X-Git-Url: http://jsfdemo.indexdata.com/?a=blobdiff_plain;f=lib%2FZOOM.pod;h=ebd3c556bb2f29f7d565259c7c239d2ea1027318;hb=07f0b92a4b3955976b6d32187a60b5a9d70747d7;hp=07746d7b306558b058bce7e91e3f5a999f89626a;hpb=5ff13e6006f9e452e3c7fb26048774b5c7af116f;p=ZOOM-Perl-moved-to-github.git diff --git a/lib/ZOOM.pod b/lib/ZOOM.pod index 07746d7..ebd3c55 100644 --- a/lib/ZOOM.pod +++ b/lib/ZOOM.pod @@ -1,4 +1,4 @@ -# $Id: ZOOM.pod,v 1.10 2005-11-18 17:55:08 mike Exp $ +# $Id: ZOOM.pod,v 1.20 2005-12-13 16:03:14 mike Exp $ use strict; use warnings; @@ -247,27 +247,9 @@ Objects of the Connection, ResultSet, ScanSet and Package classes carry with them a set of named options which affect their behaviour in certain ways. See the ZOOM-C options documentation for details: -=over 4 - -=item * - Connection options are listed at http://indexdata.com/yaz/doc/zoom.tkl#zoom.connections -=item * - -ScanSet options are listed at -http://indexdata.com/yaz/doc/zoom.scan.tkl -I<### move this obvservation down to the appropriate place> - -=item * - -Package options are listed at -http://indexdata.com/yaz/doc/zoom.ext.html -I<### move this obvservation down to the appropriate place> - -=back - These options are set and fetched using the C method, which may be called with either one or two arguments. In the two-argument form, the option named by the first argument is set to the value of @@ -424,9 +406,9 @@ http://zoom.z3950.org/api/zoom-current.html#3.4 =head4 option() - $conn->option(elementSetName => "f"); + $rs->option(elementSetName => "f"); -Allows options to be set into, and read from a ResultSet, just like +Allows options to be set into, and read from, a ResultSet, just like the Connection class's C method. There is no C method for ResultSet objects. @@ -439,7 +421,7 @@ http://indexdata.com/yaz/doc/zoom.resultsets.tkl Returns the number of records in the result set. -=head4 record(), record_immediate() +=head4 record() / record_immediate() $rec = $rs->record(0); $rec2 = $rs->record_immediate(0); @@ -489,7 +471,7 @@ efficiency gain to be had by passing 0.) Once the records have been retrieved from the server (i.e. C has completed without throwing an exception), they can be fetched much more efficiently using C - or -C, which is then guaranteed to succeed. =head4 cache_reset() @@ -501,12 +483,37 @@ scenario where you'd want to do this. =head4 sort() - if ($rs->sort("yaz", "1=4 >i") < 0) { + if ($rs->sort("yaz", "1=4 >i 1=21 >s") < 0) { die "sort failed"; } -Sorts the ResultSet in place ### - +Sorts the ResultSet in place (discarding any cached records, as they +will in general be sorted into a different position). There are two +arguments: the first is a string indicating the type of the +sort-specification, and the second is the specification itself. + +The C method returns 0 on success, or -1 if the +sort-specification is invalid. + +At present, the only supported sort-specification type is C. +Such a specification consists of a space-separated sequence of keys, +each of which itself consists of two space-separated words (so that +the total number of words in the sort-specification is even). The two +words making up each key are a field and a set of flags. The field +can take one of two forms: if it contains an C<=> sign, then it is a +BIB-1 I=I pair specifying which field to sort +(e.g. C<1=4> for a title sort); otherwise it is sent for the server to +interpret as best it can. The word of flags is made up from one or +more of the following: C for case sensitive, C for case +insensitive; C<<> for ascending order and C> for descending +order. + +For example, the sort-specification in the code-fragment above will +sort the records in C<$rs> case-insensitively in descending order of +title, with records having equivalent titles sorted case-sensitively +in ascending order of subject. (The BIB-1 access points 4 and 21 +represent title and subject respectively.) + =head4 destroy() $rs->destroy() @@ -516,7 +523,69 @@ reuse a ResultSet that has been Ced. =head2 ZOOM::Record -I<###> + $rec = $rs->record($i); + print $rec->render(); + $raw = $rec->raw(); + $marc = new_from_usmarc MARC::Record($raw); + print "Record title is: ", $marc->title(), "\n"; + +A Record object represents a record that has been retrived from the +server. + +There is no C method nor any other explicit constructor. The +only way to create a new Record is by using C (or +C, or C) on a ResultSet. + +In general, records are ``owned'' by their result-sets that they were +retrieved from, so they do not have to be explicitly memory-managed: +they are deallocated (and therefore can no longer be used) when the +result-set is destroyed. + +See the description of the C class in the ZOOM Abstract +API at +http://zoom.z3950.org/api/zoom-current.html#3.5 + +=head3 Methods + +=head4 render() + + print $rec->render() + +Returns a human-readable representation of the record. Beyond that, +no promises are made: careful programs should not make assumptions +about the format of the returned string. + +This method is useful mostly for debugging. + +=head4 raw() + + use MARC::Record + $raw = $rec->raw(); + $marc = new_from_usmarc MARC::Record($raw); + +Returns an opaque blob of data that is the raw form of the record. +Exactly what this is, and what you can do with it, varies depending on +the record-syntax. For example, XML records will be returned as, +well, XML; MARC records will be returned as ISO 2709-encoded blocks +that can be decoded by software such as the fine C +module; GRS-1 record will be ... gosh, what an interesting question. +But no-one uses GRS-1 any more, do they? + +=head4 clone() / destroy() + + $rec = $rs->record($i); + $newrec = $rec->clone(); + $rs->destroy(); + print $newrec->render(); + $newrec->destroy(); + +Usually, it's convenient that Record objects are owned by their +ResultSets and go away when the ResultSet is destroyed; but +occasionally you need a Record to outlive its parent and destroy it +later, explicitly. To do this, C the record, keep the new +Record object that is returned, and C it when it's no +longer needed. This is B situation in which a Record needs to +be destroyed. =head2 ZOOM::Exception @@ -537,26 +606,457 @@ circumstances that do not merit throwing an exception. For this reason, the return values of these methods should be checked. See the individual methods' documentation for details. +An exception carries the following pieces of information: + +=over 4 + +=item error-code + +A numeric code that specifies the type of error. This can be checked +for equality with known values, so that intelligent applications can +take appropriate action. + +=item error-message + +A human-readable message corresponding with the code. This can be +shown to users, but its value should not be tested, as it could vary +in different versions or under different locales. + +=item additional information [optional] + +A string containing information specific to the error-code. For +example, when the error-code is the BIB-1 diagnostic 109 ("Database +unavailable"), the additional information is the name of the database +that the application tried to use. For some error-codes, there is no +additional information at all; for some others, the additional +information is undefined and may just be an human-readable string. + +=item diagnostic set [optional] + +A short string specifying the diagnostic set from which the error-code +was drawn: for example, C for a ZOOM-specific error such as +C ("out of memory"), and C for a Z39.50 +error-code drawn from the BIB-1 diagnostic set. + +=back + +In theory, the error-code should be interpreted in the context of the +diagnostic set from which it is drawn; in practice, nearly all errors +are from either the ZOOM or BIB-1 diagnostic sets, and the codes in +those sets have been chosen so as not to overlap, so the diagnostic +set can usually be ignored. + +See the description of the C class in the ZOOM Abstract +API at +http://zoom.z3950.org/api/zoom-current.html#3.7 + =head3 Methods -I<###> +=head4 new() + + die new ZOOM::Exception($errcode, $errmsg, $addinfo, $diagset); + +Creates and returns a new Exception object with the specified +error-code, error-message, additional information and diagnostic set. +Applications will not in general need to use this, but may find it +useful to simulate ZOOM exceptions. As is usual with Perl, exceptions +are thrown using C. + +=head4 code() / message() / addinfo() / diagset() + + print "Error ", $@->code(), ": ", $@->message(), "\n"; + print "(addinfo '", $@->addinfo(), "', set '", $@->diagset(), "')\n"; + +These methods, of no arguments, return the exception's error-code, +error-message, additional information and diagnostic set respectively. + +=head4 render() + + print $@->render(); + +Returns a human-readable rendition of an exception. The C<""> +operator is overloaded on the Exception class, so that an Exception +used in a string context is automatically rendered. Among other +consequences, this has the useful result that a ZOOM application that +died due to an uncaught exception will emit an informative message +before exiting. =head2 ZOOM::ScanSet -I<###> + $ss = $conn->scan('@attr 1=1003 a'); + $n = $ss->size(); + ($term, $occ) = $ss->term($n-1); + $rs = $conn->search_pqf('@attr 1=1003 "' . $term . "'"); + assert($rs->size() == $occ); + +A ScanSet represents a set of candidate search-terms returned from an +index scan. Its sole purpose is to provide access to those term, to +the corresponding display terms, and to the occurrence-counts of the +terms. + +There is no C method nor any other explicit constructor. The +only way to create a new ScanSet is by using C on a +Connection. + +See the description of the C class in the ZOOM Abstract +API at +http://zoom.z3950.org/api/zoom-current.html#3.6 + +=head3 Methods + +=head4 size() + + print "Found ", $ss->size(), " terms\n"; + +Returns the number of terms in the scan set. In general, this will be +the scan-set size requested by the C option in the Connection +on which the scan was performed [default 10], but it may be fewer if +the scan is close to the end of the index. + +=head4 term() / display_term() + + $ss = $conn->scan('@attr 1=1004 whatever'); + ($term, $occurrences) = $ss->term(0); + ($displayTerm, $occurrences2) = $ss->display_term(0); + assert($occurrences == $occurrences2); + if (user_likes_the_look_of($displayTerm)) { + $rs = $conn->search_pqf('@attr 1=4 "' . $term . '"'); + assert($rs->size() == $occurrences); + } + +These methods return the scanned terms themselves. C returns +the term is a form suitable for submitting as part of a query, whereas +C returns it in a form suitable for displaying to a +user. Both versions also return the number of occurrences of the term +in the index, i.e. the number of hits that will be found if the term +is subsequently used in a query. + +In most cases, the term and display term will be identical; however, +they may be different in cases where punctuation or case is +normalised, or where identifiers rather than the original document +terms are indexed. + +=head4 option() + + print "scan status is ", $ss->option("scanStatus"); + +Allows options to be set into, and read from, a ScanSet, just like +the Connection class's C method. There is no +C method for ScanSet objects. + +ScanSet options are also described, though not particularly +informatively, at +http://indexdata.com/yaz/doc/zoom.scan.tkl + +=head4 destroy() + + $ss->destroy() + +Destroys a ScanSet object, freeing its resources. It is an error to +reuse a ScanSet that has been Ced. =head2 ZOOM::Package -I<###> + $p = $conn->package(); + $p->option(action => "specialUpdate"); + $p->option(recordIdOpaque => 145); + $p->option(record => content_of("/tmp/record.xml")); + $p->send("update"); + $p->destroy(); + +This class represents an Extended Services Package: an instruction to +the server to do something not covered by the core parts of the Z39.50 +standard (or the equivalent in SRW or SRU). Since the core protocols +are read-only, such requests are often used to make changes to the +database, such as in the record update example above. + +Requesting an extended service is a four-step process: first, create a +package associated with the connection to the relevant database; +second, set options on the package to instruct the server on what to +do; third, send the package (which may result in an exception being +thrown if the server cannot execute the requested operations; and +finally, destroy the package. + +Package options are listed at +http://indexdata.com/yaz/doc/zoom.ext.html + +The particular options that have meaning are determined by the +top-level operation string specified as the argument to C. +For example, when the operation is C (the most commonly used +extended service), the C option may be set to any of +C +(add a new record, failing if that record already exists), +C +(delete a record, failing if it is not in the database). +C +(replace a record, failing if an old version is not already present) +or +C +(add a record, replacing any existing version that may be present). + +For update, the C option should be set to the full text of the +XML record to added, deleted or replaced. Depending on how the server +is configured, it may extract the record's unique ID from the text +(i.e. from a known element such as the C<001> field of a MARCXML +record), or it may require the unique ID to passed in explicitly using +the C option. + +Extended services packages are B in the ZOOM +Abstract API at +http://zoom.z3950.org/api/zoom-current.html +They will be added in a forthcoming version, and will function much +as those implemented in this module. + +=head3 Methods + +=head4 option() + + $p->option(recordIdOpaque => "46696f6e61"); + +Allows options to be set into, and read from, a Package, just like +the Connection class's C method. There is no +C method for Package objects. + +Package options are listed at +http://indexdata.com/yaz/doc/zoom.ext.tkl + +=head4 send() + + $p->send("createdb"); + +Sends a package to the server associated with the Connection that +created it. Problems are reported by throwing an exception. The +single parameter indicates the operation that the server is being +requested to perform, and controls the interpretation of the package's +options. Valid operations include: + +=over 4 + +=item itemorder + +Request a copy of a nominated object, e.g. place an ILL request. + +=item create + +Create a new database, the name of which is specified by the +C option. + +=item drop + +Drop an existing database, the name of which is specified by the +C option. + +=item commit + +Commit changes made to the database within a transaction. + +=item update + +Modify the contents of the database by adding, deleting or replacing +records (as described above in the overview of the C +class). + +=item xmlupdate + +I have no idea what this does. + +=back + +Although the module is capable of I all these requests, not +all servers are capable of I them. Refusal is indicated by +throwing an exception. Problems may also be caused by lack of +privileges; so C must be used with caution, and is perhaps +best wrapped in a clause that checks for execptions, like so: + + eval { $p->send("create") }; + if ($@ && $@->isa("ZOOM::Exception")) { + print "Oops! ", $@->message(), "\n"; + return $@->code(); + } + +=head4 destroy() + + $p->destroy() + +Destroys a Package object, freeing its resources. It is an error to +reuse a Package that has been Ced. =head2 ZOOM::Query -I<###> + $q = new ZOOM::Query::CQL("creator=pike and subject=unix"); + $q->sortby("1=4 >i 1=21 >s"); + $rs = $conn->search($q); + $q->destroy(); + +C is a virtual base class from which various concrete +subclasses can be derived. Different subclasses implement different +types of query. The sole purpose of a Query object is to be used in a +C on a Connection; because PQF is such a common special +case, the shortcut Connection method C is provided. + +The following Query subclasses are provided, both of the providing the +same set of methods described below: + +=over 4 + +=item ZOOM::Query::PQF + +Implements Prefix Query Format (PQF), also sometimes known as Prefix +Query Notation (PQN). This esoteric but rigorous and expressive +format is described in the YAZ Manual at +http://indexdata.com/yaz/doc/tools.tkl#PQF + +=item ZOOM::Query::CQL + +Implements the Common Query Language (CQL) of SRU, the Search/Retrieve +URL. CQL is a much friendlier notation than PQF, using a simple infix +notation. The queries are passed ``as is'' to the server rather than +being compiled into a Z39.50 Type-1 query, so only CQL-compliant +servers can support such querier. CQL is described at +http://www.loc.gov/standards/sru/cql/ +and in a slight out-of-date but nevertheless useful tutorial at +http://zing.z3950.org/cql/intro.html + +=back + +See the description of the C class in the ZOOM Abstract +API at +http://zoom.z3950.org/api/zoom-current.html#3.3 + +=head3 Methods + +=head4 new() + + $q = new ZOOM::Query::CQL('title=dinosaur')); + $q = new ZOOM::Query::PQF('@attr 1=4 dinosaur')); + +Creates a new query object, compiling the query passed as its argument +according to the rules of the particular query-type being +instantiated. If compilation fails, an exception is thrown. +Otherwise, the query may be passed to the C method +. + +=head4 sortby() + + $q->sortby("1=4 >i 1=21 >s"); + +Sets a sort specification into the query, so that when a C +is run on the query, the result is automatically sorted. The sort +specification language is the same as the C sort-specification +type of the C method C, described above. + +B + +=head4 destroy() + + $p->destroy() + +Destroys a Query object, freeing its resources. It is an error to +reuse a Query that has been Ced. =head2 ZOOM::Options + $o1 = new ZOOM::Options(); + $o1->option(user => "alf"); + $o2 = new ZOOM::Options(); + $o2->option(password => "fruit"); + $opts = new ZOOM::Options($o1, $o2); + $conn = create ZOOM::Connection($opts); + $conn->connect($host); # Uses the specified username and password + +Several classes of ZOOM objects carry their own sets of options, which +can be manipulated using their C method. Sometimes, +however, it's useful to deal with the option sets directly, and the +C class exists to enable this approach. + +Option sets are B in the ZOOM +Abstract API at +http://zoom.z3950.org/api/zoom-current.html +They are an extension to that specification. + +=head3 Methods + +=head4 new() + + $o1 = new ZOOM::Options(); + $o1and2 = new ZOOM::Options($o1); + $o3 = new ZOOM::Options(); + $o1and3and4 = new ZOOM::Options($o1, $o3); + +Creates and returns a new option set. One or two (but no more) +existing option sets may be passed as arguments, in which case they +become ``parents'' of the new set, which thereby ``inherits'' their +options, the values of the first parent overriding those of the second +when both have a value for the same key. An option set that inherits +from a parent that has its own parents also inherits the grandparent's +options, and so on. + +=head4 option() / option_binary() + + $o->option(preferredRecordSyntax => "usmarc"); + $o->option_binary(iconBlob => "foo\0bar"); + die if length($o->option_binary("iconBlob") != 7); + +These methods are used to get and set options within a set, and behave +the same way as the same-named C methods - see above. As +with the C methods, values passed to and retrieved using +C are interpreted as NUL-terminated, while those passed to +and retrieved from C are binary-clean. + +=head4 bool() + + $o->option(x => "T"); + $o->option(y => "F"); + assert($o->bool("x", 1)); + assert(!$o->bool("y", 1)); + assert($o->bool("z", 1)); + +The first argument is a key, and the second is a default value. +Returns the value associated with the specified key as a boolean, or +the default value if the key has not been set. The values C (upper +case) and C<1> are considered true; all other values (including C +(lower case) and non-zero integers other than one) are considered +false. + +This method is provided in ZOOM-C because in a statically typed +language it's convenient to have the result returned as an +easy-to-test type. In a dynamically typed language such as Perl, this +problem doesn't arise, so C is nearly useless; but it is made +available in case applications need to duplicate the idiosyncratic +interpretation of truth and falsehood and ZOOM-C uses. + +=head4 int() + + $o->option(x => "012"); + assert($o->int("x", 20) == 12); + assert($o->int("y", 20) == 20); + +Returns the value associated with the specified key as an integer, or +the default value if the key has not been set. See the description of +C for why you almost certainly don't want to use this. + +=head4 set_int() + + $o->set_int(x => "29"); + +Sets the value of the specified option as an integer. Of course, Perl +happily converts strings to integers on its own, so you can just use +C for this, but C is guaranteed to use the same +string-to-integer conversion as ZOOM-C does, which might occasionally +be useful. Though I can't imagine how. + +=head4 set_callback() + I<###> +=head4 destroy() + + $o->destroy() + +Destroys an Options object, freeing its resources. It is an error to +reuse an Options object that has been Ced. + =head1 ENUMERATIONS The ZOOM module provides two enumerations that list possible return @@ -598,10 +1098,12 @@ C, C and C, -each of which specifies a client-side error. Since errors may also be -diagnosed by the server, and returned to the client, error codes may -also take values from the BIB-1 diagnostic set of Z39.50, listed at -the Z39.50 Maintenance Agency's web-site at +each of which specifies a client-side error. These codes constitute +the C diagnostic set. + +Since errors may also be diagnosed by the server, and returned to the +client, error codes may also take values from the BIB-1 diagnostic set +of Z39.50, listed at the Z39.50 Maintenance Agency's web-site at http://www.loc.gov/z3950/agency/defns/bib1diag.html All error-codes, whether client-side from the C