import sys import time import sickle from confluent_kafka import Producer, KafkaException from .harvest_common import HarvestState class HarvestOaiPmhWorker: """ Base class for OAI-PMH harvesters. Uses the 'sickle' protocol library. Typically run as a single process; harvests records and publishes in raw (XML) format to a Kafka topic, one-message-per-document. Based on Crossref importer, with the HarvestState internal class managing progress with day-level granularity. Note that this depends on the OAI-PMH endpoint being correct! In that it must be possible to poll for only records updated on a particular date (typically "yesterday"). Was very tempted to re-use for this OAI-PMH stuff to save on dev time, but i'd already built the Crossref harvester and would want something similar operationally. Oh well! """ def __init__(self, kafka_hosts, produce_topic, state_topic, start_date=None, end_date=None): self.produce_topic = produce_topic self.state_topic = state_topic self.kafka_config = { 'bootstrap.servers': kafka_hosts, 'message.max.bytes': 20000000, # ~20 MBytes; broker is ~50 MBytes } self.loop_sleep = 60*60 # how long to wait, in seconds, between date checks self.endpoint_url = None # needs override self.metadata_prefix = None # needs override self.name = "unnamed" self.state = HarvestState(start_date, end_date) self.state.initialize_from_kafka(self.state_topic, self.kafka_config) print(self.state, file=sys.stderr) def fetch_date(self, date): def fail_fast(err, msg): if err is not None: print("Kafka producer delivery error: {}".format(err), file=sys.stderr) print("Bailing out...", file=sys.stderr) # TODO: should it be sys.exit(-1)? raise KafkaException(err) producer_conf = self.kafka_config.copy() producer_conf.update({ 'delivery.report.only.error': True, 'default.topic.config': { 'request.required.acks': -1, # all brokers must confirm }, }) producer = Producer(producer_conf) api = sickle.Sickle(self.endpoint_url) date_str = date.isoformat() # this dict kwargs hack is to work around 'from' as a reserved python keyword # recommended by sickle docs try: records = api.ListRecords(**{ 'metadataPrefix': self.metadata_prefix, 'from': date_str, 'until': date_str, }) except sickle.oaiexceptions.NoRecordsMatch: print("WARN: no OAI-PMH records for this date: {} (UTC)".format(date_str), file=sys.stderr) return count = 0 for item in records: count += 1 if count % 50 == 0: print("... up to {}".format(count), file=sys.stderr) producer.produce( self.produce_topic, item.raw.encode('utf-8'), key=item.header.identifier.encode('utf-8'), on_delivery=fail_fast) producer.flush() def run(self, continuous=False): while True: current = self.state.next_span(continuous) if current: print("Fetching DOIs updated on {} (UTC)".format(current), file=sys.stderr) self.fetch_date(current) self.state.complete(current, kafka_topic=self.state_topic, kafka_config=self.kafka_config) continue if continuous: print("Sleeping {} seconds...".format(self.loop_sleep), file=sys.stderr) time.sleep(self.loop_sleep) else: break print("{} OAI-PMH ingest caught up".format(self.name), file=sys.stderr) class HarvestArxivWorker(HarvestOaiPmhWorker): """ Arxiv refs: - http://export.arxiv.org/oai2?verb=GetRecord&identifier=oai:arXiv.org:0804.2273&metadataPrefix=arXiv - http://export.arxiv.org/oai2?verb=GetRecord&identifier=oai:arXiv.org:0804.2273&metadataPrefix=arXivRaw All records are work-level. Some metadata formats have internal info about specific versions. The 'arXivRaw' format does, so i'm using that. """ def __init__(self, **kwargs): super().__init__(**kwargs) self.endpoint_url = "https://export.arxiv.org/oai2" self.metadata_prefix = "arXivRaw" self.name = "arxiv" class HarvestDoajJournalWorker(HarvestOaiPmhWorker): """ WARNING: DOAJ OAI-PMH doesn't seem to respect 'from' and 'until' params As an alternative, could use: - https://github.com/miku/doajfetch """ def __init__(self, **kwargs): super().__init__(**kwargs) self.endpoint_url = "https://www.doaj.org/oai" self.metadata_prefix = "oai_dc" self.name = "doaj-journal" class HarvestDoajArticleWorker(HarvestOaiPmhWorker): """ WARNING: DOAJ OAI-PMH doesn't seem to respect 'from' and 'until' params """ def __init__(self, **kwargs): super().__init__(**kwargs) self.endpoint_url = "https://www.doaj.org/oai.article" self.metadata_prefix = "oai_doaj" self.name = "doaj-article"