Can you tell me more about eValid's architecture? Is it based on the Trident Rendering Engine?
Yes, the browsing part of eValid is based on use of the MSHTML (Trident Rendering Engine) libraries.
Although this makes eValid a complete browser (which emulates behavior of whatever version of IE you have installed on your machine), there are a few differences in the way eValid interacts with MSHTML. The main difference is that eValid has direct, immediate, "in-memory" access to the browser DOM and this unique capability makes much of what eValid does possible.
That architecture -- incorporating direct DOM access in a free-standing executable -- also is the reason why we can use eValid in server loading work by running multiple (100's or 1,000's of) instances to impose completely realistic load.