This mode provides at-most-once message delivery. Direct messages have the following characteristics: They are not retained for clients that are not connected to a Solace appliance.They can be discarded when congestion or system failures are encountered.They can be reordered in the event of network topology changes.
Direct messages are most appropriate for messaging applications that require very high-rate or very low-latency message transmission. Direct Messaging enables applications to efficiently publish messages to a large number of clients with matching subscriptions.
This mode provides once-and-only-once message delivery. A Persistent delivery mode is used for Guaranteed Messaging, and this delivery mode is most appropriate for applications that require persistent storage of the messages they send or intend to receive.
Persistent messages have the following characteristics:They cannot be discarded or lost (once they are acknowledged by the appliance).They cannot be reordered in the event of network topology changes.They cannot be delivered more than once to a single client (unless the redelivered message flag is applied). When they match subscriptions on durable endpoints, they are retained for a client when that client is not connected.
Persistent messages are most appropriate for applications that require persistent storage of the messages they send or intend to receive. The quality of service offered by Guaranteed Messaging is analogous to JMS Persistent messaging with durable subscriptions.
This mode is functionally the same as Persistent. It exists to facilitate interaction with JMS applications. In most situations where you want to use Guaranteed Messaging, it is recommended that you use a Persistent delivery mode.