Ok so the question is, "Can I use in Apache SSI files located on another local server?"
The example is quite simple. Lets say I have an index.shtml on first server and inner.shtml on the second one.
Will this work?
If not, what can work?
Ok, so the answere to this is NO I cannot do it, but there is a way to bypass it.
If I include the call to SSI and using Mod_Proxy I can channel it to a diferent Apache. Like this:
<Location /external>
RequestHeader unset Accept-Encoding
ProxyPass http://SERVER2/api/search-software
</Location>
The apache will work on it, but remember that you have to unset the encoding in order for the GZIP not to work on it.