Implement exception handling

components/apimgt-extensions/io.entgra.devicemgt.apimgt.extension.publisher.api/pom.xml

@@ -78,6 +78,10 @@
             <groupId>io.github.openfeign</groupId>
             <artifactId>feign-okhttp</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.wso2.carbon.apimgt</groupId>
+            <artifactId>org.wso2.carbon.apimgt.api</artifactId>
+        </dependency>
     </dependencies>
 
     <build>

components/apimgt-extensions/io.entgra.devicemgt.apimgt.extension.publisher.api/src/main/java/io.entgra.devicemgt.apimgt.extension.publisher.api/APIApplicationServices.java

@@ -2,12 +2,14 @@ package io.entgra.devicemgt.apimgt.extension.publisher.api;
 
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.APIApplicationKey;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.AccessTokenInfo;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.APIApplicationServicesException;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.BadRequestException;
 
 public interface APIApplicationServices {
 
-    APIApplicationKey createAndRetrieveApplicationCredentials();
+    APIApplicationKey createAndRetrieveApplicationCredentials() throws BadRequestException, APIApplicationServicesException;
 
-    AccessTokenInfo generateAccessTokenFromRegisteredApplication(String clientId, String clientSecret);
+    AccessTokenInfo generateAccessTokenFromRegisteredApplication(String clientId, String clientSecret) throws APIApplicationServicesException;
-    AccessTokenInfo generateAccessTokenFromRefreshToken(String refreshToken, String clientId, String clientSecret);
+    AccessTokenInfo generateAccessTokenFromRefreshToken(String refreshToken, String clientId, String clientSecret) throws APIApplicationServicesException;
 
 }

components/apimgt-extensions/io.entgra.devicemgt.apimgt.extension.publisher.api/src/main/java/io.entgra.devicemgt.apimgt.extension.publisher.api/APIApplicationServicesImpl.java

@@ -5,6 +5,8 @@ import io.entgra.devicemgt.apimgt.extension.publisher.api.bean.RegistrationProfi
 import io.entgra.devicemgt.apimgt.extension.publisher.api.constants.Constants;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.APIApplicationKey;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.AccessTokenInfo;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.APIApplicationServicesException;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.BadRequestException;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.util.PublisherRESTAPIUtil;
 import okhttp3.*;
 import org.apache.commons.logging.Log;
@@ -37,6 +39,7 @@ import java.util.*;
 public class APIApplicationServicesImpl implements APIApplicationServices {
 
     private static final Log log = LogFactory.getLog(APIApplicationServicesImpl.class);
+<<<<<<< HEAD
     private static final OkHttpClient client = getOkHttpClient();
 
     private static OkHttpClient getOkHttpClient() {
@@ -57,6 +60,13 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
                 .sslSocketFactory(getSimpleTrustedSSLSocketFactory(), trustAllCerts)
                 .hostnameVerifier((hostname, sslSession) -> true).build();
     }
+=======
+//    private final OkHttpClient client;
+
+//    public APIApplicationServicesImpl() {
+//        this.client = new OkHttpClient();
+//    }
+>>>>>>> e76624c1de (Add exceptions)
 
     private static SSLSocketFactory getSimpleTrustedSSLSocketFactory() {
         try {
@@ -82,7 +92,8 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
 
     }
     @Override
-    public APIApplicationKey createAndRetrieveApplicationCredentials() {
+    public APIApplicationKey createAndRetrieveApplicationCredentials()
+            throws APIApplicationServicesException, BadRequestException {
 
         JsonObject jsonObject = new JsonObject();
         jsonObject.addProperty("callbackUrl",Constants.EMPTY_STRING);
@@ -109,6 +120,7 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
 
 //            JSONObject responseObj = new JSONObject(Objects.requireNonNull(response.body()).string());
 
+<<<<<<< HEAD
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
@@ -159,10 +171,54 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
 //            log.error("failed to call http client.", e);
 //        }
         return null;
+=======
+            String jsonString = registrationProfile.toJSON();
+            StringEntity entity = new StringEntity(jsonString, ContentType.APPLICATION_JSON);
+            request.setEntity(entity);
+
+            //ToDo: Remove hardcoded value
+            String basicAuth = getBase64Encode("admin", "admin");
+            request.setHeader(HttpHeaders.AUTHORIZATION, Constants.AUTHORIZATION_HEADER_VALUE_PREFIX + basicAuth);
+            request.setHeader(HttpHeaders.CONTENT_TYPE, Constants.APPLICATION_JSON);
+
+            HttpResponse httpResponse = httpclient.execute(request);
+
+            if (httpResponse != null) {
+                String response = PublisherRESTAPIUtil.getResponseString(httpResponse);
+                try {
+                    if(response != null){
+                        JSONParser jsonParser = new JSONParser();
+                        JSONObject jsonPayload = (JSONObject) jsonParser.parse(response);
+                        APIApplicationKey apiApplicationKey = new APIApplicationKey();
+                        apiApplicationKey.setClientId((String) jsonPayload.get(Constants.CLIENT_ID));
+                        apiApplicationKey.setClientSecret((String) jsonPayload.get(Constants.CLIENT_SECRET));
+                        return apiApplicationKey;
+                    } else {
+                        String msg = "Request payload is null. Please verify the request payload.";
+                        log.error(msg);
+                        throw new BadRequestException(msg);
+                    }
+                } catch (ParseException e) {
+                    throw new APIApplicationServicesException("Error when parsing the response " + response, e);
+                }
+            } else {
+                return null;
+            }
+        } catch (IOException e) {
+            throw new APIApplicationServicesException("Error when reading the response from buffer.", e);
+        } catch (KeyStoreException e) {
+            throw new APIApplicationServicesException("Failed loading the keystore.", e);
+        } catch (NoSuchAlgorithmException e) {
+            throw new APIApplicationServicesException("No such algorithm found when loading the ssl socket", e);
+        } catch (KeyManagementException e) {
+            throw new APIApplicationServicesException("Failed setting up the ssl http client.", e);
+        }
+>>>>>>> e76624c1de (Add exceptions)
     }
 
     @Override
-    public AccessTokenInfo generateAccessTokenFromRegisteredApplication(String consumerKey, String consumerSecret) {
+    public AccessTokenInfo generateAccessTokenFromRegisteredApplication(String consumerKey, String consumerSecret)
+        throws APIApplicationServicesException {
         List<NameValuePair> params = new ArrayList<>();
         params.add(new BasicNameValuePair(Constants.GRANT_TYPE_PARAM_NAME, Constants.PASSWORD_GRANT_TYPE));
         //ToDo: Remove hardcoded value
@@ -173,7 +229,8 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
     }
 
     @Override
-    public AccessTokenInfo generateAccessTokenFromRefreshToken(String refreshToken, String consumerKey, String consumerSecret) {
+    public AccessTokenInfo generateAccessTokenFromRefreshToken(String refreshToken, String consumerKey, String consumerSecret)
+            throws APIApplicationServicesException {
         List<NameValuePair> params = new ArrayList<>();
         params.add(new BasicNameValuePair(Constants.GRANT_TYPE_PARAM_NAME, Constants.REFRESH_TOKEN_GRANT_TYPE));
         params.add(new BasicNameValuePair(Constants.REFRESH_TOKEN_GRANT_TYPE_PARAM_NAME, refreshToken));
@@ -181,8 +238,10 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
         return getToken(params, consumerKey, consumerSecret);
     }
 
-    public AccessTokenInfo getToken(List<NameValuePair> nameValuePairs, String clientId, String clientSecret) {
+    public AccessTokenInfo getToken(List<NameValuePair> nameValuePairs, String clientId, String clientSecret)
+            throws APIApplicationServicesException{
 
+        String response = null;
         try {
             URL url = new URL("https://localhost:9443/oauth2/token");
             HttpClient httpclient = PublisherRESTAPIUtil.getHttpClient(url.getProtocol());
@@ -193,7 +252,7 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
             request.setEntity(new UrlEncodedFormEntity(nameValuePairs));
 
             HttpResponse httpResponse = httpclient.execute(request);
-            String response = PublisherRESTAPIUtil.getResponseString(httpResponse);
+            response = PublisherRESTAPIUtil.getResponseString(httpResponse);
             if (log.isDebugEnabled()) {
                 log.debug(response);
             }
@@ -210,9 +269,16 @@ public class APIApplicationServicesImpl implements APIApplicationServices {
             }
             return accessTokenInfo;
 
-        } catch (IOException | KeyStoreException | NoSuchAlgorithmException |
+        } catch (IOException e) {
-                 KeyManagementException| ParseException e) {
+            throw new APIApplicationServicesException("Error when reading the response from buffer.", e);
-            throw new RuntimeException(e);
+        } catch (KeyStoreException e) {
+            throw new APIApplicationServicesException("Failed loading the keystore.", e);
+        } catch (NoSuchAlgorithmException e) {
+            throw new APIApplicationServicesException("No such algorithm found when loading the ssl socket", e);
+        } catch (ParseException e) {
+            throw new APIApplicationServicesException("Error when parsing the response " + response, e);
+        } catch (KeyManagementException e) {
+            throw new APIApplicationServicesException("Failed setting up the ssl http client.", e);
         }
     }
 

components/apimgt-extensions/io.entgra.devicemgt.apimgt.extension.publisher.api/src/main/java/io.entgra.devicemgt.apimgt.extension.publisher.api/PublisherRESTAPIServices.java

@@ -3,9 +3,10 @@ package io.entgra.devicemgt.apimgt.extension.publisher.api;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.constants.Constants;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.APIApplicationKey;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.AccessTokenInfo;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.APIApplicationServicesException;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.BadRequestException;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.util.PublisherRESTAPIUtil;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.util.ScopeUtils;
-import org.apache.axis2.databinding.types.xsd._boolean;
 import org.apache.commons.httpclient.HttpStatus;
 import org.apache.http.HttpHeaders;
 import org.apache.http.client.methods.HttpHead;
@@ -28,104 +29,8 @@ import java.security.NoSuchAlgorithmException;
 public class PublisherRESTAPIServices {
     private static final Log log = LogFactory.getLog(PublisherRESTAPIServices.class);
 
-//    private String clientId;
+    public boolean isSharedScopeNameExists(APIApplicationKey apiApplicationKey,  AccessTokenInfo accessTokenInfo, String key)
-//    private String clientSecret;
+            throws APIApplicationServicesException, BadRequestException {
-//    private String accessToken;
-//
-//    public AccessTokenInfo registerApplication() {
-//
-//        try {
-//            URL url = new URL("https://localhost:9443/client-registration/v0.17/register");
-//            HttpClient httpclient = PublisherRESTAPIUtil.getHttpClient(url.getProtocol());
-//            HttpPost request = new HttpPost(url.toString());
-//
-//            RegistrationProfile registrationProfile = new RegistrationProfile();
-//            registrationProfile.setCallbackUrl(Constants.EMPTY_STRING);
-//            registrationProfile.setClientName(Constants.CLIENT_NAME);
-//            registrationProfile.setGrantType(Constants.GRANT_TYPE);
-//            registrationProfile.setOwner(Constants.OWNER);
-//            registrationProfile.setIsSaasApp(true);
-//
-//            String jsonString = registrationProfile.toJSON();
-//            StringEntity entity = new StringEntity(jsonString, ContentType.APPLICATION_JSON);
-//            request.setEntity(entity);
-//
-//            String basicAuth = getBase64Encode("admin", "admin");
-//
-//            request.setHeader("Authorization", "Basic " + basicAuth);
-//            request.setHeader("Content-Type", "application/json");
-//
-//            HttpResponse httpResponse = httpclient.execute(request);
-//
-//            if (httpResponse != null) {
-//
-//                String response = PublisherRESTAPIUtil.getResponseString(httpResponse);
-//                try {
-//                    if(response != null){
-//                        JSONParser jsonParser = new JSONParser();
-//                        JSONObject jsonPayload = (JSONObject) jsonParser.parse(response);
-//                        clientId = (String) jsonPayload.get(Constants.CLIENT_ID);
-//                        clientSecret = (String) jsonPayload.get(Constants.CLIENT_SECRET);
-//                    }
-//                } catch (ParseException e) {
-//                    throw new RuntimeException(e);
-//                }
-//                System.out.println(response);
-//            }
-//            System.out.println(httpResponse.getStatusLine().getStatusCode());
-//
-//        } catch (IOException | NoSuchAlgorithmException | KeyStoreException |
-//                 KeyManagementException e) {
-//            log.error("failed to call http client.", e);
-//        }
-//        return getAccessTokenFromRegisteredApplication(clientId, clientSecret);
-//
-//    }
-//
-//    public AccessTokenInfo getAccessTokenFromRegisteredApplication(String consumerKey, String consumerSecret) {
-//        List<NameValuePair> params = new ArrayList<>();
-//        params.add(new BasicNameValuePair(Constants.GRANT_TYPE_PARAM_NAME, Constants.PASSWORD_GRANT_TYPE));
-//        params.add(new BasicNameValuePair(Constants.PASSWORD_GRANT_TYPE_USERNAME, "admin"));
-//        params.add(new BasicNameValuePair(Constants.PASSWORD_GRANT_TYPE_PASSWORD, "admin"));
-//        params.add(new BasicNameValuePair(Constants.SCOPE_PARAM_NAME, Constants.SCOPES));
-//        return getToken(params, consumerKey, consumerSecret);
-//    }
-//
-//    public AccessTokenInfo getToken(List<NameValuePair> nameValuePairs, String clientId, String clientSecret) {
-//
-//        String token = null;
-//        String response = null;
-//        try {
-//            URL url = new URL("https://localhost:9443/oauth2/token");
-//            HttpClient httpclient = PublisherRESTAPIUtil.getHttpClient(url.getProtocol());
-//            HttpPost request = new HttpPost(url.toString());
-//
-//            request.addHeader("Authorization", "Basic " + getBase64Encode(clientId, clientSecret));
-//            request.addHeader("Content-Type", "application/x-www-form-urlencoded");
-//            request.setEntity(new UrlEncodedFormEntity(nameValuePairs));
-//            HttpResponse httpResponse = httpclient.execute(request);
-//            response = PublisherRESTAPIUtil.getResponseString(httpResponse);
-//            JSONParser jsonParser = new JSONParser();
-//            JSONObject jsonObject = (JSONObject) jsonParser.parse(response);
-//            AccessTokenInfo accessTokenInfo = new AccessTokenInfo();
-//            token = (String) jsonObject.get(Constants.ACCESS_TOKEN_GRANT_TYPE_PARAM_NAME);
-//            if (token != null && !token.isEmpty()){
-//                accessTokenInfo.setRefreshToken(token);
-//                accessTokenInfo.setRefreshToken((String) jsonObject.get(Constants.REFRESH_TOKEN_GRANT_TYPE_PARAM_NAME));
-//                accessTokenInfo.setExpiresIn((Long) jsonObject.get(Constants.OAUTH_EXPIRES_IN));
-//                accessTokenInfo.setTokenType((String) jsonObject.get(Constants.OAUTH_TOKEN_TYPE));
-//                accessTokenInfo.setScope((String) jsonObject.get(Constants.OAUTH_TOKEN_SCOPE));
-//            }
-//            accessToken = token;
-//            return accessTokenInfo;
-//
-//        } catch (IOException | KeyStoreException | NoSuchAlgorithmException |
-//                 KeyManagementException| ParseException e) {
-//            throw new RuntimeException(e);
-//        }
-//    }
-
-    public boolean isSharedScopeNameExists(APIApplicationKey apiApplicationKey,  AccessTokenInfo accessTokenInfo, String key){
 
         String keyValue = new String(Base64.encodeBase64((key).getBytes())).replace("=", "");
         String getScopeUrl = "https://localhost:9443/api/am/publisher/v2/scopes/" + keyValue;
@@ -144,19 +49,28 @@ public class PublisherRESTAPIServices {
                 AccessTokenInfo refreshedAccessToken = apiApplicationServices.
                         generateAccessTokenFromRefreshToken(accessTokenInfo.getRefreshToken(), apiApplicationKey.getClientId(), apiApplicationKey.getClientSecret() );
                 return isSharedScopeNameExists(apiApplicationKey,refreshedAccessToken, key);
-            } else{
+            } else if (HttpStatus.SC_BAD_REQUEST == httpResponse.getStatusLine().getStatusCode()){
+                String response = httpResponse.toString();
+                log.info(response);
+                throw new BadRequestException(response);
+            } else {
                 return false;
             }
 
-        } catch (IOException | KeyStoreException | NoSuchAlgorithmException | KeyManagementException e) {
+        } catch (IOException e) {
-            throw new RuntimeException(e);
+            throw new APIApplicationServicesException("Error when reading the response from buffer.", e);
+        } catch (KeyStoreException e) {
+            throw new APIApplicationServicesException("Failed loading the keystore.", e);
+        } catch (NoSuchAlgorithmException e) {
+            throw new APIApplicationServicesException("No such algorithm found when loading the ssl socket", e);
+        } catch (KeyManagementException e) {
+            throw new APIApplicationServicesException("Failed setting up the ssl http client.", e);
         }
     }
 
-    public void updateSharedScope(APIApplicationKey apiApplicationKey, AccessTokenInfo accessTokenInfo, Scope scope){
+    public void updateSharedScope(APIApplicationKey apiApplicationKey, AccessTokenInfo accessTokenInfo, Scope scope)
+            throws APIApplicationServicesException, BadRequestException {
 
-//        String keyValue = new String(Base64.encodeBase64((scope.getKey()).getBytes())).replace("=", "");
-//        String updateScopeUrl = "https://localhost:9443/api/am/publisher/v2/scopes/" + keyValue;
         String updateScopeUrl = "https://localhost:9443/api/am/publisher/v2/scopes/" + scope.getId();
         try {
             URL url = new URL(updateScopeUrl);
@@ -182,16 +96,20 @@ public class PublisherRESTAPIServices {
                 AccessTokenInfo accessTokenInfo1 = apiApplicationServices.
                         generateAccessTokenFromRefreshToken(accessTokenInfo.getRefreshToken(), apiApplicationKey.getClientId(), apiApplicationKey.getClientSecret() );
                 updateSharedScope(apiApplicationKey, accessTokenInfo1, scope);
-            } else {
+            } else if (HttpStatus.SC_BAD_REQUEST == httpResponse.getStatusLine().getStatusCode()){
                 String response = httpResponse.toString();
                 log.info(response);
+                throw new BadRequestException(response);
             }
 
-        } catch (IOException | KeyStoreException | NoSuchAlgorithmException | KeyManagementException e) {
+        } catch (IOException e) {
-            throw new RuntimeException(e);
+            throw new APIApplicationServicesException("Error when reading the response from buffer.", e);
+        } catch (KeyStoreException e) {
+            throw new APIApplicationServicesException("Failed loading the keystore.", e);
+        } catch (NoSuchAlgorithmException e) {
+            throw new APIApplicationServicesException("No such algorithm found when loading the ssl socket", e);
+        } catch (KeyManagementException e) {
+            throw new APIApplicationServicesException("Failed setting up the ssl http client.", e);
         }
     }
-//    static String getBase64Encode(String key, String value) {
-//        return new String(Base64.encodeBase64((key + ":" + value).getBytes()));
-//    }
 }

components/apimgt-extensions/io.entgra.devicemgt.apimgt.extension.publisher.api/src/main/java/io.entgra.devicemgt.apimgt.extension.publisher.api/exceptions/APIApplicationServicesException.java

@@ -0,0 +1,12 @@
+package io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions;
+
+public class APIApplicationServicesException extends Exception{
+
+    public APIApplicationServicesException() {super();}
+
+    public APIApplicationServicesException(String message) {super();}
+
+    public APIApplicationServicesException(String message, Throwable cause){super();}
+
+    public APIApplicationServicesException(Throwable cause){super();}
+}

components/apimgt-extensions/io.entgra.devicemgt.apimgt.extension.publisher.api/src/main/java/io.entgra.devicemgt.apimgt.extension.publisher.api/exceptions/BadRequestException.java

@@ -0,0 +1,34 @@
+/*
+ *
+ *  * Copyright (c) 2022, 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.
+ *
+ *
+ */
+
+/**
+ * Custom exception class for handling bad request exceptions.
+ */
+package io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions;
+
+public class BadRequestException extends Exception {
+
+    private static final long serialVersionUID = -2387103750774855056L;
+
+    public BadRequestException(String errorMessage) {
+        super(errorMessage);
+    }
+}

components/apimgt-extensions/org.wso2.carbon.apimgt.webapp.publisher/src/main/java/org/wso2/carbon/apimgt/webapp/publisher/APIPublisherService.java

@@ -19,6 +19,7 @@
 package org.wso2.carbon.apimgt.webapp.publisher;
 
 
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.BadRequestException;
 import org.wso2.carbon.apimgt.webapp.publisher.exception.APIManagerPublisherException;
 
 /**

components/apimgt-extensions/org.wso2.carbon.apimgt.webapp.publisher/src/main/java/org/wso2/carbon/apimgt/webapp/publisher/APIPublisherServiceImpl.java

@@ -23,6 +23,8 @@ import io.entgra.devicemgt.apimgt.extension.publisher.api.APIApplicationServices
 import io.entgra.devicemgt.apimgt.extension.publisher.api.PublisherRESTAPIServices;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.APIApplicationKey;
 import io.entgra.devicemgt.apimgt.extension.publisher.api.dto.AccessTokenInfo;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.APIApplicationServicesException;
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.BadRequestException;
 import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -361,10 +363,21 @@ public class APIPublisherServiceImpl implements APIPublisherService {
         WebappPublisherConfig config = WebappPublisherConfig.getInstance();
         List<String> tenants = new ArrayList<>(Collections.singletonList(APIConstants.SUPER_TENANT_DOMAIN));
         tenants.addAll(config.getTenants().getTenant());
+
         APIApplicationServices apiApplicationServices = new APIApplicationServicesImpl();
-        APIApplicationKey apiApplicationKey = apiApplicationServices.createAndRetrieveApplicationCredentials();
+        APIApplicationKey apiApplicationKey;
-        AccessTokenInfo accessTokenInfo = apiApplicationServices.generateAccessTokenFromRegisteredApplication(
+        AccessTokenInfo accessTokenInfo;
-                apiApplicationKey.getClientId(), apiApplicationKey.getClientSecret());
+        try {
+            apiApplicationKey = apiApplicationServices.createAndRetrieveApplicationCredentials();
+            accessTokenInfo = apiApplicationServices.generateAccessTokenFromRegisteredApplication(
+                    apiApplicationKey.getClientId(), apiApplicationKey.getClientSecret());
+        } catch (BadRequestException e) {
+            String errorMsg = "Error while generating application";
+            log.error(errorMsg, e);
+            throw new APIManagerPublisherException(e);
+        } catch (APIApplicationServicesException e) {
+            throw new RuntimeException(e);
+        }
 
         try {
             for (String tenantDomain : tenants) {
@@ -433,6 +446,10 @@ public class APIPublisherServiceImpl implements APIPublisherService {
                     }
                 } catch (IOException | DirectoryIteratorException ex) {
                     log.error("failed to read scopes from file.", ex);
+                } catch (APIApplicationServicesException | BadRequestException e) {
+                    String errorMsg = "Error while generating an OAuth token";
+                    log.error(errorMsg, e);
+                    throw new APIManagerPublisherException(e);
                 }
 
             }

components/apimgt-extensions/org.wso2.carbon.apimgt.webapp.publisher/src/main/java/org/wso2/carbon/apimgt/webapp/publisher/APIPublisherStartupHandler.java

@@ -19,6 +19,7 @@
 
 package org.wso2.carbon.apimgt.webapp.publisher;
 
+import io.entgra.devicemgt.apimgt.extension.publisher.api.exceptions.BadRequestException;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.wso2.carbon.apimgt.webapp.publisher.exception.APIManagerPublisherException;