-# $Id: ZOOM.pod,v 1.10 2005-11-18 17:55:08 mike Exp $
+# $Id: ZOOM.pod,v 1.13 2005-12-07 18:04:47 mike Exp $
use strict;
use warnings;
Once the records have been retrieved from the server
(i.e. C<records()> has completed without throwing an exception), they
can be fetched much more efficiently using C<record()> - or
-C<record_immediate(), which is then guaranteed to succeed.
+C<record_immediate()>, which is then guaranteed to succeed.
=head4 cache_reset()
=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<sort()> method returns 0 on success, or -1 if the
+sort-specification is invalid.
+
+At present, the only supported sort-specification type is C<yaz>.
+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<type>=I<value> 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<s> for case sensitive, C<i> for case
+insensitive; C<<> for ascending order and C<E<gt>> 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()
=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<new()> method nor any other explicit constructor. The
+only way to create a new Record is by using C<record()> (or
+C<record_immediate()>, or C<records()>) 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<Record> 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<Marc::Record>
+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<clone()> the record, keep the new
+Record object that is returned, and C<destroy()> it when it's no
+longer needed. This is B<only> situation in which a Record needs to
+be destroyed.
=head2 ZOOM::Exception
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<ZOOM> for a ZOOM-specific error such as
+C<ZOOM::Error::MEMORY> ("out of memory"), and C<BIB-1> 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<Exception> 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<die()>.
+
+=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
+ $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<new()> method nor any other explicit constructor. The
+only way to create a new ScanSet is by using C<scan()> on a
+Connection.
+
+See the description of the C<Scan Set> 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.
+### describe option that affects this.
+
+=head4 term() / display_term()
+
+I<###>
+
+=head4 option()
+
+I<###>
+
+=head4 destroy()
+
I<###>
=head2 ZOOM::Package
C<PACKAGE>
and
C<SCANTERM>,
-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<ZOOM> 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<ZOOM::Error>
projects / ZOOM-Perl-moved-to-github.git / blobdiff