Startup Classes and JMS - Suggestions Please!

Question

I'm in serious need of having several resources initialized before beans
start handling requests.
I tried implementing a Weblogic Startup Class, and it works fine - as long
as it's the first thing
to run! -- the problem is, when my Message Driven Beans deploy, if there are
messages waiting
for them in their durable subscriptions, they immediately start
processing... then about 30 seconds
later Weblogic (6.0sp1) gets around to starting my startup class. If I put
code in each MDB that
kicks off the initialization when they are invoked I still run into
problems, because my initialization
takes a LONG time (more than 2 minutes) - so I end up with lots of
transaction rollbacks... which
are very annoying and clutter up the log files, and scare customers of the
product.
Is there anyway to make a startup class/servlet/something that runs and
completes before any
other processing occurs?
Thanks,
James

Answer 1

Yes, Startup servlet has the same problem - it doesn't 'startup' until after
jms messages are already being delivered. :( aside from this, there are
class loader issues -servlet space and ejb space are not the same...
Thanks though,
James
"minjiang" <[email protected]> wrote in message
news:[email protected]...
Hi, did you ever try startup servlet? not startup class?
mj
James House wrote:
The only problem with creating a base class to extend is the fact that
Java only supports single inheritance, -- and I'm already inheriting...
>>
I've been involved with many projects that use WLServer, and in
almost every one of them, there has been a need for a startup class
that fires before the server starts handling requests.... strange that
I'd be the only one to need this, when the need has recurred so often.
James
"Raja Mukherjee" <[email protected]> wrote in message
news:[email protected]...
James,
If you have common initialization tasks to be shared by multiple MDBs,
I
would create an abstract class (a.k.a BeanAdapter class) where you canhave
all your initialization logics and have your MDB extend from it.
I am not convinced that the Startup class needs to run first. In fact,
I
have the same view that Startup class should run last. My only wishlist
for
startup class was that I should be able to specify order, which isaddressed
in 6.1.
I am also getting the feeling from different posts that MDB deploymentwould
have a re-try logic in 6.1, which I am beginning to look into. Check
(or
post) in JMS news group.
.raja
"James House" <[email protected]> wrote in message
news:[email protected]...
Thanks for the help... I like the pattern you pointed me to better
than
anything else... ... but in all cases (your method, Gene's, and whatI'm
currently doing) I still have to put some code in every MDB that
I deploy... : (
Put in a good word for me there at BEA and convince the appropriate
developer that startup classes should run first!
James
"Raja Mukherjee" <[email protected]> wrote in message
news:[email protected]...
James,
There are several ways to solve your problem. I normally use
setMessageDrivenContext to do all my initialization. There are two
types
of
initialization that I have performed here, first, reading theconfiguration
file and then load some utility classes in specific order. The
problem
with
the second was that you will have to use synchronized block
w/HotSpot
2.0
to
keep the order, which is ok. I don't use static block to do the
initialization, instead use an init() metod. Hopefully you got the
idea.
Recently, Gene Chuang created a pattern which esentially does the
same
and
I
liked the pattern because it was a nicer way of doing what I
needed to
do.
I
have changed all my examples to customer to use the new pattern.
You
can
find it in
http://theserverside.com/patterns/thread.jsp?thread_id=7270.
The
only think I do not use of this pattern is
initializeEveryContextSwap()
method. I am not convinced yet that I would need it (of course
that
might
change over the time).
Hope this helps, and thanks Gene.
.raja
"James House" <[email protected]> wrote in message
news:[email protected]...
Ok... here's some more detail:
The application is largely JMS based, and most of my Session
EJBs
are
invoked only my Message Driven Beans.
I have a large set of properties that need to be read from a
config
file,
and stored somewhere "globally". I also have a number of
utilities
that
need to get "warmed up" before I start doing any real processing(before
I start receiving messages from the JMS Topics). These
utilities
take
a
long time to warm up (a long time being about 45-60 seconds) -
because
they are loading hundereds of classes, and creating variousconnections
to external resources.
Currently I'm creating a Singleton object that reads the
configuration
file
name from an environment property, and it then parses the file,
and
starts
configuring all of these utilities. Since the "Startup Class"
didn't
work
(weblogic invokes it after I'm already receiving messages), I
put
code
at
the beginning of all of my MDB's onMessage() methods that calls
the
singleton's "getInstance()" method - which synchronizes on alock
object,
and does all of it's work.
I don't like this solution because:
1- I have to put code in EVERY message-driven bean that I
create -
if
I
forget one, everything is broken.
2- I have to increase the transaction time out of the entire
server
to
be over 60 seconds since the beans hang that long while theconfiguration
is
happening.
It seems very obvious that a "Startup Class" should be invoked
after
the
server has come completely up, but before it starts listening
for
requests -- isn't the whole point of a "startup class" to getthings
ready
that need to be done as soon as the server comes up? but alas,
the
person
who designed this at BEA apparently didn't agree with me on this
point!
Any suggestion on better solutions would be greatly appreciated.
James
"Raja Mukherjee" <[email protected]> wrote in message
news:[email protected]...
You can do it this way, but I would not recommend it, unless
that's
the
only
way to attack the problem at hand. But that's just me.
I have seen this problem with multiple clients and in most
cases
there
is
a
better way to handle it. If James give us a little more
information
on
what
type of configuration is he talking about and some background
of
his
application, we as a group can think and may be able to come
up
with
some
idea.
.raja
"Joel Nylund" <[email protected]> wrote in message
news:[email protected]...
you could wrap the starting of weblogic in your own class
and do
initialization
there. You have to be careful because of the way weblogic
classloaders
work, but
you may be able to do what you want. Weblogic is just a java
class,
so
you
can
start your class, then once your done initializing, just
call
weblogic.Server.main
-Joel
James House wrote:
I'm in serious need of having several resources
initialized
before
beans
start handling requests.
I tried implementing a Weblogic Startup Class, and it
works
fine -
as
long
as it's the first thing
to run! -- the problem is, when my Message Driven Beans
deploy,
if
there
are
messages waiting
for them in their durable subscriptions, they immediately
start
processing... then about 30 seconds
later Weblogic (6.0sp1) gets around to starting my startupclass.
If
I
put
code in each MDB that
kicks off the initialization when they are invoked I still
run
into
problems, because my initialization
takes a LONG time (more than 2 minutes) - so I end up with
lots
of
transaction rollbacks... which
are very annoying and clutter up the log files, and scarecustomers
of
the
product.
Is there anyway to make a startup class/servlet/something
that
runs
and
completes before any
other processing occurs?
Thanks,
James