Regarding JMS

Google

Mailing List

Home

Forum Home

JBoss - Java Application Server

Tomcat - JSP/Servlet container

Struts - A MVC web framework

iText - An open source PDF Java Library

JDOM - JDOM XML Parser

JSP - A mailing list about Java Server Pages specification and reference

J2EE - A mailing list for Java(tm) 2 Platform, Enterprise Edition

J2EE Pattern - An interest list for Sun Java Center J2EE Pattern Catalog

Servlet - A mailing list for discussion about Sun Microsystem's Java Servlet API Technology

Struts & Hibernate

Subjects

•	JSP editor plugin for eclipse ?
•	org apache jasper JasperException: Unable to compile class for JSP
•	Tomcat: Connection reset by peer: socket write error
•	Cannot retrieve definition for form bean null
•	Struts Tiles Tutorial (free Struts training)
•	Where do I download Tomcat 4 0 6?
•	Data Access Object (DAO) pattern, example DAO 's
•	Where to download Tomcat v 4 1 24 from?
•	Tomcat 5 0 16 Requested resource not available
•	Subject: Servlet : Session invalidate
•	Oracle Connection Pooling in 3 2 2
•	Servlet action is currently unavailable
•	Tomcat/Struts Unicode Encoding/Decoding problems
•	Subject: Running a Simple JMS Example
•	Tomcat and webapplication specific java library path
•	Mapping in workers2 properties
•	org apache jasper JasperException
•	problem with html:text bean throwing exception
•	Cannot find message resources under key org apache struts action MESSAGE
•	Cannot find message resources under key org apache struts action MESSAGE
•	invalid direct reference problem with solution
•	Tool for jsp debug Try Sysdeo Eclipse Plugin
•	Tomcat 5 Cannot load JDBC driver class 'null ' SQL state: null
•	weblogic ejbc
•	java properties file
•	Jboss 3 2 3 Coyote Can 't re
•	Tomcat 5, Apache2 and mod jk2 integration problem
•	JBoss example problem new to J2EE
•	Value attribute of <html:checkbox
•	url string for connecting jboss to oracle
•	javax servlet ServletException: BeanUtils populate
•	5 0 18: Windows XP Pro vs Windows 2000
•	HTTP Status 404 The requested resource is not available

Regarding JMS

Regarding JMS

2004-07-06 - By Michael Marson

Back

Reply: 1 2 3 4

With respect to the answer to #4 below, I respectfully disagree that
the answer is "No". It is true that there is no standard "client" as
such, but an MDB can participate in a transaction, and if the
transaction is rolled back the message will be retained on the queue for
redelivery, if configured as such. I believe this is part of the JMS
spec not a vendor-specific extension (we are using Weblogic 8.1), but we
are relying on the transactional nature of JMS, and the ability to have
multiple redelivery attempts, heavily in the project I am currently
working on. WLS also has error destinations where you can place
"failed" messages, so that you never truly discard messages, unless you
choose to. Again, I am not sure if this is part of the spec or
vendor-specific, so other servers may offer comparable functionality.

Hard-won side note on MDB drawbacks: if your MDB does any type of db
work (such as save message content to a database), you need to use an XA
transaction because a JMS provider is always its own resource manager,
even if the JMS store is a (the same) database.

-- --Original Message-- --
From: ashraf galal [mailto:ashrafwg@(protected)]
Sent: Sunday, July 04, 2004 5:33 PM
Subject: Re: Regarding JMS

K.Pushparaj wrote:
We are using weblogic JMS Queue and MDB in our system. I am
having
some questions on the same
1) Is there any pattern available for using message beans.
&nbs

p; The implementation of MDB uses some sort of the observer pattern
2) Where can I get the details about drawbacks of using MDB.
J2EE specification (section 17 of EJB 2.0 specification ) or
any J2EE book,
I recommend the expert one by one by Rod Johnson
3) Can I use MDB as a normal stateless session bean including
database transaction.
MDB does not have either a home interface nor remote
interface, so it is not visible
to the client, Whereas the session beans are. MDB is a message
consumers,
it does not have a client view.
Transaction in MDB have to be committed before the OnMessage() method
returns.
I don't think that possible since that means the instances of a message
driven bean
are equivalent.

4) If any exception happens can the message will be retained so
that
it will be served next time

MDB can throw system exception upon which the container discards the
bean instance.
However, the exceptions are not propagated to the client, since there
are no clients.
So, MDB cannot throw application exception. The answer is No.
Ashraf Galal

====================================================================
Companion Site: http://www.corej2eepatterns.com
J2EE BluePrints: http://java.sun.com/blueprints/corej2eepatterns
List Archive: http://archives.java.sun.com/archives/j2eepatterns-interest.html
Unsubscribing: email "signoff J2EEPATTERNS-INTEREST" to listserv@(protected)

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML xmlns:o =
"urn:schemas-microsoft-com:office:office"><HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii">
<TITLE>Message</TITLE>

<META content="MSHTML 6.00.2800.1400" name=GENERATOR></HEAD>
<BODY>
<DIV> </DIV>
<DIV>With
respect to the answer to #4 below,  I respectfully disagree that the
answer
is "No".  It is true that there is no standard "client" as such, but an
MDB
can participate in a transaction, and if the transaction is rolled back the
message will be retained on the queue for redelivery, if configured as
such.  I believe this is part of the JMS spec not a
vendor-specific extension (we are using Weblogic 8.1), but we are relying on
the
transactional nature of JMS, and the ability to have multiple redelivery
attempts, heavily in the project I am currently working on.  WLS also has
error destinations where you can place "failed" messages, so that you never
truly discard messages, unless you choose to.  Again, I am not sure if
this
is part of the spec or vendor-specific, so other servers may offer comparable
functionality.</DIV>
<DIV> </DIV>
<DIV>Hard-won side note on MDB drawbacks: if your MDB does any type of db
work
(such as save message content to a database), you need to use an XA
transaction because a JMS provider is always its own resource manager, even if
the JMS store is a (the same) database. </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>-- --Original Message-- -- From: ashraf
galal [mailto:ashrafwg@(protected)] Sent: Sunday, July 04, 2004 5:33
PM Subject: Re: Regarding JMS </DIV>
<BLOCKQUOTE style="MARGIN-RIGHT: 0px">
<DIV><PRE>K.Pushparaj wrote:<o:p></o:p></PRE><PRE>   
     We are using weblogic JMS Queue and MDB in our system.
I am having<o:p></o:p></PRE><PRE>some questions on the same<o:p></o
:p></PRE><PRE>        1) Is there
any pattern available for using message beans.<o:p></o:p><
/PRE><PRE>
        
  &nbs
p; The implementation of MDB
  uses some sort of the observer pattern<o:p></o:p></PRE><PRE>        2) Where can
I get the details about drawbacks of using MDB.<o:p></o:p>
</PRE><PRE>
        
    J2EE specification (section 17 of EJB 2.0
specification ) or any J2EE book, </PRE><PRE>I recommend the expert
one by one by Rod Johnson<o:p></o:p></PRE><PRE> 
       3) Can I use MDB as a normal stateless
session bean including<o:p></o:p></PRE><PRE>database transaction.
<o:p></o:p></PRE><PRE> 
              MDB does not have either a home interface
nor remote interface, so it is not visible </PRE><PRE>
to the
client, Whereas the session beans are. MDB is a message consumers, </PRE><PRE>it does not have a client view. </PRE><PRE>
Transaction
in MDB have to be committed before the OnMessage() method returns. </PRE><PRE>I don’t think that possible since that means the instances
of a message driven bean </PRE><PRE>are equivalent.   <o:p></o:p></PRE><PRE>
 <o:p></o:p></PRE>
<PRE>&nbsp
;       4) If any exception happens can the
message will be retained so that<o:p></o:p></PRE><PRE>
it will be
served next time<o:p></o:p>
</PRE><PRE>MDB can throw system exception upon which the container discards
the bean instance. </PRE><PRE>
However, the exceptions are not
propagated to the client, since there are no clients.  </PRE><PRE>
So, MDB cannot throw application exception. The answer is No. <o:p></o:p></PRE><PRE> Ashraf Galal<o:p></o:p></PRE
><PRE>
 <o:p></o:p></PRE><PRE>
</PRE></DIV><
/BLOCKQUOTE></BODY></HTML>
====================================================================
Companion Site: http://www.corej2eepatterns.com
J2EE BluePrints: http://java.sun.com/blueprints/corej2eepatterns
List Archive: http://archives.java.sun.com/archives/j2eepatterns-interest.html
Unsubscribing: email "signoff J2EEPATTERNS-INTEREST" to listserv@(protected)