ObjectIdentifiable oId = _idMap.get(htsId);
if (oId == null) {
// resolve hts name to id of hts
HistoricalTimeSeriesInfoSearchRequest searchRequest = new HistoricalTimeSeriesInfoSearchRequest();
searchRequest.setExternalIdSearch(new ExternalIdSearch(htsId));
searchRequest.setDataField(dataField);
searchRequest.setDataProvider(dataProvider);
searchRequest.setDataSource(dataSource);
searchRequest.setObservationTime(observationTime);
HistoricalTimeSeriesInfoSearchResult searchResult = _htsMaster.search(searchRequest);
oId = searchResult.getFirstDocument() == null ? null : searchResult.getFirstDocument().getObjectId();
// if this is a new hts, create it
if (oId == null) {