PHP4 and clustering

haylo75

Hey folks, I work as a web developer and our shop currently uses ColdFusion for scripting. We have come to find out our Macromedia rep misrepresented Macromedia's level of support for their server clustering environment when using Apache... there is none!

Thus I've been researching PHP and whether PHP4 will operate in a cluster where sessions are tracked as one virtual server. I've read a number of articles on clustering Apache, but I need to know specifically if multiple servers at the PHP level can be 'aware' of each other's sessions.

Any help you can provide is greatly appreciated!

Kerr

Weedpacket

I've never done this myself, so take this with a grain of the condiment of your choice....

I see no reason why it wouldn't work; the only hassle would be if you continue to use the default file-based storage rather than writing handlers to use a DB that all the servers can access - though perhaps you could direct all servers to the same session directory....?

Remembering that session cookies are of course limited to the domain from which they're sent - but I guess all your servers have the same domain name.

dalecosp

Ouch! salesman != consultant

I dunno if I can help on this. If the sessions were written to a common directory (i.e., NFS mount a partition on all servers in the cluster for sessions) && you passed the sessid via the URL in all cases, maybe? Dunno why not; might even work with transparent support, as the SESSID is carried in a cookie on the client. But you can't quote me on this, or take it as a guarantee. I don't run clusters........

Another solution might be to write the session info into the database ... this is often done on large apps. Each server in the cluster would be accessing the same db server(s), right? I guess this might be resource intensive, though.

Sorry it's not authoritative, I'm small fry!! 😃 😃

dalecosp

Gee, what time is it down there, Weed? 😃

Now that I've (we've?) posted, I wonder if file locking would be a problem with a 'shared session files' directory approach...since it's mode 'r', probably not?

Weedpacket

Originally posted by dalecosp
Now that I've (we've?) posted, I wonder if file locking would be a problem with a 'shared session files' directory approach...since it's mode 'r', probably not?

Probably not....??.... um... no need to lock the directory and a given session file would only be in use by whichever (single) server is handling the current request (I think....can I come up with situations where several requests from one client are being handled simultaneously by multiple servers? Maybe I can.)

haylo75

Hey folks, thanks for the ideas. I should have clarified in my original post that my two servers are running Win2K Server. We're going to load balance them in software with another box sitting in front of them. We have one database server and all servers are intranet based (currently nsweb1.xxx.com and nsweb2.xxx.com) on the same domain. When our load balancing box is set up, users will then hit nsweb.xxx.com and be redirected in a weighted round robin.

I'll be the first to say that I know very little about PHP as we have been entrenched in ColdFusion for years now. My boss was just so po'd at the Macromedia people that he wants to do anything he can to get away from them, even though the corporation I work for uses ColdFusion as their small/midrange application scripting standard.

If anyone else has previous experience and/or resources, don't hesitate to chime in!

Thanks,
Kerr

mystrymaster

I have never done thiws myself as the app I have writen have not been big enough to warrant this yet but here is an article I found
session clustered