I think this is a major step towards resolving this issue, thanks Jules.
I would like however to start a discussion about whether these
changes should go into 1.0.1. I will freely admit that I thought
that clustering features were crammed into 1.0 at the last minute
without adequate testing and discussion and that the results have
been unsatisfactory and we would be better off without them in 1.0.
I apologize for not objecting at the time.
Here are some factors that I think must be weighed in a decision
about whether to include changes to clustering in 1.0.1 or 1.1:
- when will 1.1 come out. The longer off it is, the more pressure to
get something available sooner.
- the purpose of 1.0.1: essential bugfix or development free for all
- whether the immediate changes proposed for 1.0.1 will change any
interfaces or deployment descriptors used in 1.0
- whether the proposed interfaces for 1.0.1 are expected to be stable
or will change again for 1.1
- if the clustering changes go into 1.0.1, will they actually be
production ready or at least as stable/usable as the rest of 1.0.1
Here is what I think about these factors:
- I want 1.1 to come out fairly soon, in about 3 months after 1.0.
That should mean a feature freeze in perhaps 6 weeks.
- I want 1.0.1 to only fix severe problems in 1.0 and avoid changing
any interfaces/ deployment descriptors
- AFAICT the proposals for clustering involve changing how it is set
up in 1.0, both interfaces and plans.
- Based on the work so far I don't think we will have an acceptable
stable solution for the interfaces and plans for 1.0.1
- I have no idea how stable clustering functionality might be. AFAIK
it has not been tested much if at all yet.
I think that it would be better to work on clustering in head and not
try to hurry to get something that we know will change and has not
been well tested into 1.0.1. I have no experience with actual
clustering. Will people who want to use it expect something well
tested and stable? Will they be willing to work off snapshot builds
to pick up the latest fixes? What would the reaction be to something
that only sort of works in an official release?
thanks
david jencks
On Jan 14, 2006, at 3:46 AM, Jules Gosnell wrote:
OK, Folks - here is how I see it -
Everyone knows that they are right and the other guy is wrong.
Result - DEADLOCK - everyone loses.
Solution - release locks, back off, coordinate, retry.
Releasing locks involves us all making concessions :
I suggest -
Jan, Greg and I conceded that Jeff could have been more involved in
discussion before this change went in.
Jeff concedes that Jan, Greg and I should have been involved in
discussion before he backed the change out.
We all agree to overlook all current technical differences.
We all agree to put aside whatever bad feelings may have arisen
from this incident.
OK - locks released, backing-off complete.
Now, coordination :
WADI side :
I will downgrade the log.info to a log.debug
I will remove the axion dependency.
I will resubmit the change as a patch to Jan and Jeff.
Jetty/Tomcat side :
Jan and Jeff will take this patch, and all relevant input.
If they feel that they need further discussion, they will have it.
They will implement a simple, unified solution to the issue for all
existing cases and get it in to Geronimo 1.0.1
I simply want a speedy, painless resolution so we can continue
forward.
If everyone else is happy with these terms, then here is my '+1'
Jules
Jeff Genender wrote:
Hi Jules.
A few comments. First, you made changes without discussing them
on the
dev lists.
As per the discussions in the past, both Aaron and David Jencks,
as well
as I threw in our .02 on how to integrate the clustering. I would
appreciate you discuss code ideas and changes that have such a
drastic
impact on the Geronimo code base. Here are the issues with your
check in:
1) I explained before for Jetty, and obviously now I need to do it
for
Tomcat, a -1 on Axion as a dependency. There should not be any web
application dependencies injected at the container level. This means
there is a severe architectural issue with WADI when we are injecting
these dependencies into the container.
2) You hard coded in org.codehaus.wadi.tomcat55.TomcatManager as the
distributablesession manager in the TomcatContainer. Hardcoding a
pluggable session engine is very bad, and defeats the pluggability
of a
configuration that we requested.
3) You placed log.info() in the code, and Aaron worked pretty hard to
clean those up.
4) Your integration of setting the manager (no matter what) is a
direct
clash with the
Jules, I am giving a complete -1 of checkin of 368344. These are all
for technical reasons. Please back out these changes, and bring this
discussion to the Geronimo lists as this needs some significant
discussion for implementation. I would appreciate that you please
involve the Apache way and open discussions on the lists before doing
this sort of thing in the future.
Again, I will CC the G lists to make this clear, that I would like
this
change backed out.
Jeff
Jules Gosnell wrote:
Here is a list of outstanding issues associated with this work:
- ActiveMQ's shutdown hook seems to trigger when Geronimo is
shutdown,
removing AMQ before WADI - WADI doesn't like this. I have added a
property to the node.sh script which suppresses this behaviour. I
will
document it in the Getting Started doc.
- There 'may' be issues with nodes finding each other, when a
Geronimo
node is introduced into a WADI cluster - investigating.
- Jeff - you should look over the changes and make sure that they
do not
impact on any other TC fn-ality. They were done with Emacs, so the
formatting may be offensive. Please feel free to make them your
own and
bring any issues back to the list. The WADIGBean, is no longer
used, so
you may want to remove this from the repo.
- Jan and Jeff - since this config is now done on the container
bean and
not in the geronimo-web.xml, you may no longer need to implement
your
own geronimo-web.xml schemas (I haven't looked very closely at
TC). You
may want to consider this and perhaps lose them.
- In order to get the same webapp to work in all containers
(tomcat5[05], jetty[56], geronimo-[tomcat/jetty], jboss-tomcat),
I had
to move deps back to Geronimo container-level. These include Axion,
which I know will upset Jeff. As I have stated before, WADI's
dependence
on Axion is easily removed. If Jeff or anyone wants to look at
replacing
it with Derby, it is fine with me, as long as they do some
testing and
confirm that having created a session on a single node and
restarted it,
the session survives (if the DB is still running). This needs to be
tested on all supported containers. Axion was used because it is an
in-VM DB (so imposes no further integration dependencies on the
Getting
Started stuff and is useful for unit-testing) and was in use by
Geronimo
at the time. So I suggest that any replacement needs to also be
able to
run in-vm aswell. As we go further and move WADI's actual
configuration
from the app to the container-level, these issues will disappear and
WADI will be able to be hooked to whatever persistance mechanism is
shipped in Geronimo by default.
- Jan & Jeff , you may want to consider pushing some of this session
manager selection code up into a shared GeronimoWebContainer
abstraction
so that you don't both end up maintaining similar but diverging
code...
- I may have overlooked a couple of issues. If I come across them, I
shall post them.
Further work on Geronimo integration :
- more testing
- make a new WADI release and update geronimo-trunk to use it
- look at applying diffs to a G1.0 tree and producing a binary
patch for
1.0 distros.
- update website and release it
Jules
Jules Gosnell wrote:
Guys,
Jan and I have just refactored the Geronimo Jetty and Tomcat
integrations to take the same approach to the installation of a 3rd
party session manager, to ease the integration of WADI. This is now
checked in on Geronimo's trunk.
Each top level web container GBean now supports a pair of
attributes -
LocalSessionManager and DistributableSessionManager. These may
be used
to override the container's choice of SessionManager for webapps
with
and without the <distributable/> tag present in the WEB-INF/
web.xml,
respectively.
The attributes expect to be given a classname, if required, this
class
will be loaded and instantiated. The resulting instance will be
used
as the session manager. If not provided, the container will use a
sensible default. Currently Jetty and TC are set up to use their
own
default session managers in the local case and the correct WADI
session manager in the distributable case.
This means that the same WADI-enabled webapp, with its plan held
internally (WEB-INF/geronimo-web.xml) may now be hot-deployed on
either a Jetty or a Tomcat based Geronimo, without changes :-)
I will post specific WADI issues to the WADI dev lists
([email protected], [EMAIL PROTECTED]).
This shouldn't be seen as a final position on the subject -
there is
still much to talk about, but is a useful interim step, that
allows us
to have something working whilst we figure out how to go forward.
Enjoy,
Jules
--
"Open Source is a self-assembling organism. You dangle a piece of
string into a super-saturated solution and a whole operating-system
crystallises out around it."
/**********************************
* Jules Gosnell
* Partner
* Core Developers Network (Europe)
*
* www.coredevelopers.net
*
* Open Source Training & Support.
**********************************/
