Add vpp user apis

fixes https://roadmap.entgra.net/issues/10162

components/application-mgt/io.entgra.device.mgt.core.application.mgt.common/src/main/java/io/entgra/device/mgt/core/application/mgt/common/dto/ProxyResponse.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package io.entgra.device.mgt.core.application.mgt.common.dto;
+
+public class ProxyResponse {
+
+    private int code;
+    private String data;
+    private String executorResponse;
+
+    public int getCode() { return code; }
+
+    public void setCode(int code) { this.code = code; }
+
+    public String getData() { return data; }
+
+    public void setData(String data) { this.data = data; }
+
+    public String getExecutorResponse() { return executorResponse; }
+
+    public void setExecutorResponse(String executorResponse) { this.executorResponse = executorResponse; }
+}

components/application-mgt/io.entgra.device.mgt.core.application.mgt.common/src/main/java/io/entgra/device/mgt/core/application/mgt/common/dto/VppItuneUserDTO.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package io.entgra.device.mgt.core.application.mgt.common.dto;
+
+public class VppItuneUserDTO {
+    String clientUserId;
+    String inviteCode;
+    String status;
+    String email;
+    String managedId;
+
+    public String getClientUserId() {
+        return clientUserId;
+    }
+
+    public void setClientUserId(String clientUserId) {
+        this.clientUserId = clientUserId;
+    }
+
+    public String getInviteCode() {
+        return inviteCode;
+    }
+
+    public void setInviteCode(String inviteCode) {
+        this.inviteCode = inviteCode;
+    }
+
+    public String getStatus() {
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getManagedId() {
+        return managedId;
+    }
+
+    public void setManagedId(String managedId) {
+        this.managedId = managedId;
+    }
+
+}

components/application-mgt/io.entgra.device.mgt.core.application.mgt.common/src/main/java/io/entgra/device/mgt/core/application/mgt/common/dto/VppUserDTO.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package io.entgra.device.mgt.core.application.mgt.common.dto;
+
+public class VppUserDTO extends VppItuneUserDTO {
+    int id;
+    String dmUsername;
+    int tenantId;
+    String createdTime;
+    String lastUpdatedTime;
+    String tmpPassword;
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getDmUsername() {
+        return dmUsername;
+    }
+
+    public void setDmUsername(String dmUsername) {
+        this.dmUsername = dmUsername;
+    }
+
+    public int getTenantId() {
+        return tenantId;
+    }
+
+    public void setTenantId(int tenantId) {
+        this.tenantId = tenantId;
+    }
+
+    public String getCreatedTime() {
+        return createdTime;
+    }
+
+    public void setCreatedTime(String createdTime) {
+        this.createdTime = createdTime;
+    }
+
+    public String getLastUpdatedTime() {
+        return lastUpdatedTime;
+    }
+
+    public void setLastUpdatedTime(String lastUpdatedTime) {
+        this.lastUpdatedTime = lastUpdatedTime;
+    }
+
+    public String getTmpPassword() {
+        return tmpPassword;
+    }
+
+    public void setTmpPassword(String tmpPassword) {
+        this.tmpPassword = tmpPassword;
+    }
+
+}

components/application-mgt/io.entgra.device.mgt.core.application.mgt.common/src/main/java/io/entgra/device/mgt/core/application/mgt/common/services/VPPApplicationManager.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.entgra.device.mgt.core.application.mgt.common.services;
+
+import io.entgra.device.mgt.core.application.mgt.common.dto.ProxyResponse;
+import io.entgra.device.mgt.core.application.mgt.common.dto.VppUserDTO;
+import io.entgra.device.mgt.core.application.mgt.common.exception.ApplicationManagementException;
+
+import java.io.IOException;
+
+public interface VPPApplicationManager {
+
+    VppUserDTO getUserByDMUsername() throws ApplicationManagementException;
+
+    VppUserDTO addUser(VppUserDTO userDTO) throws ApplicationManagementException;
+
+    ProxyResponse callVPPBackend(String url, String payload, String accessToken, String method) throws IOException;
+}

components/application-mgt/io.entgra.device.mgt.core.application.mgt.common/src/main/java/io/entgra/device/mgt/core/application/mgt/common/wrapper/VppItuneUserRequestWrapper.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package io.entgra.device.mgt.core.application.mgt.common.wrapper;
+
+import io.entgra.device.mgt.core.application.mgt.common.dto.VppItuneUserDTO;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class VppItuneUserRequestWrapper {
+
+    List<VppItuneUserDTO> user;
+
+    public VppItuneUserRequestWrapper() {
+        user = new ArrayList<>();
+    }
+    public List<VppItuneUserDTO> getUser() {
+        return user;
+    }
+
+    public void setUser(List<VppItuneUserDTO> user) {
+        this.user = user;
+    }
+
+}

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/impl/VppApplicationManagerImpl.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.entgra.device.mgt.core.application.mgt.core.impl;
+
+import com.google.gson.Gson;
+import io.entgra.device.mgt.core.application.mgt.common.dto.ProxyResponse;
+import io.entgra.device.mgt.core.application.mgt.common.dto.VppItuneUserDTO;
+import io.entgra.device.mgt.core.application.mgt.common.wrapper.VppItuneUserRequestWrapper;
+import io.entgra.device.mgt.core.application.mgt.common.dto.VppUserDTO;
+import io.entgra.device.mgt.core.application.mgt.common.exception.ApplicationManagementException;
+import io.entgra.device.mgt.core.application.mgt.common.services.VPPApplicationManager;
+import io.entgra.device.mgt.core.application.mgt.core.dao.ApplicationDAO;
+import io.entgra.device.mgt.core.application.mgt.core.dao.SPApplicationDAO;
+import io.entgra.device.mgt.core.application.mgt.core.dao.VisibilityDAO;
+import io.entgra.device.mgt.core.application.mgt.core.dao.common.ApplicationManagementDAOFactory;
+import io.entgra.device.mgt.core.application.mgt.core.internal.DataHolder;
+import io.entgra.device.mgt.core.application.mgt.core.lifecycle.LifecycleStateManager;
+import io.entgra.device.mgt.core.application.mgt.core.util.Constants;
+import io.entgra.device.mgt.core.application.mgt.core.util.VppHttpUtil;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.http.HttpStatus;
+
+import java.io.IOException;
+
+public class VppApplicationManagerImpl implements VPPApplicationManager {
+    private static final String APP_API = "https://vpp.itunes.apple.com/mdm/v2";
+    private static final String ASSETS = APP_API + "/assets";
+    private static final String USER_CREATE = APP_API + "users/create";
+    private static final String TOKEN = "";
+
+    private static final Log log = LogFactory.getLog(VppApplicationManagerImpl.class);
+    private ApplicationDAO applicationDAO;
+    private SPApplicationDAO spApplicationDAO;
+    private VisibilityDAO visibilityDAO;
+    private final LifecycleStateManager lifecycleStateManager;
+
+    public VppApplicationManagerImpl() {
+        initDataAccessObjects();
+        lifecycleStateManager = DataHolder.getInstance().getLifecycleStateManager();
+    }
+
+    private void initDataAccessObjects() {
+        this.applicationDAO = ApplicationManagementDAOFactory.getApplicationDAO();
+        this.visibilityDAO = ApplicationManagementDAOFactory.getVisibilityDAO();
+        this.spApplicationDAO = ApplicationManagementDAOFactory.getSPApplicationDAO();
+    }
+
+
+    @Override
+    public VppUserDTO getUserByDMUsername() throws ApplicationManagementException {
+        // TODO: Return from DAO in a tenanted manner
+        return null;
+    }
+
+    @Override
+    public VppUserDTO addUser(VppUserDTO userDTO) throws ApplicationManagementException {
+        // Call the API to add
+        try {
+            VppItuneUserDTO ituneUserDTO = userDTO;
+            VppItuneUserRequestWrapper wrapper = new VppItuneUserRequestWrapper();
+            wrapper.getUser().add(ituneUserDTO);
+
+            Gson gson = new Gson();
+            String userPayload = gson.toJson(wrapper);
+
+            ProxyResponse proxyResponse = callVPPBackend(USER_CREATE, userPayload, TOKEN, Constants.POST);
+            if (proxyResponse.getCode() == HttpStatus.SC_OK || proxyResponse.getCode() == HttpStatus.SC_CREATED) {
+                // TODO: Save the user in the DAO
+
+
+
+            }
+        } catch (IOException e) {
+            String msg = "Error while callng VPP backend";
+            log.error(msg, e);
+            throw new ApplicationManagementException(msg, e);
+        }
+
+
+        return null;
+    }
+
+    @Override
+    public ProxyResponse callVPPBackend(String url,
+                                        String payload,
+                                        String accessToken,
+                                        String method) throws IOException {
+        return VppHttpUtil.execute(url, payload, accessToken, method);
+    }
+}

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/internal/ApplicationManagementServiceComponent.java

@@ -18,7 +18,9 @@
 package io.entgra.device.mgt.core.application.mgt.core.internal;
 
 import io.entgra.device.mgt.core.application.mgt.common.services.SPApplicationManager;
+import io.entgra.device.mgt.core.application.mgt.common.services.VPPApplicationManager;
 import io.entgra.device.mgt.core.application.mgt.core.impl.AppmDataHandlerImpl;
+import io.entgra.device.mgt.core.application.mgt.core.impl.VppApplicationManagerImpl;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.osgi.framework.BundleContext;
@@ -116,6 +118,12 @@ public class ApplicationManagementServiceComponent {
             DataHolder.getInstance().setConfigManager(configManager);
             bundleContext.registerService(AppmDataHandler.class.getName(), configManager, null);
 
+
+            // TODO: Get the new instance from extension like others
+            VppApplicationManagerImpl vppApplicationManager = new VppApplicationManagerImpl();
+            DataHolder.getInstance().setVppApplicationManager(vppApplicationManager);
+            bundleContext.registerService(VPPApplicationManager.class.getName(), vppApplicationManager, null);
+
             ScheduledAppSubscriptionTaskManager taskManager = new ScheduledAppSubscriptionTaskManager();
             taskManager.scheduleCleanupTask();
 

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/internal/DataHolder.java

@@ -23,6 +23,7 @@ import io.entgra.device.mgt.core.application.mgt.common.services.AppmDataHandler
 import io.entgra.device.mgt.core.application.mgt.common.services.SPApplicationManager;
 import io.entgra.device.mgt.core.application.mgt.common.services.ReviewManager;
 import io.entgra.device.mgt.core.application.mgt.common.services.SubscriptionManager;
+import io.entgra.device.mgt.core.application.mgt.common.services.VPPApplicationManager;
 import io.entgra.device.mgt.core.application.mgt.core.lifecycle.LifecycleStateManager;
 import io.entgra.device.mgt.core.device.mgt.core.service.DeviceManagementProviderService;
 import org.wso2.carbon.ntask.core.service.TaskService;
@@ -39,6 +40,8 @@ public class DataHolder {
 
     private SPApplicationManager SPApplicationManager;
 
+    private VPPApplicationManager vppApplicationManager;
+
     private ApplicationManager applicationManager;
 
     private ReviewManager reviewManager;
@@ -142,4 +145,12 @@ public class DataHolder {
     public void setISApplicationManager(SPApplicationManager SPApplicationManager) {
         this.SPApplicationManager = SPApplicationManager;
     }
+
+    public VPPApplicationManager getVppApplicationManager() {
+        return vppApplicationManager;
+    }
+
+    public void setVppApplicationManager(VPPApplicationManager vppApplicationManager) {
+        this.vppApplicationManager = vppApplicationManager;
+    }
 }

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/util/Constants.java

@@ -100,6 +100,18 @@ public class Constants {
     }
     public static final Map<String, String> AGENT_FILE_NAMES = Collections.unmodifiableMap(AGENT_DATA);
 
+    public static final String BEARER = "Bearer ";
+
+    public static final String EXECUTOR_EXCEPTION_PREFIX = "ExecutorException-";
+    public static final String TOKEN_IS_EXPIRED = "ACCESS_TOKEN_IS_EXPIRED";
+
+    public static final int INTERNAL_ERROR_CODE = 500;
+
+    public static final String GET = "GET";
+    public static final String POST = "POST";
+    public static final String PUT = "PUT";
+    public static final String DELETE = "DELETE";
+
 
     /**
      * Database types supported by Application Management.

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/util/VppHttpUtil.java

@@ -0,0 +1,285 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.entgra.device.mgt.core.application.mgt.core.util;
+
+import com.google.gson.Gson;
+import io.entgra.device.mgt.core.application.mgt.common.dto.ProxyResponse;
+import org.apache.commons.lang.StringUtils;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.http.Consts;
+import org.apache.http.HttpEntity;
+import org.apache.http.HttpHeaders;
+import org.apache.http.HttpResponse;
+import org.apache.http.HttpStatus;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.client.methods.HttpPost;
+import org.apache.http.client.methods.HttpPut;
+import org.apache.http.client.methods.HttpRequestBase;
+import org.apache.http.entity.ContentType;
+import org.apache.http.entity.StringEntity;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClients;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import javax.servlet.http.HttpServletResponse;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+
+public class VppHttpUtil {
+    private static final Log log = LogFactory.getLog(VppHttpUtil.class);
+
+    public static ProxyResponse execute(String url,
+                                  String payload,
+                                  String accessToken,
+                                  String method) throws IOException {
+
+        HttpRequestBase endpoint = null;
+        if (Constants.GET.equalsIgnoreCase(method) || Constants.DELETE.equalsIgnoreCase(method)) {
+            endpoint = new HttpGet(url);
+            addHeaders(endpoint, accessToken);
+            return VppHttpUtil.execute(endpoint);
+        } else if (Constants.POST.equalsIgnoreCase(method)) {
+            endpoint = new HttpPost(url);
+        } else if (Constants.PUT.equalsIgnoreCase(method)) {
+            endpoint = new HttpPut(url);
+        }
+        addHeaders(endpoint, accessToken);
+
+
+        if (payload != null) {
+            HttpEntity forwardRequestBody = new StringEntity(payload, ContentType.APPLICATION_JSON.toString(), "utf-8");
+            if (Constants.POST.equalsIgnoreCase(method)) {
+                ((HttpPost) endpoint).setEntity(forwardRequestBody);
+            } else if (Constants.PUT.equalsIgnoreCase(method)) {
+                ((HttpPut) endpoint).setEntity(forwardRequestBody);
+            }
+
+        }
+        if (log.isDebugEnabled()) {
+            log.info("Forwarding request to " + url);
+        }
+        return VppHttpUtil.execute(endpoint);
+    }
+
+    private static void addHeaders(HttpRequestBase endpoint, String accessToken) {
+        endpoint.setHeader(HttpHeaders.CONTENT_TYPE, ContentType.APPLICATION_JSON.toString());
+        endpoint.setHeader(HttpHeaders.ACCEPT, ContentType.APPLICATION_JSON.toString());
+        endpoint.setHeader(HttpHeaders.AUTHORIZATION, Constants.BEARER + accessToken);
+    }
+
+
+    /***
+     *
+     * @param httpRequest - httpMethod e.g:- HttpPost, HttpGet
+     * @return response as string
+     * @throws IOException IO exception returns if error occurs when executing the httpMethod
+     */
+    private static ProxyResponse execute(HttpRequestBase httpRequest) throws IOException {
+        try (CloseableHttpClient client = getHttpClient()) {
+            HttpResponse response = client.execute(httpRequest);
+            ProxyResponse proxyResponse = new ProxyResponse();
+
+            if (response == null) {
+                log.error("Received null response for http request : " + httpRequest.getMethod() + " " + httpRequest
+                        .getURI().toString());
+                proxyResponse.setCode(Constants.INTERNAL_ERROR_CODE);
+                proxyResponse.setExecutorResponse(Constants.EXECUTOR_EXCEPTION_PREFIX + getStatusKey(
+                        Constants.INTERNAL_ERROR_CODE));
+                return proxyResponse;
+            } else {
+                int statusCode = response.getStatusLine().getStatusCode();
+                try (BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()))) {
+                    StringBuilder result = new StringBuilder();
+                    String line;
+                    while ((line = rd.readLine()) != null) {
+                        result.append(line);
+                    }
+
+                    String jsonString = result.toString();
+                    if (statusCode == HttpStatus.SC_OK || statusCode == HttpStatus.SC_CREATED) {
+                        proxyResponse.setCode(statusCode);
+                        proxyResponse.setData(jsonString);
+                        proxyResponse.setExecutorResponse("SUCCESS");
+                        return proxyResponse;
+                    } else if (statusCode == HttpStatus.SC_UNAUTHORIZED) {
+                        if (jsonString.contains("Access token expired") || jsonString
+                                .contains("Invalid input. Access token validation failed")) {
+                            proxyResponse.setCode(statusCode);
+                            proxyResponse.setExecutorResponse(Constants.TOKEN_IS_EXPIRED);
+                            return proxyResponse;
+                        } else {
+                            log.error(
+                                    "Received " + statusCode + " response for http request : " + httpRequest.getMethod()
+                                            + " " + httpRequest.getURI().toString() + ". Error message: " + jsonString);
+                            proxyResponse.setCode(statusCode);
+                            proxyResponse.setData(jsonString);
+                            proxyResponse.setExecutorResponse(
+                                    Constants.EXECUTOR_EXCEPTION_PREFIX + getStatusKey(statusCode));
+                            return proxyResponse;
+                        }
+                    }
+                    log.error("Received " + statusCode +
+                            " response for http request : " + httpRequest.getMethod() + " " + httpRequest.getURI()
+                            .toString() + ". Error message: " + jsonString);
+                    proxyResponse.setCode(statusCode);
+                    proxyResponse.setData(jsonString);
+                    proxyResponse
+                            .setExecutorResponse(Constants.EXECUTOR_EXCEPTION_PREFIX + getStatusKey(statusCode));
+                    return proxyResponse;
+                }
+            }
+        }
+    }
+
+    /***
+     *
+     * @param statusCode Provide status code, e.g:- 400, 401, 500 etc
+     * @return relative status code key for given status code.
+     */
+    public static String getStatusKey(int statusCode) {
+        String statusCodeKey;
+
+        switch (statusCode) {
+            case HttpStatus.SC_INTERNAL_SERVER_ERROR:
+                statusCodeKey = "internalServerError";
+                break;
+            case HttpStatus.SC_BAD_REQUEST:
+                statusCodeKey = "badRequest";
+                break;
+            case HttpStatus.SC_UNAUTHORIZED:
+                statusCodeKey = "unauthorized";
+                break;
+            case HttpStatus.SC_FORBIDDEN:
+                statusCodeKey = "forbidden";
+                break;
+            case HttpStatus.SC_NOT_FOUND:
+                statusCodeKey = "notFound";
+                break;
+            case HttpStatus.SC_METHOD_NOT_ALLOWED:
+                statusCodeKey = "methodNotAllowed";
+                break;
+            case HttpStatus.SC_NOT_ACCEPTABLE:
+                statusCodeKey = "notAcceptable";
+                break;
+            case HttpStatus.SC_UNSUPPORTED_MEDIA_TYPE:
+                statusCodeKey = "unsupportedMediaType";
+                break;
+            default:
+                statusCodeKey = "defaultPage";
+                break;
+        }
+        return statusCodeKey;
+    }
+
+
+    /***
+     * Handle error requests.
+     *
+     * @param resp {@link HttpServletResponse}
+     * @param proxyResponse {@link ProxyResponse}
+     * @throws IOException If error occurred when trying to send the error response.
+     */
+    public static void handleError(HttpServletResponse resp, ProxyResponse proxyResponse) throws IOException {
+        Gson gson = new Gson();
+        if (proxyResponse == null) {
+            proxyResponse = new ProxyResponse();
+            proxyResponse.setCode(HttpStatus.SC_INTERNAL_SERVER_ERROR);
+            proxyResponse.setExecutorResponse(Constants.EXECUTOR_EXCEPTION_PREFIX + VppHttpUtil
+                    .getStatusKey(Constants.INTERNAL_ERROR_CODE));
+        }
+        resp.setStatus(proxyResponse.getCode());
+        resp.setContentType(ContentType.APPLICATION_JSON.getMimeType());
+        resp.setCharacterEncoding(Consts.UTF_8.name());
+
+        proxyResponse.setExecutorResponse(null);
+        try (PrintWriter writer = resp.getWriter()) {
+            writer.write(gson.toJson(proxyResponse));
+        }
+    }
+
+    /**
+     * Handle error requests with custom error codes.
+     *
+     * @param resp      {@link HttpServletResponse}
+     * @param errorCode HTTP error status code
+     * @throws IOException If error occurred when trying to send the error response.
+     */
+    public static void handleError(HttpServletResponse resp, int errorCode)
+            throws IOException {
+        ProxyResponse proxyResponse = new ProxyResponse();
+        proxyResponse.setCode(errorCode);
+        proxyResponse.setExecutorResponse(
+                Constants.EXECUTOR_EXCEPTION_PREFIX + VppHttpUtil.getStatusKey(errorCode));
+        VppHttpUtil.handleError(resp, proxyResponse);
+    }
+
+    /***
+     *
+     * @param resp {@link HttpServletResponse}
+     * Return Success Response.
+     */
+    public static void handleSuccess(HttpServletResponse resp, ProxyResponse proxyResponse) throws IOException {
+        if (proxyResponse == null) {
+            handleError(resp, null);
+            return;
+        }
+        resp.setStatus(proxyResponse.getCode());
+        resp.setContentType(ContentType.APPLICATION_JSON.getMimeType());
+        resp.setCharacterEncoding(Consts.UTF_8.name());
+        JSONObject response = new JSONObject();
+        String responseData = proxyResponse.getData();
+
+        if (!StringUtils.isEmpty(responseData)) {
+            try {
+                if (responseData.startsWith("{")) {
+                    JSONObject responseDataJsonObj = new JSONObject(responseData);
+                    response.put("data", responseDataJsonObj);
+                } else if (responseData.startsWith("[")) {
+                    JSONArray responseDataJsonArr = new JSONArray(responseData);
+                    response.put("data", responseDataJsonArr);
+                } else {
+                    log.warn("Response data is not valid json string >> " + responseData);
+                    response.put("data", responseData);
+                }
+            } catch (JSONException e) {
+                log.error("Response data is not passable");
+                response.put("data", responseData);
+            }
+        }
+
+        try (PrintWriter writer = resp.getWriter()) {
+            writer.write(response.toString());
+        }
+    }
+
+    /**
+     * Retrieve Http client based on hostname verification.
+     *
+     * @return {@link CloseableHttpClient} http client
+     */
+    public static CloseableHttpClient getHttpClient() {
+        return HttpClients.custom().setMaxConnTotal(1).setMaxConnPerRoute(1).build();
+    }
+
+}