mod_rewrite vs. isapi_rewrite

What are the main differences?

[polythene]

I have lots of experience with isapi_rewrite (IIS), but now I need to learn mod_rewrite. What are the main differences between them?

With isapi_rewrite the biggest challenge has been finding hosting providers that support it and know how to configure it, especially with shared hosting accounts. How does that limited availability compare with mod_rewrite? Do most shared hosting accounts on Apache come with mod_rewrite already configured?

I know the syntax is slightly different, but are there any differences in the regular expression engines? In other words, can I cut and paste my existing regexp patterns that I use with isapi_rewrite and expect them to work the same?

[jdMorgan]

I would guess that mod_rewrite is more widely-available, since unlike ISAPI rewrite, it is a free module. The main exceptions are on free and cheap hosting accounts, where the host won't enable mod_rewrite due to its associated customer-support costs.

I haven't much experience with ISAPI rewrite, so I'll leave the comparisons for others to address.

Jim