X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;ds=sidebyside;f=lib%2FZOOM.pod;h=73e122a870b5b9ee45675b758fc473e2f8b81a1e;hb=01aefec56fba249c41a1cfb042aac54955cae634;hp=51d6023009f1dbee9fedf4f4e3182c01f42573b3;hpb=3389f7f4d00a9094d7a991bcd1eeb0b29c209024;p=ZOOM-Perl-moved-to-github.git diff --git a/lib/ZOOM.pod b/lib/ZOOM.pod index 51d6023..73e122a 100644 --- a/lib/ZOOM.pod +++ b/lib/ZOOM.pod @@ -1,4 +1,4 @@ -# $Id: ZOOM.pod,v 1.29 2006-02-20 11:30:58 mike Exp $ +# $Id: ZOOM.pod,v 1.37 2006-06-15 15:42:30 mike Exp $ use strict; use warnings; @@ -11,7 +11,8 @@ ZOOM - Perl extension implementing the ZOOM API for Information Retrieval use ZOOM; eval { - $conn = new ZOOM::Connection($host, $port) + $conn = new ZOOM::Connection($host, $port, + databaseName => "mydb"); $conn->option(preferredRecordSyntax => "usmarc"); $rs = $conn->search_pqf('@attr 1=4 dinosaur'); $n = $rs->size(); @@ -38,8 +39,8 @@ API such as ZOOM is that all implementations should be compatible anyway; but knowing that the same code is running is reassuring.) The ZOOM module provides two enumerations (C and -C), two utility functions C and C in -the C package itself, and eight classes: +C), three utility functions C, C +and C in the C package itself, and eight classes: C, C, C, @@ -49,12 +50,13 @@ C, C and C. -Of these, the Query class is abstract, and has three concrete +Of these, the Query class is abstract, and has four concrete subclasses: C, -C +C, +C and -C. +C. Finally, it also provides a C module which supplies a useful general-purpose logging facility. @@ -96,12 +98,20 @@ C, irrespective of whether it is a member of the C enumeration or drawn from the BIB-1 diagnostic set. -=head2 ZOOM::event() +=head2 ZOOM::event_str() -B -Lark's vomit. Do not read this section. + $msg = ZOOM::event_str(ZOOM::Event::RECV_APDU); + +Returns a human-readable English-language string corresponding to the +event code that is its own parameter. This works for any value of the +C enumeration. + +=head2 ZOOM::event() - $which = ZOOM::event([ $conn1, $conn2, $conn3 ]); + $connsRef = [ $conn1, $conn2, $conn3 ]; + $which = ZOOM::event($connsRef); + $ev = $connsRef->[$which-1]->last_event() + if ($which != 0); Used only in complex asynchronous applications, this function takes a reference to a list of Connection objects, waits until an event @@ -110,8 +120,7 @@ the connections it occurred on. The return value is a 1-based index into the list; 0 is returned if no event occurs within the longest timeout specified by the C options of all the connections. -B -This function is not yet implemented. +See the section below on asynchronous applications. =head1 CLASSES @@ -159,6 +168,9 @@ http://zoom.z3950.org/api/zoom-current.html#3.2 $conn = new ZOOM::Connection("indexdata.dk:210/gils"); $conn = new ZOOM::Connection("tcp:indexdata.dk:210/gils"); $conn = new ZOOM::Connection("http:indexdata.dk:210/gils"); + $conn = new ZOOM::Connection("indexdata.dk", 210, + databaseName => "mydb", + preferredRecordSyntax => "marc"); Creates a new Connection object, and immediately connects it to the specified server. If you want to make a new Connection object but @@ -170,6 +182,14 @@ argument. In the former case, the arguments are the name and port number of the Z39.50 server to connect to; in the latter case, the single argument is a YAZ service-specifier string of the form +When the two-option form is used (which may be done using a vacuous +second argument of zero), any number of additional argument pairs may +be provided, which are interpreted as key-value pairs to be set as +options after the Connection object is created but before it is +connected to the server. This is a convenient way to set options, +including those that must be set before connecting such as +authentication tokens. + =over 4 =item @@ -406,11 +426,8 @@ the C documentation. Returns a C enumerated value indicating the type of the last event that occurred on the connection. This is used only in -complex asynchronous applications - see the section below on -C for more information. - -B -This method has not been tested. +complex asynchronous applications - see the sections below on the +C enumeration and asynchronous applications. =head4 destroy() @@ -593,19 +610,24 @@ http://zoom.z3950.org/api/zoom-current.html#3.5 =head4 render() - print $rec->render() + print $rec->render(); + print $rec->render("charset=latin1,utf8"); 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. +If the optional argument is provided, then it is interpreted as in the +C method (q.v.) + This method is useful mostly for debugging. =head4 raw() - use MARC::Record + use MARC::Record; $raw = $rec->raw(); $marc = new_from_usmarc MARC::Record($raw); + $trans = $rec->render("charset=latin1,utf8"); 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 @@ -615,6 +637,31 @@ 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? +If the optional argument is provided, then it is interpreted as in the +C method (q.v.) + +=head4 get() + + $raw = $rec->get("raw"); + $rendered = $rec->get("render"); + $trans = $rec->get("render;charset=latin1,utf8"); + $trans = $rec->get("render", "charset=latin1,utf8"); + +This is the underlying method used by C and C, and +which in turn delegates to the C function of the +underlying ZOOM-C library. Most applications will find it more +natural to work with C and C. + +C may be called with either one or two arguments. The +two-argument form is syntactic sugar: the two arguments are simply +joined with a semi-colon to make a single argument, so the third and +fourth example invocations above are equivalent. The second argument +(or portion of the first argument following the semicolon) is used in +the C argument of C, as described in +http://www.indexdata.com/yaz/doc/zoom.records.tkl +This is useful primarily for invoking the character-set transformation +- in the examples above, from ISO Latin-1 to UTF-8 Unicode. + =head4 clone() / destroy() $rec = $rs->record($i); @@ -974,6 +1021,21 @@ relations and modifiers into Type-1 query attributes. An example CQL configuration file is included in the ZOOM-Perl distribution, in the file C +=item ZOOM::Query::CCL2RPN + +Implements CCL by compiling it on the client-side into a Z39.50 Type-1 +(RPN) query, and sending that. Because the compilation is done on the +client side, a configuration file is required to direct the mapping of +CCL constructs such as index names and boolean operators into Type-1 +query attributes. An example CCL configuration file is included in +the ZOOM-Perl distribution, in the file C + +CCL is syntactically very similar to CQL, but much looser. While CQL +is an entirely precise language in which each possible query has +rigorously defined semantics, and is thus suitable for transfer as +part of a protocol, CCL is best deployed as a human-facing UI +language. + =back See the description of the C class in the ZOOM Abstract @@ -1004,6 +1066,17 @@ if compilation fails, then diagnostic information is cached in the Connection and be retrieved using C<$conn-Eerrcode()> and related methods. + $conn->option(cclfile => "samples/ccl/default.bib"); + # or + $conn->option(cclqual => "ti u=4 s=pw\nab u=62 s=pw"); + $q = new ZOOM::Query::CCL2RPN('ti=dinosaur', $conn); + +For the C subclass, too, the Connection must be +passed into the constructor, for the same reasons as when client-side +CQL compilation is used. The C option, if defined, gives a +CCL qualification specification inline; otherwise, the contents of the +file named by the C option are used. + =head4 sortby() $q->sortby("1=4 >i 1=21 >s"); @@ -1180,6 +1253,10 @@ C, C, C, C, +C, +C, +C, +C, C, C, C, @@ -1213,11 +1290,10 @@ applications - The C method is used to return an indication of the last event that occurred on a particular connection. It always returns a value drawn from this enumeration, that is, one of C, C, C, C, -C, C, C, C, C or -C. +C, C, C, C, C, +C or C. -You almost certainly don't need to know about this. Frankly, I'm not -sure how to use it myself. +See the section below on asynchronous applications. =head1 LOGGING @@ -1324,6 +1400,70 @@ called. The log-level argument may be either a numeric value, as returned from C, or a string containing the module name. +=head1 ASYNCHRONOUS APPLICATIONS + +Although asynchronous applications are conceptually complex, the ZOOM +support for them is provided through a very simple interface, +consisting of one option (C), one function (C), +one Connection method (C and an enumeration +(C). + +The approach is as follows: + +=over 4 + +=item Initialisation + +Create several connections to the various servers, each of them having +the option C set, and with whatever additional options are +required - e.g. the piggyback retrieval record-count can be set so +that records will be returned in search responses. + +=item Operations + +Send searches to the connections, request records, etc. + +=item Event harvesting + +Repeatedly call C to discover what responses are being +received from the servers. Each time this function returns, it +indicates which of the connections has fired; this connection can then +be interrogated with the C method to discover what event +has occurred, and the return value - an element of the C +enumeration - can be tested to determine what to do next. For +example, the C event indicates that no further operations are +outstanding on the connection, so any fetched records can now be +immediately obtained. + +=back + +Here is a very short program (omitting all error-checking!) which +demonstrates this process. It parallel-searches three servers (or more +of you add them the list), displaying the first record in the +result-set of each server as soon as it becomes available. + + use ZOOM; + @servers = ('z3950.loc.gov:7090/Voyager', + 'bagel.indexdata.com:210/gils', + 'agricola.nal.usda.gov:7190/Voyager'); + for ($i = 0; $i < @servers; $i++) { + $z[$i] = new ZOOM::Connection($servers[$i], 0, + async => 1, # asynchronous mode + count => 1, # piggyback retrieval count + preferredRecordSyntax => "usmarc"); + $r[$i] = $z[$i]->search_pqf("mineral"); + } + while (($i = ZOOM::event(\@z)) != 0) { + $ev = $z[$i-1]->last_event(); + print("connection ", $i-1, ": ", ZOOM::event_str($ev), "\n"); + if ($ev == ZOOM::Event::ZEND) { + $size = $r[$i-1]->size(); + print "connection ", $i-1, ": $size hits\n"; + print $r[$i-1]->record(0)->render() + if $size > 0; + } + } + =head1 SEE ALSO The ZOOM abstract API,