Resolution:

1). EMS 8.0.0 should be backward compatible with previous versions in so far as  you can use EMS 5.x, 6.x and 7.x clients with the EMS 8.0.0 server. Also, you can use EMS 8.0.0 clients with EMS 5.x, 6.x and 7.x servers.

2).. The new features introduced in EMS 8.0.0 can not work with previous versions.

For example, if you implement delivery delay in a EMS 8.0.0 client, it won’t work when sending message to a EMS 5.x, 6.x and 7.x server.

For EMS route, JMS 2.0.0 introduced one new header JMSDeliveryTime. Though the JMS 2.0 message with this new header can be successfully routed to EMS 5.x, 6.x and 7.x servers from an EMS 8.0.0 server, EMS 5.x, 6.x and 7.x servers will not recognize the new header and will ignore it. If you want to use the new features in EMS 8.0.0, we recommend you to upgrade all servers and clients to EMS 8.0.0.

3). EMS 8.0.0 includes some enhancements and changes to the database store feature.  After installing the new version of EMS, you must run the EMS Schema Export Tool with the -updateall -export options to apply these changes to your database store implementation.

Compatibility of EMS 8.0.0 with previous versions.