Lighthouse Studio (formerly SSI Web) is Sawtooth Software's web survey software. Lighthouse Studio creates surveys for general interviewing (CiW) as well as surveys for conjoint analysis (ACBC, CBC, ACA, and CVA) and MaxDiff. The surveys are created by using the Lighthouse Studio authoring interface on a local PC. The Lighthouse Studio authoring program then creates various files that describe the study. These files, in conjunction with Lighthouse Studio's Perl script files, are then uploaded to a remote web server to run the survey. For a brief introduction to this process see How Lighthouse Studio Works.
- Server Side Documentation for Lighthouse Studio version 9.X.X
- Server Side Documentation for SSI Web version 8.X.X
- Server Side Documentation for SSI Web version 7.X.X
- Server Side Documentation for SSI Web version 6.X.X
- Server Side Documentation for SSI Web version 5.X.X
- Server Side Documentation for SSI Web version 3.X.X
Rather than using Sawtooth Software hosting services, you can also choose to host surveys on your own servers. However, it can be tricky to configure your server if you do not have much experience in this field. Because every self-hosted server has been configured differently, we recommend talking to your hosting provider. In addition to the links above, here are three additional articles about server configuration that may help your provider.
- http://www.sawtoothsoftware.com/1379 (Server Requirements)
- http://www.sawtoothsoftware.com/1637 (Server Requirements FAQ)
- http://www.sawtoothsoftware.com/1638 (Survey Context Diagram)
SSI Web v8 and above are compatible with loadbalanced environments. Perl is not using any local server session variables, so the load balancer doesn't need to keep track of which client connected to which server.
We recommend using the latest stable version of a MySQL compatible database application server if you plan to use Linux (MySQL, or MariaDB for example). Microsoft SQL server is technically compatible, but installing and configuring the Perl packages to connect from Linux/Unix to MS SQL seems to be a huge pain. If you are using Microsoft Internet Information Services (IIS) to run Perl, then you can choose either MS SQL or MySQL compatible databases as your database application.
We've seen the best stability and performance of SSI Web surveys on Linux servers setup to use NGINX with Perl FastCGI (fcgiwrap). The main difference here is that it tends to use the least RAM with the best throughput, even under heavy loads. Apache with mod_perl or mod_proxy to Perl FastCGI is also supported with great performance. Microsoft Internet Information Services also works great, but will generally require more RAM.
Perl FastCGI conserves RAM by re-using the Perl Interpreter for each request, and since the Interpreter doesn't have to be loaded into memory for each request, the turn around time for each request is lower. FastCGI also limits the number of open Perl Interpreters and queues requests so the RAM usage is far more predictable than in a "classic" CGI context where each new script.cgi request spawns a new process.