WebLogic Server Frequently Asked Questions
A. If your WebLogic Server "freezes," you will need to collect certain diagnostic information, including thread dumps and Java garbage collection metrics, before contacting BEA Technical Support. For details, see Generate a Log File and Check Garbage Collection.
A. You can configure a java.net socket to use SOCKS by setting a Java system property. For details, see How do I make Java work with a proxy server?. Once the property is set, WebLogic socket connections use the SOCKS proxy.
A. Connection delays are often caused by DNS problems. WebLogic performs a reverse lookup on the hostname from which a new connection is made. If the DNS reverse lookup is not working properly because the connection is coming from a proxy server, it could be responsible for the delay. You might want to work with your system administrator to determine whether DNS and the third-party networking software are working properly. Try writing a simple server program that performs a reverse lookup on any connection made to it. If that lookup is delayed, then you know that the proxy server is the source of the problem.
A. "CORBA" support means many things to many people. It often means simply IIOP and ORB support and does not use many CORBA services. WebLogic supports CORBA in multiple ways. The WebLogic Server 8.1 implementation of RMI-IIOP allows you to: connect Java RMI clients to WebLogic Server using the standardized IIOP protocol; connect CORBA/IDL clients, including those written in C++, to WebLogic Server; interoperate between WebLogic Server and Tuxedo clients; connect a variety of clients to EJBs hosted on WebLogic Server. For more information, see Using WebLogic RMI over IIOP.
A. Unfortunately, a significant performance hit occurs when you use HTTP tunneling. We have optimized it somewhat, but, because everything is encapsulated in HTTP, HTTP tunneling is slower than direct Java-to-Java TCP/IP connections.
A. You can add a startup script to your UNIX rc scripts to run WebLogic Server at UNIX boot time. For information about creating startup scripts, refer to Starting an Administration Server Using a Script in Administration Console Online Help.
A. Response time for a servlet is about 5 times slower when you are running a screen saver on the machine, particularly for the OpenGL screen savers. Try turning off your screen saver and see if that helps!
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.
A. 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.
This allocates 32 megabytes of Java heap memory to WebLogic Server, which improves performance and allows WebLogic Server to handle more simultaneous connections. You can increase this value if necessary.
RMI-IIOP is for Java programmers who want to program to the RMI interfaces but use IIOP as the underlying transport. RMI-IIOP provides interoperability with other CORBA objects implemented in various languages, but only if all the remote interfaces are originally defined as Java RMI interfaces. It is of particular interest to programmers using Enterprise JavaBeans (EJBs), because the remote object model for EJB is RMI-based. It also allows you to use the standardized IIOP protocol and have a lightweight (minimal weblogic classes) client.
Java IDL is for CORBA programmers who want to program in Java based on interfaces defined in CORBA IDL. This is "business as usual" CORBA programming, supporting Java in exactly the same way as other languages like C++ or COBOL. If you want to integrate C++ (or any other language your orb supports into IDL) you would use the CORBA IDL method of programming.
A. If the existing CORBA object has its remote interfaces defined originally in CORBA IDL, then interoperability is not possible. RMI-IIOP applications can interoperate with other CORBA objects only when their remote interfaces are originally defined as Java RMI interfaces.
A. T3 provides a framework for WebLogic Server messages that support for enhancements. These enhancements include abbreviations and features, such as object replacement, that work in the context of WebLogic Server clusters and HTTP and other product tunneling.
T3 predates Java Object Serialization and RMI, while closely tracking and leveraging these specifications. T3 is a superset of Java Object. Serialization or RMI; anything you can do in Java Object Serialization and RMI can be done over T3.
T3 is mandated between WebLogic Servers and between programmatic clients and a WebLogic Server cluster. HTTP and IIOP are optional protocols that can be used to communicate between other processes and WebLogic Server. It depends on what you want to do. For example, when you want to communicate between
JPDA is integrated in the Java 2 Platform, Standard Edition (J2SE) SDK 1.3 on all platforms and SDK 1.2.2 for Linux. There is a download available from Sun to add JPDA support to the J2SE SDK 1.2.2 on Solaris and Microsoft Window platforms. If you are using J2SE SDK 1.2.2 on these platforms you must first get this download.
To allow a debugger to attach to the virtual machine that WebLogic runs you have to start WebLogic in debug mode. In order to start WebLogic in debug mode using a Sun virtual machine follow these steps (start with step one only if using a Solaris platform):
LD_LIBRARY_PATHenvironment variable to prepend