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From Jan Bartel <j...@mortbay.com>
Subject Re: WADI integration
Date Mon, 12 Dec 2005 22:14:07 GMT
Dave,

I'll quickly address a couple of your points re WADI in Geronimo
and leave Jules/Jeff to respond to the rest.


> Will WADI ongoing enhancements be easily integrated into an existing
> Geronimo v1 installation on a user machine or is a geronimo rebuild
> required?
That's a little difficult to answer. The level of integration at the
moment means that Geronimo directly depends on only a single WADI
class, reducing the possibility of a full rebuild, and making it very
likely that enhancements will be a drop-in replacement set of WADI
jars. Of course, that may change down the road a bit.


> Looking forward to seeing the "Getting Started" document.  Any hints
> currently available on how to setup WADI within geronimo?

How to set up WADI with Jetty as the container:

<web-app xmlns="http://geronimo.apache.org/xml/ns/j2ee/web/jetty-1.0"
    configId="wadi">

    <context-root>/wadi</context-root>
    <context-priority-classloader>false</context-priority-classloader>
    <session-manager>org.codehaus.wadi.jetty5.JettyManager</session-manager>
</web-app>


How to set up WADI with Tomcat as the container:

<web-app xmlns="http://geronimo.apache.org/xml/ns/j2ee/web/tomcat-1.0"
    configId="myapp">

    <context-root>/myapp</context-root>
    <context-priority-classloader>false</context-priority-classloader>
    <manager>WADI</manager>


    <gbean name="WADI"
           class="org.apache.geronimo.tomcat.cluster.WADIGBean"/>
</web-app>

Other than that, you need to have some wadi descriptors in your
WEB-INF and a couple of jars in WEB-INF/lib depending on which
features of wadi you are using (for example, you may need the
axion jar in WEB-INF/lib). We are working on more doco, but 
for now, here's a link to the "Getting Started" doco on the 
WADI site:
http://wadi.codehaus.org/getting-started/index.html

Jeff and I have begun discussing how to move the WADI setup from
container-specific configuration into the generic Geronimo web
schema, so stay tuned for developments in Geronimo 1.1.

cheers
Jan

Dave Colasurdo wrote:
> Jeff/Jules,
> 
> Thanks for the update..
> 
> I'm wondering what the best bet is for Web-Tier clustering for Geronimo
> v1 users.  Jeff had introduced some GBean changes awhile back to
> temporarily enable Tomcat clustering independent of WADI.  Now that a
> portion of WADI has been introduced into Geronimo v1, I'm wondering
> which option is best for v1 users.  Clearly, WADI is the better
> long-term solution, just wondering if it will provide comparable
> capability to straight Geronimo tomcat clustering in the G v1 timeframe.
> 
> Of course, more questions...
> 
> Will WADI ongoing enhancements be easily integrated into an existing
> Geronimo v1 installation on a user machine or is a geronimo rebuild
> required?
> 
> Looking forward to seeing the "Getting Started" document.  Any hints
> currently available on how to setup WADI within geronimo?
> 
> What is the current best bet for httpsession replication (for failover)
> of 3-4 cluster members?  Is the database performance worse than the
> 1->all memory replication?
> 
> Does/will WADI allow for cluster members to exist on multiple subnets?
> 
> Thanks
> -Dave-
> 
> 
> Jules Gosnell wrote:
> 
>> Jeff Genender wrote:
>>
>>> Dave,
>>>
>>> Thanks for noticing ;-)
>>>
>>> Dave Colasurdo wrote:
>>>
>>>> I see that WADI has recently been integrated into Geronimo.
>>>> Great Job!!!
>>>>
>>>> Can someone please provide a quick high level description of what
>>>> is/isn't available from WADI in Geronimo v1?
>>>>
>>>> Tomcat clustering
>>>
>>>
>>>
>>>
>>> Yes
>>>
>>>> Jetty clustering
>>>
>>>
>>>
>>>
>>> Yes
>>>
>>>> Load Balancing
>>>
>>>
>>>
>>>
>>> Yes through AJP
>>>
>>> I will let Jules go into the rest when he wakes up and give a proper
>>> response.
>>
>>
>>
>>
>> Thanks, Jeff,
>>
>> Load-balancing :
>>
>> We don't ship our own load-balancer. WADI's philosophy is that the
>> load-balancer is part of the deployment environment into which it must
>> fit. WADI will work with any load-balancer. It is likely that
>> companies will have spent thousands of dollars on state of the art
>> hardware and will not want to be constrained into running a free java
>> load-balancer on a linux box, just so that they can run WADI. Many
>> open source load-balancers are available, if you are not in this
>> situation. Apache HTTPD/Mod_JK is  common solution.
>>
>>>
>>>> HttpSession failover
>>>
>>>
>>>
>> This is implemented by maintaining and frequently refreshing redundant
>> off-node copies of session data.
>>
>> We have a preliminary impl in place, but it is only hooked up to a DB
>> backend - full in-vm replication is the goal - a cuple of months away,
>> hopefully.
>>
>>>> -file based
>>>
>>>
>>>
>> We have a file-system based persistant store - this could be extended
>> for replication.
>>
>>>> -database
>>>
>>>
>>>
>> We have a store, tested on mysql, that can be used for long-term
>> persistance, paging and replication - slow.
>>
>>>> -mem to mem (one to all)
>>>
>>>
>>>
>> You will be able to do one to all - but it is not the intended default
>> - it doesn't scale further than a few nodes.
>>
>>>> -mem to mem (one to one/several)
>>>
>>>
>>>
>> This is the current plan. I expect most sites to maintain one or two
>> redundant copies. This should increase session availability
>> sufficiently for most deployments.
>>
>>>> -distributed cache
>>>
>>>
>>>
>> specifically for sessions - running, but not yet production-ready. The
>> Getting Started guide on the website, will, when it is published (over
>> the next few days) walk you through examples.
>>
>> generalised, for use with application space POJOs - via a JCache API -
>> on the roadmap, but NYI.
>>
>>>> Sticky Session
>>>
>>>
>>>
>> Depends on the load-balancer. We have an integration for mod_jk. More
>> integrations (just a pluggable class) will be written as and when the
>> need arises. They will generally just manipulate cookies or the
>> session id. Many load-balancers that are simply associating cookies
>> with nodes internally, will not need any form of integration, they
>> will just work .
>>
>>>> Cluster membership (manual, auto-discovery)
>>>
>>>
>>>
>> Auto-discovery - we sit on top of activecluster which provides
>> services such as the cluster abstraction, membership change
>> notification and death detection. On top of this WADI provides a
>> self-partitioning, self-healing substrate, the basis of a distributed
>> hash table in which sessions are and later POJOs will be stored.
>>
>>>> Centralized/independent mgmt
>>>
>>>
>>>
>> Currently independant, I guess - via JMX, with which WADI components
>> may be registered as they are built by Spring, via their JMX Exporter.
>> We have opened various channels to talk about centralised management,
>> but have no concrete design as yet.
>>
>>>> Deployment (independent, centralized, farming)
>>>
>>>
>>>
>> In my peripheral vision, not currently a core part of WADI, although
>> definitely required for Geronimo clustering. This is part of some
>> wider discussions which need to be held soon. Exactly how WADI core or
>> extended technology may be fitted into this remains to be decided.
>>
>>>> Anything above Web Tier clustering?
>>>
>>>
>>>
>> Yes. We have started our OpenEJB SFSB integration. SFSBs, in
>> clustering terms, behave very similarly to HttpSessions. Gianny Damour
>> is working on this. It won't be in Geronimo-1.0, but we hope that it
>> is not too far away. We are also looking at application-server level
>> abstractions, such as User and Application level sessions, which will
>> allow Geronimo to maintain the colocation of all resources related to
>> a user or a user/application interaction. The POJO stuff discussed
>> above will give us application space capability. Then we are left with
>> things like farmed deployment etc, that you have also mentioned.
>>
>>>>
>>>> Thanks
>>>> -Dave-
>>>
>>>
>>>
>> Hope that helps, Dave.
>>
>> If you are at ApacheCon, I shall be around from monday til thursday -
>> drop me a mail and we can hook up.
>>
>> Jules
>>
>>
> 


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