Connection Basics

The examples in Chapter 3, "Developing CORBA Applications" and Chapter 2, "Enterprise JavaBeans" showed how to connect to Oracle, start a database server session, and activate a CORBA server object or an EJB, using a single URL specification. In the client examples, connection and object look up was done as follows:

1. Hashtable env = new Hashtable();
2. env.put(javax.naming.Context.URL_PKG_PREFIXES, "oracle.aurora.jndi");
3. env.put(javax.naming.Context.SECURITY_PRINCIPAL, username);
4. env.put(javax.naming.Context.SECURITY_CREDENTIALS, password);
5. env.put(javax.naming.Context.SECURITY_AUTHENTICATION, ServiceCtx.NON_SSL_LOGIN);
6. Context ic = new InitialContext(env);
7. myHello hello =
    (myHello) ic.lookup("sess_iiop://localhost:2481:ORCL/test/myHello");
8. System.out.println(hello.helloWorld());
    

        

In this example there are four basic operations:

• Lines 1-5 set up an environment for the JNDI initial context.

• Line 6 creates the JNDI initial context.

• Line 7 looks up a published object. (See "URL Syntax" for a discussion of the URL syntax.)

• Line 8 invokes a method on the object.

In line 7 above, when a client looks up an object, the client and server are doing a lot of things automatically:

• On the lookup() invocation, a session IIOP connection is made to the ORCL instance of the localhost database.

• The server establishes a database session.

• The client is authenticated, using the NON_SSL_LOGIN protocol, with the username and password specified in the environment context.

• Using the CosNaming service, the client locates the published object /test/myHelloServer in the session namespace.

• On a client method invocation, the server activates the object and registers it with the basic object adapter (BOA).

• The client-side ORB narrows the object to the correct type, using the helper class that was published along with /test/myHello.

When the object reference is returned, the client can invoke a method such as helloWorld() on the activated, narrowed object, as in line 8 above. This example shows a CORBA server object being looked up and activated, but a similar set of steps, including the narrowing, occurs when an EJB is activated through its home interface.

In the remainder of this chapter the connection, service and session context establishment, and authentication steps are broken out and described separately. There are many code examples to show you how to control session invocation in a much finer-grained way than in the basic example above.

This chapter also describes various kinds of client authentication in addition to the NON_SSL_LOGIN method that the basic examples use. This chapter also discusses other aspects of security.

---