The Azure Service Bus transport is backward compatible with the legacy Azure Service Bus transport under certain conditions.
Conditions
Forwarding topology
The Azure Service Bus transport only supports the forwarding topology.
Single namespace
The Azure Service Bus transport only supports a single namespace.
Topic path must match
Both transports must be configured using the same topic path for publishing to work properly. The Azure Service Bus transport must use the same topic as the old Azure Service Bus transport. Also, only one topic path is allowed.
Therefore, for publishers that are using the legacy transport version 7 or lower, the number of entities in a bundle must be restricted to one using:
forwardingTopology.NumberOfEntitiesInBundle(1);
Namespace alias is not used
The Azure Service Bus transport doesn't support namespace aliases.
Sanitization rules must be aligned
If the legacy transport sanitizes entity names, the sanitization logic must be updated to be compatible with the new transport.
For example, for the ValidateAndHashIfNeeded strategy, the sanitization functions must include the strategy logic to preserve the same entity names.
For queue names, or event names that crossed the threshold of 50 characters, it is necessary to precalculate the MD5 hash and store that as the subscription or rule name. Alternatively simply configure the subscription or rule name already used in production as a hardcoded value.
var migrationTopology = TopicTopology.MigrateFromSingleDefaultTopic();
migrationTopology.OverrideSubscriptionNameFor("QueueName", "ShortenedSubscriptionName");
migrationTopology.EventToMigrate<MyEvent>("ShortenedRuleName");