Another interface that is particularly suitable for metadata harvesting processes is provided by DeepGreen with an OAI-PMH compliant request/query option (see Open Archives Initiative (dt.)). This type of metadata query can be addressed via the web address https://www.oa-deepgreen.de/oaipmh/ , e.g. with the command curl in a shell (bashtcsh, etc.):

$ curl -s https://www.oa-deepgreen.de/oaipmh/...

In the process, the ... can be replaced by the two possible call variants all or repo of the DeepGreen OAI-PMH interface. As usual, in the following, GET always means the complete curl line given above:

  • CallGET /all

    List of all successfully delivered notifications
    GET /all[?<params (i.e. oai_verb + params)>]
    
  • CallGET /repo

    List of notifications delivered to one facility
    GET /repo/<repo_id>[?<params (i.e. oai_verb + params)>]
    

As an illustrative example, the identification of the DeepGreen-OAI-PMH-interface is given:

$ curl -k -s https://www.oa-deepgreen.de/oaipmh/all?verb=Identify | xml_pp
<?xml version="1.0" encoding="UTF-8"?>
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
  <responseDate>2018-08-17T10:47:33Z</responseDate>
  <request verb="Identify">http://www.oa-deepgreen.de/oaipmh/all</request>
  <Identify>
    <repositoryName>DeepGreen Prototype OAI-PMH Endpoint</repositoryName>
    <baseURL>http://www.oa-deepgreen.de/oaipmh/all</baseURL>
    <protocolVersion>2.0</protocolVersion>
    <adminEmail>***</adminEmail>
    <earliestDatestamp>2018-05-19T08:47:33Z</earliestDatestamp>
    <deletedRecord>transient</deletedRecord>
    <granularity>YYYY-MM-DDThh:mm:ssZ</granularity>
  </Identify>
</OAI-PMH>

Please note that the earliest possible timestamp (earlierstDatestamp) is always approximately “-3 months” from the call date (responseDate), as DeepGreen only keeps item data up to date and thus in stock for so long (moving wall principle).

Metadata received from DeepGreen

It should be expressly pointed out once again that DeepGreen’s OAI-PMH interface only offers metadata. The delivery of full texts via OAI-PMH is not (and will not be in the future!) envisaged.

For the sake of clarity, the most common OAI verbs supported by DeepGreen are listed below:

Possible parameters for OAI verbs from DeepGreen
GET <hhtp-Adresse/...>?verb=Identify
#
# This OAI verb has no further parameters
#

GET <http-Adresse/...>?verb=[ListIdentifiers|ListRecords]&from=<YYYY-MM-DD>
#
# Specification optional; determines from when the notifications are listed
#

GET <http-Adresse/...>?verb=[ListIdentifiers|ListRecords]&until=<YYYY-MM-DD>
#
# Specification optional, specifies a (maximum) end date until which the notifications are listed
#

GET <http-Adresse/...>?verb=GetRecord?identifier=<oai_id>
#
# Required; specifies the particular record to be fetched for this OAI verb.
#

For all OAI verbs that return one or more data sets, the parameter ...&metadataPrefix=oai_dc must also be appended. So if it makes sense (or is mandatory) for an OAI verb, several parameters are linked with the & sign.

Thehttp-Header return value is always 200 OK for all OAI requests (according to the OAI-PMHspecification):

  • http-Header return values

    Code

    Description

    200 OK

    HTTP 1.1  200 OK
    Content-Type: text/xml; charset=utf-8
    
    [XML response to OAI-PMH request;
     either content (e.g. list of records) or error message]
    
Examples for the use of the OAI-PMH interface

Exemplary result of an OAI-PMH call (with fictitious account number 1234567890 ; the notification IDs are marked with asterisks):

#
#  ListIdentifiers
#
$ curl -k -s "https://www.oa-deepgreen.de/oaipmh/repo/1234567890?verb=ListIdentifiers&metadataPrefix=oai_dc" | xml_pp
<?xml version="1.0" encoding="UTF-8"?>
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
  <responseDate>2018-08-20T12:03:31Z</responseDate>
  <request metadataPrefix="oai_dc" verb="ListIdentifiers">http://www.oa-deepgreen.de/oaipmh/repo/1234567890</request>
  <ListIdentifiers>
    <header xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/">
      <identifier>oai:www.oa-deepgreen.de/notification:*****</identifier>
      <datestamp>2018-08-03T07:56:26Z</datestamp>
    </header>
    <header xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/">
      <identifier>oai:www.oa-deepgreen.de/notification:*****</identifier>
      <datestamp>2018-07-04T12:41:44Z</datestamp>
    </header>
    <header xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/">
      <identifier>oai:www.oa-deepgreen.de/notification:*****</identifier>
      <datestamp>2018-06-18T13:39:04Z</datestamp>
    </header>
  </ListIdentifiers>
</OAI-PMH>

Another example with concrete data sets. Using the notification IDs (marked with an asterisk here), the authorised repositories could obtain the articles via DeepGreen’s web API, if necessary:

#
#  ListRecords
#
$ curl -k -s "https://www.oa-deepgreen.de/oaipmh/repo/1234567890?verb=ListRecords&metadataPrefix=oai_dc" | xml_pp
<?xml version="1.0" encoding="UTF-8"?>
<OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
  <responseDate>2018-08-20T12:24:10Z</responseDate>
  <request metadataPrefix="oai_dc" verb="ListRecords">http://www.oa-deepgreen.de/oaipmh/repo/1234567890</request>
  <ListRecords>
    <record>
      <header xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/">
        <identifier>oai:www.oa-deepgreen.de/notification:*****</identifier>
        <datestamp>2018-08-10T08:29:00Z</datestamp>
      </header>
      <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/">
        <oai_dc:dc xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
          <dc:title>Healthcare IT Utilization and Penetration among Physicians: Novel IT Solutions in Healthcare – Use and Acceptance in Hospitals</dc:title>
          <dc:publisher>S. Karger AG</dc:publisher>
          <dc:identifier>issn:0014-312X</dc:identifier>
          <dc:identifier>issn:1421-9921</dc:identifier>
          <dc:identifier>doi:10.1159/000490241</dc:identifier>
          <dc:creator>Ferdinand Vogt</dc:creator>
          <dc:creator>Fritz Seidl</dc:creator>
          <dc:creator>Giuseppe Santarpino</dc:creator>
          <dc:creator>Martijn van Griensven</dc:creator>
          <dc:creator>Martin Emmert</dc:creator>
          <dc:creator>Guenther Edenharter</dc:creator>
          <dc:creator>Dominik Pförringer</dc:creator>
          <dc:contributor>eDepartment of Anaesthesiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany</dc:contributor>
          <dc:contributor>bDepartment of Trauma Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany</dc:contributor>
          <dc:contributor>bDepartment of Trauma Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; cDepartment of Experimental Trauma Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany</dc:contributor>
          <dc:contributor>aDepartment of Cardiac Surgery, Klinikum Nürnberg, Paracelsus Medical University, Nuremberg, Germany</dc:contributor>
          <dc:contributor>cDepartment of Experimental Trauma Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany</dc:contributor>
          <dc:contributor>dInstitute of Management (IFM), School of Business and Economics, Friedrich Alexander University Erlangen-Nuremberg, Nuremberg, Germany</dc:contributor>
          <dc:date>2018-07-26T00:00:00Z</dc:date>
          <dc:rights>Alliance License DFG</dc:rights>
          <dc:subject>Original Paper</dc:subject>
          <dc:subject>Health monitoring</dc:subject>
          <dc:subject>Information technology</dc:subject>
          <dc:subject>Physicians</dc:subject>
          <dc:subject>Demand</dc:subject>
          <dc:subject>Outlook</dc:subject>
          <dc:subject>Expectations</dc:subject>
          <dc:subject>Data storage</dc:subject>
          <dc:subject>Healthcare IT</dc:subject>
        </oai_dc:dc>
      </metadata>
    </record>
    <record>
      <header xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/">
        <identifier>oai:www.oa-deepgreen.de/notification:*****</identifier>
        <datestamp>2018-08-10T08:34:06Z</datestamp>
      </header>
      <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/">
        <oai_dc:dc xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd">
          <dc:title>Gastrointestinal Stromal Tumors: Clinical Symptoms, Location, Metastasis Formation, and Associated Malignancies in a Single Center Retrospective Study</dc:title>
          <dc:publisher>S. Karger AG</dc:publisher>
          <dc:identifier>issn:0257-2753</dc:identifier>
          <dc:identifier>issn:1421-9875</dc:identifier>
          <dc:identifier>doi:10.1159/000489556</dc:identifier>
          <dc:creator>Ali Aghdassi</dc:creator>
          <dc:creator>Agnes Christoph</dc:creator>
          <dc:creator>Frank Dombrowski</dc:creator>
          <dc:creator>Paula Döring</dc:creator>
          <dc:creator>Christoph Barth</dc:creator>
          <dc:creator>Jan Christoph</dc:creator>
          <dc:creator>Markus M. Lerch</dc:creator>
          <dc:creator>Peter Simon</dc:creator>
          <dc:contributor>aDepartment of Medicine A, University Medicine Greifswald, Greifswald, Germany</dc:contributor>
          <dc:contributor>dChair of Medical Informatics, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany</dc:contributor>
          <dc:contributor>cGastroenterologische Praxis, Kempten, Germany</dc:contributor>
          <dc:contributor>bInstitute of Pathology, University Medicine Greifswald, Greifswald, Germany</dc:contributor>
          <dc:date>2018-06-05T00:00:00Z</dc:date>
          <dc:rights>Alliance License DFG</dc:rights>
          <dc:subject>Stomach and Duodenum: Original Paper</dc:subject>
          <dc:subject>Gastrointestinal stromal tumor</dc:subject>
          <dc:subject>Gastrointestinal oncology</dc:subject>
          <dc:subject>Gastrointestinal symptoms</dc:subject>
          <dc:subject>Gastrointestinal tract</dc:subject>
          <dc:subject>Metastasis</dc:subject>
          <dc:subject>Recurrence</dc:subject>
        </oai_dc:dc>
      </metadata>
    </record>
  </ListRecords>
</OAI-PMH>