migraing application from Jboss 7.1 AS to Jboss EAP 6
by Ali, Saqib
Will applications developed using Jboss 7.1 AS work on Jboss 6 EAP? What
are some of the things I should look out for?
We have an application that was developed by a 3rd party. Currently the
application is working fine on Jboss 7.1 AS, but we need to move to Jboss
EAP 6. Will it be a clean migration or will it require code changes?
Thanks.
13 years
[EJB3] - How do javax.ejb.Singletons work?
by John Lee
John Lee [https://community.jboss.org/people/jhn134910] created the discussion
"How do javax.ejb.Singletons work?"
To view the discussion, visit: https://community.jboss.org/message/804718#804718
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Are singletons implemented using synchronized methods?
I have an EJB singleton, say:
@Singleton
public void MySingleton {
...
public void receive(final String string) {
x.callMyBlockingMethod(string);
}
}
Consider the scenario, where this is running in JBOSS standalone. This singleton shall be called from multiple threads, with names Thread-1, Thread-2 and Thread-3 in that order. Thread-1 calls the blocking method which doesn't return for 10 seconds. Thread-2 arrives at the receive method shortly after Thread-1, followed shortly by Thread-3 and both wait for the lock to be released by Thread-1. Is there anything in the EJB standard regarding singletons that guarantees that Thread-2 shall aquire the lock before Thread-3 once Thread-1 releases it?
>From my testing with synchronized methods I have verified that synchronized methods provide no such guarantee.
I'm going to test this singleton behaviour but if my test shows that Thread-2 is indeed processed before Thread-3 and order is maintained, it shall not tell me that this is guaranteed behaviour, and is merely a consequence of using a particular OS, JVM or EJB container implementation. So does @Singleton offer any guarantees?
If it does, are there any gotchas about using this behavior to queue up client requests against singleton where they wait to acquire the lock?
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13 years
[jBPM] - Design pattern for routing to multiple jBPM processes?
by Jim B
Jim B [https://community.jboss.org/people/jamesbeam] created the discussion
"Design pattern for routing to multiple jBPM processes?"
To view the discussion, visit: https://community.jboss.org/message/804680#804680
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I am using jBPM 5.4 with persistence. I am still a jBPM noob, so thanks in advance for your patience getting through this explanation...
I have a ksession that will be running multiple long-running processes. These process flows are the same - only the variables in the processes are different.
The basic use case it that I have events coming into a "router" that based upon message content will be passed to an existing process instance (if the related process exists). If a process instance does not yet exist for that event, a new one is created.
I would greatly appreciate any thoughts on design patterns to implement this (managing processes in the kession and routing events to them).
Relating to design, I have considered;
1) Create a single-node process with a "routing" WorkItemHandler node. This instance will receive the event and perform all of the checking/routing/process instantiation logic. Basically, iterate through each process in the kession for the
2) Create business rules that checks for (and creates) objects in the ksession representing each process that is running.
Pseudo code for rules would be something like:
rule "Send to existing process"
when
$newEventBean : NewEventBean()
$myProcessBean : MyProcessBean(subject matches $newEventBean.subject)
then
<signal $myProcessBean.processId with $newEventBean>
rule "Create if process doesn't exist"
when
$newEventBean : NewEventBean()
not($myProcessBean : MyProcessBean(subject matches $newEventBean.subject))
then
$newProcessBean: NewProcessBean();
$newProcessBean.subject = $newEventBean.subject;
$newProcessBean.instantiate(thisKsession); <<---inserts new process instance into ksession
insert($newProcessBean);
(and when a process ends, it would need to retract the related newProcessBean)
I am more familiar with java development than drools rule-jbpm integration, so I am leaning towards option 1. (Specifically, for example, I'm not sure how to create a process from a rule or how to signal one, so I'd more likely to implement methods like NewProcessBean.instantiate() in a java method in my newProcessBean anyway :) )
Any thoughts about option 1 or 2? Am I missing a more obvious/better solution?
(Possibly something like sending a signal to a ksession where the correct process catches it and acknowledges it in some way - so that if an acknowledgement isn't received a new process is created. Can a process be configured to ALWAYS catch a signal AFTER another process, so that my "final" process could act like an "otherwise" statement and would just instantiate a new process?)
Thank you again for any thoughts,
-J
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13 years
