Which of the following are true about the transaction
support in the WebLogic server?
a. WebLogic Server allows transactions to be terminated
only by the client that created the transaction.
b. WebLogic Server does not support multithreaded
transactional clients.
c. A client or a server object cannot invoke methods on
an object that is participating in another transaction.
d. WebLogic server supports Nested Transactions
Choices A and C are correct. WebLogic Server provides a
Transaction Service that supports transactions in EJB
and RMI applications. WebLogic Server allows
transactions to be terminated only by the client that
created the transaction. WebLogic Server implements the
flat transaction model. Nested transactions are not
supported.
WebLogic Server supports multithreaded transactional
clients. Clients can make transaction requests
concurrently in multiple threads. In WebLogic Server, a
client or a server object cannot invoke methods on an
object that is infected with (or participating in)
another transaction. The method invocation issued by the
client or the server will return an exception. Also in
WebLogic Server, clients using third-party
implementations of the Java Transaction API (for Java
applications) are not supported.
Which of the following programs can be created using the
ZAC Publish Wizard tool?Choices:
a. Installer
b. Deployer
c. Bootstrap
d. Packager
Choices A and C are correct. To publish to a WebLogic
Server, we can use the ZAC publish wizard. For this, the
server must be running, and you will need to know a user
and password that has permission to publish. You can
also use the ZAC Publish Wizard to create a set of
native programs - an installer and a bootstrap - for
various operating systems that become part of a
published Java application.
The installer program is a native executable that
installs your published Java program on the local
machine. It doesn't require a Java environment itself,
so it can run out-of-the-box in the native OS. The
bootstrap is also a native program; the user runs the
bootstrap to invoke the published application. The
bootstrap takes care of monitoring for updates,
downloading and updating the user's application, and
other administrative ZAC functions.
How do I configure WebLogic to use a SOCKS proxy?
You can configure a java.net socket to use SOCKS by
setting a Java system property.
How does WebLogic support CORBA and client communication
via IIOP?
"CORBA" support means many things to many people. It
often means simply IIOP /ORB support and not much on
CORBA services. WebLogic supports CORBA in multiple
ways.
First, Java clients can tunnel through a CORBA
environment to WebLogic Server. We call this "IIOP
tunneling," and it is intended for use with applets
coming through an IIOP firewall, such as the IONA
Wonderwall product. This is a Java-to-Java model riding
over an IIOP communications framework.
WebLogic RMI over IIOP provides RMI services for many
clients (including CORBA clients) over IIOP.
WebLogic Enterprise Connectivity enables you to create
IIOP connection pools to a BEA WebLogic Enterprise
System, allowing you to execute WebLogic Enterprise
CORBA objects from WebLogic Server servlets and
Enterprise JavaBeans.
Can WebLogic Server start with a UNIX boot?
You can add a startup script to your UNIX rc scripts to
run WebLogic Server at UNIX boot time. Here is an
example from an HP-UX 11 system, running under JDK 1.1.
You need to supply the URL for your WebLogic Server and
your system password. This file, wlstart, is placed in
the /sbin/init.d directory and there is a link to it in
the /sbin/rc2.d directory:
export SHLIB_PATH=\
/home/user1/weblogic/lib/hpux11:/oracle/8.0.4/lib
export CLASSPATH=/home/user1/weblogic/classes:\
/home/user1/weblogic/lib/weblogicaux.jar
export ORACLE_home=/oracle/8.0.4
export ORACLE_SID=DEMO
export ORACLE_TERM=vt100
export QAT=/home/user1/weblogic
cd $QAT
PATH=/sbin:/usr/sbin:/usr/bin:/opt/java/bin
export PATH
case $1 in
'start')
java -ms64m -mx64m -verbosegc weblogic.Server > \
/home/user1/weblogic/server.out 2> #emp;
;;
'stop')
java weblogic.Admin URL shutdown system password
;;
*)
echo "usage: $0 {start|stop}"
;;
esac
You should work with your UNIX system administrator to
set up scripts similar to this for your system
Why do I get "NoClassDefFound"/"Too Many Open
files"messages on Solaris?
Problem: When I am using WebLogic Server on Solaris and
try to run my application, I get a "NoClassDefFound"
error, although the class causing the error does exist
and is in the right directory. In fact, there are other
classes in the same directory that are getting loaded. I
also get a "Too many open files" error.
We have seen this situation when the user account runs
out of file descriptors. On Solaris, each user account
has a certain limited number of file descriptors. You
can find out how many file descriptors you have with the
limit command in csh.
You can increase file descriptors if you have enough
privileges with the ulimit command in the csh.
Otherwise, ask your system administrator to increase the
file descriptors available to your processes.
A stateful session bean implementing the
SessionSynchronization interface is deployed on the
WebLogic server. Which of the following callback methods
may be invoked on the bean?
a. beforeBegin
b. afterBegin
c. beforeCompletion
d. afterCompletion
Choices B, C and D are correct. A stateful session bean
using container-managed transactions can implement the
javax.ejb.SessionSynchronization interface to provide
transaction synchronization notifications. This
interface defines only 3 methods - afterBegin(),
beforeCompletion() and afterCompletion().
The afterBegin() callback method is called when the bean
becomes part of a transaction. It is called before the
EJB Object delegates the business method invocation to
the bean instance. If the transaction is committed, the
bean will be notified through its beforeCompletion()
method. If the transaction is rolled back, this method
is not invoked. The afterCompletion() method is always
invoked whether the transaction ended with a commit or a
rollback. A is incorrect because beforeBegin is not a
method defined in the SessionSynchronization interface.
The home of a Product CMP entity bean has a finder
method, which returns an Enumeration of all the products
whose price falls below a certain value, which is passed
as the method argument. If there are no products in the
database to match the above criteria what will be the
result of a call to this finder method?
a. EJBException is thrown
b. ObjectNotFoundException is thrown
c. NoSuchEntityException is thrown
d. An empty enumeration is returned
Choice D is correct. Find methods that return a single
remote reference throw a FinderException if an
application error occurs and a ObjectNotFoundException
if a matching bean cannot be found. The
ObjectNotFoundException is a subtype of FinderException
and is only thrown by find methods, which return single
remote references.
The findByPrimaryKey() method returns only one remote
reference since there is a one-to-one relationship
between a primary key's value and an entity. Find
methods that return an Enumeration or Collection type
return an empty collection or enumeration if no matching
beans can be found or throw a FinderException if an
application error occurs. NoSuchEntityException is a
system exception thrown by the ejbLoad() method of an
entity bean when the database row to be loaded is not
found and also by the ejbStore() method when the
database row to be updated cannot be found. It is a
subclass of EJBException.
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