[imp] High Availability / Load Balancing

[Lee]

The more i think about it, the more worried I get about the SQL 
sessions implementation. Not only does it require an additional 
dependancy for horde (we use ldap for prefs), but it more importantly 
introduces a single point of failure. Ive been giving this some thought 
and I think I have a far more elegant solutions. I'm not an expert on 
horde's APIs, but the following seems like it should work:

Get around the sessions problem:

We use DNS round robins to distribute load equally based on DNS 
sequentially resolving each of the servers in the round-robin. Although 
this continuous round-robin is nice, we could approximate the same 
distribution by choosing a server only once (when you first load 
http://webmail.myorg.com). When a user then hits the target horde 
implementation, horde would rely on the actual server name: 
http://webmail1.myorg.com, http://webmail2.myorg.com, or 
http://webmail3.myorg.com.


Get around the attachments problem:

Theoretically, when a user adds an attachment (uploads it), horde could 
create an array called attachments[1] = "path/to/file/uploaded" (like 
wise for a 2nd, 3rd etc... attachments). When the use then clicks the 
send button, the send funtion(s) try to attach the files that are store 
on the server. If the files are not there, horde just uses its 
attachments array to re-upload the files and attach them.


I'm really not an expert on horde's APIs, but the above seems like it 
should both be easy to implement and provide for 100% load balancing 
capability. If you guys agree, I might start taking a stab at 
implementing it this week.

Sincerely,
Lee


On Sunday, December 15, 2002, at 11:01 AM, Chuck Hagenbuch wrote:

> Quoting Dominic Ijichi <dom@ijichi.org>:
>
>> auto_prepend_file = "/opt/data/htdocs/sessionlib/adodb-session.php"
>
> FYI, you'll probably get better performance using Horde's SQL session
> handler implementation; as it is, you're loading *two* database 
> abstraction
> libraries all the time...
>
> -chuck
>
> --
> Charles Hagenbuch, <chuck@horde.org>
> "People ask me all the time what it will be like living without 
> otters."
>  - Google, thanks to Harpers
>
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