- added earliestPublicationDate for App/Models/Dataset.ts

- new classes TokenWorkerService.ts, TokenWorker.ts and ResumptionToken.ts for using REDIS with paging OAI results
- deletd public/asstes2/langCodeMap.xml: integrated it directly in datasetxml2oai-pmh.xslt
- added redis npm package
- added TokenWorkerProvider.ts for using singleton of TokenWorkerService inside OaiController.ts
- added config/oai.ts for oai related configs from .env-file
- adapted XmlModel.ts for grting domDocument from database

app/Models/Dataset.ts

@@ -214,4 +214,12 @@ export default class Dataset extends DatasetExtension {
         foreignKey: 'document_id',
     })
     public xmlCache: HasOne<typeof DocumentXmlCache>;
+
+    static async earliestPublicationDate(): Promise<Dataset | null> {
+        const serverState = 'published';
+
+        const model = await this.query().where('server_state', serverState).orderBy('server_date_published', 'asc').first();
+
+        return model || null;
+    }
 }