SEBSERV-250 made disableConnection call asynchronous when there are more

then one connection involved. This result in immediately response on UI
side.

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/SEBClientConnectionService.java

@@ -9,7 +9,9 @@
 package ch.ethz.seb.sebserver.webservice.servicelayer.session;
 
 import java.security.Principal;
+import java.util.Collection;
 
+import ch.ethz.seb.sebserver.gbl.model.EntityKey;
 import ch.ethz.seb.sebserver.gbl.model.session.ClientConnection;
 import ch.ethz.seb.sebserver.gbl.model.session.ClientEvent;
 import ch.ethz.seb.sebserver.gbl.util.Result;
@@ -124,6 +126,17 @@ public interface SEBClientConnectionService {
      * @return A Result refer to the closed ClientConnection instance, or refer to an error if happened */
     Result<ClientConnection> disableConnection(String connectionToken, Long institutionId);
 
+    /** This is used to disable multiple undefined or requested ClientConnection attempt from the SEB Server side
+     * <p>
+     * This will save the existing ClientConnections that are in UNDEFINED or REQUESTED state, in new DISABLED state and
+     * flush caches.
+     *
+     * @param connectionTokens String array of connection tokens of connections to disable
+     * @param institutionId institution identifier
+     * @return A Result refer to a list of EntityKey of the closed ClientConnection instances, or refer to an error if
+     *         happened */
+    Result<Collection<EntityKey>> disableConnections(final String[] connectionTokens, final Long institutionId);
+
     /** Used to check current cached ping times of all running connections and
      * if a ping time is overflowing, creating a ping overflow event or if an
      * overflowed ping is back to normal, a ping back to normal event. */

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientConnectionServiceImpl.java

@@ -10,10 +10,13 @@ package ch.ethz.seb.sebserver.webservice.servicelayer.session.impl;
 
 import java.math.BigDecimal;
 import java.security.Principal;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.UUID;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.apache.commons.lang3.BooleanUtils;
 import org.apache.commons.lang3.StringUtils;
@@ -24,6 +27,7 @@ import org.springframework.cache.CacheManager;
 import org.springframework.context.annotation.Lazy;
 import org.springframework.stereotype.Service;
 
+import ch.ethz.seb.sebserver.gbl.model.EntityKey;
 import ch.ethz.seb.sebserver.gbl.model.exam.Exam;
 import ch.ethz.seb.sebserver.gbl.model.sebconfig.SEBClientConfig;
 import ch.ethz.seb.sebserver.gbl.model.sebconfig.SEBClientConfig.VDIType;
@@ -571,6 +575,20 @@ public class SEBClientConnectionServiceImpl implements SEBClientConnectionServic
         });
     }
 
+    @Override
+    public Result<Collection<EntityKey>> disableConnections(final String[] connectionTokens, final Long institutionId) {
+        return Result.tryCatch(() -> {
+
+            return Stream.of(connectionTokens)
+                    .map(token -> disableConnection(token, institutionId)
+                            .onError(error -> log.error("Failed to disable SEB client connection: {}", token))
+                            .getOr(null))
+                    .filter(clientConnection -> clientConnection != null)
+                    .map(clientConnection -> clientConnection.getEntityKey())
+                    .collect(Collectors.toList());
+        });
+    }
+
     @Override
     public void updatePingEvents() {
         try {

src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamMonitoringController.java

@@ -11,6 +11,7 @@ package ch.ethz.seb.sebserver.webservice.weblayer.api;
 import java.util.Collection;
 import java.util.EnumSet;
 import java.util.Objects;
+import java.util.concurrent.Executor;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.validation.Valid;
@@ -18,6 +19,7 @@ import javax.validation.Valid;
 import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.http.MediaType;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.bind.WebDataBinder;
@@ -34,6 +36,7 @@ import ch.ethz.seb.sebserver.gbl.Constants;
 import ch.ethz.seb.sebserver.gbl.api.API;
 import ch.ethz.seb.sebserver.gbl.api.EntityType;
 import ch.ethz.seb.sebserver.gbl.api.authorization.PrivilegeType;
+import ch.ethz.seb.sebserver.gbl.async.AsyncServiceSpringConfig;
 import ch.ethz.seb.sebserver.gbl.model.Domain;
 import ch.ethz.seb.sebserver.gbl.model.Page;
 import ch.ethz.seb.sebserver.gbl.model.exam.Exam;
@@ -67,13 +70,15 @@ public class ExamMonitoringController {
     private final AuthorizationService authorization;
     private final PaginationService paginationService;
     private final SEBClientNotificationService sebClientNotificationService;
+    private final Executor executor;
 
     public ExamMonitoringController(
             final SEBClientConnectionService sebClientConnectionService,
             final SEBClientInstructionService sebClientInstructionService,
             final AuthorizationService authorization,
             final PaginationService paginationService,
-            final SEBClientNotificationService sebClientNotificationService) {
+            final SEBClientNotificationService sebClientNotificationService,
+            @Qualifier(AsyncServiceSpringConfig.EXECUTOR_BEAN_NAME) final Executor executor) {
 
         this.sebClientConnectionService = sebClientConnectionService;
         this.examSessionService = sebClientConnectionService.getExamSessionService();
@@ -81,6 +86,7 @@ public class ExamMonitoringController {
         this.authorization = authorization;
         this.paginationService = paginationService;
         this.sebClientNotificationService = sebClientNotificationService;
+        this.executor = executor;
     }
 
     /** This is called by Spring to initialize the WebDataBinder and is used here to
@@ -293,14 +299,16 @@ public class ExamMonitoringController {
 
         checkPrivileges(institutionId, examId);
 
-        // TODO do this async like registerInstruction
         if (connectionToken.contains(Constants.LIST_SEPARATOR)) {
-            final String[] tokens = StringUtils.split(connectionToken, Constants.LIST_SEPARATOR);
+            // If we have a bunch of client connections to disable, make it asynchronously and respond to the caller immediately
-            for (int i = 0; i < tokens.length; i++) {
+            this.executor.execute(() -> {
-                final String token = tokens[i];
+                final String[] tokens = StringUtils.split(connectionToken, Constants.LIST_SEPARATOR);
-                this.sebClientConnectionService.disableConnection(token, institutionId)
+                this.sebClientConnectionService
-                        .onError(error -> log.error("Failed to disable SEB client connection: {}", token));
+                        .disableConnections(tokens, institutionId)
-            }
+                        .onError(error -> log.error(
+                                "Unexpected error while disable connection. See previous logs for more information.",
+                                error));
+            });
         } else {
             this.sebClientConnectionService
                     .disableConnection(connectionToken, institutionId)