QUESTION: What is EJB QL?
ANSWER: EJB QL is a Query Language provided for navigation across a network of enterprise beans and dependent objects defined by means of container managed persistence. EJB QL is introduced in the EJB 2.0 specification. The EJB QL query language defines finder methods for entity beans with container managed persistenceand is portable across containers and persistence managers. EJB QL is used for queries of two types of finder methods: Finder methods that are defined in the home interface of an entity bean and which return entity objects. Select methods, which are not exposed to the client, but which are used by the Bean Provider to select persistent values that are maintained by the Persistence Manager or to select entity objects that are related to the entity bean on which the query is defined.
QUESTION: What technologies are included in J2EE?
ANSWER: The primary technologies in J2EE are: Enterprise JavaBeansTM (EJBsTM), JavaServer PagesTM (JSPsTM), Java Servlets, the Java Naming and Directory InterfaceTM (JNDITM), the Java Transaction API (JTA), CORBA, and the JDBCTM data access API.
QUESTION: What is the Java Authentication and Authorization Service (JAAS) 1.0?
ANSWER: The Java Authentication and Authorization Service (JAAS) provides a way for a J2EE application to authenticate and authorize a specific user or group of users to run it. JAAS is a Java programing language version of the standard Pluggable Authentication Module (PAM) framework that extends the Java 2 platform security architecture to support user-based authorization.
QUESTION: Must my bean-managed persistence mechanism use the WebLogic JTS driver?
ANSWER: BEA recommend that you use the TxDataSource for bean-managed persistence.
QUESTION: Must EJBs be homogeneously deployed across a cluster? Why?
ANSWER: Yes. Beginning with WebLogic Server version 6.0, EJBs must be homogeneously deployed across a cluster for the following reasons:
To keep clustering EJBs simple
To avoid cross server calls which results in more efficiency. If EJBs are not deployed on all servers, cross server calls are much more likely.
To ensure that every EJB is available locally
To ensure that all classes are loaded in an undeployable way
Every server must have access to each EJB's classes so that it can be bound into the local JNDI tree. If only a subset of the servers deploys the bean, the other servers will have to load the bean's classes in their respective system classpaths which makes it impossible to undeploy the beans.
QUESTION: Is an XSLT processor bundled in WebLogic Server?
ANSWER: Yes, we bundle an XSLT processor, based on Apache's Xalan 2.0.1 processor, in WebLogic Server 6.1.
QUESTION: How do I increase WebLogic Server memory?
ANSWER: Increase the allocation of Java heap memory for WebLogic Server. (Set the minimum and the maximum to the same size.) Start WebLogic Server with the -ms32m option to increase the allocation, as in this example:
$ java ... -ms32m -mx32m ...
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.
QUESTION: What causes Java.io exceptions in the log file of WebLogic Server?
ANSWER: You may see messages like these in the log file:
(Windows NT)
java.io.IOException Connection Reset by Peer
java.io.EOFException Connection Reset by Peer
(Solaris)
java.io.Exception: Broken pipe
These messages occur when you are using servlets. A client initiates an HTTP request, and then performs a series of actions on the browser:
1. Click Stop or enter equivalent command or keystrokes
2. Click Refresh or enter equivalent command or keystrokes
3. Send a new HTTP request.
The messages indicate that WebLogic Server has detected and recovered from an interrupted HTTP request.
QUESTION: What is the function of T3 in WebLogic Server?
ANSWER: 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
A browser and WebLogic Server-use HTTP
An ORB and WebLogic Server-IIOP.
