ExpressDesk supports a Highly Available, Scalable architecture, through the 'HA-Package' Product.

The main advantages of the 'HA-Package' are that :  in case of outage of one of the ExpressAgent servers, no conversation is lost; the expressDesk solution is scalable, as several servers can be used in parallel to balance the workload.

The 'HA-Package' provides you with :

  1. A 'Conversation Failover service' : this is a lightweight Windows service, running on each Ms Lync Front-end server of your Lync infrastructure. This 'FailOver Service' monitors the traffic, and captures the events where packets were not successfully routed to ExpressAgent servers (for instance due to network outages, power loss, hadrware or software issue,...). It will force the Lync clients to re-send 'SIP Invite messages', in order to re-establish the conversation with one of the remaining ExpressAgent servers
  2. Support for 'Failover Activities' in ExpressAgent : Those failover activities are constantly serialized to a SQL Server database. When a conversation is re-routed from a server who failed to a healthy ExpressAgent server, the healthy server will recover the conversation from the database, and continue where it was.

In order to provide a fully redundant service, without any single point fo failure, it is of course needed to setup a SQL Server Cluster.

Note that Microsoft SQL Server Licenses must be purchased separately and are not included as part of our Licenses.