Chapter 32 Creating and Using EAServer Pseudocomponents

Instantiating pseudocomponents

To instantiate a pseudocomponent, call the ORB.object_to_string method, passing a URL that specifies the information required to load the component. Java, C++, and ActiveX all use a variation of this method.

Pseudocomponent object URLs

The object URL for a pseudocomponent specifies the shared library file or Java class that contains the implementation, the EAServer package name, and the EAServer component name.

Identifying a C++ pseudocomponent

To identify a C++ pseudocomponent, format a URL as follows:

pseudo://cpp/library/package/component

Where:

library is the base name of the shared library or DLL that contains the component implementation, for example, mypseudo to indicate a file named mypseudo.dll. The location of the library must be specified in the system's library search path.
package is the Jaguar Manager package name.
component is the Jaguar Manager component name.

Identifying a Java pseudocomponent

To identify a Java pseudocomponent, format a URL as follows:

pseudo://java/java-package/jaguar-package/component

Where:

java-package is the is the dot-notation name of the Java package that contains the component skeleton. This package is the same as the package used by the implementation class. For example, if the implementation class is com.sybase.sample.MyJavaPseudo, specify com.sybase.sample as the Java package name. The code base under which the class is deployed must be specified in the CLASSPATH.
jaguar-package is the Jaguar Manager package name.
component is the Jaguar Manager component name.

Instantiating pseudocomponents from Java

Java applications or EAServer Java components can instantiate pseudocomponents implemented in Java or C++. Java applets cannot instantiate pseudocomponents. In order to instantiate a C++ pseudocomponent, the environment for a Java application must include all the settings required by the EAServer C++ client runtime, and the location of the library must be specified in the system's library search path. Java stub classes for the pseudocomponent must be available.

You can instantiate a pseudocomponent any time after initializing and instantiating an ORB instance. Call the ORB.string_to_object method, passing a URL formatted as described in "Pseudocomponent object URLs". Narrow the returned object to an interface supported by the component. See Chapter 12, "Creating CORBA Java Clients" for more information on the ORB interface and narrowing objects to an interface.

Example: instantiating a C++ pseudocomponent

The following fragment instantiates a pseudocomponent proxy for a C++ component in the DLL CppPseudo.dll that is installed in the package Demo and has component name PseudoCpp. The returned object is narrowed to Arithmetic interface. On UNIX platforms, this syntax also works for a shared library with base name "CppPseudo", as in CppPseudo.so.

String url = "pseudo://cpp/CppPseudo/Demo/PseudoCPP";
_comp = ArithmeticHelper.narrow(
  orb.string_to_object(url) );

Example: instantiating a Java pseudocomponent

The following fragment instantiates a pseudocomponent proxy for a Java component. The implementation class and skeleton class are in the Java package Sample.PseudoComponents. The component is installed in the EAServer package Demo and has component name PseudoJava. The returned object is narrowed to Arithmetic interface.

String url =   "pseudo://java/Sample.PseudoComponents/Demo/PseudoJava";
_comp = ArithmeticHelper.narrow(
  orb.string_to_object(url) );

Instantiating pseudocomponents from C++

C++ standalone programs or EAServer components can instantiate pseudocomponents implemented in C++. Pseudocomponents implemented in Java can be instantiated only by C++ components that are executing in EAServer.

In order to instantiate a C++ pseudocomponent in a standalone program, the environment must include all the settings required by the EAServer C++ client runtime, and the location of the library must be specified in the system's library search path.

You can instantiate a pseudocomponent any time after initializing and instantiating an ORB instance. Call the ORB.string_to_object method, passing a URL formatted as described in "Pseudocomponent object URLs". Narrow the returned object to an interface supported by the component. See Chapter 15, "Creating CORBA C++ Clients" for more information on the ORB interface and narrowing objects to an interface.

Example: instantiating a C++ pseudocomponent

The following fragment instantiates a pseudocomponent proxy for a C++ component in the DLL CppPseudo.dll that is installed in the package Demo and has component name PseudoCpp. The returned object is narrowed to PseudocomponentDemo::Arithmetic interface. On UNIX platforms, this syntax also works for a shared library with base name "CppPseudo", as in CppPseudo.so.

String url = "pseudo://cpp/CppPseudo/Demo/PseudoCPP";
obj = orb->string_to_object(url);
PseudocomponentDemo::Arithmetic_var arith = 
  PseudocomponentDemo::Arithmetic::_narrow(obj);

Example: instantiating a Java pseudocomponent

String url =   "pseudo://java/Sample.PseudoComponents/Demo/PseudoJava";
obj = orb->string_to_object(url);
PseudocomponentDemo::Arithmetic_var arith = 
  PseudocomponentDemo::Arithmetic::_narrow(obj);