diff --git a/src/main/java/de/ids_mannheim/korap/KorapCollection.java b/src/main/java/de/ids_mannheim/korap/KorapCollection.java
index fdb0ff3..bebd668 100644
--- a/src/main/java/de/ids_mannheim/korap/KorapCollection.java
+++ b/src/main/java/de/ids_mannheim/korap/KorapCollection.java
@@ -50,6 +50,9 @@
     // Logger
     private final static Logger log = LoggerFactory.getLogger(KorapCollection.class);
 
+    // This advices the java compiler to ignore all loggings
+    public static final boolean DEBUG = false;
+
     // user?
     public KorapCollection (KorapIndex ki) {
 	this.index = ki;
@@ -63,7 +66,9 @@
 	try {
 	    JsonNode json = mapper.readValue(jsonString, JsonNode.class);
 	    if (json.has("collections")) {
-		log.trace("Add meta collection");
+		if (DEBUG)
+		    log.trace("Add meta collection");
+
 		for (JsonNode collection : json.get("collections")) {
 		    this.fromJSON(collection);
 		};
@@ -78,15 +83,31 @@
 	this.filter = new ArrayList<FilterOperation>(5);
     };
 
+    // Create a collection based on UIDs
+    public KorapCollection (String ... uids) {
+	this.filter = new ArrayList<FilterOperation>(5);
+	BooleanFilter filter = new BooleanFilter();
+	if (DEBUG)
+	    log.debug("UID based collection: {},{}", uids[0], uids[1]);
+	filter.or("UID", uids);
+	if (DEBUG)
+	    log.debug("UID based filter: {}", filter.toString());
+	this.filter(filter);
+    };
+
+
     public void fromJSON(JsonNode json) throws QueryException {
 	String type = json.get("@type").asText();
 
 	if (type.equals("korap:meta-filter")) {
-	    log.trace("Add Filter");
+	    if (DEBUG)
+		log.trace("Add Filter");
 	    this.filter(new KorapFilter(json.get("@value")));
 	}
+
 	else if (type.equals("korap:meta-extend")) {
-	    log.trace("Add Extend");
+	    if (DEBUG)
+		log.trace("Add Extend");
 	    this.extend(new KorapFilter(json.get("@value")));
 	};
     };
@@ -101,7 +122,8 @@
 
     // The checks asre not necessary
     public KorapCollection filter (BooleanFilter filter) {
-	log.trace("Added filter: {}", filter.toString());
+	if (DEBUG)
+	    log.trace("Added filter: {}", filter.toString());
 	if (filter == null) {
 	    log.warn("No filter is given");
 	    return this;
@@ -111,7 +133,7 @@
 	    log.warn("Filter can't be wrapped");
 	    return this;
 	};
-	FilterOperation fo = new FilterOperation(f,false);
+	FilterOperation fo = new FilterOperation(f, false);
 	if (fo == null) {
 	    log.warn("Filter operation invalid");
 	    return this;
@@ -127,7 +149,8 @@
 
 
     public KorapCollection extend (BooleanFilter filter) {
-	log.trace("Added extension: {}", filter.toString());
+	if (DEBUG)
+	    log.trace("Added extension: {}", filter.toString());
 	this.filter.add(
 	    new FilterOperation(
 		(Filter) new QueryWrapperFilter(filter.toQuery()),
@@ -160,7 +183,10 @@
 	return sb.toString();
     };
 
-    // DEPRECATED BUT USED IN TEST CASES
+    /**
+     * Search in the virtual collection. This is just used for
+     * testing purposes and not recommended for serious usage. 
+     */
     public KorapResult search (SpanQuery query) {
 	return this.index.search(this, query, 0, (short) 20, true, (short) 5, true, (short) 5);
     };
@@ -180,7 +206,8 @@
 	    ArrayList<FilterOperation> filters = (ArrayList<FilterOperation>) this.filter.clone();
 
 	    FilterOperation kcInit = filters.remove(0);
-	    log.trace("FILTER: {}", kcInit);
+	    if (DEBUG)
+		log.trace("FILTER: {}", kcInit);
 
 	    // Init vector
 	    DocIdSet docids = kcInit.filter.getDocIdSet(atomic, null);
@@ -188,17 +215,18 @@
 	    DocIdSetIterator filterIter = docids.iterator();
 
 	    if (filterIter != null) {
-		log.trace("InitFilter has effect");
-		// System.err.println("Init has an effect");
+		if (DEBUG)
+		    log.trace("InitFilter has effect");
 		bitset.or(filterIter);
 		noDoc = false;
 	    };
 
 	    if (!noDoc) {
 		for (FilterOperation kc : filters) {
-		    log.trace("FILTER: {}", kc);
+		    if (DEBUG)
+			log.trace("FILTER: {}", kc);
 
-		    // BUG!!!
+		    // TODO: BUG!!!!!!!!!!
 		    docids = kc.filter.getDocIdSet(atomic, kc.isExtension() ? null : bitset);
 		    filterIter = docids.iterator();
 
@@ -217,7 +245,6 @@
 		    };
 		    if (kc.isExtension()) {
 			// System.err.println("Term found!");
-			// log.trace("Extend filter");
 			// System.err.println("Old Card:" + bitset.cardinality());
 			bitset.or(filterIter);
 			// System.err.println("New Card:" + bitset.cardinality());
@@ -260,6 +287,7 @@
     };
 
     // This is only for testing purposes!
+    @Deprecated
     public HashMap getTermRelation(String field) throws Exception {
 	if (this.index == null) {
 	    HashMap<String,Long> map = new HashMap<>(1);
@@ -270,6 +298,7 @@
 	return this.index.getTermRelation(this, field);
     };
 
+    @Deprecated
     public String getTermRelationJSON(String field) throws IOException {
 	ObjectMapper mapper = new ObjectMapper();
 	StringWriter sw = new StringWriter();
diff --git a/src/main/java/de/ids_mannheim/korap/KorapDocument.java b/src/main/java/de/ids_mannheim/korap/KorapDocument.java
index 3857ecc..e8792b4 100644
--- a/src/main/java/de/ids_mannheim/korap/KorapDocument.java
+++ b/src/main/java/de/ids_mannheim/korap/KorapDocument.java
@@ -106,20 +106,26 @@
 	this.ID = ID;
     };
 
+    @JsonProperty("ID")
+    public String getID () {
+	return this.ID;
+    };
+
     public void setUID (int UID) {
 	this.UID = UID;
     };
 
+    public void setUID (String UID) {
+	if (UID != null)
+	    this.UID = Integer.parseInt(UID);
+    };
+
+
     @JsonProperty("UID")
     public int getUID () {
 	return this.UID;
     };
 
-    @JsonProperty("ID")
-    public String getID () {
-	return this.ID;
-    };
-
     public void setTitle (String title) {
 	this.title = title;
     };
diff --git a/src/main/java/de/ids_mannheim/korap/KorapFilter.java b/src/main/java/de/ids_mannheim/korap/KorapFilter.java
index d97dd6e..f9052d9 100644
--- a/src/main/java/de/ids_mannheim/korap/KorapFilter.java
+++ b/src/main/java/de/ids_mannheim/korap/KorapFilter.java
@@ -225,6 +225,8 @@
     };
 
     public BooleanFilter or (String type, String ... terms) {
+	if (DEBUG)
+	    log.debug("Got some terms here");
 	BooleanFilter bf = new BooleanFilter();
 	bf.or(type, terms);
 	return bf;
diff --git a/src/main/java/de/ids_mannheim/korap/KorapIndex.java b/src/main/java/de/ids_mannheim/korap/KorapIndex.java
index cbcbd1a..f99da41 100644
--- a/src/main/java/de/ids_mannheim/korap/KorapIndex.java
+++ b/src/main/java/de/ids_mannheim/korap/KorapIndex.java
@@ -187,6 +187,7 @@
 	fieldsToLoad = new HashSet<String>(16);
 	fieldsToLoad.add("author");
 	fieldsToLoad.add("ID");
+	fieldsToLoad.add("UID");
 	fieldsToLoad.add("title");
 	fieldsToLoad.add("subTitle");
 	fieldsToLoad.add("textClass");
@@ -230,6 +231,7 @@
     public IndexReader reader () {
 	if (!readerOpen)
 	    this.openReader();
+	// Todo: Maybe use DirectoryReader.openIfChanged(DirectoryReader)
 
 	return this.reader;
     };
@@ -277,19 +279,32 @@
 	};
     };
 
+    /*
+     * Some of these addDoc methods will probably be DEPRECATED,
+     * as they were added while the API changed slowly.
+     */
+
 
     // Add document to index as FieldDocument
-    public FieldDocument addDoc (FieldDocument fd) throws IOException {
-	
-	// Open writer if not already opened
-	if (this.writer == null)
-	    this.writer = new IndexWriter(this.directory, this.config);
+    public FieldDocument addDoc (FieldDocument fd) {
 
-	// Add document to writer
-	this.writer.addDocument( fd.doc );
-	if (++commitCounter > autoCommit) {
-	    this.commit();
-	    commitCounter = 0;
+	try {
+	
+	    // Open writer if not already opened
+	    if (this.writer == null)
+		this.writer = new IndexWriter(this.directory, this.config);
+
+	    // Add document to writer
+	    this.writer.addDocument( fd.doc );
+	    if (++commitCounter > autoCommit) {
+		this.commit();
+		commitCounter = 0;
+	    };
+	}
+
+	// Failed to add document
+	catch (IOException e) {
+	    log.error("File json not found");
 	};
 	return fd;
     };
@@ -310,31 +325,35 @@
 
 
     // Add document to index as JSON file
-    public FieldDocument addDoc (File json) throws IOException {
-	FieldDocument fd = this.mapper.readValue(json, FieldDocument.class);
-	return this.addDoc(fd);
+    public FieldDocument addDoc (File json) {
+	try {
+	    FieldDocument fd = this.mapper.readValue(json, FieldDocument.class);
+	    return this.addDoc(fd);
+	}
+	catch (IOException e) {
+	    log.error("File json not parseable");	    
+	};
+	return (FieldDocument) null;
     };
 
 
     // Add document to index as JSON file
-    public FieldDocument addDocFile(String json) throws IOException {
+    public FieldDocument addDocFile(String json) {
 	return this.addDocFile(json, false);
     };
 
-
-    // Add document to index as JSON file (possibly gzipped)
-    public FieldDocument addDocFile(String json, boolean gzip) {
+    private FieldDocument _addDocfromFile (String json, boolean gzip) {
 	try {
 	    if (gzip) {
 
 		// Create json field document
 		FieldDocument fd = this.mapper.readValue(
-		    new GZIPInputStream(new FileInputStream(json)),
+		  new GZIPInputStream(new FileInputStream(json)),
 		    FieldDocument.class
 		);
-		return this.addDoc(fd);
+		return fd;
 	    };
-	    return this.addDoc(json);
+	    return this.mapper.readValue(json, FieldDocument.class);
 	}
 
 	// Fail to add json object
@@ -344,6 +363,20 @@
 	return (FieldDocument) null;
     };
 
+    // Add document to index as JSON file (possibly gzipped)
+    public FieldDocument addDocFile(String json, boolean gzip) {
+	return this.addDoc(this._addDocfromFile(json, gzip));
+    };
+
+    // Add document to index as JSON file (possibly gzipped)
+    public FieldDocument addDocFile(int uid, String json, boolean gzip) {
+	FieldDocument fd = this._addDocfromFile(json, gzip);
+	if (fd != null) {
+	    fd.setUID(uid);
+	    return this.addDoc(fd);
+	};
+	return fd;
+    };
 
     // Commit changes to the index
     public void commit () throws IOException {
@@ -1065,20 +1098,22 @@
 	HashSet<String> fieldsToLoadLocal = new HashSet<>(fieldsToLoad);
 	fieldsToLoadLocal.add(field);
 
-	int i = 0;
-	long t1 = 0, t2 = 0;
-	int startIndex = kr.getStartIndex();
-	int count = kr.getItemsPerPage();
-	int hits = kr.itemsPerPage() + startIndex;
-	int limit = ks.getLimit();
-	boolean cutoff = ks.doCutOff();
+	int i                  = 0;
+	long t1                = 0,
+	     t2                = 0;
+	int startIndex         = kr.getStartIndex();
+	int count              = kr.getItemsPerPage();
+	int hits               = kr.itemsPerPage() + startIndex;
+	int limit              = ks.getLimit();
+	boolean cutoff         = ks.doCutOff();
 	short itemsPerResource = ks.getItemsPerResource();
 
-
+	// Check if there is work to do at all
 	if (limit > 0) {
 	    if (hits > limit)
 		hits = limit;
 
+	    // Nah - nothing to do! \o/
 	    if (limit < startIndex)
 		return kr;
 	};
@@ -1100,7 +1135,10 @@
 
 		int oldLocalDocID = -1;
 
-		// Use OpenBitSet;
+		/*
+		 * Todo: There may be a way to now early if the bitset is emty
+		 * by using OpenBitSet - but this may not be as fast as I think.
+		 */
 		Bits bitset = collection.bits(atomic);
 
 		PositionsToOffset pto = new PositionsToOffset(atomic, field);
@@ -1261,7 +1299,7 @@
 
 	// Only load ID
 	HashSet<String> fieldsToLoadLocal = new HashSet<>();
-	fieldsToLoadLocal.add("ID");
+	fieldsToLoadLocal.add("UID");
 
 	// List<KorapMatch> atomicMatches = new ArrayList<KorapMatch>(10);
 
@@ -1275,6 +1313,7 @@
 	    };
 
 	    int matchcount = 0;
+	    String uniqueDocIDString;;
 	    int uniqueDocID = -1;
 
 	    for (AtomicReaderContext atomic : this.reader().leaves()) {
@@ -1313,10 +1352,12 @@
 			};
 
 			// Read document id from index
-			/*
-			uniqueDocID = lreader.document(localDocID, fieldsToLoadLocal).get("ID");
-			*/
-			uniqueDocID = localDocID;
+			uniqueDocIDString =
+			    lreader.document(localDocID, fieldsToLoadLocal).get("UID");
+
+			if (uniqueDocIDString != null)
+			    uniqueDocID = Integer.parseInt(uniqueDocIDString);
+
 			previousDocID = localDocID;
 		    }
 		    else {
diff --git a/src/main/java/de/ids_mannheim/korap/KorapMatch.java b/src/main/java/de/ids_mannheim/korap/KorapMatch.java
index d46fa0e..16e69d9 100644
--- a/src/main/java/de/ids_mannheim/korap/KorapMatch.java
+++ b/src/main/java/de/ids_mannheim/korap/KorapMatch.java
@@ -351,6 +351,8 @@
 	    this.setCorpusID(doc.get("corpusID"));
 	if (fields.contains("ID"))
 	    this.setDocID(doc.get("ID"));
+	if (fields.contains("UID"))
+	    this.setUID(doc.get("UID"));
 	if (fields.contains("author"))
 	    this.setAuthor(doc.get("author"));
 	if (fields.contains("textClass"))
diff --git a/src/main/java/de/ids_mannheim/korap/KorapNode.java b/src/main/java/de/ids_mannheim/korap/KorapNode.java
index 0c88f75..7227085 100644
--- a/src/main/java/de/ids_mannheim/korap/KorapNode.java
+++ b/src/main/java/de/ids_mannheim/korap/KorapNode.java
@@ -40,6 +40,13 @@
     private static String name = "tanja";
 
 
+    /*
+     * Todo: Add shutdown hook,
+     * see: https://10.0.10.12/trac/korap/browser/KorAP-modules/KorAP-REST/src/main/java/de/ids_mannheim/korap/web/Application.java
+     * https://10.0.10.12/trac/korap/browser/KorAP-modules/KorAP-REST/src/main/java/de/ids_mannheim/korap/web/ShutdownHook.java
+     */
+
+
     /**
      * Starts Grizzly HTTP server exposing JAX-RS resources defined in this application.
      * @return Grizzly HTTP server.
diff --git a/src/main/java/de/ids_mannheim/korap/filter/BooleanFilter.java b/src/main/java/de/ids_mannheim/korap/filter/BooleanFilter.java
index 57392bf..fecfd46 100644
--- a/src/main/java/de/ids_mannheim/korap/filter/BooleanFilter.java
+++ b/src/main/java/de/ids_mannheim/korap/filter/BooleanFilter.java
@@ -40,6 +40,9 @@
     // Logger
     private final static Logger log = LoggerFactory.getLogger(KorapFilter.class);
 
+    // This advices the java compiler to ignore all loggings
+    public static final boolean DEBUG = false;
+
     private BooleanQuery bool;
     private String error;
 
@@ -49,6 +52,10 @@
 
     public BooleanFilter or (String type, String ... terms) {
 	for (String term : terms) {
+
+	    if (DEBUG)
+		log.trace("Filter: OR {}={}", type, term);
+
 	    bool.add(
 	        new TermQuery(new Term(type, term)),
 		BooleanClause.Occur.SHOULD
diff --git a/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java b/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java
index e7ad688..7a845be 100644
--- a/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java
+++ b/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java
@@ -236,12 +236,12 @@
     @Override
     public void setUID (int ID) {
 	super.setUID(ID);
-	this.addInt("UID", ID);
+	this.addString("UID", new Integer(ID).toString());
     };
 
     @Override
     public void setLayerInfo (String layerInfo) {
-	System.err.println(layerInfo);
+	// System.err.println(layerInfo);
 	super.setLayerInfo(layerInfo);
 	this.addStored("layerInfo", layerInfo);
     };
diff --git a/src/main/java/de/ids_mannheim/korap/server/Resource.java b/src/main/java/de/ids_mannheim/korap/server/Resource.java
index 2ac540a..0577d93 100644
--- a/src/main/java/de/ids_mannheim/korap/server/Resource.java
+++ b/src/main/java/de/ids_mannheim/korap/server/Resource.java
@@ -23,6 +23,7 @@
 import de.ids_mannheim.korap.KorapNode;
 import de.ids_mannheim.korap.KorapIndex;
 import de.ids_mannheim.korap.KorapSearch;
+import de.ids_mannheim.korap.KorapCollection;
 import de.ids_mannheim.korap.KorapMatch;
 import de.ids_mannheim.korap.KorapResult;
 import de.ids_mannheim.korap.server.KorapResponse;
@@ -77,7 +78,7 @@
      * http://stackoverflow.com/questions/19765582/how-to-make-jersey-use-gzip-compression-for-the-response-message-body
     */
     @PUT
-    @Path("/{textID}")
+    @Path("/index/{textID}")
     @Produces(MediaType.APPLICATION_JSON)
     @Consumes(MediaType.APPLICATION_JSON)
     public String add (@PathParam("textID") Integer uid,
@@ -124,6 +125,7 @@
      * Commit data changes to the index
      */
     @POST
+    @Path("/index")
     @Produces(MediaType.APPLICATION_JSON)
     public String commit () {
 
@@ -135,21 +137,57 @@
 	    version = index.getVersion();
 
 	// There are documents to commit
-	if (index.getUnstaged() != 0) {
-	    try {
-		index.commit();
-	    }
-	    catch (IOException e) {
-		// Set HTTP to ???
-		return kresp.setErrstr(e.getMessage()).toJSON();
-	    };
-
+	try {
+	    index.commit();
+	}
+	catch (IOException e) {
 	    // Set HTTP to ???
-	    return kresp.setMsg("Unstaged data was committed").toJSON();
+	    return kresp.setErrstr(e.getMessage()).toJSON();
 	};
 
 	// Set HTTP to ???
-	return kresp.setMsg("No unstaged data available").toJSON();
+	return kresp.setMsg("Unstaged data was committed").toJSON();
+    };
+
+    /**
+     * Find matches in the lucene index and return them as results.
+     *
+     * @param text_id
+     */
+    @POST
+    @Produces(MediaType.APPLICATION_JSON)
+    @Consumes(MediaType.APPLICATION_JSON)
+    public String find (String json, @Context UriInfo uri) {
+
+	// Get index
+	KorapIndex index = KorapNode.getIndex();
+
+	// Search index
+        if (index != null) {
+	    KorapSearch ks = new KorapSearch(json);
+
+	    // Get query parameters
+	    MultivaluedMap<String,String> qp = uri.getQueryParameters();
+
+	    // Build Collection based on a list of uids
+	    KorapCollection kc = new KorapCollection(
+	      qp.get("uid").toArray(new String[0])
+            );
+
+	    // TODO: RESTRICT COLLECTION TO ONLY RESPECT SELF DOCS (REPLICATION)
+
+	    // Override old collection
+	    ks.setCollection(kc);
+
+	    // Only return the first match per text
+	    ks.setItemsPerResource(1);
+
+            return ks.run(index).toJSON();
+	};
+	// Response with error message
+        KorapResult kr = new KorapResult();
+        kr.setError("Index not found");
+        return kr.toJSON();
     };
 
 
diff --git a/src/test/java/de/ids_mannheim/korap/filter/TestKorapCollection.java b/src/test/java/de/ids_mannheim/korap/filter/TestKorapCollection.java
index 020c081..ba62e86 100644
--- a/src/test/java/de/ids_mannheim/korap/filter/TestKorapCollection.java
+++ b/src/test/java/de/ids_mannheim/korap/filter/TestKorapCollection.java
@@ -7,6 +7,12 @@
 import de.ids_mannheim.korap.KorapResult;
 import de.ids_mannheim.korap.KorapQuery;
 import de.ids_mannheim.korap.filter.BooleanFilter;
+
+
+import org.apache.lucene.index.Term;
+import org.apache.lucene.search.spans.SpanOrQuery;
+import org.apache.lucene.search.spans.SpanQuery;
+import org.apache.lucene.search.spans.SpanTermQuery;
 import org.apache.lucene.search.spans.SpanQuery;
 
 import static org.junit.Assert.*;
@@ -82,7 +88,7 @@
 	// System.err.println(kr.toJSON());
     };
 
-    @Ignore
+    @Test
     public void filterExampleAtomic () throws IOException {
 	
 	// That's exactly the same test class, but with multiple atomic indices
@@ -202,6 +208,45 @@
 	assertEquals(87, kr.totalResults());
 	// System.out.println(kr.toJSON());
     };
+
+
+    @Test
+    public void uidCollection () throws IOException {
+	
+	// Construct index
+	KorapIndex ki = new KorapIndex();
+	// Indexing test files
+	int uid = 1;
+	for (String i : new String[] {"00001",
+				      "00002",
+				      "00003",
+				      "00004",
+				      "00005",
+				      "00006",
+				      "02439"}) {
+	    FieldDocument fd = ki.addDocFile(
+		uid++,
+	        getClass().getResource("/wiki/" + i + ".json.gz").getFile(),
+		true
+	    );
+	};
+	ki.commit();
+
+	assertEquals("Documents", 7, ki.numberOf("documents"));
+	assertEquals("Sentences", 281, ki.numberOf("sentences"));
+
+	SpanQuery sq = new SpanTermQuery(new Term("tokens", "s:der"));
+	KorapResult kr = ki.search(sq, (short) 10);
+        assertEquals(86,kr.getTotalResults());
+
+	// Create Virtual collections:
+	KorapCollection kc = new KorapCollection(new String[]{"2", "3", "4"});
+	kc.setIndex(ki);
+	assertEquals("Documents", 3, kc.numberOf("documents"));
+
+	kr = kc.search(sq);
+        assertEquals(39,kr.getTotalResults());
+    };
 };
 
 
diff --git a/src/test/java/de/ids_mannheim/korap/server/ResourceTest.java b/src/test/java/de/ids_mannheim/korap/server/ResourceTest.java
index 5f2365f..ee84419 100644
--- a/src/test/java/de/ids_mannheim/korap/server/ResourceTest.java
+++ b/src/test/java/de/ids_mannheim/korap/server/ResourceTest.java
@@ -71,7 +71,7 @@
 	    }) {
 
 	    String json = StringfromFile(getClass().getResource("/wiki/" + i + ".json").getFile());
-	    KorapResponse kresp = target.path("/" + i).
+	    KorapResponse kresp = target.path("/index/" + i).
 		request("application/json").
 		put(Entity.json(json), KorapResponse.class);
 
@@ -84,7 +84,7 @@
 	    assertEquals(kresp.getVersion(), "0.42");
 	};
 
-	KorapResponse kresp = target.path("/").
+	KorapResponse kresp = target.path("/index").
 	    request("application/json").
 	    post(Entity.text(""), KorapResponse.class);
 	assertEquals(kresp.getNode(), "milena");