ds-present

Transforming access layer for metadata. Acts as a proxy for ds-storage providing multiple views on metadata, such as MODS, JSON-LD and SolrJsonDocument.

Developed and maintained by the Royal Danish Library.

⚠️ Warning: Copyright Notice

Please note that it is not permitted to download and/or otherwise reuse content from the DR-archive at The Danish Royal Library.

Requirements

• Maven 3
• Java 11
• For production or integration test: A running ds-storage

Test run

Build and start the service using jetty with

mvn package jetty:run

After this, the Swagger UI should be available at http://localhost:9073/ds-present/api/.

The endpoint record/{id} should now respond when requesting a record with the ID local.test:luftfoto-sample.xml (the GUI might be a little slow to render the response).

Test run with remote storage

Install ds-storage and follow its instructions for starting a test instance.

Navigate to the ds-present-corpus folder and upload samples to the running ds-storage:

cd src/test/resources/xml/corpus/
./post_to_storage.sh albert-einstein.xml hvidovre-teater.xml simonsen-brandes.xml tystrup-soroe.xml homiliae-super-psalmos.xml work_on_logic.xml joergen_hansens_visebog.xml responsa.xml

After this, a record for ID doms.radio:albert-einstein.xml should be delivered when requested from the /record/{id} endpoint.

Test with Solr

Solr fundamentals

In DS, Solr operates with versioned collections. Upon first start or if a full reindex is needed, a timestamped collection is created. Access to the collection is done through two aliases:

• ds is used for searching
• ds-write is used for updating

Normally the two aliases will point to the same timestamped collection, but if a full index rebuild is underway, ds will point to the complete old collection while ds-write will point to the new collection being created. When the full index rebuild has finished, ds will be switched to the new collection.

This method ensures that there are no disruptions to Solr search. It is used in production at the Royal Danish Library and also on devel + stage for consistency.

The how-to below expects the version of the Solr configuration to be specified in schema.xml as a special field looking like this:

 <field name="_ds_1.0.0_" type="string" indexed="false" stored="false"/>

If the schema is changed, the version must be updated using Semantic Versioning

Initial setup of Solr Cloud

ds-present comes with convenience scripts for downloading, installing and starting Solr 9 in Cloud mode.

  bin/cloud_install.sh
  bin/cloud_start.sh
 
  bin/cloud_ds.sh new
  bin/cloud_ds.sh align

Check that the collection was created by visiting http://localhost:10007/solr/#/~cloud?view=graph

After this Solr is available at http://localhost:10007/solr/

Operating Solr

The cloud can be stopped and started with

bin/cloud_stop.sh
bin/cloud_start.sh

Aliases and collections can be seen from the admin gui or by calling

bin/cloud_alias.sh

and

bin/cloud_status.sh

Clear all records in the ds-20231114-1446 collection, but keep the collection:

bin/cloud_clear.sh ds-20231114-1446

Fully delete a concrete collection, e.g. ds-20231114-1446:

bin/cloud_delete.sh ds-20231114-1446

Configuration update without reindex

If the Solr configuration is changed in a way that does not require a full reindex, the configuration can be assigned to an existing collection.

The existing collection should be the one that the alias ds-write points to. In that case the updated configuration can be assigned with

bin/cloud_ds.sh update

If not, the aliases and collections can be listed with bin/cloud_alias.sh and the relevant collection can be fiven as argument

bin/cloud_ds.sh update <a-specific-collection>

If this is during development and the Solr config version has not been bumped, the update can be forced:

FORCE_CONFIG=true bin/cloud_ds.sh update

Full reindex

If a fresh index is needed, the alias mehanism ensures that this is done without disrupting the existing collection.

Create a new empty index with

bin/cloud_ds.sh new

This will create a new index and set the ds-write alias to point to it. It can be inspected with

bin/cloud_alias.sh

which should give something like

Aliases:
{
  "ds-write": "ds-20231116-1240",
  "ds": "ds-20231116-1045"
}

Collections:
ds-20231116-1045
ds-20231116-1051
ds-20231116-1240

Note how ds-write and ds points to different collections.

Perform the full reindex (http://<develserver>/ds-datahandler/api/#/ds-datahandler/solrIndex). Users of the index (ds-license and ds-discover) will continue to query the old index while this takes place.

When the index has finished, adjust the ds alias to point to the new full collection

bin/cloud_ds.sh align

Users of the index (ds-license and ds-discover) will now use the new index.

Extract SolrJSONDocuments and index in Solr

With ds-storage populated with the sample documents and ds-present running, use the ds-present API to call /records for collection remote and send them to Solr.

This can be done from the command line with

curl -s 'http://localhost:9073/ds-present/v1/records?collection=remote&maxRecords=1000&format=SolrJSON' > solrdocs.json

Indekser dem i Solr:

curl -X POST -H 'Content-Type: application/json' 'http://localhost:10007/solr/ds/update' --data-binary @solrdocs.json

curl -X POST -H 'Content-Type: application/json' 'http://localhost:10007/solr/ds/update' --data-binary '{ "commit": {} }'

General setup

copy conf/ds-present-behaviour.yaml to conf/ds-present-environment.yaml and adjust URLs for the storages in the new file.

Build & run

Build with

mvn package

Test the webservice with

mvn jetty:run

The Swagger UI is available at http://localhost:9073/ds-present/api/.

Using a client to call the service

This project produces a support JAR containing client code for calling the service from Java. This can be used from an external project by adding the following to the pom.xml:

<!-- Used by the OpenAPI client -->
<dependency>
    <groupId>org.openapitools</groupId>
    <artifactId>jackson-databind-nullable</artifactId>
    <version>0.2.2</version>
</dependency>

<dependency>
    <groupId>dk.kb.present</groupId>
    <artifactId>ds-present</artifactId>
    <version>1.0-SNAPSHOT</version>
    <type>jar</type>
    <classifier>classes</classifier>
    <!-- Do not perform transitive dependency resolving for the OpenAPI client -->
    <exclusions>
        <exclusion>
          <groupId>*</groupId>
          <artifactId>*</artifactId>
        </exclusion>
    </exclusions>
</dependency>

after this a client can be created with

    DsPresentClient presentClient = new DsPresentClient("https://example.com/ds-present/v1");

During development, a SNAPSHOT for the OpenAPI client can be installed locally by running

mvn install

See the file DEVELOPER.md for developer specific details and how to deploy to tomcat.