Migration of a durable client in a publish/subscribe system from a first server of a cluster to a second server of the cluster. The method comprises the second server receiving subscription information of the durable client; the second server establishing a message queue for the durable client; the second server sending a switch command to all active servers of the cluster; in response to the second server obtaining, from an active server, an acknowledgement of the switch command, the second server inserting a marker to the message queue indicating switching point of the active server; and in response to the second server obtaining, from the first server, a message indicating the first server flushed all messages prior to respective switching points for all active servers, connecting the durable client to the second server and transmitting messages thereto by the second server. As a result, the durable client is migrated from the first server to the second server without disrupting data traffic to uninvolved clients.