May 2010 - jboss-user - Jboss List Archives

[EJB 3.0] - EJB3.1 Singleton Beans in AS 6.0.0 M3

by jaikiran pai

jaikiran pai [http://community.jboss.org/people/jaikiran] modified the document: "EJB3.1 Singleton Beans in AS 6.0.0 M3" To view the document, visit: http://community.jboss.org/docs/DOC-15105 -------------------------------------------------------------- h5. Overview JBoss AS 6.0.0.M3 which was released on May 5th 2010, introduces support for EJB3.1 Singleton beans. h5. What to download and how to use You can download JBoss AS 6.0.0.M3 from http://www.jboss.org/jbossas/downloads.html here. After downloading the AS, start and stop it once to make sure it boots without any issues. The next step would be to deploy a EJB3.1 Singleton bean into this server. h5. EJB3.1 Singleton bean: Note that the examples shown below are just for the sake of illustrating the usage of singleton beans and as such don't hold much meaning. Let's deploy a very simple singleton bean which exposes a remote view: package org.jboss.ejb3.singleton.example; public interface Counter { void incrementCount(); void decrementCount(); int getCount(); } package org.jboss.ejb3.singleton.example; import javax.ejb.EJB; import javax.ejb.Remote; import javax.ejb.Singleton; import org.jboss.ejb3.annotation.RemoteBinding; @Singleton @Remote(Counter.class) @RemoteBinding (jndiBinding = "SimpleCounterRemoteJNDIName") public class SimpleCounter implements Counter { // we use a calculator to increment/decrement the count @EJB private Calculator calculator; // Maintains the current count private int count; @Override public int getCount() { return this.count; } @Override public void incrementCount() { this.count = this.calculator.add(this.count, 1); } @Override public void decrementCount() { this.count = this.calculator.subtract(this.count, 1); } } package org.jboss.ejb3.singleton.example; import javax.ejb.Singleton; @Singleton public class Calculator { public int add(int a, int b) { return a + b; } public int subtract(int a, int b) { return a - b; } } So in the example above, we have a Counter interface which is exposed as the remote view for the SimpleCounter Singleton bean. Notice that the SimpleCounter class is marked with @Singleton annotation: @Singleton @Remote(Counter.class) @RemoteBinding (jndiBinding = "SimpleCounterRemoteJNDIName") public class SimpleCounter implements Counter { ... The SimpleCounter internally uses a Calculator to do the increment and decrement operations. As you can see, the Calculator is being injected into the SimpleCounter by using a @EJB annotation: // we use a calculator to increment/decrement the count @EJB private Calculator calculator; If you look at the Calculator class, you will notice that it is a singleton bean with a no-interface view: @Singleton public class Calculator { ... So effectively, in this example, we have 2 singleton beans. One is exposing a remote view and the other is exposing a no-interface view. Now package all these classes into a .jar and deploy it to the server which you downloaded earlier. That's it! You now have the beans deployed on the server. The next step is to write a simple client which access the Counter to perform the operations. In this example, let's use a standalone java class which through its main() method, looks up the remote view of the SimpleCounter and invokes the operations. Here's the client: package org.jboss.ejb3.singleton.example.client; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import org.jboss.ejb3.singleton.example.Counter; public class Client { public static void main(String args[]) throws Exception { Context ctx = new InitialContext(); // lookup the counter bean Counter counter = (Counter) ctx.lookup("SimpleCounterRemoteJNDIName"); System.out.println("Initial count is " + counter.getCount()); // let's increment once counter.incrementCount(); System.out.println("Count after increment is " + counter.getCount()); // now let's just look up the counter once more // and see whether the incremented state is still maintained (it should be!) Counter oneMoreCounter = (Counter) ctx.lookup("SimpleCounterRemoteJNDIName"); // should be 1 System.out.println("Count from another counter is " + oneMoreCounter.getCount()); // now let's decrement oneMoreCounter.decrementCount(); // should be 0 System.out.println("Count after decrementing is " + counter.getCount()); } } In the client code, we first lookup the SimpleCounter singleton bean and try out a couple of operations through it. We then again lookup the same singleton bean and try out some more operations on it. Remember that since it's a singleton bean, all these operations will finally end up being called on the same singleton bean instance. So effectively, you will have a single state irrespective of the proxy instance on which you are invoking the operations. h5. What should I try next? The above example was just to get you started with EJB3.1 Singleton beans. Try out the singleton beans within your own applications and let us know if you run into any issues. Feel free to start a discussion about any issues around this, in our http://community.jboss.org/community/ejb3 EJB3 user forum or ping us on http://www.jboss.org/ejb3/chat.html IRC. The more issues you find now, the better - because we can get some of them fixed before AS 6.0.0.M3 is released. h5. I have some tutorial for singleton beans, Can I contribute? Similar to our other EJB3 tutorials, we are going to include a tutorial for singleton beans. Infact, the example that is posted here in the wiki, can perhaps be just added as a tutorial in SVN. If anyone of you wants to contribute a different tutorial and a chapter in our guide, then feel free to let us know - either through the forums or IRC. h5. Known issues: Currently there are a couple of known-issues in the singleton bean implementation: 1) PostConstruct/PreDestroy are not invoked in a transactional context https://jira.jboss.org/jira/browse/EJBTHREE-2070 EJBTHREE-2070 2) The @DependsOn for a Singleton bean is not yet implemented -------------------------------------------------------------- Comment by going to Community [http://community.jboss.org/docs/DOC-15105] Create a new document in EJB 3.0 at Community [http://community.jboss.org/choose-container!input.jspa?contentType=102&co...]

15 years, 11 months

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Re: [jboss-user] [jBPM] - jBPM- Transaction isolation level

by Maurice de Chateau

Maurice de Chateau [http://community.jboss.org/people/MohReece] replied to the discussion "jBPM- Transaction isolation level" To view the discussion, visit: http://community.jboss.org/message/541577#541577 -------------------------------------------------------------- Hi Alexander, You're not mentioning which version of jBPM you're using, but in the user guide for version 3.2.x ( http://docs.jboss.com/jbpm/v3.2/userguide/html/persistence.html#isolation... http://docs.jboss.com/jbpm/v3.2/userguide/html/persistence.html#isolation...) you can read the following: "+Make sure that the database isolation level that you configure for your JDBC connection is at least READ_COMMITTED.+ +Almost all features run OK even with READ_UNCOMMITTED (isolation level 0 and the only isolation level supported by HSQLDB). But race conditions might occur in the job executor and with synchronizing multiple tokens.+" So that's quite clear in itself. But if you want a little more background, you can read this JIRA issue ( *https://jira.jboss.org/jira/browse/JBPM-983 JBPM-983*), in which Tom Baeyens explains about the underlying reasoning for this persistence aspect. Regards, Maurice -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541577#541577] Start a new discussion in jBPM at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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Re: [jboss-user] [Beginner's Corner] - Deployment Exception

by Wolfgang Knauf

Wolfgang Knauf [http://community.jboss.org/people/WolfgangKnauf] replied to the discussion "Deployment Exception" To view the discussion, visit: http://community.jboss.org/message/541579#541579 -------------------------------------------------------------- Hi, your app seems to miss a JAR file: > 19:20:41,299 ERROR [[/dnbtools]] Exception starting filter ResponseOverrideFilterjava.lang.ClassNotFoundException: org.displaytag.filter.ResponseOverrideFilter Best regards Wolfgang -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541579#541579] Start a new discussion in Beginner's Corner at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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Re: [jboss-user] [Beginner's Corner] - Deployment Exception

by Peter Johnson

Peter Johnson [http://community.jboss.org/people/peterj] replied to the discussion "Deployment Exception" To view the discussion, visit: http://community.jboss.org/message/541542#541542 -------------------------------------------------------------- The text you appended is cut off, and thus the root cause is not there. You need to either increase the command line buffer size (mine is at 9000 lines) si that you can see the full first excpetion, or grab the first exception related to your app in the server.log file and post that. -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541542#541542] Start a new discussion in Beginner's Corner at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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Re: [jboss-user] [jBPM] - Why does my Fork end 3 times instead of 2 (in jBPM 4.3)?

by Johan DykstrÃ¶m

Johan DykstrÃ¶m [http://community.jboss.org/people/jody4711] replied to the discussion "Why does my Fork end 3 times instead of 2 (in jBPM 4.3)?" To view the discussion, visit: http://community.jboss.org/message/541538#541538 -------------------------------------------------------------- Hi, Now, I have tried my process with jBPM 4.4-SNAPSHOT, and it did work. But the company I work for will not go to production with a snap shot release. When will version 4.4 be released? I know the question has been asked before, but is there an estimate? Regards, Johan -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541538#541538] Start a new discussion in jBPM at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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[jBPM] - Access Spring Beans from jBPM installed as JBossAS service

by Alexey Kakunin

Alexey Kakunin [http://community.jboss.org/people/akakunin] created the discussion "Access Spring Beans from jBPM installed as JBossAS service" To view the discussion, visit: http://community.jboss.org/message/541532#541532 -------------------------------------------------------------- Hi! I have web-application, build with using Spring and used jBPM 4.3 In process definitions I'm activelly using Spring beans for different handlers - hopefully jBPM 4.x has very good integration with Spring. Now, by some reasons, I want to move jBPM engine into service in JBossAS 5.1 (jBPM allowed to do it), get process engine from JNDI and use it from my application. Question is - in this case - are there any way to access from process definition, deployed into jBPM process engine, installed as separate service spring beans defined in my web-application? Has anybody expereince to setup such configuration? -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541532#541532] Start a new discussion in jBPM at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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[JBoss Microcontainer Development POJO Server] - Implementing a non-flat deployment for Weld Integration

by Flavia Rainone

Flavia Rainone [http://community.jboss.org/people/flavia.rainone%40jboss.com] created the discussion "Implementing a non-flat deployment for Weld Integration" To view the discussion, visit: http://community.jboss.org/message/541531#541531 -------------------------------------------------------------- This thread is for https://jira.jboss.org/jira/browse/WELDINT-1 WELDINT-1. Taking a look at how the deployers are implemented today, I figured I should start by creating a non-flat version of WeldDiscoveryEnvironment first, so we could have a new environment input fot the new non-flat Deployment implementation. There a few assumptions I'm making right now that I would like to validate: - the deployment continues to exist per top level only, the only difference we are going to have is in the BeanDeploymentArchives (BDAs) - if Deployment.loadBeanDeploymentArchive requests for a non-existing BDA, I should search for all archives in the deployment that are not currently BDAs. If one archive containing the requested class is found, I create a BDA for it and return it. If the assumptions above are correct, the main question I have right now regards two different deployments that can see each other. So, in the scenario described by the Deployment interface javadoc example, whereas we have ejb-jar A and ear B. This is going to be translated in two different deployments, each one containg one or more BDAs (in the case of the ejb-jar, one BDA only). Since those BDAs can see each other, there must be a way for me to reach Deployment A BDAs from Deployment B BDAs. Is there some SPI in the current implementation of weld integration that supports that? -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541531#541531] Start a new discussion in JBoss Microcontainer Development POJO Server at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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[Datasource Configuration] - Multiple datasources different IP's Dynamic selection of each

by Ken Barnes

Ken Barnes [http://community.jboss.org/people/kenbarnesjr] created the discussion "Multiple datasources different IP's Dynamic selection of each" To view the discussion, visit: http://community.jboss.org/message/541523#541523 -------------------------------------------------------------- I have one jboss server that runs on a box with 30+ instances of sybase one the same box with each instance of sybase having a different ip. I have some web services that clients connect to wanting interaction with any one of the databases. I can get the Ip address of each that are calling but I need a way to specify the datasource via JNDI that each should use. Is there any way that I can have one datasource defined in Sybase-ds.xml and then in a module or some mechanism dynamically select the datasource according to IP and have the web service that utilzes the datasoure have the right one. Would i need 30 ds.xml files each creating a jndi datasource ? Thanks for the help -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541523#541523] Start a new discussion in Datasource Configuration at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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[Beginner's Corner] - Deployment Exception

by ashmitha viswam

ashmitha viswam [http://community.jboss.org/people/Ashmitha] created the discussion "Deployment Exception" To view the discussion, visit: http://community.jboss.org/message/541520#541520 -------------------------------------------------------------- The following error occurs when i try to deploy my project.. Any help would be greatly appreciated Thanks Ashmitha . -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541520#541520] Start a new discussion in Beginner's Corner at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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[JBoss Cache] - pom.xml points to missing version 1.6

by Bill Middleton

Bill Middleton [http://community.jboss.org/people/wjm] created the discussion "pom.xml points to missing version 1.6" To view the discussion, visit: http://community.jboss.org/message/541507#541507 -------------------------------------------------------------- Both HEAD and the 3.2.4 GA tag have a pom.xml with version == 1.6 which doesnt seem to exist (anymore) in the repository. Just FYI -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541507#541507] Start a new discussion in JBoss Cache at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&cont...]

15 years, 11 months

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jboss-user May 2010