Forum OpenACS Q&A: Virtual Hosting with ACS/AOLServer

Posted by Edward Wilson on 03/19/04 04:51 PM

Please forgive me if this is the wrong place to ask this question or if this question has been discussed at length before.

Can Apache style virtual hosting be configured on AOLServer and ACS? Also, I'm not interested in port mapping redirects just pure, clean, virtual hosting as is done with Apache.

The only thing that prevented me from deploying OpenACS two years ago was AOLServer's poor support for Virtual hosting. You guys are _still_ the only ones who seem to get the MySQL/Postgresql debate, and understand that Postgresql is the _superior_ database -- which keeps me coming back for more.

_ed

2: Re: Virtual Hosting with ACS/AOLServer (response to 1)

Posted by C. R. Oldham on 03/19/04 05:27 PM

With AOLserver 4, yes, you can virtual host more in an Apache style. I don't think, however, that anyone has actually run multiple OpenACS instances in this configuration, or even a single OpenACS instance with additional "bare" AOLserver instances. OpenACS loads a *ton* of Tcl into the server. If you have to restart the server (to load new packages for example) in the vhost scenario you will have to down *all* your servers.

However, this is still true with Apache--you can't restart a single virtual host.

Currently (OCT members want to chime in here?) I think the community party line is that each OpenACS instance should run on its own AOLserver. That's not to say you couldn't try it out. ScottG in particular did a lot of work to make sure that nsopenssl would work with virtual hosts (barring the issue that the ssl negotiation occurs before the Host: header is transmitted so it still isn't possible to host multiple https servers on the same IP).

The AOLserver core team may be working on ways to restart individual virtual hosts. It is technically possible, though it might not be feasible.

--cro

3: Re: Virtual Hosting with ACS/AOLServer (response to 2)

Posted by Tom Ayles on 03/19/04 05:47 PM

I think the most recent discussion of this was in this thread.

>OpenACS loads a *ton* of Tcl into the server.

I'm guessing that seem as no-one has knowingly pulled it off, this might be a tough one to answer, but: Does anyone know how the resource consumption of running multiple OpenACS instances in a 'single' AOLServer would compare to running them in seperate AOLServer instances? Or in terms of security? I'm debating whether its worth spending the time to try and get the former configuration working...

TIA,
Tom

4: Re: Virtual Hosting with ACS/AOLServer (response to 1)

Posted by C. R. Oldham on 03/19/04 05:57 PM

And here's another thread that talks a little about resource usage:

https://openacs.org/forums/message-view?message_id=100780

5: Re: Virtual Hosting with ACS/AOLServer (response to 1)

Posted by Don Baccus on 03/19/04 06:04 PM

Well, AOLserver4 gives you quite a few options when you choose to virtually host in regard to how memory and threads are shared between the various sites being run. So you should be able to run a bunch of sites more efficiently using AOLserver4 virtual hosting than with separate instances.

But restart time would be an issue, as mentioned above. You may or may not care ... my personal sites only go down every few months and if it takes a few minutes to restart, so be it. But high-volume commercial sites are a different story (then again, you're probably not going to virtual host busy sites on one box anyway).

The alternative, multiple AOLserver instances with virtual hosting handled upstream, is potentially more expensive in the use of resources by AOLserver but is more flexible.

OpenACS works fine virtual hosted within AOLserver.

6: Re: Virtual Hosting with ACS/AOLServer (response to 1)

Posted by Walter McGinnis on 03/20/04 08:27 AM

I just set up 6 low traffic virtual hosts with each having an OpenACS instance with one IP under AOLServer 4 on FreeBSD 5.1 thanks to Vinod's docs here:

http://www.panoptic.com/wiki/aolserver/98

As people have mentioned each OpenACS instance loads A LOT of tcl, but it works. It takes a significant amount of time to restart. I had to add a swap file (http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/adding-swap-space.html), but otherwise things went fine. For non-heavy development, low traffic sites, it seems ok.