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From David Jencks <>
Subject Re: Pulling Geronimo Configuration
Date Wed, 11 Feb 2009 16:11:27 GMT

On Feb 11, 2009, at 7:41 AM, Russell E Glaue wrote:

> David Jencks wrote:
>> On Feb 10, 2009, at 1:52 PM, Russell E Glaue wrote:
>>> David Jencks wrote:
>>>> On Feb 10, 2009, at 8:09 AM, Chance Yeoman wrote:
>>>>> Hello All,
>>>>> I am interested in setting up geronimo installations that can pull
>>>>> installed plugins and their dependencies exclusively from a  
>>>>> repository
>>>>> within a master geronimo server.  I hope to eventually have an
>>>>> automated process allowing cluster members to poll a cluster- 
>>>>> specific
>>>>> geronimo server repository for available, locally uninstalled
>>>>> plugins.  My goal is to be able to more easily manage  
>>>>> geographically
>>>>> separated cluster members and to quickly add or reinitialize  
>>>>> nodes.
>>>>> I've been having trouble getting started as I receive HTTP 401
>>>>> responses when installing remote plugins using the admin  
>>>>> interface,
>>>>> even with security turned off on the maven-repo URL.  I can list  
>>>>> the
>>>>> contents of the remote server's repository, but not install  
>>>>> plugins.
>>>> That's pretty odd.  Can you show the urls being used?  You should  
>>>> be
>>>> able to check that it's working with a browser.
>>>>> My question is:  Is using the GeronimoAsMavenServlet even the  
>>>>> correct
>>>>> approach to pull-based configuration?  How have others implemented
>>>>> configuration pulling?  Any advice would be greatly appreciated.
>>>> If you use a geronimo server as the plugin repo then
>>>> GeronimoAsMavenServlet is the correct approach.  However, if I  
>>>> were you
>>>> I would give significant consideration to using nexus as the plugin
>>>> repo.  I think you will have a much easier time integrating this  
>>>> with a
>>>> reasonable build/qa process.  In particular, if you build the  
>>>> plugins
>>>> using maven with the car-maven-plugin, you can set the distribution
>>>> management repos to be the nexus server and have mvn deploy or mvn
>>>> release make the plugin available to the appropriate production  
>>>> servers.
>>> For satisfying this scenario, how does nexus compare to Archiva, or
>>> Artifactory?
>>> Archiva:
>>> Artifactory:
>> I only have experience with nexus and it's worked great for me.   
>> I'm not
>> thrilled with the license.  I haven't actually looked but have a  
>> strong
>> impression that it has a lot more/better features than the older  
>> managers.
>>>> I hope you are also aware of the plugin-based clustering/farming  
>>>> support
>>>> that may provide the features you need for easy rollout to mutliple
>>>> servers.  If the existing features there don't exactly match your  
>>>> needs
>>>> please work with us to improve this.  For instance IIUC since you
>>>> indicate your cluster members are geographically separate the  
>>>> current
>>>> multicast discovery of cluster members may not work for you...  
>>>> however
>>>> changing this to a hardcoded set of servers should be pretty  
>>>> easy.  Or
>>>> perhaps you want a hybrid approach where a bunch of multicast- 
>>>> connected
>>>> sub-clusters aggregate to a controller.
>>> I think the desire is to pull down the artifacts, initiated from  
>>> the end
>>> geronimo server. So if Geronimo starts up, it can go to the central
>>> Maven repo
>>> and see if it needs to pull down anything for configuration.
>>> The plugin-based farming, from my understanding, does the opposite.
>> Your understanding is incomplete.  With plugin based farming the  
>> actual
>> artifacts are pulled by each cluster member from the repository.
>>> The central
>>> server pushes out the new artifacts to the end web servers. And
>>> perhaps this
>>> introduces a few possibly undesired circumstances:
>>> 1. Centrally pushed out, all servers receive the updates at one  
>>> time, not
>>> staggering the updates. Unless you put the servers into multiple
>>> groups so that
>>> each group can receive updates at different times. But that is more
>>> administration.
>>> 2. If a server is offline when the push-out occurs, it is out of  
>>> date
>>> when it
>>> comes back online. Some kind of re-sync has to happen.
>>> If the end geronimo server does a pull on start-up, then it will
>>> always be in
>>> sync at run time. If we know what triggers the pull, an  
>>> administrator can
>>> program this into a distributed command (like Rio, or RHN Satellite
>>> command) to
>>> tell the server to sync itself.
>> Plugin based farming does pretty much this administration step.  The
>> admin server keeps (in a db) plugins, plugin lists, clusters and
>> plugin-list to plugin and cluster to plugin list associations.  It
>> listens on a multicast address.  When a cluster member starts up it
>> starts a heartbeat ping on that multicast address.  When the admin
>> server recognizes a new cluster member it sends it a list of all the
>> plugins that are supposed to be installed on it.  The cluster member
>> then installs all the missing plugins on the list.
>> If you don't like multicast you have to figure out some other way for
>> the cluster members to find the admin server, such as by telling it.
>> Then when the admin server fails and you have to move it you need a  
>> way
>> to tell all the cluster members to look elsewhere.  I know  
>> multicast is
>> often frowned on but I couldn't think of a plausible alternative that
>> seemed like it would actually work.  If you have any ideas I'd love  
>> to
>> hear them.
> Multicast is a good option to have available.
> But we will probably have 40 Geronimo Installs, with perhaps 120+  
> Geronimo
> instances, and distributed over separated LANS. Another option to  
> multicast
> would be nice.

I agree, but I haven't figured out what it should be yet.  For your  
use would you consider multicast on each LAN with hardcoded  
connections between them?

> Have you considered:
> Rio -
> All application deployed services and Rio itself is managable using  
> JMX, with
> notification support that includes an elegant peer-to-peer event  
> model, allowing
> interested consumers to be notified of application and management  
> specific
> events related to SLA enforcement, application deployment and  
> service availability.
> Sun Jini = Apache River -
> River could use some help to move forward. Perhaps backed by  
> Geronimo it might
> get more interest.

I have nothing against jini or leases but AFAIK the service discovery  
in jini relies either on multicast or on configuring the location of  
some "admin" server, which is basically what we already do.  For our  
purposes I don't see the need to pull in another entire infrastructure  
framework.  If you have more or different information I'd love to know  

david jencks

>> If you don't have any need for dynamic plugin administration but are
>> happy to kill, reinstall, and restart a cluster member whenever the
>> plugins change then you could do something pretty easily with  
>> gshell to
>> start the server and install a list of plugins on it.... you can  
>> script
>> this very easily so you'd only be shipping a script to the cluster  
>> members.
> Actually, the Rio project can do this very nicely, in a distributed  
> fashion.
> You can script it to install more plugins, and execute it remotely/ 
> centrally.
> But we are more interested in a centrally managed system, which we  
> could
> "mirror" out the requirements.
> -RG
>> thanks
>> david jencks
>>> -RG
>>>> thanks
>>>> david jencks
>>>>> Thank you,
>>>>> Chance

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