Adding javaDoc

provider/register-azure/pom.xml

@@ -90,7 +90,7 @@
         <dependency>
             <groupId>org.opengroup.osdu</groupId>
             <artifactId>core-lib-azure</artifactId>
-            <version>0.0.18</version>
+            <version>0.0.21</version>
         </dependency>
         <dependency>
             <groupId>org.opengroup.osdu</groupId>

provider/register-azure/src/main/java/org/opengroup/osdu/register/provider/azure/subscriber/SubscriptionRepository.java

@@ -64,6 +64,32 @@ public class SubscriptionRepository implements ISubscriptionRepository {
     @Autowired
     private PushSubscription pushSubscription;
 
+    /**
+     * @param input     Subscription Object
+     * @return          Subscription Object
+     *
+     *  This method creates a Record for the subscription in CosmosDb along
+     *  with a Push Subscription in Event Grid.
+     *
+     *  Expected Flow -> Create a record in Cosmos Db along with a Push Subscription in Event Grid
+     *  Possible Failures ->
+     *  1) Creating PushSubscription in Event Grid
+     *     How it is handled -> Delete the record in Cosmos Db as well
+     *     Possible Issue -> What happens if this delete operation on Cosmos Db fails?
+     *     Users won't be able to create a subscription again with same Topic and
+     *     push endpoint combination since system will generate 409 on next retry
+     *     because of presence of record with same Id in Cosmos Db
+     *
+     *     How to resolve this?
+     *     createPushSubscriptionIfDoesNotExist method takes care of that
+     *     When Cosmos Db throws 409 while creating a new record we can check if a Push Subscription
+     *     for that Record already exists in Event Grid or not.
+     *     If present -> Return 409
+     *     If not present -> We can try creating the Push Subscription again in Event Grid
+     *                       Also we will update the record in Cosmos Db in case other fields might
+     *                       be different like description etc.
+     *
+     */
     @Override
     public Subscription create(Subscription input) {
 
@@ -78,11 +104,11 @@ public class SubscriptionRepository implements ISubscriptionRepository {
         }
         catch (AppException e) {
             if(e.getError().getCode() == 409) {
-                // This case will handle the scenario where creating PushSubscription in EventGrid failed
-                // but we failed to delete the corresponding record from Cosmos Db. Since the operation
-                // failed last time throwing 500, user should be able to create the subscription with
-                // the same topic and pushEndpoint combination.
-                SubscriptionDoc output = checkIfPushSubscriptionExists(doc);
+                // This flow is added to handle the scenario where creating PushSubscription in EventGrid failed
+                // and deleting the corresponding record from Cosmos Db was also unsuccessful.
+                // This will result in an 500 Exception so the user should be able to create the subscription with
+                // the same topic and pushEndpoint combination again
+                SubscriptionDoc output = createPushSubscriptionIfDoesNotExist(doc);
                 input.setNotificationId(output.getNotificationId());
                 return input;
             }
@@ -136,6 +162,12 @@ public class SubscriptionRepository implements ISubscriptionRepository {
                 .collect(Collectors.toList());
     }
 
+    /**
+     * @param id    Identifier for the subscription
+     * @return      true if subscription successfully deleted
+     *              false if subscription not found
+     *              Exception thrown -> AppException with Status Codes 409 and 500
+     */
     @Override
     public boolean delete(String id) {
 
@@ -195,17 +227,14 @@ public class SubscriptionRepository implements ISubscriptionRepository {
                 .collect(Collectors.toList());
     }
 
-    private SubscriptionDoc checkIfPushSubscriptionExists(SubscriptionDoc input) {
+    private SubscriptionDoc createPushSubscriptionIfDoesNotExist(SubscriptionDoc input) {
         try {
             // We are fetching the record from cosmos db again because we want to use the original
             // notification-id to create the Push Subscription
             Optional<SubscriptionDoc> originalDoc = cosmosStore.findItem(dpsHeaders.getPartitionId(), azureBootstrapConfig.getCosmosDBName(), cosmosContainerConfig.getSubscriptionContainerName(), input.getId(), dpsHeaders.getPartitionId(), SubscriptionDoc.class);
-            if(!originalDoc.isPresent()) {
-                throw new AppException(500, "Server Error", "Unexpected error creating subscription");
-            }
-            input.setNotificationId(originalDoc.get().getNotificationId());
+            originalDoc.ifPresent(subscriptionDoc -> input.setNotificationId(subscriptionDoc.getNotificationId()));
 
-            // We will check if Push Subscription does not exist we should try creating it again since
+            // We will check if Push Subscription does not exist then we should try creating it again since
             // the corresponding record in the Cosmos Db is already present
             pushSubscription.getPushSubscription(input.getNotificationId(), input.getTopic());
             logger.error("A subscriber already exists with the same topic and endpoint combination");