JMS supports persistent and Non-PersistentEms Supports Reliable, Persistent, Non-Persistent

Relaible delivery mode:Senders/ publishers dont get any reply back from Ems server if there are any issues in sending message, Ems will reply back if the connection between Ems and Publisher/sender fails.

Persistent Mode:If the publisher/sender sends the message as persistent then the message should be stored in the disk(Sync-db file )case1:Fail safe set on destination when the message is send by publisher/sender in persistent wayThis will make the ems server write the message to disk , till then it will block publisher/sender from sending further messages , once the write operation is complete it sends back a confirmation to publisher/receiver.case2:Fail safe not set on destination when the message is send by publisher/sender in persistent wayThis will make the ems server , and sends a confirmation back to publisher/sender saying that it has written to disk but actually it is in process of writing the message to disk.In this duration if Ems server goes down there is no way a publisher/sender can know the message is stored and sent from server to Whoever interested in the message.

Non-Persistent:In this mode Ems server sends confirmation back to publisher/sender that Ems has received the message , it stores the message in async-db.If the server goes down then this message cannot be received by the receivers when the Ems Server is made running again.

Note:Failsafe works with persistent but not with Non-persistent message delivery.