diff --git a/src/main/java/de/ids_mannheim/korap/sru/KorapClient.java b/src/main/java/de/ids_mannheim/korap/sru/KorapClient.java
index fccc24a..1c313c0 100644
--- a/src/main/java/de/ids_mannheim/korap/sru/KorapClient.java
+++ b/src/main/java/de/ids_mannheim/korap/sru/KorapClient.java
@@ -7,7 +7,9 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import org.apache.http.HttpStatus;
 import org.apache.http.NameValuePair;
@@ -30,6 +32,8 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import de.ids_mannheim.korap.util.RedirectStrategy;
+import eu.clarin.sru.server.SRUConstants;
+import eu.clarin.sru.server.SRUException;
 
 /**
  * Client to KorAP public services supporting calls to the resource,
@@ -50,6 +54,9 @@
     private static ObjectMapper objectMapper = new ObjectMapper();
     private static Logger logger =
             (Logger) LoggerFactory.getLogger(KorapClient.class);
+    
+    // pid : cq
+    public static Map<String, String> virtualCorpora = new HashMap<>();
 
     /**
      * Constructs a KorapClient with the given number of records per
@@ -105,6 +112,16 @@
             InputStream jsonStream = response.getEntity().getContent();
             try {
                 resources = objectMapper.readValue(jsonStream, KorapResource[].class);
+                
+                // update vc map
+                if (resources.length > virtualCorpora.size()) {
+                	for (KorapResource r : resources) {
+                		String[] urlParts = r.getLandingPage().split("cq=");
+                		if (urlParts.length > 1 && !urlParts[1].isEmpty()) {
+                			virtualCorpora.put(r.getResourceId(), urlParts[1]);
+                		}
+                	}
+                }
             }
             catch (JsonParseException | JsonMappingException e) {
                 throw e;
@@ -140,10 +157,11 @@
      * 
      * @throws HttpResponseException
      * @throws IOException
+     * @throws SRUException 
      */
     public KorapResult query (String query, QueryLanguage queryLanguage,
             String version, int startRecord, int maximumRecords,
-            String[] corpora) throws HttpResponseException, IOException {
+            String[] corpora) throws IOException, SRUException {
 
         if (query == null) {
             throw new NullPointerException("Query is null.");
@@ -274,10 +292,13 @@
      * @param corpora 
      * @return a HttpGet request
      * @throws URISyntaxException
+     * @throws IOException 
+     * @throws SRUException 
      */
-    private HttpGet createSearchRequest (String query,
-            QueryLanguage queryLanguage, String version, int startRecord,
-            int maximumRecords, String[] corpora) throws URISyntaxException {
+	private HttpGet createSearchRequest (String query,
+			QueryLanguage queryLanguage, String version, int startRecord,
+			int maximumRecords, String[] corpora)
+			throws URISyntaxException, IOException, SRUException {
 
         if (maximumRecords <= 0) {
             maximumRecords = defaultNumOfRecords;
@@ -288,37 +309,80 @@
             maximumRecords = defaultMaxRecords;
         }
         
-        String corpusQuery = "";
-        if (corpora != null && corpora.length > 0) {
-            for (int i = 0; i < corpora.length; i++) {
-                corpusQuery += "corpusSigle=" + corpora[i];
-                if (i != corpora.length - 1) {
-                    corpusQuery += "|";
-                }
-            }
-        }
+        String corpusQuery = resolveVirtualCorpus(corpora);
+//        if (corpora != null && corpora.length > 0) {
+//            for (int i = 0; i < corpora.length; i++) {
+//                corpusQuery += "corpusSigle=" + corpora[i];
+//                if (i != corpora.length - 1) {
+//                    corpusQuery += "|";
+//                }
+//            }
+//        }
 
-        List<NameValuePair> params = new ArrayList<NameValuePair>();
-        params.add(new BasicNameValuePair("q", query));
-        params.add(new BasicNameValuePair("ql", queryLanguage.toString()));
-        if (!corpusQuery.isEmpty()){
-            params.add(new BasicNameValuePair("cq", corpusQuery));
-        }
-        params.add(new BasicNameValuePair("v", version));
-        params.add(new BasicNameValuePair("context", DEFAULT_CONTEXT_TYPE));
-        params.add(new BasicNameValuePair("count",
-                String.valueOf(maximumRecords)));
-        params.add(
-                new BasicNameValuePair("offset", String.valueOf(startRecord)));
-
-        URIBuilder builder = new URIBuilder(serviceUri + "/search");
-        builder.addParameters(params);
-
-        URI uri = builder.build();
+        URI uri = createSearchUri(query, queryLanguage, version, startRecord,
+		maximumRecords, corpusQuery, false);
+        
         logger.info("Query URI: " + uri.toString());
         HttpGet request = new HttpGet(uri);
         return request;
     }
+    
+	private String resolveVirtualCorpus (String[] corpora)
+			throws URISyntaxException, IOException, SRUException {
+		String corpusQuery = "";
+    	if (corpora != null && corpora.length > 0) {
+            for (int i = 0; i < corpora.length; i++) {
+            	String pid = corpora[i]; 
+            	String cq = virtualCorpora.get(pid);
+            	if (cq != null) {
+            		corpusQuery += " & " + cq;
+            	}
+            	else {
+            		retrieveResources();
+            		cq = virtualCorpora.get(pid);
+            		if (cq != null) {
+                		corpusQuery += " & " + cq;
+            		}
+					else {
+						throw new SRUException(
+								SRUConstants.SRU_GENERAL_SYSTEM_ERROR,
+								"Virtual corpus with pid: " + pid
+										+ " is not found.");
+					}
+        		}            	
+            }
+        }
+    	return corpusQuery;
+	}
+    
+	private URI createSearchUri (String query, QueryLanguage queryLanguage,
+			String version, int startRecord, int maximumRecords,
+			String corpusQuery, boolean authenticationRequired)
+			throws URISyntaxException {
+
+		List<NameValuePair> params = new ArrayList<NameValuePair>();
+		params.add(new BasicNameValuePair("q", query));
+		params.add(new BasicNameValuePair("ql", queryLanguage.toString()));
+		if (!corpusQuery.isEmpty()) {
+			params.add(new BasicNameValuePair("cq", corpusQuery));
+		}
+		params.add(new BasicNameValuePair("v", version));
+		params.add(new BasicNameValuePair("context", DEFAULT_CONTEXT_TYPE));
+		params.add(new BasicNameValuePair("count",
+				String.valueOf(maximumRecords)));
+		params.add(
+				new BasicNameValuePair("offset", String.valueOf(startRecord)));
+
+		if (authenticationRequired) {
+			params.add(
+					new BasicNameValuePair("access-rewrite-disabled", "true"));
+		}
+
+        URIBuilder builder = new URIBuilder(serviceUri + "/search");
+        builder.addParameters(params);
+        URI uri = builder.build();
+        return uri;
+    }
 
     /**
      * Sends a request to the MatchInfo API to get the annotations of
diff --git a/src/main/resources/resources.json b/src/main/resources/resources.json
deleted file mode 100644
index eb27b3f..0000000
--- a/src/main/resources/resources.json
+++ /dev/null
@@ -1,20 +0,0 @@
-[
-	{
-		"id": "WPD17",
-		"description": "German Wikipedia article corpus 2017",
-		"name": "Wikipedia articles 2017",
-		"data": {}
-	},
-	{
-		"id": "WDD17",
-		"description": "German Wikipedia talk corpus 2017",
-		"name": "Wikipedia talk corpus 2017",
-		"data": {}
-	},
-	{
-		"id": "WUD17",
-		"description": "German Wikipedia user talk corpus 2017",
-		"name": "Wikipedia user talk 2017",
-		"data": {}
-	}
-]
\ No newline at end of file
diff --git a/src/main/webapp/WEB-INF/endpoint-description.xml b/src/main/webapp/WEB-INF/endpoint-description.xml
index ed90d1f..80b8f02 100644
--- a/src/main/webapp/WEB-INF/endpoint-description.xml
+++ b/src/main/webapp/WEB-INF/endpoint-description.xml
@@ -12,7 +12,6 @@
     <SupportedDataViews>
         <SupportedDataView id="hits" delivery-policy="send-by-default">application/x-clarin-fcs-hits+xml</SupportedDataView>
         <SupportedDataView id="adv" delivery-policy="send-by-default">application/x-clarin-fcs-adv+xml</SupportedDataView>
-        <SupportedDataView id="kwic" delivery-policy="need-to-request">application/x-clarin-fcs-kwic+xml</SupportedDataView>
     </SupportedDataViews>
     <SupportedLayers>
         <SupportedLayer id="l1" result-id="http://clarin.ids-mannheim.de/korapsru/layers/text">text</SupportedLayer>
diff --git a/src/test/java/de/ids_mannheim/korap/test/BaseTest.java b/src/test/java/de/ids_mannheim/korap/test/BaseTest.java
index 560a11e..3fc8726 100644
--- a/src/test/java/de/ids_mannheim/korap/test/BaseTest.java
+++ b/src/test/java/de/ids_mannheim/korap/test/BaseTest.java
@@ -44,13 +44,13 @@
         mockServer.stop();
     }
 
-    protected void createRetrieveResource () throws IOException {
+    protected void createExpectationForRetrieveResource () throws IOException {
         String korapResources = IOUtils.toString(
                 ClassLoader.getSystemResourceAsStream(
                         "korap-api-responses/resources.json"),
                 StandardCharsets.UTF_8);
 
-        mockClient.reset()
+        mockClient
                 .when(request().withMethod("GET").withPath("/resource"))
                 .respond(response()
                         .withHeader(new Header("Content-Type",
@@ -66,7 +66,7 @@
                         "korap-api-responses/" + jsonFilename),
                 StandardCharsets.UTF_8);
 
-        mockClient.reset()
+        mockClient
                 .when(request().withMethod("GET").withPath("/search")
                         .withQueryStringParameter("q", query)
                         .withQueryStringParameter("ql", queryLanguage)
diff --git a/src/test/java/de/ids_mannheim/korap/test/KorapClientTest.java b/src/test/java/de/ids_mannheim/korap/test/KorapClientTest.java
index 30b5ec3..0206da7 100644
--- a/src/test/java/de/ids_mannheim/korap/test/KorapClientTest.java
+++ b/src/test/java/de/ids_mannheim/korap/test/KorapClientTest.java
@@ -13,6 +13,7 @@
 import de.ids_mannheim.korap.sru.KorapResource;
 import de.ids_mannheim.korap.sru.KorapResult;
 import de.ids_mannheim.korap.sru.QueryLanguage;
+import eu.clarin.sru.server.SRUException;
 
 /**
  * The tests are based on the sample corpus from the Goethe corpus.
@@ -29,10 +30,11 @@
         c = new KorapClient("http://localhost:1080", 25, 50);
     }
 
-    @Test
-    public void testCQLQuery () throws HttpResponseException, IOException {
+	@Test
+	public void testCQLQuery ()
+			throws HttpResponseException, IOException, SRUException {
 
-        createExpectationForSearch("der", "cql", "1.2", "50",
+		   createExpectationForSearch("der", "cql", "1.2", "50",
                 "search-der.jsonld");
 
         result = c.query("der", QueryLanguage.CQL, "1.2", 51, 1, null);
@@ -49,8 +51,9 @@
 
     }
 
-    @Test
-    public void testOrQuery () throws HttpResponseException, IOException {
+	@Test
+	public void testOrQuery ()
+			throws HttpResponseException, IOException, SRUException {
 
         createExpectationForSearch("(\"blaue\"|\"grüne\")", "fcsql", "2.0", "0",
                 "search-or.jsonld");
@@ -106,11 +109,14 @@
     @Test
     public void testRetrieveResource ()
             throws HttpResponseException, Exception {
-        createRetrieveResource();
+        createExpectationForRetrieveResource();
         KorapResource[] resources = c.retrieveResources();
         assertEquals(3, resources.length);
-        assertEquals("WPD17", resources[0].getResourceId());
-        assertEquals("WDD17", resources[1].getResourceId());
-        assertEquals("WUD17", resources[2].getResourceId());
+		assertEquals("http://hdl.handle.net/10932/00-03B6-558F-4E10-6201-1",
+				resources[0].getResourceId());
+        assertEquals("http://hdl.handle.net/10932/00-03B6-558F-5EA0-6301-B", 
+        		resources[1].getResourceId());
+        assertEquals("http://hdl.handle.net/10932/00-03B6-558F-6EF0-6401-F", 
+        		resources[2].getResourceId());
     }
 }
diff --git a/src/test/java/de/ids_mannheim/korap/test/KorapSRUTest.java b/src/test/java/de/ids_mannheim/korap/test/KorapSRUTest.java
index ef6511a..d04b0f2 100644
--- a/src/test/java/de/ids_mannheim/korap/test/KorapSRUTest.java
+++ b/src/test/java/de/ids_mannheim/korap/test/KorapSRUTest.java
@@ -40,7 +40,7 @@
                         "korap-api-responses/search-fein.jsonld"),
                 StandardCharsets.UTF_8);
 
-        mockClient.reset()
+        mockClient
                 .when(request().withMethod("GET").withPath("/search")
                         .withQueryStringParameter("q", "fein")
                         .withQueryStringParameter("ql", "cql")
@@ -53,6 +53,27 @@
                                 "application/json; charset=utf-8"))
                         .withBody(searchResult).withStatusCode(200));
     }
+    
+    private void createExpectationForSearchFeinWithUnknownCq () throws IOException {
+        String searchResult = IOUtils.toString(
+                ClassLoader.getSystemResourceAsStream(
+                        "korap-api-responses/search-fein-unknown-cq.jsonld"),
+                StandardCharsets.UTF_8);
+
+        mockClient
+                .when(request().withMethod("GET").withPath("/search")
+                        .withQueryStringParameter("q", "fein")
+                        .withQueryStringParameter("ql", "cql")
+                        .withQueryStringParameter("v", "1.2")
+                        .withQueryStringParameter("context", "sentence")
+                        .withQueryStringParameter("count", "25")
+                        .withQueryStringParameter("offset", "0")
+                        .withQueryStringParameter("cq","corpusSigle=unknown"))
+                .respond(response()
+                        .withHeader(new Header("Content-Type",
+                                "application/json; charset=utf-8"))
+                        .withBody(searchResult).withStatusCode(200));
+    }
 
     private void createExpectationForMatchInfoFein () throws IOException {
         String matchInfoResult = IOUtils.toString(
@@ -124,17 +145,45 @@
     public void searchRetrieveWithResourceId ()
             throws IOException, URISyntaxException, IllegalStateException,
             SAXException, ParserConfigurationException {
-        createExpectationForSearchFein();
+    	createExpectationForRetrieveResource();
+    	createExpectationForSearchFein();
         createExpectationForMatchInfoFein();
 
         ClientResponse response = resource()
                 .queryParam("operation", "searchRetrieve")
                 .queryParam("query", "fein").queryParam("version", "1.2")
-                .queryParam("x-fcs-context", "GOE").get(ClientResponse.class);
+                .queryParam("x-fcs-context", "http://hdl.handle.net/10932/00-03B6-558F-4E10-6201-1").get(ClientResponse.class);
 
         InputStream entity = response.getEntity(InputStream.class);
         checkSearchRetrieveResponseSRUVersion1_2(entity);
     }
+    
+    @Test
+    public void searchRetrieveWithUnknownResourceId ()
+            throws IOException, URISyntaxException, IllegalStateException,
+            SAXException, ParserConfigurationException {
+    	
+    	createExpectationForRetrieveResource();
+    	createExpectationForSearchFeinWithUnknownCq();
+        createExpectationForMatchInfoFein();
+
+        ClientResponse response = resource()
+                .queryParam("operation", "searchRetrieve")
+                .queryParam("query", "fein").queryParam("version", "1.2")
+                .queryParam("x-fcs-context", "unknown").get(ClientResponse.class);
+
+		InputStream entity = response.getEntity(InputStream.class);
+		docBuilder = factory.newDocumentBuilder();
+		Document doc = docBuilder.parse(entity);
+
+		NodeList diagnosticUri = doc.getElementsByTagName("diag:uri");
+		assertEquals("info:srw/diagnostic/1/1",
+				diagnosticUri.item(0).getTextContent());
+
+		NodeList diagnosticMessage = doc.getElementsByTagName("diag:message");
+		assertEquals("Virtual corpus with pid: unknown is not found.",
+				diagnosticMessage.item(0).getTextContent());
+	}
 
     @Test
     public void searchRetrieveFCSQLTest ()
@@ -279,7 +328,7 @@
             throws URISyntaxException, ClientProtocolException, IOException,
             IllegalStateException, SAXException {
 
-        createRetrieveResource();
+        createExpectationForRetrieveResource();
 
         ClientResponse response = resource().queryParam("operation", "explain")
                 .queryParam("x-fcs-endpoint-description", "true")
diff --git a/src/test/resources/korap-api-responses/resources.json b/src/test/resources/korap-api-responses/resources.json
index 64eb69c..929572a 100644
--- a/src/test/resources/korap-api-responses/resources.json
+++ b/src/test/resources/korap-api-responses/resources.json
@@ -1,59 +1,65 @@
 [
-    {
-        "resourceId": "WPD17",
-        "titles": {
-            "de": "Deutsche Wikipedia Artikel 2017",
-            "en": "German Wikipedia Articles 2017"
-        },
-        "description": "A collection of articles of German Wikipedia from July 1st, 2017.",
-        "languages": ["deu"],
-        "layers": {
-            "18": "marmot/m",
-            "19": "marmot/p",
-            "23": "opennlp/p",
-            "11": "corenlp/p",
-            "27": "tt/l",
-            "28": "tt/p"
-        },
-         "institution" : "Wikimedia Foundation",
-         "landingPage" : "https://korap.ids-mannheim.de?corpusSigle=WPD17"
+  {
+    "resourceId": "http://hdl.handle.net/10932/00-03B6-558F-4E10-6201-1",
+    "titles": {
+      "de": "Deutsche Wikipedia Artikel 2017",
+      "en": "German Wikipedia Articles 2017"
     },
-    {
-        "resourceId": "WDD17",
-        "titles": {
-            "de": "Deutsche Wikipedia-Diskussionskorpus 2017",
-            "en": "German Wikipedia talk corpus 2017"
-        },
-        "description": "A collection of talk pages of German Wikipedia from July 1st, 2017.",
-        "languages": ["deu"],
-        "layers": {
-            "18": "marmot/m",
-            "19": "marmot/p",
-            "23": "opennlp/p",
-            "11": "corenlp/p",
-            "27": "tt/l",
-            "28": "tt/p"
-        },
-        "institution" : "Wikimedia Foundation",
-         "landingPage" : "https://korap.ids-mannheim.de?corpusSigle=WDD17"
+    "description": "A collection of articles of German Wikipedia from July 1st, 2017.",
+    "languages": [
+      "deu"
+    ],
+    "layers": {
+      "1": "opennlp/p",
+      "14": "marmot/m",
+      "15": "marmot/p",
+      "29": "corenlp/p",
+      "30": "tt/l",
+      "31": "tt/p"
     },
-    {
-        "resourceId": "WUD17",
-        "titles": {
-            "de": "Deutsche Wikipedia-Benutzerdiskussionskorpus 2017",
-            "en": "German Wikipedia talk corpus 2017"
-        },
-        "description": "A collection of user talk pages of German Wikipedia from July 1st, 2017.",
-        "languages": ["deu"],
-        "layers": {
-            "18": "marmot/m",
-            "19": "marmot/p",
-            "23": "opennlp/p",
-            "11": "corenlp/p",
-            "27": "tt/l",
-            "28": "tt/p"
-        },
-        "institution" : "Wikimedia Foundation",
-         "landingPage" : "https://korap.ids-mannheim.de?corpusSigle=WUD17"
-    }
+    "institution": "IDS Mannheim",
+    "landingPage": "https://korap.ids-mannheim.de?cq=corpusSigle=WPD17"
+  },
+  {
+    "resourceId": "http://hdl.handle.net/10932/00-03B6-558F-5EA0-6301-B",
+    "titles": {
+      "de": "Deutsche Wikipedia-Diskussionskorpus 2017",
+      "en": "German Wikipedia talk corpus 2017"
+    },
+    "description": "A collection of talk pages of German Wikipedia from July 1st, 2017.",
+    "languages": [
+      "deu"
+    ],
+    "layers": {
+      "1": "opennlp/p",
+      "14": "marmot/m",
+      "15": "marmot/p",
+      "29": "corenlp/p",
+      "30": "tt/l",
+      "31": "tt/p"
+    },
+    "institution": "IDS Mannheim",
+    "landingPage": "https://korap.ids-mannheim.de?cq=corpusSigle=WDD17"
+  },
+  {
+    "resourceId": "http://hdl.handle.net/10932/00-03B6-558F-6EF0-6401-F",
+    "titles": {
+      "de": "Deutsche Wikipedia-Benutzerdiskussionskorpus 2017",
+      "en": "German Wikipedia user talk corpus 2017"
+    },
+    "description": "A collection of user talk pages of German Wikipedia from July 1st, 2017.",
+    "languages": [
+      "deu"
+    ],
+    "layers": {
+      "1": "opennlp/p",
+      "14": "marmot/m",
+      "15": "marmot/p",
+      "29": "corenlp/p",
+      "30": "tt/l",
+      "31": "tt/p"
+    },
+    "institution": "IDS Mannheim",
+    "landingPage": "https://korap.ids-mannheim.de?cq=corpusSigle=WUD17"
+  }
 ]
\ No newline at end of file
diff --git a/src/test/resources/korap-api-responses/search-fein-unknown-cq.jsonld b/src/test/resources/korap-api-responses/search-fein-unknown-cq.jsonld
new file mode 100644
index 0000000..f886d50
--- /dev/null
+++ b/src/test/resources/korap-api-responses/search-fein-unknown-cq.jsonld
@@ -0,0 +1,95 @@
+{
+  "@context": "http://korap.ids-mannheim.de/ns/KoralQuery/v0.3/context.jsonld",
+  "meta": {
+    "count": 25,
+    "startIndex": 0,
+    "timeout": 10000,
+    "context": {
+      "left": [
+        "token",
+        6
+      ],
+      "right": [
+        "token",
+        6
+      ]
+    },
+    "fields": [
+      "ID",
+      "UID",
+      "textSigle",
+      "corpusID",
+      "author",
+      "title",
+      "subTitle",
+      "textClass",
+      "pubPlace",
+      "pubDate",
+      "availability",
+      "layerInfos",
+      "docSigle",
+      "corpusSigle"
+    ],
+    "version": "0.63.3",
+    "benchmark": "0.19016714 s",
+    "totalResources": 0,
+    "totalResults": 0,
+    "serialQuery": "tokens:s:ich",
+    "itemsPerPage": 25
+  },
+  "query": {
+    "@type": "koral:token",
+    "wrap": {
+      "@type": "koral:term",
+      "match": "match:eq",
+      "layer": "orth",
+      "key": "ich",
+      "foundry": "opennlp",
+      "rewrites": [
+        {
+          "@type": "koral:rewrite",
+          "src": "Kustvakt",
+          "editor": "Kustvakt",
+          "operation": "operation:injection",
+          "scope": "foundry",
+          "_comment": "Default foundry has been added."
+        }
+      ]
+    }
+  },
+  "collection": {
+    "@type": "koral:docGroup",
+    "operation": "operation:and",
+    "operands": [
+      {
+        "@type": "koral:doc",
+        "match": "match:eq",
+        "type": "type:regex",
+        "value": "CC.*",
+        "key": "availability"
+      },
+      {
+        "@type": "koral:doc",
+        "match": "match:eq",
+        "value": "unknown",
+        "key": "corpusSigle"
+      }
+    ],
+    "rewrites": [
+      {
+        "@type": "koral:rewrite",
+        "src": "Kustvakt",
+        "editor": "Kustvakt",
+        "operation": "operation:override",
+        "original": {
+          "@type": "koral:doc",
+          "match": "match:eq",
+          "value": "unknown",
+          "key": "corpusSigle"
+        },
+        "_comment": "Free corpus access policy has been added."
+      }
+    ]
+  },
+  "matches": []
+}
\ No newline at end of file