Top 100+ Bea Weblogic Server Interview Questions And Answers
Question 1. What Is Bea Weblogic?
BEA WebLogic is a J2EE software server and additionally an HTTP net server through BEA Systems of San Jose, California, for Unix, Linux, Microsoft Windows, and different platforms. WebLogic helps Oracle, DB2, Microsoft SQL Server, and other JDBC-compliant databases. WebLogic Server supports WS-Security and is compliant with J2EE 1.3.
BEA WebLogic Server is part of the BEA WebLogic Platform. The other elements of WebLogic Platform are:
Portal, which includes Commerce Server and Personalization Server (that is constructed on a BEA-produced Rete policies engine),
WebLogic Workshop, an IDE for Java, and
JRockit, a JVM for Intel CPUs.
WebLogic Server consists of .NET interoperability and supports the subsequent local integration abilities:
Native employer-grade JMS messaging
J2EE Connector Architecture
IBM WebSphere MQ connectivity
BEA WebLogic Server Process Edition also consists of Business Process Management and Data Mapping capability. WebLogic helps protection policies managed by means of Security Administrators.
The BEA WebLogic Server Security Model includes:
Separate software commercial enterprise good judgment from safety code
Complete scope of security insurance for all J2EE and non-J2EE additives
Question 2. Why Is There No Polymorphic-type Response From A Create() Or Find() Method?
The EJB Specification prohibits this conduct, and the weblogic.Ejbc compiler exams for this conduct and prohibits any polymorphic type of reaction from a create() or locate() method.
The purpose the create() and discover() techniques aren't polymorphic is just like the purpose constructors aren't polymorphic in Java. The derived instructions usually do no longer recognise or can not initialize the bottom class nicely.
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Question 3. Can I Use A Native Two-tier Driver For A Browser Applet?
No. Within an unsigned applet, you can not load local libraries over the cord, access the local file system, or hook up with any host besides the host from that you loaded the applet. The applet security manager enforces those regulations on applets as safety against applets being capable of do unsavory things to unsuspecting users.
If you are attempting to use jDriver for Oracle from an applet, then you definately are violating the primary restrict. Your applet will fail whilst it tries to load the local (non-Java layer) library that allows jDriver for Oracle to make calls into the non-Java Oracle customer libraries. If you take a look at the exception this is generated, you may see that your applet fails in java.Lang.System.LoadLibrary, due to the fact the security supervisor determined that you have been trying to load a neighborhood library and halted the applet.
You can, but, use the WebLogic JTS or Pool driving force for JDBC connectivity in applets. When you operate this kind of WebLogic multitier JDBC drivers, you want one reproduction of WebLogic jDriver for Oracle (or another two-tier JDBC motive force) for the connection between the WebLogic Server and the DBMS.
Question 4. How Do Stubs Work In A Weblogic Server Cluster?
Clients that connect to a WebLogic Server cluster and appearance up a clustered item attain a reproduction-aware stub for the item. This stub consists of the listing of to be had server instances that host implementations of the object. The stub additionally consists of the burden balancing good judgment for distributing the weight amongst its host servers.
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Question five. Why Did My Jdbc Code Throw A Roll Back Sql Exception?
Your JDBC code might also throw the following exception:
"The coordinator has rolled returned the transaction.
No further JDBC access is authorized inside this transaction."
The WebLogic JTS JDBC motive force throws this exception when the contemporary JDBC connection transaction rolls back previous to or at some point of the JDBC call. This exception indicates that the transaction wherein the JDBC connection was collaborating become rolled back at some point prior to or at some stage in the JDBC call.
The rollback may additionally have took place in an earlier EJB invoke that turned into part of the transaction, or the rollback may additionally have passed off because the transaction timed out. In both case, the transaction may be rolled lower back, the relationship returned to the pool and the database resources released. In order to proceed, the JTS JDBC connection must be closed and reopened in a brand new transaction.
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Question 6. Can I Enable Requests To A Jdbc Connection Pool For A Database Connection To Wait Until A Connection Is Available?
No, there is no manner to permit a request to anticipate a pool connection, and from the device point of view there need to not be. Each requests that waits for a connection ties up one of the fixed wide variety of execute threads within the server, that can otherwise be going for walks some other server challenge. Too many waiting requests could tie up all of the execute threads and freeze the server.
Question 7. How Do I Connect To An Sql Server Instance That Is Running On A Machine With Multiple Instances Of Sql Server 2000?
Each example of MS SQL Server must be listening on a exclusive port. So, you can use the port wide variety in the houses which you pass to the getConnection() approach or, in case of connection swimming pools,
you may specify the port assets within the following residences:
To discover the port variety where every MS SQL Server example is running, run the server network software (in the Microsoft SQL Server program group), choose the server example, choose TCP/IP, and click on the residences button.
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Question 8. What Type Of Object Is Returned By Resultset.Getobject()?
WebLogic jDriver for Oracle usually returns a Java object that preserves the precision of the records retrieved.
WebLogic jDriver for Oracle returns the subsequent from the getObject() approach:
For columns of sorts NUMBER(n) and NUMBER(m,n): a Double is lower back if the defined precision of the column can be represented through a Double; otherwise BigDecimal is back.
For columns of type NUMBER: Because there is no express precision, the Java kind to go back is decided based totally at the real price in every row, and this may vary from row to row. An Integer is returned if the price has a zero-valued fractional issue and the price may be represented by an integer.
For instance, 1.0000 can be an integer. A lengthy is lower back for a price consisting of 123456789123.00000. If a fee has a non-zero fractional issue, a Double is again if the precision of the cost may be represented by a Double; in any other case a BigDecimal is returned.
Question nine. How Do I Call Oracle Stored Procedures That Take No Parameters?
Here is what we use that works:
CallableStatement cstmt = conn.PrepareCall("Begin procName;
wherein procName is the name of an Oracle stored method. This is preferred Oracle SQL syntax that works with any Oracle DBMS.
You might also use the subsequent syntax:
CallableStatement cstmt = conn.PrepareCall("call procName;");
This code, which conforms to the Java Extended SQL spec, will paintings with any DBMS, not just Oracle.
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Question 10. Why Do I Get An Error While Trying To Retrieve The Text For Ora-12705?
This blunders happens if you have not set the ORACLE_HOME surroundings variable well - a common mistake. In order to use WebLogic jDriver for Oracle, the Oracle consumer software needs to be installed and ORACLE_HOME have to be set.
You may additionally see this mistake message in case you attempt to use WebLogic jDriver for Oracle's internationalization skills with a language/codeset aggregate that isn't always established on your machine. If you get the ORA-12705 error with the appropriate mistakes textual content, then either you have got set NLS_LANG improperly, or you do now not have the right codesets installed on your gadget.
Question eleven. How Do I Prevent Errors When Running T3dbping?
When you are testing your Oracle database connections below UNIX, you may run SQL*PLUS and can successfully ping the database the usage of utils.Dbping. However, while you operate the multitier utils.T3dbping application, you acquire an ORA-12154 errors message.
First, make certain that your ORACLE_HOME surroundings variable is efficaciously set to factor for your Oracle installation. This variable have to be set inside the environment in which the WebLogic server is walking.
In the C-shell difficulty the following command:
$ setenv ORACLE_HOME route
in which course is the path in your Oracle set up.
In the Bourne shell, difficulty the subsequent instructions:
$ export ORACLE_HOME
wherein path is the path on your Oracle set up. When you ping your database the usage of the 2-tier utils.Dbping software, the JDBC motive force loads the database client library and establishes the relationship to the database. When you operate the multitier utils.T3dbping software, the WebLogic Server hundreds a two-tier driver and makes use of it to establish a database connection. In each instances, the same method is used to connect to the database. SQL*PLUS works because it doesn't require ORACLE_HOME to discover the client libraries.
If you are still experiencing problems, do this:
Open a command shell.
Run the two-tier version of utils.Dbping in this shell.
Start WebLogic in this shell from the command line:
$ java -ms32m -mx32m weblogic.Server
Open a 2nd command shell.
Run the utils.T3dbping inside the 2nd shell against the server going for walks inside the first command shell.
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Question 12. Why Am I Getting An Ora-01000: Maximum Open Cursors Exceeded Error, Even Though I Closed All Resultset, Statement, And Connection Objects?
This is an Oracle trouble. According to Oracle's documentation, dynamic cursors can continue to be open from run to run in a consultation and are not closeable when a method closes. To work around this problem, you may increase the range of open cursors allowed inside the database or you could reset the relationship pool (close and reopen database connections in the connection pool).
To reset the connection pool, you can untarget and retarget the connection pool using the Administration Console. You can also use the reset() technique via the JMX API or the RESET_POOL command at the WebLogic Server command line interface.
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Question 13. Are There C/c++ Interfaces To Wls Jms?
No, this isn't always supported:
Write your very own interfaces using JNI.
Setup a Servlet that your C/C++ client calls to generate a JMS message. You have to spawn a couple of threads in C++ and use multiple posts to skip messages via http.
Question 14. How Do I Configure Jms Security?
The correct way to set up security for JMS is to go to the console, choose ACLs in the tree view, then create some get right of entry to manipulate lists.
Set the ACL call which need to be weblogic.Jms.Queue.QUEUENAME or weblogic.Jms.Topic.TOPICNAME.
Enter the New Permission of ship or acquire.
Enter a comma separated listing of customers or corporations.
Select Grant Permission.
Select "saved to the realm implementation" to shop your adjustments.
This will replace the fileRealm.Properties document with lines that appear to be the following:
If you don't have an ACL for a queue or subject matter, protection is extensive open.There are also ACL's for having access to the JNDI context; the JNDI context is a requirement for to begin with having access to JMS.
Question 15. How Do I Use A Temporary Destination?
You ought to create a template on each JMSServer where you want on the way to create brief locations. You can specify a couple of JMSServer entries to guide Temporary Template and the system will load balance among the ones JMS servers to setup the temporary vacation spot.
The JMSServer is defined some thing like:
After the template call, you could set any queue/subject matter characteristic you want within the template (now not such as a JNDI name or subject matter multicast settings). The template is at the outer maximum stage; that is, it should no longer be nested on your .
Temporary destinations can most effective be fed on with the aid of the developing connection. Using subjects, you create your transient subject matter and subscribe to that brief topic. If you need someone to publish to that temporary subject matter, you want to tell that someone what your subject matter is. You can ship them a message and consist of your brief topic within the JMSReplyTo area. The creator of the TemporaryTopic and the subscriber should be one within the same.
TemporaryTopic myTopic = mySession.CreateTemporaryTopic();
TopicSubscriber = mySession.CreateSubscriber(myTopic);
Temporary subjects do no longer get names and can not be subscribed to by using different connections. When you create a temporary topic, the JMS issuer returns a javax.Jms.Topic. You then need to put it up for sale that topic to other events (folks who want to put up to the topic), putting it for your JMSReplyTo field a good way to respond. In wellknown, nobody else can join the topic. You put it on the market the subject any way you want. Topics are serializable (or, in our case, externalizable), which lets in you to skip them round in RMI calls, through a report, binding it to a name in JNDI, and so on. In quick, create the topic on the subscriber aspect and put it up for sale in order that others can submit. You can get a couple of subscribers at the equal connection and get concurrent processing using multiple periods.
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Question 16. Which Types Of Jdbc Databases Does Weblogic Jms Support?
The JMS database may be any database this is handy via a JDBC driver.
WebLogic helps and provides JDBC drivers for the subsequent databases:
Microsoft SQL (MSSQL) Server (Versions 6.5 and seven)
Oracle (Version eight.1.6)
Sybase (Version 12)
Question 17. How Do The Wls Jms 6.1 Server/vacation spot Message Maximum And Threshold Values Work?
The byte and message maximum values are quotas - not flow control. Message quotas prevent a WebLogic JMS server from filling up with messages and probable walking out of reminiscence, causing unexpected outcomes. When you reach your quota, JMS prevents further sends with a ResourceAllocationException (instead of blockading). You can set quotas on man or woman destinations or on a server as a whole.
The thresholds are also no longer flow manipulate - even though they would be higher appropriate to that utility than the quotas. The thresholds are truly settings that once passed cause a message to be logged to the console to will let you recognise which you are falling at the back of.
Note that the messages most placing on a connection factory isn't a quota. This specifies the maximum numbers of remarkable messages which can exist once they had been driven from the server but earlier than an asynchronous customer has visible them; it defaults to a value of 10.
Question 18. Does Weblogic Jms Support Clustering?
WebLogic JMS supports cluster-huge, obvious access to destinations from any server inside the cluster. A system administrator can set up cluster-extensive, transparent get admission to to locations from any server within the cluster through configuring a couple of connection factories and the usage of goals to assign them to WebLogic Servers. Each connection manufacturing facility can be deployed on a couple of WebLogic Servers.
The software uses the Java Naming and Directory Interface (JNDI) to look up a connection manufacturing unit and create a connection to establish communication with a JMS server. Each JMS server handles requests for a fixed of destinations. Requests for locations now not handled by using a JMS server are forwarded to the perfect server.
You can configure multiple JMS servers on the diverse nodes in the cluster so long as you give them different names. You can assign locations to the numerous JMS servers.
One problem to be privy to is the propagation put off in replicating entries in JNDI. If you've got an MDB deployed on one node but reference a vacation spot on another node, the deployment may additionally fail with a javax.Naming.NamingException exception. The trouble occurs due to the fact the server isn't always synced up to the JNDI from the far off server (JMS server) yet, so the JNDI lookup of destination as part of MDB deployment will fail. One workaround is for every MDB to reference a nearby destination.
Another approach is installation the MDBs after the server boots (plus a postpone for JNDI propagation). To get around dropping messages earlier than the MDB is deployed, use long lasting subscribers. This hassle is constant for MDBs in WLS 6.1, where the MDB might be deployed and reconnection may be retried till the destination is to be had.
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Question 19. What Happens If Acknowledge() Is Called Within A Transaction?
As consistent with the JMS specification, when you are in a transaction, the acknowledgeMode is unnoticed. If renowned() is known as within a transaction, it's far overlooked.
Question 20. How Should I Use Sorted Queues?
Destination keys are used to outline the type order for a selected vacation spot. Destination keys can be message header or property fields. For a listing of legitimate message header and property fields, refer to the Programming WebLogic JMS.
Queues may be taken care of in ascending or descending order based on the vacation spot key. A vacation spot is taken into consideration to be first-in-first-out if a vacation spot secret's defined as ascending for the JMSMessageID message header field, and closing-in-first-out if defined as descending. The key defined for the JMSMessageID header area, if precise, must be the closing key defined inside the list of keys.
You can outline more than one vacation spot keys to kind a destination.
Question 21. How Do I Get A Thread Dump To Help Track Down A Problem?
Ways to get a thread dump:
Try strolling this from the command line (after strolling the setEnv script in /bea/wlserver6.1/config/mydomain/):
java weblogic.Admin -url t3://localhost:7001 THREAD_DUMP
On Windows, from the console window, enter Ctrl+Break.
On UNIX, signal the server using kill -three.
Question 22. Why Do I Get An Exception When Trying To Find A Connection Factory?
The exception is usually some thing like java.Io.InvalidClassException or java.Lang.NoClassDefFoundError.
Make positive weblogic.Jar is within the CLASSPATH of the client. Also make certain you have the proper Java run-time jar files protected (i.E., you might need rt.Jar).
Question 23. What Is The No_acknowledge Acknowledge Mode Used For?
The NO_ACKNOWLEDGE renowned mode indicates that obtained messages do not need to be specifically recounted which improves overall performance, but risks that messages are misplaced. This mode is supported for programs that do not require the satisfactory of carrier supplied via consultation acknowledge and that don't need to incur the associated overhead. V Messages sent to a NO_ACKNOWLEDGE session are immediately deleted from the server. Messages received on this mode are not recovered and, as a result, messages can be misplaced and/or replica message may be added if an initial try to deliver a message fails.
Note: You need to keep away from using this mode in case your utility can not handle misplaced or duplicate messages. Duplicate messages may be sent if an initial try to supply a message fails.
In addition, we do now not advocate that this acknowledge mode be used with persistent messaging, as it implies a fine of service that can be too low for chronic messaging to be useful.
Question 24. When Should I Use Server Session Pools And Connection Consumers?
WebLogic JMS implements an optionally available JMS facility for defining a server-managed pool of server classes. This facility allows an software to technique messages simultaneously. A ConnectionConsumer object uses a server session to procedure obtained messages. If message visitors is heavy, the relationship consumer can load each server consultation with more than one messages to minimize thread context switching. Multiple connection customers can proportion server classes in a server consultation pool.
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Question 25. How Do I Publish An Xml Message?
Follow these steps:
Generate XML from the DOM document tree.
Serialize the generated DOM file to a StringWriter.
Call toString on the StringWriter and skip it into message.SetText.
Publish the message.
Question 26. What Is The Standard Way To Create Threads, Do Initialization, Etc. Within The Application Server?
Threads have to generally not be created by way of the consumer at once is because matters won't paintings efficiently. User-created threads do not have a number of the thread-neighborhood variables pre-set by means of WebLogic while it creates it's personal execute threads, the associated transaction context, or the environment including the proper class loader.
The WebLogic-specific manner of doing this is with a startup elegance or the use of the WebLogic Time Services. The transportable way to do this is to define a load-on-startup servlet, doing the initialization in the init() method and the cleanup inside the smash() method.
The servlet itself does not anything. This approach also permits for undeploy/redeploy of the utility without restarting the server, which includes proper cleanup/initialization every time. It also vendors extra dynamic management of the structured lessons with out restarting the server.
Question 27. Is It Better To Have More Or Fewer Sessions For A Given Number Of Subscribers?
Using N periods for N subscribers offers you concurrency up to N simultaneous threads of execution furnished you have got as many threads to work with. Each Session gets its own thread as long as there are enough threads to be had. Otherwise, the periods serially reuse the to be had threads.
One consultation for N subscribers serializes all subscribers thru that one session. If the burden is heavy they'll no longer be able to preserve up with out the extra threads.
If you are using CLIENT_ACKNOWLEDGE, N classes offers you N separate message streams that may be for my part recovered. Having one consultation crosses the streams supplying you with less control.
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Question 28. What Are Pending Messages In The Console?
Pending way the message could have been:
sent in a transaction however no longer dedicated.
Acquired and not stated.
Received and now not committed.
Problem to a redelivery put off (as of WebLogic Server 6.1).
Challenge to a transport time (as of WebLogic Server 6.1).
A rolled again message stays pending until the transaction honestly rolls back. Rolling it again multiple times does not motive double counting, nor does an exception that set a transaction as rollbackOnly observed by an actual rollback.
Current implies messages that are not pending.
Total implies overall due to the fact server closing commenced. The byte counts only don't forget the payload of messages which incorporates the homes and the body however now not the header.
Question 29. How Do I Put A Message Back On The Queue For Processing?
The following are numerous processes:
Use a transacted session, then rollback the session so the message will pass returned to the queue.
Use Session.CLIENT_ACKNOWLEDGE whilst developing a session, then get better the consultation so the message will pass returned to the queue.
Use a JTA transaction, then rollback the transaction so the message will move back to the queue.
Question 30. What Can I Do When I Get Java.Lang.Outofmemoryerror Because Producers Are Faster Than Consumers?
Quotas may be used to assist this situation. Your sender will then obtain ResourceAllocationExceptions and the server will live up. WLS 6.X does not help paging of messages out of memory.
As of WLS 6.1 SP02 or later, you could use the Message Paging function, that can free up treasured digital reminiscence at some stage in height message load intervals by using swapping out messages from virtual memory to persistent garage when message masses attain a specific threshold.
Question 31. How Do I Debug Weblogic Server Using Visual Cafe four.1?
You can install VisualCafe Enterprise Edition four.1 and fasten it to the server, quite much because it labored for 3.X.
The following are steps for debugging the use of VC four.1. You may additionally trade the directory names as necessary:
Install it under D:VisualCafeEE. No special alternatives are needed.
Install the license beneath C:Program FilesCommon FilesWebGain Shared.
Start ddservices by means of selecting Start -> Programs -> WebGain Studio Professional ->Visual Cafe Enterprise Edition four.1 -> Distributed Debugging Services -> Start DD Services (Java2 - 1.Three)
Start WebLogic Server using debugvm.Exe rather than java.Exe.
change "%JAVA_HOMEpercentbinjava" -hotspot -ms64m -mx64m to visualcafeEEjdk13bindebugvm.Exe
Run startWebLogic. It prints out a few debugging records.
Run VisualCafe - Start -> Programs -> WebGain Studio Professional -> Visual Cafe Enterprise Edition 4.1 -> Visual Cafe Enterprise Edition four.1
From the File menu, choose Attach to Process. If the entirety is working successfully, you must see your gadget call.
Click the + signal to expand the tree and select your going for walks WebLogic Server.
Question 32. Can An Mdb Be A Message Producer Or Both A Producer And Consumer?
Yes. You haven't any JMS context in the MDB so you will need to set up a connection, consultation and producer your self. One option is to do this every time you come back into the onMessage routine for the MDB. This is enough if the message price is particularly low. The 2nd option is to establish the important objects in ejbActivate().
Note that the items aren't serializable in order that they cannot be passivated for a stateful consultation bean or an entity bean. When the EJB deactivates, you need to shut the associated items. The third alternative is that you could building up a JMS connection/sender consultation pool inside a startup class entire along with your personal synchronization and blocking off to get a connection.
Question 33. How Does Concurrency Work For Message-driven Beans?
The way concurrency is carried out for Queues is by using spawning one JMSSession consistent with MDB instance inside the pool. Since JMSSessions are processed in parallel by using JMS, concurrency is received naturally this manner and JMS takes care of delivering the message to, at maximum, one listener. If an MDB is deployed to multiple servers in a cluster, JMSSessions are created for every MDB example on each server and load balancing can be achieved throughout them.
For Topics in WebLogic JMS 6.1, there's one JMSSession in step with bean instance within the pool. Because of the manner Topics work, the session, and thus every bean example, gets a duplicate of every message posted on that Topic. (There changed into also a problem that brought on parallel processing no longer to paintings efficiently. This has been constant for WLS 6.0 Service Pack 1.)
Within a single server, one topic client is used to skip out messages to multiple threads to get the concurrency even as generating most effective a unmarried copy of every message. You can configure multiple MDBs to concentrate at the same topic and each MDB will get hold of a copy of every message. When the usage of multiple servers, every server gets its personal purchaser and therefore its own replica of each message. It is not currently possible to percentage a client across multiple servers. If you want a message to be processed through precisely one MDB, use a queue.
One consumer had an instance wherein subject matter MDBs are needed in which there could be multiple implementations of the MDBs listening on the identical subject matter. In other phrases, multiple MDB with a distinctive implementation may be subscribing to the identical subject matter. The patron has no advanced way of understanding what number of distinctive types of MDBs may be listening on the same subject matter, however it's far feasible for there to be multiple listener, consequently subjects, now not queues. For each type of MDB listening on the subject, the message is delivered precisely as soon as (i.E., the message can be delivered precisely as soon as to an instance in every named MDB pool listening on the subject).
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Question 34. Can The Messaging Bridge Handle Two-section Or Global Transactions Between Separate Weblogic Server Domains Or Between Different Releases?
Yes, as long as the conversation is among source and goal WebLogic domain names which are both going for walks release 6.1 SP3 or later, and the bridge is configured to apply the Exactly-once fine of carrier.
Question 35. Can I Configure The Messaging Bridge To Automatically Downgrade The Quality Of Service If The Exactly-once Service Is Not Available On Either The Source Or Target Bridge Destination?
Yes, just make certain to choose the QOS Degradation Allowed take a look at field at the Messaging Bridge -> Configuration -> General management console page.
Question 36. Can The Messaging Bridge Forward Durable Subscription Messages Between Separate Weblogic Server 6.1 And Release 7.0 Or Later Domains?
Yes, so long as the WebLogic 7.Zero area is using Service Pack 1 or later. To enable durable messages throughout the messaging bridge the use of the Administration Console, select the Durability Enabled attribute on the Messaging Bridge -> Configuration -> General tab.
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Question 37. How Does Weblogic Support Corba And Client Communication Via Iiop?
"CORBA" aid means many things to many humans. It regularly method absolutely IIOP /ORB guide and not a good deal on CORBA services. WebLogic supports CORBA in multiple methods.
First, Java customers can tunnel via a CORBA environment to WebLogic Server. We name this "IIOP tunneling," and it is supposed to be used with applets coming thru an IIOP firewall, inclusive of the IONA Wonderwall product. This is a Java-to-Java version driving over an IIOP communications framework.
WebLogic RMI over IIOP offers RMI offerings for lots customers (along with CORBA clients) over IIOP.
WebLogic Enterprise Connectivity permits you to create IIOP connection pools to a BEA WebLogic Enterprise System, allowing you to execute WebLogic Enterprise CORBA items from WebLogic Server servlets and Enterprise JavaBeans.
Question 38. Why Do I Get "noclassdeffound"/"too Many Open Files"messages On Solaris?
When I am using WebLogic Server on Solaris and try to run my software, I get a "NoClassDefFound" blunders, even though the elegance inflicting the mistake does exist and is within the proper directory. In reality, there are other classes within the equal listing which are getting loaded. I additionally get a "Too many open files" error.
We have seen this situation while the person account runs out of file descriptors. On Solaris, every consumer account has a certain restrained range of file descriptors. You can find out how many file descriptors you have with the restriction command in csh.
You can increase record descriptors if you have sufficient privileges with the ulimit command inside the csh. Otherwise, ask your system administrator to boom the report descriptors to be had for your tactics.
Question 39. How Do I Increase Weblogic Server Memory?
Increase the allocation of Java heap reminiscence for WebLogic Server. (Set the minimal and the maximum to the identical size.) Start WebLogic Server with the -ms32m option to boom the allocation, as in this example:
$ java ... -ms32m -mx32m ...
This allocates 32 megabytes of Java heap reminiscence to WebLogic Server, which improves overall performance and lets in WebLogic Server to deal with extra simultaneous connections. You can increase this cost if essential.
Question 40. Java-corba Integration: Rmi-iiop Or Java Idl?
It is essential to understand the difference among those approaches of integrating Java with CORBA.
RMI-IIOP is for Java programmers who need to program to the RMI interfaces but use IIOP because the underlying transport. RMI-IIOP offers interoperability with different CORBA gadgets carried out in diverse languages, however handiest if all the remote interfaces are at first defined as Java RMI interfaces. It is of unique interest to programmers the use of Enterprise JavaBeans (EJBs), because the faraway item version for EJB is RMI-based.
Java IDL is for CORBA programmers who need to application in Java based totally on interfaces described in CORBA IDL. This is "commercial enterprise as standard" CORBA programming, assisting Java in precisely the same way as other languages like C++ or COBOL.
Question forty one. What Is The Function Of T3 In Weblogic Server?
T3 offers a framework for WebLogic Server messages that help for enhancements. These improvements include abbreviations and functions, together with object substitute, that paintings within the context of WebLogic Server clusters and HTTP and other product tunneling.
T3 predates Java Object Serialization and RMI, at the same time as carefully monitoring and leveraging those specs. T3 is a superset of Java Object. Serialization or RMI; anything you can do in Java Object Serialization and RMI may be performed over T3.
T3 is remitted among WebLogic Servers and among programmatic clients and a WebLogic Server cluster. HTTP and IIOP are non-compulsory protocols that may be used to communicate between other procedures and WebLogic Server. It depends on what you need to do.
For instance, while you want to communicate among
A browser and WebLogic Server-use HTTP
An ORB and WebLogic Server-IIOP.
Question 42. How Do I Restrict Access To Servlets And Jsps?
The Java Servlet API Specification v2.2 lets in you to declaratively restrict access to specific Servlets and JSPs the usage of the Web Application Deployment descriptor. Section thirteen.3.2 of the specification has an example deployment descriptor that uses declarative safety.
Question 43. Which Xml Parser Comes With Weblogic Server 6.1?
We bundle a parser, based totally on Apache's Xerces 1.3.1 parser, in WebLogic Server 6.1. In addition, we consist of a WebLogic proprietary high-overall performance non-validating parser that you may use for small to medium sized XML documents. The WebLogic XML Registry permits you to configure the parser you need to use for precise record sorts.
Question forty four. How Can I Avoid Resourceexceptions When Sending More Requests For Database Connections From The Pool Than Are Currently Available?
The fundamental hassle is too few sources (database connections inside the connection pool) for the work load. The accurate response is to growth the maximum range of connections inside the connection pool. Optimally designed packages best require the server to have one pool connection in step with execute thread.
The proper software reaction to a useful resource exception isn't to retry the request in a decent loop, which would tie up execute threads on the server.
You need to design your utility to gracefully fail if no connections are to be had. Try to make certain that you get the connection as past due as feasible to your software code and return them to the pool as early as possible so you do not see as many NoResource exceptions. It is higher to have the relationship as a technique level variable and near the connection in a eventually block as inside the following example:
Sooner or later
trap (Exception forget about) // continually return the connection to pool
Question 45. What Is Error Ora-6502?
The default period of a string bound to an OUTPUT parameter of a CallableStatement is 128 characters. If the price you assign to the bound parameter exceeds that length, you will get this mistake.
You can modify the duration of the price of the certain parameter by means of passing an explicit length with the scale argument to the CallableStatement.RegisterOutputParameter() technique.
Question 46. How Do I Bind String Values In A Preparedstatement?
Suppose you are attempting to tget the PreparedStatement class to bind Strings in a statement. The setString() technique would not seem to work.
Here is how you have set up the PreparedStatement:
String pstmt = "choose n_name from n_table where n_name LIKE
PreparedStatement ps = conn.PrepareStatement(pstmt);
playstation .SetString(1, "SMIT");
ResultSet rs = ps.ExecuteQuery();
The preceding code does not paintings because the whole fee wishes to be laid out in a String (without the use of embedded charges) after which bound to an unquoted question-mark (?).
Here is the corrected code:
String matchvalue = "smit%";
String pstmt = "pick n_name from n_table in which n_name LIKE ?";
PreparedStatement playstation = conn.PrepareStatement(pstmt);
ResultSet rs = ps.ExecuteQuery();
Question forty seven. How Do I Use A Startup Class To Initialize And Later Reference Jms Objects?
You can use a shutdown magnificence that does some thing like the following:
JMSobject WLSobject = null;
WLSobject = JMSStartUp.GetJMSobject();
Servlets can provide a pleasing method to offer both initialization and cleanup.
Question forty eight. How Is Security Handled In The Weblogic J2ee Connector Architecture?
Due to the fact that the contemporary configuration and packaging necessities for useful resource adapters in WebLogic Server require the hand-enhancing of the weblogic-ra.Xml file, any new passwords detailed in the security-predominant-map entries are completed in clear-text.
BEA knows the significance of shielding security passwords. Hence, we provide a Converter Tool that allows for the encryption of all passwords present within the weblogic-ra.Xml document. The Converter Tool is distributed within the preferred weblogic.Jar file.
Question 49. Must Ejbs Be Homogeneously Deployed Across A Cluster? Why?
Yes. Beginning with WebLogic Server version 6.Zero, EJBs should be homogeneously deployed throughout a cluster for the following reasons:
To preserve clustering EJBs simple
To avoid move server calls which results in greater efficiency. If EJBs aren't deployed on all servers, move server calls are more likely.
To ensure that each EJB is to be had regionally
To make certain that every one classes are loaded in an undeployable way
Every server should have get right of entry to to every EJB's instructions in order that it could be certain into the local JNDI tree. If simplest a subset of the servers deploys the bean, the opposite servers will have to load the bean's instructions of their respective machine classpaths which makes it not possible to undeploy the beans.