. If freeWAIS-sf is compiled with `-DPROXIMITY', word positions are returned otherwise character postitions. In an scalar context the number of occurances of the word is returned. Wais::headline $headline = Wais::headline($database, $docid); The function retrieves the headline (only the text!) of the document numbered `$docid'. Wais::document $text = &Wais::document($database, $docid); The function retrieves the text of the document numbered `$docid'. Protocol Wais::generate_search_apdu $apdu = Wais::generate_search_apdu($query,$database); $relevant = [$id1, 'TEXT', $id2, 'HTML']; $apdu = Wais::generate_search_apdu($query,$database,$relevant); Document id's must be of type `WAIS::Docid' as returned by `Wais::Result::header' or Wais::Search::header. $WAIS::maxdoc may be set to modify the number of documents to retrieve. Wais::generate_retrieval_apdu $apdu = Wais::generate_retrieval_apdu($database, $docid, $type); $apdu = Wais::generate_retrieval_apdu($database, $docid, $type, $chunk); Request to send the `$chunk''s chunk of the document whichs id is `$docid' (must be of type `WAIS::Docid'). $chunk defaults to `0'. $Wais::CHARS_PER_PAGE may be set to influence the chunk size. Wais::local_answer $answer = Wais::local_answer($apdu); Answer the request by local search/retrieval. The message header is stripped from the result for convenience (see the code of `Wais::Search' rsp. documentaion of Wais::Search::new below). Wais::Search::new $result = Wais::Search::new($message); Turn the result message in an object of type `Wais::Search'. The following methods are available: diagnostics, header, and text. Result of the message is pretty the same as for `Wais::Result'. Just the tags are missing. Wais::Docid::new $result = new Wais::Docid($distserver, $distdb, $distid, $copyright, $origserver, $origdb, $origid); Only the first four arguments are manatory. Wais::Docid::split ($distserver, $distdb, $distid, $copyright, $origserver, $origdb, $origid) = Wais::Docid::split($result); ($distserver, $distdb, $distid) = Wais::Docid::split($result); ($distserver, $distdb, $distid) = $result->split; The inverse of `Wais::Docid::new' =over 10 diagnostics Return an array of references to `[$code, $message]' header Return an array of references to `[$score, $lines, $length, $headline, $types, $docid]'. text Returns the chunk of the document requested. For documents larger than $Wais::CHARS_PER_PAGE more than one request must be send. Wais::Search::DESTROY The objects will be destroyed by Perl. VARIABLES $Wais::version Generated by: `sprintf(buf, "Wais %3.1f%d", VERSION, PATCHLEVEL);' $Wais:errmsg Set to an verbose error message if something went wrong. Most functions return `undef' on failure after setting `$Wais:errmsg'. $Wais::maxdoc Maximum number of hits to return when searching. Defaults to `40'. $Wais::CHARS_PER_PAGE Maximum number of bytes to retrieve in a single retrieve request. `Wais:Retrieve' sends multiple requests if necessary to retrieve a document. `CHARS_PER_PAGE' defaults to `4096'. $Wais::timeout Number of seconds to wait for an answer from remote servers. Defaults to 120. $Wais::maxnumfd Maximum number of file descriptors to use simultaneously in `Wais::Search'. Defaults to `10'. Access to the basic freeWAIS-sf reduction functions Wais::Type::stemmer(*word*) reduces *word* using the well know Porter algorithm. AU: Porter, M.F. TI: An Algorithm for Suffix Stripping JT: Program VO: 14 PP: 130-137 PY: 1980 PM: JUL Wais::Type::soundex(*word*) computes the 4 byte Soundex code for *word*. AU: Gadd, T.N. TI: 'Fisching for Werds'. Phonetic Retrieval of written text in Information Retrieval Systems JT: Program VO: 22 NO: 3 PP: 222-237 PY: 1988 Wais::Type::phonix(*word*) computes the 8 byte Phonix code for *word*. AU: Gadd, T.N. TI: PHONIX: The Algorithm JT: Program VO: 24 NO: 4 PP: 363-366 PY: 1990 PM: OCT BUGS `Wais::Search' currently splits the request in groups of `$Wais::maxnumfd' requests. Since some requests of the group might be local and/or some might refer to the same host/port, groups may not use all `$Wais::maxnumfd' possible file descriptors. Therefore some performance my be lost when more than `$Wais::maxnumfd' requests are processed. AUTHOR Ulrich Pfeifer