sorry it was meant to be a private msg... Emerson Cargnin - SICREDI Serviços wrote:
i have been looking at your servicelcoator imp and i have some questions :
1 - does it always create a new initial context for every new home?
2 - why doesn't putting the logic in lazy loading of homes after the null testing for a given home?
Greg Turner wrote:
All
I have been working on this problem. I would like to know what you think of my solution.
First of all, you can cache EJBHome objects, but not EntityBean or SessionBean objects. There are many Locator patterns on the web such as this one:
http://java.sun.com/blueprints/corej2eepatterns/Patterns/ServiceLocator.html
There is one problem with them. That is, if the EJBHome object goes stale for whatever reason, say its server goes down, then it does not work, and you have to re-get the InitialContext and then re-get the home object from the InitialContext after the EJBHome's server comes back up. I have come up with what I think might be a solution. Here are 3 attached java source files. The EjbHomeLocator does the caching of the EJBHome objects. But for a FooBean and FooHome, the FooHomeService takes care of the stale EJBHome problem. My intention is that a XDoclet task could be written that would generate the FooHomeService.java source so that would not have to be written for each bean.
What do you think?
Emerson Cargnin - SICREDI Serviços wrote:
I have some questions regarding to caching homes and session beans in the remote client :
1- I already cache initicalcontext and homes in businness delegate, is it secure to cache the real session object as a static attribute in business delegate and reuse it across a long time ?
2- If i call the same session object instance simultaneously from two different threads it will serialize the business method calls?
I made this question because we use a satellite line between web and ejb layers (bank office and central bank site) and it takes 1,5 seconds to the cached home to just create the session facade bean.
if someone has any better approache, i'd appreciate.
Thanks in advance
xxxxxxxxxxxxxxxxxxxxxxxxxxxx
| Emerson Cargnin |
| Analista de Sistemas Sr. |
| Tel : (051) 3358-4959 |
| SICREDI Serviços |
| Porto Alegre - Brasil |
|xxxxxxxxxxxxxxxxxxxxxxxxxx|
-------------------------------------------------------
This sf.net email is sponsored by: Influence the future of Java(TM) technology. Join the Java Community Process(SM) (JCP(SM)) program now. http://ads.sourceforge.net/cgi-bin/redirect.pl?sunm0002en
_______________________________________________
JBoss-user mailing list
[EMAIL PROTECTED]
https://lists.sourceforge.net/lists/listinfo/jboss-user
------------------------------------------------------------------------
/*
**************************************************************************
* Copyright (c) 2002 Tiburon Enterprise Systems, Inc. All rights reserved.
* com.tes.framework.ejbs.homeservice.EjbHomeLocator.java
**************************************************************************
*/
package com.tes.framework.ejbs.homeservice;
import java.util.Properties;
import javax.ejb.EJBHome;
import javax.naming.Context;
import javax.naming.InitialContext;
// this class is located in the Concurrent.jar file which comes with JBoss !
import EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap;
/**
* This class keeps a cache of EJBHomes. If a EJBHome object becomes stale,
* we ignore issue of trying to get a new instance from same Context. We just
* get a new Context and try again. This is because whether or not there are
* multiple instances of the same EJBHome into context is a vendor implementation
* specific issue.
*
* This class ignores the issue of whether or not it is possible to have different
* EJBHomes on different machines but cached in Context with same key. Probably should
* revisit this !!
*
* This class assumes we are not using a clustered Jndi. Need to revisit this issue !!
*/
public class EjbHomeLocator {
private static EjbHomeLocator INSTANCE = new EjbHomeLocator ();
// We use this implementation of a HashMap because it neatly
// handles all issues of concurrent puts and gets to the HashMap
private ConcurrentReaderHashMap homes;
public static EJBHome getEjbHome (String key, boolean refreshCache, Properties props) throws Exception {
return INSTANCE.nonStaticGetEjbHome (key, refreshCache, props);
}
private EjbHomeLocator () {
homes = new ConcurrentReaderHashMap();
}
private EJBHome nonStaticGetEjbHome (String key, boolean refreshCache, Properties props) throws Exception {
EJBHome home = null;
if (refreshCache)
refreshCache (key, props);
home = (EJBHome)homes.get (key);
// If we got a null home and we did not call for a refresh of cache
// then do the refresh and try again. So, first time calling this will
// force getting the home from Context. But if we already called for
// a refresh, we don't do it again.
if (home == null && !refreshCache) {
refreshCache (key, props);
home = (EJBHome)homes.get (key);
}
return home;
}
private void refreshCache (String key, Properties props) throws Exception {
Context ctx = new InitialContext (props);
EJBHome home = (EJBHome)ctx.lookup (key);
homes.put (key, home);
}
}
------------------------------------------------------------------------
/*
**************************************************************************
* Copyright (c) 2002 Tiburon Enterprise Systems, Inc. All rights reserved.
* com.tes.image.ejbs.homeservice.ImageHomeService.java
**************************************************************************
*/
package foo;
import java.util.Properties;
import com.tes.framework.ejbs.homeservice.EjbHomeLocator;
import com.tes.framework.ejbs.homeservice.HomeServiceException;
import com.tes.ejbs.interfaces.Foo;
import com.tes.ejbs.interfaces.FooHome;
/**
* We claim this class can be generated by a xDoclet task which reads the
* JavaDoc comments in the FooBean.java file. So, the comments needs to
* include the following information:
*
* Amount of Sleep Interval
* Amount of Max Wait Interval
* Properties of Context/Machine where this ejb will live.
* What methods of FooHome we want to expose in this service.
*/
public class FooHomeService {
private static long sleepInterval = 2000; // 2 seconds
private static long maxWaitInterval = 10000; // 10 seconds
/**
* This method gets EJBHome from EjbHomeLocator, then calls appropriate method on home.
* If there is any exception thrown, then go to sleep for a while (sleepInterval), then
* wake up and try again. We don't keep trying forever and after a certain point (maxWaitInterval)
* we quit and throw a HomeServiceException.
*/
public static Foo create (int id, String name) throws HomeServiceException {
Foo foo = null;
boolean firstime = true;
long amtTimeWaited = 0;
Exception ex = null;
long startTime = System.currentTimeMillis();
while (foo == null && amtTimeWaited < maxWaitInterval)
try {
FooHome fooHome = (FooHome)EjbHomeLocator.getEjbHome (FooHome.JNDI_NAME, !firstime, getProperties());
foo = fooHome.create (id, name);
}
catch (Exception e) {
ex = e;
foo = null;
firstime = false;
try { Thread.sleep (sleepInterval); } catch (Exception ee) {};
amtTimeWaited = System.currentTimeMillis() - startTime;
}
if (foo == null)
throw new HomeServiceException (ex);
return foo;
}
public static Foo findByPrimaryKey (Integer pk) throws HomeServiceException {
Foo foo = null;
boolean firstime = true;
long amtTimeWaited = 0;
Exception ex = null;
long startTime = System.currentTimeMillis();
while (foo == null && amtTimeWaited < maxWaitInterval)
try {
FooHome fooHome = (FooHome)EjbHomeLocator.getEjbHome (FooHome.JNDI_NAME, !firstime, getProperties());
foo = fooHome.findByPrimaryKey (pk);
}
catch (Exception e) {
ex = e;
foo = null;
firstime = false;
try { Thread.sleep (sleepInterval); } catch (Exception ee) {};
amtTimeWaited = System.currentTimeMillis() - startTime;
}
if (foo == null)
throw new HomeServiceException (ex);
return foo;
}
public static void remove (Object key) throws HomeServiceException {
boolean firstime = true;
long amtTimeWaited = 0;
Exception ex = null;
long startTime = System.currentTimeMillis();
while (amtTimeWaited < maxWaitInterval)
try {
FooHome fooHome = (FooHome)EjbHomeLocator.getEjbHome (FooHome.JNDI_NAME, !firstime, getProperties());
fooHome.remove (key);
return;
}
catch (Exception e) {
ex = e;
firstime = false;
try { Thread.sleep (sleepInterval); } catch (Exception ee) {};
amtTimeWaited = System.currentTimeMillis() - startTime;
}
throw new HomeServiceException (ex);
}
private static Properties getProperties () {
Properties props = new Properties();
props.put ("java.naming.factory.initial","org.jnp.interfaces.NamingContextFactory");
props.put ("java.naming.provider.url","jnp://localhost:1099");
props.put ("java.naming.factory.url.pkgs","org.jboss.naming:org.jnp.interfaces");
return props;
}
}
------------------------------------------------------------------------
/*
**************************************************************************
* Copyright (c) 2002 Tiburon Enterprise Systems, Inc. All rights reserved.
* com.tes.framework.ejbs.homeservice.HomeServiceException.java
**************************************************************************
*/
package com.tes.framework.ejbs.homeservice;
import java.io.PrintStream;
import java.io.PrintWriter;
public class HomeServiceException extends Exception {
private Exception nestedException;
public HomeServiceException (String s) {
super(s);
nestedException = null;
}
public HomeServiceException (Exception nestedException) {
super();
this.nestedException = nestedException;
}
public HomeServiceException (String s, Exception nestedException) {
super(s);
this.nestedException = nestedException;
}
public void printStackTrace() {
super.printStackTrace();
if (nestedException != null)
nestedException.printStackTrace();
}
public void printStackTrace(PrintStream ps) {
super.printStackTrace(ps);
if (nestedException != null)
nestedException.printStackTrace(ps);
}
public void printStackTrace(PrintWriter pw) {
super.printStackTrace(pw);
if (nestedException != null)
nestedException.printStackTrace(pw);
}
public Exception getNestedException() {
return nestedException;
}
}
-- xxxxxxxxxxxxxxxxxxxxxxxxxxxx | Emerson Cargnin | | Analista de Sistemas Sr. | | Tel : (051) 3358-4959 | | SICREDI Serviços | | Porto Alegre - Brasil | |xxxxxxxxxxxxxxxxxxxxxxxxxx| ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
