>>Here's a quote from a book. "ISAPI applications can be executed by IIS in a fashion similar to CGI, but they run in the same memory space as the Web server. In fact, ISAPI applications are constructed as dynamic-link libraries that can run as much as 20 times faster than equivalent CGI applications."
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>>Can someone please elaborate on the Same memory space and why that would improve performance? Also explain how ISAPI applications are constructed as dll's and how this would also improve performance.
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>>I know. I know. I'm just trying to get a handle on this stuff.
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>>Dan
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>I'm just getting into this myself, but I *think* I have it right.
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>CGI is an EXE than will allocate it's own memory. This means that if it crashes, it doesn't affect anything else. It must also be loaded for each call to it, so if 50 people hit your web site, it will be loaded 50 times. The cross-application calls (this is called marshalling) from the web server to CGI are expensive (meaning they take time and resources)
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>ISAPI runs as a DLL, and uses the same memory space as the web server. This means that if the DLL crashes, your web server can go down too. However, because it is in the same memory space, the marshalling of data from the web server to ISAPI is very fast. Also, the DLL is only loaded once, so you don't have the problems of 50 instances as above.
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>I guess to sum this up, it's kinda like the difference between in-process and out-of-process COM servers.

That's very helpful. Thank you.

Dan