Which of the following connectors is NOT known to support transactions?

The HTTP connector is not designed to support transactions in the same way that the other connectors listed do. In the context of integration and messaging, transactions ensure that a series of actions either all complete successfully or none at all, maintaining data integrity and consistency.

Connectors like JMS, Database, and VM have built-in mechanisms to manage transactions. For example, with JMS, you can publish messages in a transactional manner, ensuring that the sending and receiving of messages occur as a single unit of work. Database connectors can make use of database transactions, allowing for rollback capabilities if an error occurs during data operations. Similarly, the VM connector, which is used for intra-application communication, also supports transaction management, enabling scenarios where multiple actions can be grouped and executed together.

In contrast, the HTTP connector typically handles stateless interactions without the concept of a transaction. Each HTTP request is independent, making it unsuitable for scenarios where it's critical to ensure that all operations are either completed successfully or reverted. This stateless nature is what sets the HTTP connector apart in this context, making it the only one in the list that does not inherently support transaction management.