oai2client.php

<?php
/**
 * http://www.openarchives.org/OAI/2.0/guidelines-harvester.htm
 * 8. Harvesting all the Metadata from a Repository
 *
 * Proxies, aggregators and other such agents may wish to harvest a complete copy of a repository 
 * including set structure and all metadata formats. One strategy for doing this would be:
 *
 * # Issue an Identify request to find the finest datestamp granularity supported.
 * # Issue a ListMetadataFormats request to obtain a list of all metadataPrefixes supported.
 * # Harvest using ListRecords requests for each metadataPrefix supported. Knowledge of the
 *   datestamp granularity allows for less overlap if granularities finer than a day are supported.
 * # Set structure can be inferred from the setSpec elements in the header blocks of each record
 *   returned (consistency checks are possible).
 * # Items may be reconstructed from the constituent records. Local datestamps must be assigned to
 *   harvested items.
 * # Provenance and other information in <about> blocks may be re-assembled at the item level if it
 *   is the same for all metadata formats harvested. However, this information may be supplied
 *   differently for different metadata formats and may thus need to be store separately for each
 *   metadata format.
 */

class OAI2Client {

    public function __construct($server_base_url) {
        $this->server_base_url = $server_base_url;
        require_once('./curl.php');
        $this->curl = new Curl();
    }

    public function Identify() {
        return $this->curl->get($this->server_base_url.'?verb=Identify');
    }

    public function ListMetadataFormats($identifier = '') {
        $url = $this->server_base_url.'?verb=ListMetadataFormats';
        if (!empty($identifier)) {
            $url .= "&identifier={$identifier}";
        }
        return $this->curl->get($url);
    }

    public function ListSets($resumptionToken = '') {
        $url = $this->server_base_url.'?verb=ListSets';
        return $this->curl->get($url);
    }

    public function ListIdentifiers($options = array()) {

        $options_default = array('from' => null,
                                 'until' => null,
                                 'set' => null,
                                 'resumptionToken' => null,
                                 'metadataPrefix' => null); // required

        $url = $this->server_base_url.'?verb=ListIdentifiers';

        if (!empty($options['metadataPrefix'])) {
            $url .= "&metadataPrefix={$options['metadataPrefix']}";
        }
        return $this->curl->get($url);
    }

    public function ListRecords($options = array()) {

        $options_default = array('from' => null,
                                 'until' => null,
                                 'set' => null,
                                 'resumptionToken' => null,
                                 'metadataPrefix' => null); // required

        $url = $this->server_base_url.'?verb=ListRecords';

        if (!empty($options['metadataPrefix'])) {
            $url .= "&metadataPrefix={$options['metadataPrefix']}";
        }
        return $this->curl->get($url);
    }

    public function GetRecord($identifier, $metadataPrefix) {
        $url = $this->server_base_url.'?verb=ListRecords';
        $url .= "&identifier={$identifier}&metadataPrefix={$metadataPrefix}";
        return $this->curl->get($url);
    }
}