Load balancing interviewing engines

Load balancing in UNICOM Intelligence Interviewer allows you to distribute interviewing load evenly across all Interviewing servers or engines in a cluster. UNICOM Intelligence Interviewer is installed with a load balancing script but you can write your own scripts that fine tune the performance for your cluster. The most common scenario for this is if you have application servers with different CPUs or memory.

Load balancing scripts are written in the UNICOM Intelligence Scripting Language (mrScriptBasic) and are stored on each application server.

The default script that comes with UNICOM Intelligence Interviewer is called defaultload.mrs; it is in the UNICOM Intelligence Interviewer installation folder Server subfolder: see Default UNICOM Intelligence Interviewer load balancing script.

To use a different script, you can change the filename or location in the registry: see Load balancing settings. After changing the registry, stop and restart the interviewing engines so that the change can take effect.

Uninstalling UNICOM Intelligence Interviewer does not delete .mrs files. Instead, it renames them by appending a date and time to the filenames. If you install a later version of UNICOM Intelligence Interviewer, you can reinstate your load balancing system by renaming the files to remove the date and time.

▪Use external load balancing in front of the Web Service tier servers. The web service tier is stateless, so requests can failover between web service tier instances. You can setup load balancing with an external load balancer by using URLs that depict different virtual directories, rather than simply using IP addresses for the different web sites. For example, you could load balance multiple mriWeb virtual directories by configuring the external load balancer to balance the load between http://server1/mrIweb1, http://server1/mrIWeb2, and so on.

▪UNICOM Intelligence automatically load-balances requests to the Interview Service tier for web surveys (UNICOM Intelligence Interviewer load balancing). Failover is supported on the Interview tier: that is, if an interview tier server fails, the survey automatically failovers to the next least loaded interviewing engine.