Question 1 :
What is BEA Weblogic?
BEA WebLogic is a J2EE application server and also an HTTP web server by BEA Systems of San Jose, California, for Unix, Linux, Microsoft Windows, and other platforms. WebLogic supports 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 Platformâ„¢. The other parts of WebLogic Platform are:
* Portal, which includes Commerce Server and Personalization Server (which is built on a BEA-produced Rete rules engine),
* WebLogic Integration,
* WebLogic Workshop, an IDE for Java, and
* JRockit, a JVM for Intel CPUs.
WebLogic Server includes .NET interoperability and supports the following native integration capabilities:
* Native enterprise-grade JMS messaging
* J2EE Connector Architecture
* WebLogic/Tuxedo Connector
* COM+ Connectivity
* CORBA connectivity
* IBM WebSphere MQ connectivity
BEA WebLogic Server Process Edition also includes Business Process Management and Data Mapping functionality.
WebLogic supports security policies managed by Security Administrators. The BEA WebLogic Server Security Model includes:
* Separate application business logic from security code
* Complete scope of security coverage for all J2EE and non-J2EE components
Question 2 :
Can I use a "native" two-tier driver for a browser applet?
No. Within an unsigned applet, you cannot load native libraries over the wire, access the local file system, or connect to any host except the host from which you loaded the applet. The applet security manager enforces these restrictions on applets as protection against applets being able to do unsavory things to unsuspecting users.
If you are trying to use jDriver for Oracle from an applet, then you are violating the first restriction. Your applet will fail when it attempts to load the native (non-Java layer) library that allows jDriver for Oracle to make calls into the non-Java Oracle client libraries. If you look at the exception that is generated, you will see that your applet fails in java.lang.System.loadLibrary, because the security manager determined that you were attempting to load a local library and halted the applet.
You can, however, use the WebLogic JTS or Pool driver for JDBC connectivity in applets. When you use one of these WebLogic multitier JDBC drivers, you need one copy of WebLogic jDriver for Oracle (or any other two-tier JDBC driver) for the connection between the WebLogic Server and the DBMS.
Question 3 :
I'm using a WebLogic multitier driver in an applet as an interface to a DBMS. If I run the class using the Sun Appletviewer on my local machine, I have no problems. But when I try to run the applet in a Netscape browser, it will not connect?
If Appletviewer works and Netscape does not, it is an indication that you are violating a Netscape security restriction. In this case, the violation is that an applet cannot open a socket to a machine other than the one from which it loaded the applet. To solve this problem, you will have to serve your applet code from the same machine that hosts the DBMS.
In addition, the IP naming format you use in the applet CODEBASE and the constructor for the T3Client must match. That is, you can't use dot-notation in one place and a domain name in the other.
Question 4 :
I tried to run two of the applets in the examples directory of the distribution. I installed the WebLogic classes on my local machine (NT server) and on another machine (a Windows 95 client). I am not using any browsers, just trying to run the applets with Appletviewer. The applets work fine when I run Appletviewer from the NT server, but do not work at all from the Windows 95 client. ?
There are two possible problems: Either the CODEBASE tag is not properly set in the applet HTML file, or the class files are not properly loaded on the HTTP server.
The applet works on the NT server because you installed the WebLogic distribution on your NT server. Even if the applet cannot successfully load the necessary classes from the HTTP server, it does find them in your local CLASSPATH. But when you try to run it from the Windows 95 client, the applet must load the classes over the wire from the HTTP server, and if you haven't installed them correctly, it will fail.
Question 5 :
How do stubs work in a WebLogic Server cluster?
Clients that connect to a WebLogic Server cluster and look up a clustered object obtain a replica-aware stub for the object. This stub contains the list of available server instances that host implementations of the object. The stub also contains the load balancing logic for distributing the load among its host servers.