Terminology

This section defines some of the basic terms that are used in this chapter. See also Appendix D, "Abbreviations and Acronyms" for a list of common acronyms used in Java and distributed object computing.

client

A client is an object, an application, or an applet that makes a request of a server object. It is important to remember that a client need not be a Java application running on a workstation or a network computer. Nor an applet downloaded by a web browser. A server object can be a client of another server object. "Client" refers to a role in a requestor/server relationship, not to a physical location or a kind of computer system.

marshalling

In distributed object computing, marshalling refers to the process by which the ORB passes requests and data between clients and server objects.

object adapter

Each CORBA ORB implements an object adapter (OA), which the interface between the ORB and the message-passing objects. CORBA 2.0 specifies that a basic object adapter (BOA) must exist, but most of the details of its interface are left up to individual CORBA vendors. Future CORBA standards will require a vendor-neutral portable object adapter (POA). Oracle intends to support a POA in a future release.

request

A request is a method invocation. Other words and phrases that are sometimes used in its stead are method call and message.

server object

A CORBA server object is a Java object that is activated by the server, typically on a first request from a client.

session

A session always means a database session. It is conceptually the same kind of session as that established when a tool such as SQL*Plus connects to Oracle. The differences in the CORBA case are:

• The database session is established using the IIOP protocol, while a SQL*Plus session is established using the Net8 TTC protocol.

• An IIOP session is handled by a Java virtual machine (JVM) that runs in the database server.

Important Note: To use CORBA with Oracle8i, the database must be configured so that the listener can recognize incoming IIOP requests, in addition to TTC requests. DBAs and system administrators should see the Net8 Administrator's Guide for information on setting up the database and the listener to accept incoming IIOP requests.

See Chapter 4, "Connections and Security", for more information about sessions.

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