Open Data
The 9.320 metadata records of the "Helios" repository are available as open data. The information is provided for harvesting via an OAI-PMH protocol interface
This open data service is open to everyone and is meant to be accessed by OAI-PMH compliant harvesters or any application that issues OAI-PMH requests (you can find related tools here).
Detailed technical information
  • Protocol: OAI-PMH version 2.0
  • OAI-PMH base URL: http://helios-eie.ekt.gr/EIE_oai/request
  • Identify
  • Identify the OAI-PMH interface: http://helios-eie.ekt.gr/EIE_oai/request?verb=Identify
  • Sets
  • The set structure of Helios repository: http://helios-eie.ekt.gr/EIE_oai/request?verb=ListSets
    Currently, there are 3 sets:
    1. driver: set that contains all publications that are applicable for harvessting via the Driver - Digital Repository Infrastacture Viseion for European Research
    2. hdl_10442_{i}: where "i" is the handle of each Helios collection
  • Metadata Formats
  • The list of metadata formats that are supported by Helios OAI-PMH service: http://helios-eie.ekt.gr/EIE_oai/request?verb=ListMetadataFormats
    Currently, we support 1 metadata format:
    1. oai_dc: Dublin Core metadata format
  • Dates
  • Every OAI-PMH metadata record has a datestamp associated with it, which is the last modification time of that record. Datetime granularity on the Helios OAI-PMH service is set at second level, e.g. '2013-01-23T07:13:59Z'.
    The OAI-PMH interface does not support selective harvesting based on publication date. The datestamps are designed to support incremental harvesting of updates on an ongoig basis. It is not possible to selectively harvest only, say, records published in February 2001.
  • Record Harvesting
  • List of identifiers: http://helios-eie.ekt.gr/EIE_oai/request?verb=ListIdentifiers
    [required parameters: metadataPrefix],[optional parameters: set, from, until, resumptionToken]
  • List of Records: http://helios-eie.ekt.gr/EIE_oai/request?verb=ListRecords
    [required parameters: metadataPrefix],[optional parameters: set, from, until, resumptionToken]
  • A specific record: http://helios-eie.ekt.gr/EIE_oai/request?verb=GetRecord
    [required parameters: identifier, metadataPrefix]
  • Selective Harvesting
  • Selective harvesting can be performed by the use of accompanying parameters in the aforementioned URL requests. Available parameters are:
    • identifier: specifies a specific record identifier. [supported by GetRecord verb]
    • metadataPrefix: specifies the metadata format that the records will be returned in. [supported by ListIdentifiers, ListRecords and GetRecord verbs]
    • set: specifies the set that returned records must belong to. [supported by ListIdentifiers and ListRecords verbs]
    • from: specifies that records returned must have been created/update/deleted on or after this date. [supported by ListIdentifiers and ListRecords verbs]
    • until: specifies that records returned must have been created/update/deleted on or before this date. [supported by ListIdentifiers and ListRecords verbs]
    • resumptionToken: a token previously provided by the server to resume a request where it last left off. [supported by ListIdentifiers and ListRecords verbs]
  • Responses
  • Responses from the Helios OAI-PMH service are unordered and are capped at 100 records in each single result set.
  • If a request results in more than 100 hits, OAI-PMH will return the first 100 with a that can be used to get the remaining items.
  • Compression of responses is managed by sending an appropriate HTTP 'Accept-Encoding' header , e.g.

    Accept-Encoding: gzip;q=1.0, identity;q=0.5

    The two compression formats supported are 'gzip ' and 'deflate'.
  • Update schedule
  • New publications are submitted daily and metadata is made available via the OAI-PMH directly afterwards.
  • Once an initial harvest has been completed, the copy may be maintained by making imcremental harvesting requests with the from date set to the date of last harvest (from is best taken from the last server response).
If you have questions please contact us


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