[Seaside] [ANN] mod_cluster for Seaside

Julian Fitzell jfitzell at gmail.com
Tue Oct 5 23:25:59 UTC 2010

Very cool Philippe. We really need more integration with this kind of


On Tue, Oct 5, 2010 at 4:00 PM, Philippe Marschall
<philippe.marschall at gmail.com> wrote:
> Hi
> Have you ever wished Apache and Seaside would know each other better?
> That Apache could tell Seaside where it was and vice versa? That
> Seaside could tell Apache the load of the image so intelligent load
> balancing decisions can be made? That you can dynamically add and
> remove Seaside images from a cluster without restarting Apache or
> messing with configuration files? The guys at JBoss though the same
> and wrote mod_cluster [1].
> How does this actually work? There are two Apache modules involved.
> mod_advertise sends UDP broadcasts about Apache's location, you might
> have several on different hosts in the network. mod_cluster_manager
> allows remote configuration of Apache. Seaside will connect to the
> advertised Apache instances and tell them where it is (host, port,
> protocol, urls). This is kind of schizophrenic because the backend
> makes a request to the frontend but anyway.
> What do you need to get started? First you need to set up the
> Smalltalk parts (not the Apache config) of mod_proxy_balancer [2]. If
> you're just using a single image mod_cluster is overkill and
> clustering without sticky session doesn't get you very far (unless
> you're on GemStone). Then you need to setup mod_cluster itself, the
> easiest way is to grab the binaries from JBoss [3] and follow the
> installation instructions [4]. And finally you need to load ModCluster
> from [5]. You start the magic with:
> JBPharoAdvertiseListener startOnHost: 'yourIp' jvmRoute: 'yourRoute'
> I should note the code is in the state "barely works on my machine",
> there are likely a ton of bugs left.
> Here's some of the limitations I'm aware of:
>  - does not work on Mac due to UDP network stack problems
>  - host address has to be hardcoded because there's no way of finding
> it out on Pharo on Unix
>  - has never been run under Windows
>  - not yet split into different packages, you always get the tests and
> the Pharo implementation
>  - no Metacello configuration yet
>  - the load is always reported as 100%
>  [1] http://www.jboss.org/mod_cluster
>  [2] http://book.seaside.st/book/advanced/deployment/deployment-apache/mod-proxy-balancer
>  [3] http://www.jboss.org/mod_cluster/downloads/1-1-0.html
>  [4] http://docs.jboss.org/mod_cluster/1.1.0/html/Quick_Start_Guide.html#d0e264
>  [5] http://www.squeaksource.com/ajp
> Cheers
> Philippe
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