demo code for the jadice knowledge base article at https://levigo.de/info/x/kYHHAQ

ModifyPDFMetadata.java

import java.util.Calendar;

import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.jempbox.xmp.XMPMetadata;
import org.apache.jempbox.xmp.XMPSchemaBasic;
import org.apache.jempbox.xmp.XMPSchemaDublinCore;
import org.apache.jempbox.xmp.XMPSchemaPDF;
import org.w3c.dom.Document;

import com.levigo.jadice.server.Job;
import com.levigo.jadice.server.client.JobFactory;
import com.levigo.jadice.server.client.jms.JMSJobFactory;
import com.levigo.jadice.server.nodes.StreamInputNode;
import com.levigo.jadice.server.nodes.StreamOutputNode;
import com.levigo.jadice.server.pdf.PDFMetadataNode;

public class ModifyPDFMetadata {
  
  public void clearMetadata() throws Exception {
    final JobFactory jf = new JMSJobFactory(new ActiveMQConnectionFactory("tcp://localhost:61616"), JMSJobFactory.DEFAULT_QUEUE_NAME);
    final Job job = jf.createJob();
    job.setType("Clear PDF Metadata");
    
    final PDFMetadataNode pdfMetadata = new PDFMetadataNode();
    
    // Clear any metadata:
    pdfMetadata.setAuthor(null);
    pdfMetadata.setCreator(null);
    pdfMetadata.setCreationDate(null);
    pdfMetadata.setKeywords(null);
    pdfMetadata.setModificationDate(null);
    pdfMetadata.setProducer(null);
    pdfMetadata.setSubject(null);
    pdfMetadata.setTitle(null);
    pdfMetadata.setXmpMetaData(null);
    
    job.attach(new StreamInputNode()
        .appendSuccessor(pdfMetadata)
        .appendSuccessor(new StreamOutputNode()));
  }
  
  public void writeXMP() throws Exception {
    final JobFactory jf = new JMSJobFactory(new ActiveMQConnectionFactory("tcp://localhost:61616"), JMSJobFactory.DEFAULT_QUEUE_NAME);
    final Job job = jf.createJob();
    job.setType("Write XMP to PDF");
    
    XMPMetadata xmlMeta = new XMPMetadata();
    XMPSchemaPDF pdfScheme = xmlMeta.addPDFSchema();
    pdfScheme.setProducer("ACME PDF Producer");
    pdfScheme.setKeywords("XMP, demo, jadice server");

    XMPSchemaBasic basicScheme = xmlMeta.addBasicSchema();
    Calendar createDate = Calendar.getInstance();
    createDate.set(2015, 0, 1, 12, 0, 0); // 1st of January 2015, 12:00
    basicScheme.setCreateDate(createDate);

    Calendar modifyDate = Calendar.getInstance();
    modifyDate.set(2015, 1, 28, 12, 0, 0); // 28th of February 2015, 12:00
    basicScheme.setModifyDate(modifyDate);

    XMPSchemaDublinCore dc = xmlMeta.addDublinCoreSchema();
    dc.setTitle("XMP demonstration document");
    dc.setDescription("This document is the result of the PDFMetadataNode of jadice server");
    dc.addCreator("John Doe");

    // Provide metadata as DOM document
    Document dom = xmlMeta.getXMPDocument();

    final PDFMetadataNode pdfMetadata = new PDFMetadataNode();
    pdfMetadata.setXmpMetaData(dom);
    
    job.attach(new StreamInputNode()
        .appendSuccessor(pdfMetadata)
        .appendSuccessor(new StreamOutputNode()));
  }
}