fix quit instruction, added default indicator, connection status filter

src/main/java/ch/ethz/seb/sebserver/gui/service/session/ClientConnectionTable.java

@@ -41,6 +41,7 @@ import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 
 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.model.Domain;
 import ch.ethz.seb.sebserver.gbl.model.EntityKey;
@@ -85,10 +86,13 @@ public final class ClientConnectionTable {
     private final Table table;
     private final ColorData colorData;
     private final EnumSet<ConnectionStatus> statusFilter;
+    private String statusFilterParam = "";
+    private boolean statusFilterChanged = false;
 
     private int tableWidth;
     private boolean needsSort = false;
     private LinkedHashMap<Long, UpdatableTableItem> tableMapping;
+    private final Set<Long> toDelete = new HashSet<>();
     private final MultiValueMap<String, Long> sessionIds;
 
     private final Color darkFontColor;
@@ -180,39 +184,6 @@ public final class ClientConnectionTable {
         saveStatusFilter();
     }
 
-    private void saveStatusFilter() {
-        try {
-            this.resourceService
-                    .getCurrentUser()
-                    .putAttribute(
-                            USER_SESSION_STATUS_FILTER_ATTRIBUTE,
-                            StringUtils.join(this.statusFilter, Constants.LIST_SEPARATOR));
-        } catch (final Exception e) {
-            log.warn("Failed to save status filter to user session");
-        }
-    }
-
-    private void loadStatusFilter() {
-        try {
-            final String attribute = this.resourceService
-                    .getCurrentUser()
-                    .getAttribute(USER_SESSION_STATUS_FILTER_ATTRIBUTE);
-            if (attribute != null) {
-                this.statusFilter.clear();
-                Arrays.asList(StringUtils.split(attribute, Constants.LIST_SEPARATOR))
-                        .forEach(name -> this.statusFilter.add(ConnectionStatus.valueOf(name)));
-
-            } else {
-                this.statusFilter.clear();
-                this.statusFilter.add(ConnectionStatus.DISABLED);
-            }
-        } catch (final Exception e) {
-            log.warn("Failed to load status filter to user session");
-            this.statusFilter.clear();
-            this.statusFilter.add(ConnectionStatus.DISABLED);
-        }
-    }
-
     public void withDefaultAction(final PageAction pageAction, final PageService pageService) {
         this.table.addListener(SWT.MouseDoubleClick, event -> {
             final Tuple<String> selection = getSingleSelection();
@@ -300,7 +271,12 @@ public final class ClientConnectionTable {
     }
 
     public void updateValues() {
+        if (this.statusFilterChanged) {
+            this.toDelete.clear();
+            this.toDelete.addAll(this.tableMapping.keySet());
+        }
         this.restCallBuilder
+                .withHeader(API.EXAM_MONITORING_STATE_FILTER, this.statusFilterParam)
                 .call()
                 .get(error -> {
                     log.error("Error poll connection data: ", error);
@@ -312,7 +288,21 @@ public final class ClientConnectionTable {
                             data.getConnectionId(),
                             connectionId -> new UpdatableTableItem(connectionId));
                     tableItem.push(data);
+                    if (this.statusFilterChanged) {
+                        this.toDelete.remove(data.getConnectionId());
+                    }
                 });
+
+        if (this.statusFilterChanged && !this.toDelete.isEmpty()) {
+            this.toDelete.stream().forEach(id -> {
+                final UpdatableTableItem item = this.tableMapping.remove(id);
+                final List<Long> list = this.sessionIds.get(item.connectionData.clientConnection.userSessionId);
+                if (list != null) {
+                    list.remove(id);
+                }
+            });
+            this.statusFilterChanged = false;
+        }
     }
 
     public void updateGUI() {
@@ -370,6 +360,45 @@ public final class ClientConnectionTable {
                         (e1, e2) -> e1, LinkedHashMap::new));
     }
 
+    private void saveStatusFilter() {
+        try {
+            this.resourceService
+                    .getCurrentUser()
+                    .putAttribute(
+                            USER_SESSION_STATUS_FILTER_ATTRIBUTE,
+                            StringUtils.join(this.statusFilter, Constants.LIST_SEPARATOR));
+        } catch (final Exception e) {
+            log.warn("Failed to save status filter to user session");
+        } finally {
+            this.statusFilterParam = StringUtils.join(this.statusFilter, Constants.LIST_SEPARATOR);
+            this.statusFilterChanged = true;
+        }
+    }
+
+    private void loadStatusFilter() {
+        try {
+            final String attribute = this.resourceService
+                    .getCurrentUser()
+                    .getAttribute(USER_SESSION_STATUS_FILTER_ATTRIBUTE);
+            if (attribute != null) {
+                this.statusFilter.clear();
+                Arrays.asList(StringUtils.split(attribute, Constants.LIST_SEPARATOR))
+                        .forEach(name -> this.statusFilter.add(ConnectionStatus.valueOf(name)));
+
+            } else {
+                this.statusFilter.clear();
+                this.statusFilter.add(ConnectionStatus.DISABLED);
+            }
+        } catch (final Exception e) {
+            log.warn("Failed to load status filter to user session");
+            this.statusFilter.clear();
+            this.statusFilter.add(ConnectionStatus.DISABLED);
+        } finally {
+            this.statusFilterParam = StringUtils.join(this.statusFilter, Constants.LIST_SEPARATOR);
+            this.statusFilterChanged = true;
+        }
+    }
+
     private final class UpdatableTableItem implements Comparable<UpdatableTableItem> {
 
         final Long connectionId;
@@ -567,8 +596,12 @@ public final class ClientConnectionTable {
 
             this.connectionData = connectionData;
 
-            if (!this.duplicateChecked && StringUtils.isNotBlank(connectionData.clientConnection.userSessionId)) {
+            if (!this.duplicateChecked &&
-                ClientConnectionTable.this.sessionIds.add(connectionData.clientConnection.userSessionId,
+                    this.connectionData.clientConnection.status != ConnectionStatus.DISABLED &&
+                    StringUtils.isNotBlank(connectionData.clientConnection.userSessionId)) {
+
+                ClientConnectionTable.this.sessionIds.add(
+                        connectionData.clientConnection.userSessionId,
                         this.connectionId);
                 this.duplicateChecked = true;
             }

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/exam/ExamAdminService.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2020 ETH Zürich, Educational Development and Technology (LET)
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+package ch.ethz.seb.sebserver.webservice.servicelayer.exam;
+
+import ch.ethz.seb.sebserver.gbl.model.exam.Exam;
+import ch.ethz.seb.sebserver.gbl.util.Result;
+
+public interface ExamAdminService {
+
+    /** Adds a default indicator that is defined by configuration to a given exam.
+     *
+     * @param exam The Exam to add the default indicator
+     * @return the Exam with added default indicator */
+    Result<Exam> addDefaultIndicator(final Exam exam);
+
+    /** Applies all additional SEB restriction attributes that are defined by the
+     * type of the LMS of a given Exam to this given Exam.
+     * 
+     * @param exam the Exam to apply all additional SEB restriction attributes
+     * @return the Exam */
+    Result<Exam> applyAdditionalSEBRestrictions(final Exam exam);
+
+}

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/exam/ExamAdminServiceImpl.java

@@ -0,0 +1,130 @@
+/*
+ * Copyright (c) 2020 ETH Zürich, Educational Development and Technology (LET)
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+package ch.ethz.seb.sebserver.webservice.servicelayer.exam;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Lazy;
+import org.springframework.stereotype.Service;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+
+import ch.ethz.seb.sebserver.gbl.Constants;
+import ch.ethz.seb.sebserver.gbl.api.EntityType;
+import ch.ethz.seb.sebserver.gbl.api.JSONMapper;
+import ch.ethz.seb.sebserver.gbl.model.exam.Exam;
+import ch.ethz.seb.sebserver.gbl.model.exam.Indicator;
+import ch.ethz.seb.sebserver.gbl.model.exam.Indicator.IndicatorType;
+import ch.ethz.seb.sebserver.gbl.model.exam.OpenEdxSebRestriction;
+import ch.ethz.seb.sebserver.gbl.model.institution.LmsSetup;
+import ch.ethz.seb.sebserver.gbl.model.institution.LmsSetup.LmsType;
+import ch.ethz.seb.sebserver.gbl.profile.WebServiceProfile;
+import ch.ethz.seb.sebserver.gbl.util.Result;
+import ch.ethz.seb.sebserver.webservice.servicelayer.dao.AdditionalAttributesDAO;
+import ch.ethz.seb.sebserver.webservice.servicelayer.dao.ExamDAO;
+import ch.ethz.seb.sebserver.webservice.servicelayer.dao.IndicatorDAO;
+import ch.ethz.seb.sebserver.webservice.servicelayer.lms.LmsAPIService;
+import ch.ethz.seb.sebserver.webservice.servicelayer.lms.SebRestrictionService;
+
+@Lazy
+@Service
+@WebServiceProfile
+public class ExamAdminServiceImpl implements ExamAdminService {
+
+    private final ExamDAO examDAO;
+    private final IndicatorDAO indicatorDAO;
+    private final AdditionalAttributesDAO additionalAttributesDAO;
+    private final LmsAPIService lmsAPIService;
+    private final JSONMapper jsonMapper;
+
+    private final String defaultIndicatorName;
+    private final String defaultIndicatorType;
+    private final String defaultIndicatorColor;
+    private final String defaultIndicatorThresholds;
+
+    protected ExamAdminServiceImpl(
+            final ExamDAO examDAO,
+            final IndicatorDAO indicatorDAO,
+            final AdditionalAttributesDAO additionalAttributesDAO,
+            final LmsAPIService lmsAPIService,
+            final JSONMapper jsonMapper,
+            @Value("${sebserver.webservice.api.exam.indicator.name:Ping}") final String defaultIndicatorName,
+            @Value("${sebserver.webservice.api.exam.indicator.type:LAST_PING}") final String defaultIndicatorType,
+            @Value("${sebserver.webservice.api.exam.indicator.color:b4b4b4}") final String defaultIndicatorColor,
+            @Value("${sebserver.webservice.api.exam.indicator.thresholds:[{\"value\":2000.0,\"color\":\"22b14c\"},{\"value\":5000.0,\"color\":\"ff7e00\"},{\"value\":10000.0,\"color\":\"ed1c24\"}]}") final String defaultIndicatorThresholds) {
+
+        this.examDAO = examDAO;
+        this.indicatorDAO = indicatorDAO;
+        this.additionalAttributesDAO = additionalAttributesDAO;
+        this.lmsAPIService = lmsAPIService;
+        this.jsonMapper = jsonMapper;
+
+        this.defaultIndicatorName = defaultIndicatorName;
+        this.defaultIndicatorType = defaultIndicatorType;
+        this.defaultIndicatorColor = defaultIndicatorColor;
+        this.defaultIndicatorThresholds = defaultIndicatorThresholds;
+    }
+
+    @Override
+    public Result<Exam> addDefaultIndicator(final Exam exam) {
+        return Result.tryCatch(() -> {
+
+            final Collection<Indicator.Threshold> thresholds = this.jsonMapper.readValue(
+                    this.defaultIndicatorThresholds,
+                    new TypeReference<Collection<Indicator.Threshold>>() {
+                    });
+
+            final Indicator indicator = new Indicator(
+                    null,
+                    exam.id,
+                    this.defaultIndicatorName,
+                    IndicatorType.valueOf(this.defaultIndicatorType),
+                    this.defaultIndicatorColor,
+                    thresholds);
+
+            this.indicatorDAO.createNew(indicator)
+                    .getOrThrow();
+
+            return this.examDAO
+                    .byPK(exam.id)
+                    .getOrThrow();
+        });
+    }
+
+    @Override
+    public Result<Exam> applyAdditionalSEBRestrictions(final Exam exam) {
+        return Result.tryCatch(() -> {
+            final LmsSetup lmsSetup = this.lmsAPIService.getLmsSetup(exam.lmsSetupId)
+                    .getOrThrow();
+
+            if (lmsSetup.lmsType == LmsType.OPEN_EDX) {
+                final List<String> permissions = Arrays.asList(
+                        OpenEdxSebRestriction.PermissionComponent.ALWAYS_ALLOW_STUFF.key,
+                        OpenEdxSebRestriction.PermissionComponent.CHECK_CONFIG_KEY.key);
+
+                this.additionalAttributesDAO.saveAdditionalAttribute(
+                        EntityType.EXAM,
+                        exam.id,
+                        SebRestrictionService.SEB_RESTRICTION_ADDITIONAL_PROPERTY_NAME_PREFIX +
+                                OpenEdxSebRestriction.ATTR_PERMISSION_COMPONENTS,
+                        StringUtils.join(permissions, Constants.LIST_SEPARATOR_CHAR))
+                        .getOrThrow();
+            }
+
+            return this.examDAO
+                    .byPK(exam.id)
+                    .getOrThrow();
+        });
+    }
+
+}

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/lms/impl/moodle/MoodleRestTemplateFactory.java

@@ -28,6 +28,7 @@ import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.client.ClientHttpRequestFactory;
+import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -180,7 +181,7 @@ final class MoodleRestTemplateFactory {
         private CharSequence accessToken = null;
 
         private final Map<String, String> tokenReqURIVars;
-        private final HttpEntity<?> tokenReqEntity = new HttpEntity<>(null);
+        private final HttpEntity<?> tokenReqEntity = new HttpEntity<>(new LinkedMultiValueMap<>());
 
         protected MoodleAPIRestTemplate(
 
@@ -272,7 +273,7 @@ final class MoodleRestTemplateFactory {
                 functionReqEntity = new HttpEntity<>(body, headers);
 
             } else {
-                functionReqEntity = new HttpEntity<>(null);
+                functionReqEntity = new HttpEntity<>(new LinkedMultiValueMap<>());
             }
 
             final ResponseEntity<String> response = super.exchange(

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

@@ -15,6 +15,7 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
+import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.annotation.Lazy;
@@ -133,20 +134,19 @@ public class SebInstructionServiceImpl implements SebInstructionService {
                     .append(Constants.COLON)
                     .append(Constants.DOUBLE_QUOTE)
                     .append(clientInstruction.getType())
-                    .append(Constants.DOUBLE_QUOTE)
+                    .append(Constants.DOUBLE_QUOTE);
-                    .append(Constants.COMMA)
+
+            if (StringUtils.isNotBlank(attributes)) {
+                sBuilder.append(Constants.COMMA)
                         .append(Constants.DOUBLE_QUOTE)
                         .append(JSON_ATTR)
                         .append(Constants.DOUBLE_QUOTE)
-                    .append(Constants.COLON);
+                        .append(Constants.COLON)
-            if (attributes == null || attributes.isEmpty()) {
+                        .append(Constants.CURLY_BRACE_OPEN)
-                sBuilder.append(Constants.NULL);
-
-            } else {
-                sBuilder.append(Constants.CURLY_BRACE_OPEN)
                         .append(attributes)
                         .append(Constants.CURLY_BRACE_CLOSE);
             }
+
             return sBuilder
                     .append(Constants.CURLY_BRACE_CLOSE)
                     .toString();

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

@@ -10,7 +10,6 @@ package ch.ethz.seb.sebserver.webservice.weblayer.api;
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -37,7 +36,6 @@ import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
-import ch.ethz.seb.sebserver.gbl.Constants;
 import ch.ethz.seb.sebserver.gbl.api.API;
 import ch.ethz.seb.sebserver.gbl.api.APIMessage;
 import ch.ethz.seb.sebserver.gbl.api.APIMessage.APIMessageException;
@@ -49,12 +47,10 @@ import ch.ethz.seb.sebserver.gbl.model.Domain.EXAM;
 import ch.ethz.seb.sebserver.gbl.model.Page;
 import ch.ethz.seb.sebserver.gbl.model.PageSortOrder;
 import ch.ethz.seb.sebserver.gbl.model.exam.Exam;
-import ch.ethz.seb.sebserver.gbl.model.exam.OpenEdxSebRestriction;
 import ch.ethz.seb.sebserver.gbl.model.exam.QuizData;
 import ch.ethz.seb.sebserver.gbl.model.exam.SebRestriction;
 import ch.ethz.seb.sebserver.gbl.model.institution.LmsSetup;
 import ch.ethz.seb.sebserver.gbl.model.institution.LmsSetup.Features;
-import ch.ethz.seb.sebserver.gbl.model.institution.LmsSetup.LmsType;
 import ch.ethz.seb.sebserver.gbl.model.user.UserRole;
 import ch.ethz.seb.sebserver.gbl.profile.WebServiceProfile;
 import ch.ethz.seb.sebserver.gbl.util.Result;
@@ -64,11 +60,11 @@ import ch.ethz.seb.sebserver.webservice.servicelayer.authorization.Authorization
 import ch.ethz.seb.sebserver.webservice.servicelayer.authorization.UserService;
 import ch.ethz.seb.sebserver.webservice.servicelayer.authorization.impl.SEBServerUser;
 import ch.ethz.seb.sebserver.webservice.servicelayer.bulkaction.BulkActionService;
-import ch.ethz.seb.sebserver.webservice.servicelayer.dao.AdditionalAttributesDAO;
 import ch.ethz.seb.sebserver.webservice.servicelayer.dao.ExamDAO;
 import ch.ethz.seb.sebserver.webservice.servicelayer.dao.FilterMap;
 import ch.ethz.seb.sebserver.webservice.servicelayer.dao.UserActivityLogDAO;
 import ch.ethz.seb.sebserver.webservice.servicelayer.dao.UserDAO;
+import ch.ethz.seb.sebserver.webservice.servicelayer.exam.ExamAdminService;
 import ch.ethz.seb.sebserver.webservice.servicelayer.lms.LmsAPIService;
 import ch.ethz.seb.sebserver.webservice.servicelayer.lms.SebRestrictionService;
 import ch.ethz.seb.sebserver.webservice.servicelayer.sebconfig.ExamConfigService;
@@ -84,7 +80,7 @@ public class ExamAdministrationController extends EntityController<Exam, Exam> {
 
     private final ExamDAO examDAO;
     private final UserDAO userDAO;
-    private final AdditionalAttributesDAO additionalAttributesDAO;
+    private final ExamAdminService examAdminService;
     private final LmsAPIService lmsAPIService;
     private final ExamConfigService sebExamConfigService;
     private final ExamSessionService examSessionService;
@@ -99,10 +95,10 @@ public class ExamAdministrationController extends EntityController<Exam, Exam> {
             final BeanValidationService beanValidationService,
             final LmsAPIService lmsAPIService,
             final UserDAO userDAO,
+            final ExamAdminService examAdminService,
             final ExamConfigService sebExamConfigService,
             final ExamSessionService examSessionService,
-            final SebRestrictionService sebRestrictionService,
+            final SebRestrictionService sebRestrictionService) {
-            final AdditionalAttributesDAO additionalAttributesDAO) {
 
         super(authorization,
                 bulkActionService,
@@ -113,7 +109,7 @@ public class ExamAdministrationController extends EntityController<Exam, Exam> {
 
         this.examDAO = examDAO;
         this.userDAO = userDAO;
-        this.additionalAttributesDAO = additionalAttributesDAO;
+        this.examAdminService = examAdminService;
         this.lmsAPIService = lmsAPIService;
         this.sebExamConfigService = sebExamConfigService;
         this.examSessionService = examSessionService;
@@ -337,29 +333,9 @@ public class ExamAdministrationController extends EntityController<Exam, Exam> {
 
     @Override
     protected Result<Exam> notifyCreated(final Exam entity) {
-        return Result.tryCatch(() -> {
+        return this.examAdminService
-
+                .addDefaultIndicator(entity)
-            final LmsSetup lmsSetup = this.lmsAPIService.getLmsSetup(entity.lmsSetupId)
+                .flatMap(this.examAdminService::applyAdditionalSEBRestrictions);
-                    .getOrThrow();
-
-            // if we have an Open edX LMS involved, add additional initial SEB restriction attributes
-            if (lmsSetup.lmsType == LmsType.OPEN_EDX) {
-                final List<String> permissions = Arrays.asList(
-                        OpenEdxSebRestriction.PermissionComponent.ALWAYS_ALLOW_STUFF.key,
-                        OpenEdxSebRestriction.PermissionComponent.CHECK_CONFIG_KEY.key);
-
-                this.additionalAttributesDAO.saveAdditionalAttribute(
-                        EntityType.EXAM,
-                        entity.id,
-                        SebRestrictionService.SEB_RESTRICTION_ADDITIONAL_PROPERTY_NAME_PREFIX +
-                                OpenEdxSebRestriction.ATTR_PERMISSION_COMPONENTS,
-                        StringUtils.join(permissions, Constants.LIST_SEPARATOR_CHAR))
-                        .getOrThrow();
-
-            }
-
-            return entity;
-        });
     }
 
     @Override

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

@@ -187,7 +187,7 @@ public class ExamMonitoringController {
                         examId,
                         filterStates.isEmpty()
                                 ? Objects::nonNull
-                                : conn -> conn != null && filterStates.contains(conn.clientConnection.status))
+                                : conn -> conn != null && !filterStates.contains(conn.clientConnection.status))
                 .getOrThrow();
     }
 

src/test/java/ch/ethz/seb/sebserver/gbl/model/exam/IndicatorTest.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2020 ETH Zürich, Educational Development and Technology (LET)
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+package ch.ethz.seb.sebserver.gbl.model.exam;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collection;
+
+import org.junit.Test;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+
+import ch.ethz.seb.sebserver.gbl.api.JSONMapper;
+import ch.ethz.seb.sebserver.gbl.model.exam.Indicator.IndicatorType;
+import ch.ethz.seb.sebserver.gbl.model.exam.Indicator.Threshold;
+
+public class IndicatorTest {
+
+    @Test
+    public void testDefault() throws IOException {
+        final Indicator indicator = new Indicator(
+                null,
+                1L,
+                "Ping",
+                IndicatorType.LAST_PING,
+                "b4b4b4",
+                Arrays.asList(
+                        new Indicator.Threshold(2000d, "22b14c"),
+                        new Indicator.Threshold(5000d, "ff7e00"),
+                        new Indicator.Threshold(10000d, "ed1c24")));
+
+        final JSONMapper mapper = new JSONMapper();
+        final String jsonString = mapper.writeValueAsString(indicator);
+        assertEquals(
+                "{\"examId\":1,\"name\":\"Ping\",\"type\":\"LAST_PING\",\"color\":\"b4b4b4\",\"thresholds\":[{\"value\":2000.0,\"color\":\"22b14c\"},{\"value\":5000.0,\"color\":\"ff7e00\"}",
+                jsonString);
+
+        final String threholds =
+                "[{\"value\":2000.0,\"color\":\"22b14c\"},{\"value\":5000.0,\"color\":\"ff7e00\"},{\"value\":10000.0,\"color\":\"ed1c24\"}]";
+        final Collection<Threshold> values = mapper.readValue(threholds, new TypeReference<Collection<Threshold>>() {
+        });
+
+        assertEquals(
+                "[Threshold [value=2000.0, color=22b14c], Threshold [value=5000.0, color=ff7e00], Threshold [value=10000.0, color=ed1c24]]",
+                values.toString());
+    }
+
+}