GRS1(3pm)

NAME
Net::Z3950::Record::GRS1 - Perl package used to encode GRS-1 records.

SYNOPSIS
  use Net::Z3950::GRS1;

  my $a_grs1_record = new Net::Z3950::Record::GRS1;
  my $another_grs1_record = new Net::Z3950::Record::GRS1;

  $a_grs1_record->AddElement($type, $value, $content);
  $a_grs1_record->Render();

DESCRIPTION
This Perl module helps you to create and manipulate GRS-1 records (generic record syntax). So far, you have only access to three methods:

  new
Creates a new GRS-1 object,

  my $grs1 = new Net::Z3950::GRS1;

  AddElement
Lets you add entries to a GRS-1 object. The method should be called this way,

  $grs1->AddElement($type, $value, $which, $content);

where $type should be an integer, and $value is free text. The $which argument should contain one of the constants listed in Appendix A. Finally, $content contains the "thing" that should be stored in this entry. The structure of $content should match the chosen element data type. For

  $which == Net::Z3950::GRS1::ElementData::String;

$content should be some kind of scalar. If on the other hand,

  $which == Net::Z3950::GRS1::ElementData::Subtree;

$content should be a GRS1 object.

  Render
This method digs through the GRS-1 data structure and renders the record. You call it this way,

  $grs1->Render();

If you want to access the rendered record through a variable, you can do it like this,

  my $record_as_string;
  $grs1->Render(POOL => \$record_as_string);

If you want it stored in a file, Render should be called this way,

  $grs1->Render(FILE => 'record.grs1');

When no file name is specified, you can choose to stream the rendered record, for instance,

  $grs1->Render(HANDLE => *STDOUT);             ## or
  $grs1->Render(HANDLE => *STDERR);             ## or
  $grs1->Render(HANDLE => *MY_HANDLE);

  Hash2grs
This method converts a hash into a GRS-1 object. Scalar entries within the hash are converted into GRS-1 string elements. A hash entry can itself be a reference to another hash. In this case, the new referenced hash will be converted into a GRS-1 subtree. The method is called this way,

  $grs1->Hash2grs($href, $mapping);

where $href is the hash to be converted and $mapping is referenced hash specifying the mapping between keys in $href and (type, value) pairs in the $grs1 object. The $mapping hash could for instance look like this,

  my $mapping = {
                        title   =>      [2, 1],
                        author  =>      [1, 1],
                        issn    =>      [3, 1]
                };

If the $grs1 object contains data prior to the invocation of Hash2grs, the new data represented by the hash is simply added.

APPENDIX A
These element data types are specified in the Z39.50 protocol:

  Net::Z3950::GRS1::ElementData::Octets
  Net::Z3950::GRS1::ElementData::Numeric
  Net::Z3950::GRS1::ElementData::Date
  Net::Z3950::GRS1::ElementData::Ext
  Net::Z3950::GRS1::ElementData::String                 <---
  Net::Z3950::GRS1::ElementData::TrueOrFalse
  Net::Z3950::GRS1::ElementData::OID
  Net::Z3950::GRS1::ElementData::IntUnit
  Net::Z3950::GRS1::ElementData::ElementNotThere
  Net::Z3950::GRS1::ElementData::ElementEmpty
  Net::Z3950::GRS1::ElementData::NoDataRequested
  Net::Z3950::GRS1::ElementData::Diagnostic
  Net::Z3950::GRS1::ElementData::Subtree                <---

Only the '<---' marked types are so far supported in this package.

AUTHOR
Anders Sønderberg Mortensen <sondberg@indexdata.dk> Index Data ApS, Copenhagen, Denmark. 2001/03/09

SEE ALSO
Specification of the GRS-1 standard, for instance in the Z39.50 protocol specification.