Clean up `Connector` usages (#90)

* migrate all connector-string uses to Connector enum, and fail early for unsupported connectors

* extra null guards + clean up equals for enums

* unify the parameter checking for jks too

* make empty/null inputs fail earlier

* exception instead of empty return

6 files changed, 164 insertions, 271 deletions

diff --git a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsHelper.java b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsHelper.java
index 5e7e3bd0..22178921 100644
--- a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsHelper.java
+++ b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsHelper.java
@@ -34,11 +34,7 @@ import java.net.URL;
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
 import java.security.cert.CertificateException;
-import java.util.ArrayList;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Map;
-import java.util.UUID;
+import java.util.*;
 
 import javax.imageio.ImageIO;
 import jakarta.servlet.RequestDispatcher;
@@ -391,17 +387,14 @@ public class PdfAsHelper {
 				new ByteArrayDataSource(documentToSign.getInputData()), baos);
 
 		// Get Connector
+		val connector = coreParams.getConnector();
+		val keyIdentifier = coreParams.getKeyIdentifier();
+		PdfAsHelper.checkConnectorSupported(connector, keyIdentifier);
 
 		IPlainSigner signer;
-		if (coreParams.getConnector().equals(Connector.MOA)) {
-			String keyIdentifier = coreParams.getKeyIdentifier();
+		if (connector == Connector.MOA) {
 
 			if (keyIdentifier != null) {
-				if (!WebConfiguration.isMoaEnabled(keyIdentifier)) {
-					throw new PdfAsWebException("MOA connector ["
-							+ keyIdentifier + "] disabled or not existing.");
-				}
-
 				String url = WebConfiguration.getMoaURL(keyIdentifier);
 				String timeout = WebConfiguration.getMoaTimeout(keyIdentifier);
 				String keyId = WebConfiguration.getMoaKeyID(keyIdentifier);
@@ -413,19 +406,12 @@ public class PdfAsHelper {
 				config.setValue(IConfigurationConstants.MOA_SIGN_KEY_ID, keyId);
 				config.setValue(IConfigurationConstants.MOA_SIGN_CERTIFICATE,
 						certificate);
-			} else {
-				if (!WebConfiguration.getMOASSEnabled()) {
-					throw new PdfAsWebException("MOA connector disabled.");
-				}
 			}
 
 			signer = new PAdESSigner(new MOAConnector(config));
 		
 		
-		} else if (coreParams.getConnector().equals(Connector.JKS)) {
-			String keyIdentifier = coreParams.getKeyIdentifier();
-
-			boolean ksEnabled = false;
+		} else if (connector == Connector.JKS) {
 			String ksFile = null;
 			String ksAlias = null;
 			String ksPass = null;
@@ -433,14 +419,12 @@ public class PdfAsHelper {
 			String ksType = null;
 
 			if (keyIdentifier != null) {
-				ksEnabled = WebConfiguration.getKeystoreEnabled(keyIdentifier);
 				ksFile = WebConfiguration.getKeystoreFile(keyIdentifier);
 				ksAlias = WebConfiguration.getKeystoreAlias(keyIdentifier);
 				ksPass = WebConfiguration.getKeystorePass(keyIdentifier);
 				ksKeyPass = WebConfiguration.getKeystoreKeyPass(keyIdentifier);
 				ksType = WebConfiguration.getKeystoreType(keyIdentifier);
 			} else {
-				ksEnabled = WebConfiguration.getKeystoreDefaultEnabled();
 				ksFile = WebConfiguration.getKeystoreDefaultFile();
 				ksAlias = WebConfiguration.getKeystoreDefaultAlias();
 				ksPass = WebConfiguration.getKeystoreDefaultPass();
@@ -448,27 +432,6 @@ public class PdfAsHelper {
 				ksType = WebConfiguration.getKeystoreDefaultType();
 			}
 
-			if (!ksEnabled) {
-				if (keyIdentifier != null) {
-					throw new PdfAsWebException("JKS connector ["
-							+ keyIdentifier + "] disabled or not existing.");
-				} else {
-					throw new PdfAsWebException(
-							"DEFAULT JKS connector disabled.");
-				}
-			}
-
-			if (ksFile == null || ksAlias == null || ksPass == null
-					|| ksKeyPass == null || ksType == null) {
-				if (keyIdentifier != null) {
-					throw new PdfAsWebException("JKS connector ["
-							+ keyIdentifier + "] not correctly configured.");
-				} else {
-					throw new PdfAsWebException(
-							"DEFAULT JKS connector not correctly configured.");
-				}
-			}
-
 			signer = new PAdESSignerKeystore(ksFile, ksAlias, ksPass,
 					ksKeyPass, ksType);
 			
@@ -541,11 +504,11 @@ public class PdfAsHelper {
 	}
 
 	public static void startSignatureJson(HttpServletRequest request, HttpServletResponse response, 
-	    ServletContext context, String connector, PdfasSignRequest pdfAsRequest) throws Exception {
+	    ServletContext context, Connector connector, PdfasSignRequest pdfAsRequest) throws Exception {
 	  HttpSession session = request.getSession();
         
     log.info("Starting signature in session: " + session.getId());    
-    session.setAttribute(PDF_PROCESSING_REQUEST, pdfAsRequest);    
+    session.setAttribute(PDF_PROCESSING_REQUEST, pdfAsRequest);
     
     StatusRequest statusRequest = initializeSigningContextForNewDocument(request, connector, pdfAsRequest);    
     session.setAttribute(PDF_STATUS, statusRequest);
@@ -553,7 +516,7 @@ public class PdfAsHelper {
 	}
 
   public static void startSignature(HttpServletRequest request, HttpServletResponse response,
-      ServletContext context, String connector, PdfasSignRequest pdfAsRequest) throws Exception {    
+      ServletContext context, Connector connector, PdfasSignRequest pdfAsRequest) throws Exception {
     HttpSession session = request.getSession();
     log.info("Starting signature in session: " + session.getId());    
     session.setAttribute(PDF_PROCESSING_REQUEST, pdfAsRequest);    
@@ -566,7 +529,7 @@ public class PdfAsHelper {
             
   }
 	
-  private static StatusRequest.Stage1 initializeSigningContextForNewDocument(HttpServletRequest request, String connector, PdfasSignRequest pdfAsRequest)
+  private static StatusRequest.Stage1 initializeSigningContextForNewDocument(HttpServletRequest request, Connector connector, PdfasSignRequest pdfAsRequest)
       throws PdfAsWebException, WriterException, IOException, PdfAsException, PDFASError {   
     HttpSession session = request.getSession();
     
@@ -643,23 +606,14 @@ public class PdfAsHelper {
     
   }
 
-  private static IPlainSigner getSignerFromConnector(String connector, Configuration config, HttpSession session) throws PdfAsWebException {
-    if (connector.equals("bku") || connector.equals("onlinebku")
-        || connector.equals("mobilebku")) {
-      BKUSLConnector conn = new BKUSLConnector(config);
-      session.setAttribute(PDF_SL_CONNECTOR, conn);
-      return new PAdESSigner(conn);
-      
-
-    } else if (connector.equals("sl20")) {
-      SL20Connector conn = new SL20Connector(config);
-      session.setAttribute(PDF_SL_CONNECTOR, conn);
-      return new PAdESSigner(conn);
-            
-    } else {
-      throw new PdfAsWebException(
-          "Invalid connector (bku | onlinebku | mobilebku | moa | jks | sl20)");
-    }    
+  private static IPlainSigner getSignerFromConnector(Connector connector, Configuration config, HttpSession session) throws PdfAsWebException {
+	val slConnector = switch(connector) {
+		case BKU, ONLINEBKU, MOBILEBKU -> new BKUSLConnector(config);
+		case SECLAYER20 -> new SL20Connector(config);
+		default -> throw new PdfAsWebException("Invalid connector (bku | onlinebku | mobilebku | sl20)");
+	};
+	session.setAttribute(PDF_SL_CONNECTOR, slConnector);
+	return new PAdESSigner(slConnector);
   }
 	
 	public static byte[] getCertificate(
@@ -769,10 +723,10 @@ public class PdfAsHelper {
 		// IPlainSigner plainSigner = (IPlainSigner) session
 		// .getAttribute(PDF_SIGNER);
 
-		String connector = (String) session.getAttribute(PDF_SL_INTERACTIVE);
+		Connector connector = (Connector) session.getAttribute(PDF_SL_INTERACTIVE);
+		PdfAsHelper.checkConnectorSupported(connector, null);
 
-		if (connector.equals("bku") || connector.equals("onlinebku")
-				|| connector.equals("mobilebku")) {
+		if (connector == Connector.BKU || connector == Connector.ONLINEBKU || connector == Connector.MOBILEBKU) {
 			BKUSLConnector bkuSLConnector = (BKUSLConnector) session
 					.getAttribute(PDF_SL_CONNECTOR);
 
@@ -809,7 +763,8 @@ public class PdfAsHelper {
 		// IPlainSigner plainSigner = (IPlainSigner) session
 		// .getAttribute(PDF_SIGNER);
 
-		String connector = (String) session.getAttribute(PDF_SL_INTERACTIVE);
+		Connector connector = (Connector) session.getAttribute(PDF_SL_INTERACTIVE);
+		PdfAsHelper.checkConnectorSupported(connector, null);
 
 		//load connector
 		ISLConnector slConnector = (ISLConnector) session.getAttribute(PDF_SL_CONNECTOR);
@@ -1412,28 +1367,19 @@ public class PdfAsHelper {
 		}
 
 		String baseURL = publicURL + PDF_USERENTRY_PAGE;
-		try {
-			return baseURL + "?" + UIEntryPointServlet.REQUEST_ID_PARAM + "="
-					+ URLEncoder.encode(storeId, "UTF-8");
-		} catch (UnsupportedEncodingException e) {
-			log.warn("Encoding not supported for URL encoding", e);
-		}
-		return baseURL + "?" + UIEntryPointServlet.REQUEST_ID_PARAM + "="
-				+ storeId;
-	}
-
-	public static String generateBKUURL(String connector) {
-		if (connector.equals("bku")) {
-			return WebConfiguration.getLocalBKUURL();
-		} else if (connector.equals("onlinebku")) {
-			return WebConfiguration.getOnlineBKUURL();
-		} else if (connector.equals("mobilebku")) {
-			return WebConfiguration.getHandyBKUURL();
-		} else if (connector.equals("sl20")) {
-			return WebConfiguration.getSecurityLayer20URL();
-		}
-		return WebConfiguration.getLocalBKUURL();
-	}
+      return baseURL + "?" + UIEntryPointServlet.REQUEST_ID_PARAM + "="
+              + URLEncoder.encode(storeId, StandardCharsets.UTF_8);
+    }
+
+	public static String generateBKUURL(Connector connector) {
+      return switch (connector) {
+		case BKU -> WebConfiguration.getLocalBKUURL();
+		case ONLINEBKU -> WebConfiguration.getOnlineBKUURL();
+        case MOBILEBKU -> WebConfiguration.getHandyBKUURL();
+		case SECLAYER20 -> WebConfiguration.getSecurityLayer20URL();
+        default -> throw new IllegalStateException("Attempt to get BKU URL for connector: "+connector.name());
+      };
+    }
 
 	public static void setFromDataUrl(HttpServletRequest request) {
 		request.setAttribute(REQUEST_FROM_DU, (Boolean) true);
@@ -1443,7 +1389,7 @@ public class PdfAsHelper {
 		Object obj = request.getAttribute(REQUEST_FROM_DU);
 		if (obj != null) {
 			if (obj instanceof Boolean) {
-				return ((Boolean) obj).booleanValue();
+				return (Boolean) obj;
 			}
 		}
 		return false;
@@ -1642,7 +1588,7 @@ public class PdfAsHelper {
 			log.trace("SL20 response to VDA: " + respContainer);
 			StringWriter writer = new StringWriter();
 			writer.write(respContainer.toString());						
-			final byte[] content = writer.toString().getBytes("UTF-8");
+			final byte[] content = writer.toString().getBytes(StandardCharsets.UTF_8);
 			response.setStatus(HttpServletResponse.SC_OK);
 			response.setContentLength(content.length);
 			response.setContentType(ContentType.APPLICATION_JSON.toString());						
@@ -1656,4 +1602,82 @@ public class PdfAsHelper {
 		}
 	}
 
+	private static boolean anyNull(Object... any) {
+		return (Arrays.stream(any).anyMatch(Objects::isNull));
+	}
+
+	public static void checkConnectorSupported(Connector connector, String keyIdentifier) throws PdfAsWebException {
+		if (connector == null) {
+			throw new PdfAsWebException("Invalid or unknown connector value");
+		} else if (connector == Connector.BKU) {
+			if (!WebConfiguration.getLocalBKUEnabled()) {
+				throw new PdfAsWebException("Connector bku is not enabled in configuration");
+			}
+			if (WebConfiguration.getLocalBKUURL() == null) {
+				throw new PdfAsWebException("Connector bku is not properly configured");
+			}
+		} else if (connector == Connector.ONLINEBKU) {
+			if (!WebConfiguration.getOnlineBKUEnabled()) {
+				throw new PdfAsWebException("Connector onlinebku is not enabled in configuration");
+			}
+			if (WebConfiguration.getOnlineBKUURL() == null) {
+				throw new PdfAsWebException("Connector onlinebku is not properly configured");
+			}
+		} else if (connector == Connector.MOBILEBKU) {
+			if (!WebConfiguration.getMobileBKUEnabled()) {
+				throw new PdfAsWebException("Connector mobilebku is not enabled in configuration");
+			}
+			if (WebConfiguration.getHandyBKUURL() == null) {
+				throw new PdfAsWebException("Connector mobilebku is not properly configured");
+			}
+		} else if (connector == Connector.SECLAYER20) {
+			if (!WebConfiguration.getSL20Enabled()) {
+				throw new PdfAsWebException("Connector sl20 is not enabled in configuration");
+			}
+			if (WebConfiguration.getSecurityLayer20URL() == null) {
+				throw new PdfAsWebException("Connector sl20 is not properly configured");
+			}
+		} else if (connector == Connector.MOA) {
+			if (keyIdentifier != null) {
+				if (!WebConfiguration.isMoaEnabled(keyIdentifier)) {
+					throw new PdfAsWebException("Connector moa[keyId="+keyIdentifier+"] is not enabled in configuration");
+				}
+			} else {
+				if (!WebConfiguration.getMOASSEnabled()) {
+					throw new PdfAsWebException("Connector moa[default] is not enabled in configuration");
+				}
+			}
+		} else if (connector == Connector.JKS) {
+			if (keyIdentifier != null) {
+				if (!WebConfiguration.getKeystoreEnabled(keyIdentifier)) {
+					throw new PdfAsWebException("Connector jks[keyId="+keyIdentifier+"] is not enabled in configuration");
+				}
+				if (
+					anyNull(
+						WebConfiguration.getKeystoreFile(keyIdentifier),
+						WebConfiguration.getKeystoreAlias(keyIdentifier),
+						WebConfiguration.getKeystorePass(keyIdentifier),
+						WebConfiguration.getKeystoreKeyPass(keyIdentifier),
+						WebConfiguration.getKeystoreType(keyIdentifier)))
+				{
+					throw new PdfAsWebException("Connector jks[keyId="+keyIdentifier+"] is not properly configured");
+				}
+			} else {
+				if (!WebConfiguration.getKeystoreDefaultEnabled()) {
+					throw new PdfAsWebException("Connector jks[default] is not enabled in configuration");
+				}
+				if (
+					anyNull(
+						WebConfiguration.getKeystoreDefaultFile(),
+						WebConfiguration.getKeystoreDefaultAlias(),
+						WebConfiguration.getKeystoreDefaultPass(),
+						WebConfiguration.getKeystoreDefaultKeyPass(),
+						WebConfiguration.getKeystoreDefaultType()))
+				{
+					throw new PdfAsWebException("Connector jks[default] is not properly configured");
+				}
+			}
+		}
+	}
+
 }
diff --git a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsParameterExtractor.java b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsParameterExtractor.java
index ede5fdf5..7178e38d 100644
--- a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsParameterExtractor.java
+++ b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/helper/PdfAsParameterExtractor.java
@@ -28,6 +28,7 @@ import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.Map;
 
+import at.gv.egiz.pdfas.api.ws.PDFASSignParameters.Connector;
 import jakarta.servlet.http.HttpServletRequest;
 
 import org.apache.commons.lang3.StringUtils;
@@ -82,8 +83,8 @@ public class PdfAsParameterExtractor {
 	private static final Logger logger = LoggerFactory
 			.getLogger(PdfAsParameterExtractor.class);
 
-	public static String getConnector(HttpServletRequest request) {
-		return (String)request.getAttribute(PARAM_CONNECTOR);
+	public static Connector getConnector(HttpServletRequest request) {
+		return Connector.fromString((String)request.getAttribute(PARAM_CONNECTOR));
 	}
 
 	public static Map<String,String> getDynamicSignatureBlockParameters(HttpServletRequest request) throws Exception {
diff --git a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/ExternSignServlet.java b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/ExternSignServlet.java
index 18754288..3b39ee16 100644
--- a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/ExternSignServlet.java
+++ b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/ExternSignServlet.java
@@ -308,16 +308,15 @@ public class ExternSignServlet extends HttpServlet {
 		}
 		
 		// Get Connector
-		String connector = PdfAsParameterExtractor.getConnector(request);
-		if (connector == null) {
-			throw new PdfAsException("No connector specified");
-		}
+		Connector connector = PdfAsParameterExtractor.getConnector(request);
+		String keyIdentifier = PdfAsParameterExtractor.getKeyIdentifier(request);
+		PdfAsHelper.checkConnectorSupported(connector, keyIdentifier);
 		
 		String transactionId = PdfAsParameterExtractor.getTransactionId(request);
 		
 		statisticEvent.setFilesize(pdfData.length);
 		statisticEvent.setProfileId(null);
-		statisticEvent.setDevice(connector);
+		statisticEvent.setDevice(connector.toString());
 
 		String invokeUrl = PdfAsParameterExtractor.getInvokeURL(request);
 		PdfAsHelper.setInvokeURL(request, response, invokeUrl);
@@ -361,8 +360,8 @@ public class ExternSignServlet extends HttpServlet {
               
     CoreSignParams coreParams = new CoreSignParams();                   
     coreParams.setSignatureBlockParameters(dynamicSignatureBlockArguments);    
-    coreParams.setConnector(Connector.fromString(connector));
-    coreParams.setKeyIdentifier(PdfAsParameterExtractor.getKeyIdentifier(request));
+    coreParams.setConnector(connector);
+    coreParams.setKeyIdentifier(keyIdentifier);
     coreParams.setOverrides(PdfAsParameterExtractor.getOverwriteMap(request));        
     coreParams.setPreprocessor(PdfAsParameterExtractor.getPreProcessorMap(request));
     coreParams.setInvokeErrorUrl(errorUrl);
@@ -384,67 +383,18 @@ public class ExternSignServlet extends HttpServlet {
 		
 		
 		//IPlainSigner signer;
-		if (connector.equals("bku") || connector.equals("onlinebku") || connector.equals("mobilebku")
-				|| connector.equals("sl20")) {
+		if (Connector.isAsynchronous(connector)) {
 			// start asynchronous signature creation
-			
-			if(connector.equals("bku")) {
-				if(WebConfiguration.getLocalBKUURL() == null) {
-					throw new PdfAsWebException("Invalid connector bku is not supported");
-				}
-			}
-			if(connector.equals("mobilebku")) {
-				if(WebConfiguration.getHandyBKUURL() == null) {
-					throw new PdfAsWebException("Invalid connector mobilebku is not supported");
-				}
-			}
-			if(connector.equals("onlinebku")) {
-				if(WebConfiguration.getOnlineBKUURL() == null) {
-					throw new PdfAsWebException("Invalid connector bku is not supported");
-				}
-			}
-			if (connector.equals("sl20")) {
-				if(WebConfiguration.getSecurityLayer20URL() == null) {
-					throw new PdfAsWebException("Invalid connector bku is not supported");
-				}
-			}
 
 			PdfAsHelper.setStatisticEvent(request, response, statisticEvent);
 			
-	    // sign document
+	    	// sign document
 			PdfAsHelper.startSignature(request, response, getServletContext(), connector, data);
 
 			return;
 			
-		} else if (connector.equals("jks") || connector.equals("moa")) {
-			// start synchronous siganture creation
-			
-			if(connector.equals("jks")) {
-				
-				String keyIdentifier = PdfAsParameterExtractor.getKeyIdentifier(request);
-
-				boolean ksEnabled = false;
-
-				if (keyIdentifier != null) {
-					ksEnabled = WebConfiguration.getKeystoreEnabled(keyIdentifier);
-				} else {
-					ksEnabled = WebConfiguration.getKeystoreDefaultEnabled();
-				}
-
-				if (!ksEnabled) {
-					if(keyIdentifier != null) {
-						throw new PdfAsWebException("JKS connector [" + keyIdentifier + "] disabled or not existing.");
-					} else {
-						throw new PdfAsWebException("DEFAULT JKS connector disabled.");
-					}
-				}
-			}
-			
-			if(connector.equals("moa")) {
-				if(!WebConfiguration.getMOASSEnabled()) {
-					throw new PdfAsWebException("Invalid connector moa is not supported");
-				}
-			}
+		} else {
+			// start synchronous signature creation
 
 			// sign document
 			PdfasSignResponse pdfSignedData = PdfAsHelper.synchronousServerSignature(data);
@@ -462,9 +412,6 @@ public class ExternSignServlet extends HttpServlet {
 			PdfAsHelper.gotoProvidePdf(getServletContext(), request, response);
 			return;
 			
-		} else {
-			throw new PdfAsWebException("Invalid connector (bku | moa | jks | onlinebku | mobilebku)");
-			
 		}
 	}
 }
diff --git a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/JSONAPIServlet.java b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/JSONAPIServlet.java
index 343e18f2..a9b282a2 100644
--- a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/JSONAPIServlet.java
+++ b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/JSONAPIServlet.java
@@ -87,7 +87,7 @@ public class JSONAPIServlet extends HttpServlet {
 
         String profile = jsonObject.has(JSON_PROFILE) ? jsonObject.getString(JSON_PROFILE) : null;
         String position = jsonObject.has(JSON_POSITION) ? jsonObject.getString(JSON_POSITION) : null;
-        String connector = jsonObject.getString(JSON_CONNECTOR);
+        Connector connector = Connector.fromString(jsonObject.getString(JSON_CONNECTOR));
         String input = jsonObject.getString(JSON_INPUT);
         String requestID = jsonObject.has(JSON_REQUEST_ID) ? jsonObject.getString(JSON_REQUEST_ID) : null;
 
@@ -106,40 +106,14 @@ public class JSONAPIServlet extends HttpServlet {
 
         try {
 
-            if(connector == null) {
-                throw new ServletException(
-                        "Invalid connector value!");
-            }
-
-            PDFASSignParameters.Connector connectorEnum = null;
-
-            if(PDFASSignParameters.Connector.MOA.equalsName(connector)) {
-                connectorEnum = PDFASSignParameters.Connector.MOA;
-            } else if(PDFASSignParameters.Connector.JKS.equalsName(connector)) {
-                connectorEnum = PDFASSignParameters.Connector.JKS;
-            } else if(PDFASSignParameters.Connector.BKU.equalsName(connector)) {
-                connectorEnum = PDFASSignParameters.Connector.BKU;
-            } else if(PDFASSignParameters.Connector.MOBILEBKU.equalsName(connector)) {
-                connectorEnum = PDFASSignParameters.Connector.MOBILEBKU;
-            } else if(PDFASSignParameters.Connector.ONLINEBKU.equalsName(connector)) {
-                connectorEnum = PDFASSignParameters.Connector.ONLINEBKU;
-            } else if(PDFASSignParameters.Connector.SECLAYER20.equalsName(connector)) {
-                connectorEnum = PDFASSignParameters.Connector.SECLAYER20;
-            } 
-
-            if(connectorEnum == null) {
-                throw new ServletException(
-                        "Invalid connector value!");
-            }
-
-            // TODO: check connector is enabled!
+            PdfAsHelper.checkConnectorSupported(connector, null);
 
             statisticEvent.setFilesize(inputDocument.length);
             statisticEvent.setProfileId(profile);
-            statisticEvent.setDevice(connector);
+            statisticEvent.setDevice(connector.toString());
 
             PDFASSignParameters parameters = new PDFASSignParameters();
-            parameters.setConnector(connectorEnum);
+            parameters.setConnector(connector);
             parameters.setPosition(position);
             parameters.setProfile(profile);
 
@@ -156,8 +130,8 @@ public class JSONAPIServlet extends HttpServlet {
                         signatureBlockParametersMap.put(values[0], values[1]);
                     }
                 }
-            }catch(Exception e){
-                e.printStackTrace();
+            } catch(Exception e) {
+                logger.warn("Failed to process JSON sbp parameter", e);
             }
             
             
@@ -167,7 +141,7 @@ public class JSONAPIServlet extends HttpServlet {
             
             CoreSignParams coreParams = new CoreSignParams();                   
             coreParams.setSignatureBlockParameters(signatureBlockParametersMap);    
-            coreParams.setConnector(Connector.fromString(connector));
+            coreParams.setConnector(connector);
             data.setCoreParams(coreParams);
 
             DocumentToSign document = new DocumentToSign();
@@ -178,8 +152,7 @@ public class JSONAPIServlet extends HttpServlet {
             
             
             
-            if (PDFASSignParameters.Connector.MOA.equals(connectorEnum)
-                    || PDFASSignParameters.Connector.JKS.equals(connectorEnum)) {
+            if (!Connector.isAsynchronous(connector)) {
                 // Plain server based signatures!!
               
                                                                   
@@ -236,36 +209,8 @@ public class JSONAPIServlet extends HttpServlet {
 
                 // start asynchronous signature creation
 
-                    if (PDFASSignParameters.Connector.BKU.equals(connectorEnum)) {
-                        if (WebConfiguration.getLocalBKUURL() == null) {
-                            throw new PdfAsWebException(
-                                    "Invalid connector bku is not supported");
-                        }
-                    }
-
-                    if (PDFASSignParameters.Connector.ONLINEBKU.equals(connectorEnum)) {
-                        if (WebConfiguration.getOnlineBKUURL() == null) {
-                            throw new PdfAsWebException(
-                                    "Invalid connector onlinebku is not supported");
-                        }
-                    }
-
-                    if (PDFASSignParameters.Connector.MOBILEBKU.equals(connectorEnum)) {
-                        if (WebConfiguration.getHandyBKUURL() == null) {
-                            throw new PdfAsWebException(
-                                    "Invalid connector mobilebku is not supported");
-                        }
-                    }
-                    
-                    if (PDFASSignParameters.Connector.SECLAYER20.equals(connectorEnum)) {
-                        if (WebConfiguration.getSecurityLayer20URL() == null) {
-                            throw new PdfAsWebException(
-                                    "Invalid connector mobilebku is not supported");
-                        }
-                    }
-
-                    PdfAsHelper.startSignatureJson(request, response, getServletContext(),
-                        connectorEnum.toString(), data);
+                PdfAsHelper.startSignatureJson(request, response, getServletContext(),
+                    connector, data);
 
                 JSONStartResponse jsonStartResponse = PdfAsHelper.startJsonProcess(request, response, getServletContext());
 
diff --git a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/UIEntryPointServlet.java b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/UIEntryPointServlet.java
index 2842c7e2..9c20e1a1 100644
--- a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/UIEntryPointServlet.java
+++ b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/servlets/UIEntryPointServlet.java
@@ -90,6 +90,7 @@ public class UIEntryPointServlet extends HttpServlet {
 			PdfAsHelper.setStatisticEvent(req, resp, statisticEvent);
 			
 			Connector connector = pdfAsRequest.getCoreParams().getConnector();
+			PdfAsHelper.checkConnectorSupported(connector, null);
 
 			String invokeUrl = pdfAsRequest.getCoreParams().getInvokeUrl();
 			PdfAsHelper.setInvokeURL(req, resp, invokeUrl);
@@ -125,41 +126,10 @@ public class UIEntryPointServlet extends HttpServlet {
 			log.debug("Starting signature creation with: " + connector);
 
 			// IPlainSigner signer;
-			if (connector.equals(Connector.BKU)
-					|| connector.equals(Connector.ONLINEBKU)
-					|| connector.equals(Connector.MOBILEBKU)
-					|| connector.equals(Connector.SECLAYER20)) {
+			if (Connector.isAsynchronous(connector)) {
 				// start asynchronous signature creation
-
-				if (connector.equals(Connector.BKU)) {
-					if (WebConfiguration.getLocalBKUURL() == null) {
-						throw new PdfAsWebException(
-								"Invalid connector bku is not supported");
-					}
-				}
-
-				if (connector.equals(Connector.ONLINEBKU)) {
-					if (WebConfiguration.getOnlineBKUURL() == null) {
-						throw new PdfAsWebException(
-								"Invalid connector onlinebku is not supported");
-					}
-				}
-
-				if (connector.equals(Connector.MOBILEBKU)) {
-					if (WebConfiguration.getHandyBKUURL() == null) {
-						throw new PdfAsWebException(
-								"Invalid connector mobilebku is not supported");
-					}
-				}
-				
-				if (connector.equals(Connector.SECLAYER20)) {
-					if (WebConfiguration.getSecurityLayer20URL() == null) {
-						throw new PdfAsWebException(
-								"Invalid connector mobilebku is not supported");
-					}
-				}
 				
-				PdfAsHelper.startSignature(req, resp, getServletContext(), connector.toString(), pdfAsRequest);
+				PdfAsHelper.startSignature(req, resp, getServletContext(), connector, pdfAsRequest);
 				
 			} else {
 				throw new PdfAsWebException("Invalid connector ("
diff --git a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/ws/PDFASSigningImpl.java b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/ws/PDFASSigningImpl.java
index 667816e5..83e59706 100644
--- a/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/ws/PDFASSigningImpl.java
+++ b/pdf-as-web/src/main/java/at/gv/egiz/pdfas/web/ws/PDFASSigningImpl.java
@@ -28,6 +28,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import at.gv.egiz.pdfas.lib.api.PdfAs;
 import at.gv.egiz.pdfas.lib.impl.ErrorExtractor;
 import jakarta.jws.WebService;
 import jakarta.xml.ws.WebServiceException;
@@ -90,28 +91,31 @@ public class PDFASSigningImpl implements PDFASSigning {
       log.warn("SOAP Sign Request is null!");
       return null;
     }
+    if (request.getParameters() == null) {
+      throw new WebServiceException("SOAP Sign Request parameters are missing");
+    }
 
     // map request into internal data-structure
     final PdfasSignRequest internalReq = buildOperationRequest(request);
 
+    val connector = internalReq.getCoreParams().getConnector();
+    val keyIdentifier = internalReq.getCoreParams().getKeyIdentifier();
+
     final StatisticEvent statisticEvent = new StatisticEvent();
     statisticEvent.setSource(Source.SOAP);
     statisticEvent.setOperation(Operation.SIGN);
     statisticEvent.setUserAgent(UserAgentFilter.getUserAgent());
     statisticEvent.setProfileId(request.getParameters().getProfile());
-    statisticEvent.setDevice(request.getParameters().getConnector().toString());
+    if (connector != null) {
+      statisticEvent.setDevice(connector.toString());
+    }
     statisticEvent.setStartNow();
 
     PDFASSignResponse response = new PDFASSignResponse();
     try {
-      if (request.getParameters().getConnector() == null) {
-        throw new WebServiceException(
-            "Invalid connector value!");
-      }
+      PdfAsHelper.checkConnectorSupported(connector, keyIdentifier);
 
-      if (request.getParameters().getConnector().equals(Connector.MOA)
-          || request.getParameters().getConnector()
-              .equals(Connector.JKS)) {
+      if (!Connector.isAsynchronous(connector)) {
 
         // perform technical signing process
         final PdfasSignResponse internalResp = PdfAsHelper.synchronousServerSignature(internalReq);
@@ -212,24 +216,23 @@ public class PDFASSigningImpl implements PDFASSigning {
 
     // map request into internal data-structure
     final PdfasSignRequest internalReq = buildOperationRequest(request);
+    val connector = internalReq.getCoreParams().getConnector();
+    val keyIdentifier = internalReq.getCoreParams().getKeyIdentifier();
 
     final StatisticEvent statisticEvent = new StatisticEvent();
     statisticEvent.setSource(Source.SOAP);
     statisticEvent.setOperation(Operation.SIGNBULK);
     statisticEvent.setUserAgent(UserAgentFilter.getUserAgent());
-    statisticEvent.setDevice(internalReq.getCoreParams().getConnector().toString());
+    if (connector != null) {
+      statisticEvent.setDevice(connector.toString());
+    }
     statisticEvent.setStartNow();
 
     PdfasSignMultipleResponse response = new PdfasSignMultipleResponse();
     try {
-      if (internalReq.getCoreParams().getConnector() == null) {
-        throw new WebServiceException(
-            "Invalid connector value!");
-      }
+      PdfAsHelper.checkConnectorSupported(connector, keyIdentifier);
 
-      if (internalReq.getCoreParams().getConnector().equals(Connector.MOA)
-          || internalReq.getCoreParams().getConnector()
-              .equals(Connector.JKS)) {
+      if (!Connector.isAsynchronous(connector)) {
 
         // perform technical signing process
         final PdfasSignResponse internalResp = PdfAsHelper.synchronousServerSignature(internalReq);
@@ -372,6 +375,9 @@ public class PDFASSigningImpl implements PDFASSigning {
     coreParams.setTransactionId(request.getTransactionId());
     data.setCoreParams(coreParams);
 
+    if (request.getInput() == null || request.getInput().isEmpty()) {
+      throw new WebServiceException("SignMultipleRequest contains no input documents");
+    }
     request.getInput().forEach(el -> {
       final DocumentToSign document = new DocumentToSign();
       document.setInputData(el.getInputData());