Hi, On Sep 15, 2005, at 8:36 PM, Gonzalo Barrio wrote:
> Pedro, how many concurrent users have in sapo ? couple of thousands. > Are you using this clustering feature ? I'm moving today to cluster: several instances of pyMSNt load-balanced by JID. The source code will be available (probably GPL) sometime this weekend. It works for me now. It was written in-house, aroun 160 lines of perl code, mostly error recovery and startup. The real loadbalancing is around 3 or 4 lines :) > What hard and soft ? > I mean msn1, msn2, msn3 ...... all reponding msn.im.sapo.com.pt, > because > I think that I can add this feature on jabberd2 modifying some things > on > the router and sm component. In this way, we can clusterize all kind of > components (except mu-conference I think again) Ok. I can identify 3 types of balancing you need to cover all the situations I faced. Those are: - stateless: you don't care where the stanza's go, just round-robin, least load, whatever, distribute them; - statefull based on 'from': my packets must go to the same instance, like MSN/AIM/ICQ, etc. Basically, any situation where the component keeps a session for you. - statefull based on 'to': text conferencing. you can have several rooms, and some rooms go to chat1 and others go to chat2. Pubsub jep60 might also applied, not a problem for us just yet. Also, right now, I don't care if the instances are up or down. Our balancer get's a packet, hashes the jid to a integer, modulus number of instances, and forwards (using <route>) the original stanza to the choosen destination. The only difference between those three types of algorithm above is the field that you use to distribute the stanzas. I don't think you need to modify anything on the server. You only need a component that takes ownership of your main domain name (msn.im.sapo.pt) in our case, and start N instances of your component. One think that is required: each component must respond to the main domain name and a secondary name. In some server (like XCP that we use), you can have a linkname (based on the ID) and a host filter. Our balancer needs that. We send the stanzas to the linkname, and the stanzas include the main domain name. Notice that our code does not do any kind of rewriting. There is no need to do it. Also, it's just a normal component with a single TCP connection to the server. It does not connect directly to the other instances. All the traffic is through the server. Also, notice that only the stanzas to the main domain go through the balancer. The replies flow directly from the component instances to the client. If you server does not trust the components and checks all the stanzas received to see if they match the from with the linkname, for example, you will have trouble. Finally, the only requirements on the component that you wish to balance are: - they need to support linkname and hostname: pyMSNt supports that with the <useXCP> tag, that's your linkname; - they need to support <route> stanzas: simple really, just drop the <route></route> and use the XML inside as if it came from the socket. Regarding jabberd2, my suggestion would be that you don't implement this inside the server, but as a external component. Oh, and if you write something like this in C, I will be extremely interested :)... On our roadmap is moving xbalance.pl to C, but only if we need it. > Then only thing I don't want to do is to reinvent the weel..... :-) Same here. I searched the web for something like this and found nothing, so I just coded it. I think that if we can agree on a spec we can build one of these components in C and use it with all the jabber servers that support JEP-0100. That would be cool. My problem with C, btw, is that I don't know which library to use as a base of this component. If you have some ideas about that, I would love to ear them. Thanks, -- HIId: Pedro Melo SMTP: [EMAIL PROTECTED] XMPP: [EMAIL PROTECTED]
