Offline Document Indexer Guide

The offline document indexer is a server plugin that - if enabled - fills a separate Solr core with information about all existing documents that are offline. Based on this Solr core's information, the delivery component might provide redirects for links to documents that had been online before.

Sophora Primary Server configuration

The offline document indexer plugin relies on some configuration properties which must be set on the Sophora Primary Server. These properties are listed below.

Solr fields

By default, the Solr documents representing offline documents have the following fields

An additional list of properties might be passed through the offlineDocumentIndexer.propertyNames property. For all of these properties a Solr field matching the field naming conventions will be added. A Solr field name consists of the actual property name whereas ":" is replaced by "_" plus a suffix indicating type and multivalue status.
The sophora property sophora-content:title would result in the Solr field sophora-content_title_t.

Sophora Replica Server configuration

The offline document indexer does not require a specific configuration for the Sophora Replica Servers to be enabled. However the Sophora Replica Server needs to properly propagate its hostname to the Sophora Primary Server so that the Sophora Primary Server can actually access the Sophora Replica Servers Solr. The Sophora Replica Server will try to determine its own hostname and propagate this as part of its ServerInfo-Object. Commonly this determined hostname is not fully qualified and therefore the Sophora Primary Server might have trouble reaching the Sophora Replica Server. In order to correct this you can explicitly set a fully qualified host name for a Sophora Replica Server.

Delivery example

One way to use the offline core are redirects. For this purpose you have to create a class that implements the interface IRedirectBuilder.
The class might look like this:

public class ProjectRedirectBuilder implements IRedirectBuilder {

	private static final String OFFLINE_CORE_NAME = "offline";
	private static final String REDIRECT_DOCUMENT_S = "redirectDocument_s";
	private static final String SOPHORA_STRUCTURE_NODE_S = "sophora_structureNode_s";

	private static final Logger log = LoggerFactory.getLogger(ProjectRedirectBuilder.class);

	private final String[] fields = { "*" };

	@Override
	public String createRedirectUrl(SophoraUrl url, IContentMapContext context) {
		if (url == null || StringUtils.isBlank(url.getSophoraId())) {
			return null;
		}

		String sophoraId = url.getSophoraId();
			
		SolrQuery solrQuery = new SolrQuery();
		solrQuery.setQuery("sophora_id_s:" + sophoraId);
		solrQuery.setFields(fields);
		solrQuery.setRows(1);
		solrQuery.setStart(0);
		solrQuery.addSort("score", ORDER.desc);

		SolrResult solrResult = SolrClient.query(OFFLINE_CORE_NAME, solrQuery);

		String redirectDocumentUuid = null;

		if (solrResult != null && !solrResult.getEntries().isEmpty()) {
			SolrDocument solrDocument = solrResult.getEntries().get(0);

			if (solrDocument.containsKey(REDIRECT_DOCUMENT_S)) {
				// Ein RedirectDocument ist vorhanden
				try {
					String redirectDocUuid = (String) solrDocument.getFieldValue(REDIRECT_DOCUMENT_S);
					context.getDocumentByUuid(redirectDocUuid);
					return createRedirectUrlForUuid(context, redirectDocUuid);
				} catch (ItemNotFoundException e) {
					log.debug(e.getMessage(), e);
				}
			}

			// Strukturknotenhierarchie nach default Dokumenten durchgehen
			String structureNodeUuid = (String) solrDocument.getFieldValue(SOPHORA_STRUCTURE_NODE_S);
			StructureInfo origStructureInfo = context.getStructureInfo(UUID.fromString(structureNodeUuid));
			List<UUID> structureNodeHierarchy = origStructureInfo.getStructureNodeHierarchy();
			List<UUID> reverseStructureNodeHierarchy = Lists.reverse(structureNodeHierarchy);
			for (UUID snUuid : reverseStructureNodeHierarchy) {
				StructureInfo structureInfo = context.getStructureInfo(snUuid);
				UUID defaultDocumentUUID = structureInfo.getDefaultDocumentUUID();
				if (defaultDocumentUUID != null) {
					redirectDocumentUuid = defaultDocumentUUID.toString();
					break;
				}
			}

			return new RedirectResult(createRedirectUrlForUuid(context, redirectDocumentUuid));
		}

		return null;
	}

	private String createRedirectUrlForUuid(IContentMapContext context, String redirectDocumentUuid) {
		String redirectUrl = null;
		if (StringUtils.isNotBlank(redirectDocumentUuid)) {
			redirectUrl = context.createUrl(false, false, true, (String) null, redirectDocumentUuid, (String) null, (String) null, new HashMap<String, Object>(), new HashMap<String, Object>(), null, null);
			redirectUrl = "/" + StringUtils.substringAfter(redirectUrl.replaceFirst("/", ""), "/");
			log.debug("Creating redirect url {} for document uuid {}", redirectUrl, redirectDocumentUuid);
		}
		return redirectUrl;
	}
}

Technical details

Though the offline documents core is available on solrs for Sophora Primary Server and Sophora Replica Servers (either replication and staging), all of the indexing processes are done by the Sophora Primary Server.
Updating a Sophora Replica Server is not part of the regular synchronization process. When a new Sophora Replica Server connects then it will get updated by the Sophora Primary Server just by comparing the current offline documents core with the overall list of offline documents.
The offline documents index will not contain any documents that are deleted.

Controlling the OfflineIndexer through JMX

The Sophora Primary Server will provide a specific JMX-Bean if the OfflineIndexer is activated. This bean is com.subshell.sophora.server.plugins/OfflineDocumentIndexer and will provide a list of indexers where there is one indexer for each server including the Sophora Primary Server. Each indexer comes with these properties:

This bean also offers operations on these indexers. They all take the ID of the indexer as input.

• deactiveIndexer: Explicitly deactivates a single indexer
• activateIndexer: Activates a deactivated indexer
• fullRebuild: Rebuilds the index from scratch. You might want to use this if you have configured new properties for your offline index and want them to be present on all indexed documents. We do not recommend to trigger a rebuild of all indexers at the same time.
• rebuildSince: Rebuild the index considering all the documents modified since a given timestamp. You might want to use this if the last full rebuild is for some reason interrupted. The format of this timestamp is dd.MM.yyyy HH:mm

If an indexer is activated (either due to the JMX operation or due to its corresponding Sophora server reconnecting to the Sophora Primary Server after having been disonnected for some time) then it will automatically fill its queue with all the IDs of documents that have been set offline since the latest modification to offline index of this server.

A full rebuild therefore is only performed if the offline core on the server is completely empty or the JMX operation "fullRebuild" has been triggered.