http://www.traders-soft.com/ts/index.htm OR http://www.tssupport.com/ or http://www.dynastoresoftware.com/Dynaloader/index.asp You will find OnDemandSever for eSignal for Tradestation only provides data "On Demand". It does NOT save it in Global Server. Dynaloader/esignal for TS does save it to Global Server for future use. I like Uniserver compared to Dynaloader since it is built into Global Server. I have used both.
I'm currently testing out Dynaloader (it doesn't seem like the other offers any trial period). Dynaloader works really well, but like rts said it's a data gathering machine. The only data it gets is tick, 1min, 5min, and daily bars. I wish they had something between 5min and daily as Esignal only goes back a couple months with 5min bars - not enough for intraday backtesting. Other than that it's a pretty good program.
Checking the tssupport site, it looks like they have a trial version of Uniserver but it's limited to just MSFT. Someone in one of their forums asked for a fully functional version and they gave it to them for a week. You might be able to get the same if you ask.