EMIT CLIENT AND SERVER BINDINGS¶

The following idlj command generates an IDL file named My.idl with client-side bindings.

idlj My.idl

The previous syntax is equivalent to the following:

idlj -fclient My.idl

The next example generates the server-side bindings, and includes the client-side bindings plus the skeleton, all of which are POA (Inheritance Model).

idlg -fserver My.idl

If you want to generate both client and server-side bindings, then use one of the following (equivalent) commands:

idlj -fclient -fserver My.idl

idlj -fall My.idl

There are two possible server-side models: the Portal Servant Inheritance Model and the Tie Model. See Tie Delegation Model.

Portable Servant Inheritance Model. The default server-side model is the Portable Servant Inheritance Model. Given an interface My defined in My.idl, the file MyPOA.java is generated. You must provide the implementation for the My interface, and the My interface must inherit from the MyPOA class. MyPOA.java is a stream-based skeleton that extends the org.omg.PortableServer.Servant class at http://docs.oracle.com/javase/8/docs/api/org/omg/PortableServer/Servant.html The My interface implements the callHandler interface and the operations interface associated with the IDL interface the skeleton implements.The PortableServer module for the Portable Object Adapter (POA) defines the native Servant type. See Portable Object Adapter (POA) at http://docs.oracle.com/javase/8/docs/technotes/guides/idl/POA.html In the Java programming language, the Servant type is mapped to the Java org.omg.PortableServer.Servant class. It serves as the base class for all POA servant implementations and provides a number of methods that can be called by the application programmer, and methods that are called by the POA and that can be overridden by the user to control aspects of servant behavior.Another option for the Inheritance Model is to use the -oldImplBase flag to generate server-side bindings that are compatible with releases of the Java programming language before Java SE 1.4. The -oldImplBase flag is nonstandard, and these APIs are deprecated. You would use this flag only for compatibility with existing servers written in Java SE 1.3. In that case, you would need to modify an existing make file to add the -oldImplBase flag to the idlj compiler. Otherwise POA-based server-side mappings are generated. To generate server-side bindings that are backward compatible, do the following:

idlj -fclient -fserver -oldImplBase My.idl

idlj -fall -oldImplBase My.idl

Given an interface My defined in My.idl, the file _MyImplBase.java is generated. You must provide the implementation for the My interface, and the My interface must inherit from the _MyImplBase class.

Tie Delegation Model. The other server-side model is called the Tie Model. This is a delegation model. Because it is not possible to generate ties and skeletons at the same time, they must be generated separately. The following commands generate the bindings for the Tie Model:

idlj -fall My.idl

idlj -fallTIE My.idl

For the My interface, the second command generates MyPOATie.java. The constructor to the MyPOATie class takes a delegate. In this example, using the default POA model, the constructor also needs a POA. You must provide the implementation for the delegate, but it does not have to inherit from any other class, only the interface MyOperations. To use it with the ORB, you must wrap your implementation within the MyPOATie class, for example:

ORB orb = ORB.init(args, System.getProperties());

// Get reference to rootpoa & activate the POAManager

POA rootpoa = (POA)orb.resolve_initial_references("RootPOA");

rootpoa.the_POAManager().activate();

// create servant and register it with the ORB

MyServant myDelegate = new MyServant();

myDelegate.setORB(orb); 

// create a tie, with servant being the delegate.

MyPOATie tie = new MyPOATie(myDelegate, rootpoa);

// obtain the objectRef for the tie

My ref = tie._this(orb);

You might want to use the Tie model instead of the typical Inheritance model when your implementation must inherit from some other implementation. Java allows any number of interface inheritance, but there is only one slot for class inheritance. If you use the inheritance model, then that slot is used up. With the Tie Model, that slot is freed up for your own use. The drawback is that it introduces a level of indirection: one extra method call occurs when a method is called.

For server-side generation, Tie model bindings that are compatible with versions of the IDL to Java language mapping in versions earlier than Java SE 1.4.

idlj -oldImplBase -fall My.idl

idlj -oldImplBase -fallTIE My.idl

For the My interface, the this generates My_Tie.java. The constructor to the My_Tie class takes an impl object. You must provide the implementation for impl, but it does not have to inherit from any other class, only the interface HelloOperations. But to use it with the ORB, you must wrap your implementation within My_Tie, for example:

ORB orb = ORB.init(args, System.getProperties());

// create servant and register it with the ORB

MyServant myDelegate = new MyServant();

myDelegate.setORB(orb); 

// create a tie, with servant being the delegate.

MyPOATie tie = new MyPOATie(myDelegate);

// obtain the objectRef for the tie

My ref = tie._this(orb);

SPECIFY ALTERNATE LOCATIONS FOR EMITTED FILES¶

If you want to direct the emitted files to a directory other than the current directory, then call the compiler this way: idlj -td /altdir My.idl.

For the My interface, the bindings are emitted to /altdir/My.java, etc., instead of ./My.java.

SPECIFY ALTERNATE LOCATIONS FOR INCLUDE FILES¶

If the My.idl file includes another idl file, MyOther.idl, then the compiler assumes that the MyOther.idl file resides in the local directory. If it resides in /includes, for example, then you call the compiler with the following command:

idlj -i /includes My.idl

If My.idl also included Another.idl that resided in /moreIncludes, for example, then you call the compiler with the following command:

idlj -i /includes -i /moreIncludes My.idl

Because this form of include can become long, another way to indicate to the compiler where to search for included files is provided. This technique is similar to the idea of an environment variable. Create a file named idl.config in a directory that is listed in your CLASSPATH variable. Inside of idl.config, provide a line with the following form:

includes=/includes;/moreIncludes

The compiler will find this file and read in the includes list. Note that in this example the separator character between the two directories is a semicolon (;). This separator character is platform dependent. On the Windows platform, use a semicolon, on the Unix platform, use a colon, and so on.

EMIT BINDINGS FOR INCLUDE FILES¶

By default, only those interfaces, structures, and so on, that are defined in the idl file on the command line have Java bindings generated for them. The types defined in included files are not generated. For example, assume the following two idl files:

My.idl file:

#include <MyOther.idl>

interface My

{

};

MyOther.idl file:

interface MyOther

{

};

There is a caveat to the default rule. Any #include statements that appear at the global scope are treated as described. These #include statements can be thought of as import statements. The #include statements that appear within an enclosed scope are treated as true #include statements, which means that the code within the included file is treated as though it appeared in the original file and, therefore, Java bindings are emitted for it. Here is an example:

My.idl file:

#include <MyOther.idl>

interface My

{

  #include <Embedded.idl>

};

MyOther.idl file:

interface MyOther

{

};

Embedded.idl

enum E {one, two, three};

Runidlj My.idlto generate the following list of Java files. Notice that MyOther.java is not generated because it is defined in an import-like #include. But E.java was generated because it was defined in a true #include. Notice that because the Embedded.idl file is included within the scope of the interface My, it appears within the scope of My (in MyPackage). If the -emitAll flag had been used, then all types in all included files would have been emitted.

./MyHolder.java

./MyHelper.java

./_MyStub.java

./MyPackage

./MyPackage/EHolder.java

./MyPackage/EHelper.java

./MyPackage/E.java

./My.java

INSERT PACKAGE PREFIXES¶

Suppose that you work for a company named ABC that has constructed the following IDL file:

Widgets.idl file:

module Widgets

{

  interface W1 {...};

  interface W2 {...};

};

If you run this file through the IDL-to-Java compiler, then the Java bindings for W1 and W2 are placed within the Widgets package. There is an industry convention that states that a company's packages should reside within a package named com.<company name>. To follow this convention, the package name should be com.abc.Widgets. To place this package prefix onto the Widgets module, execute the following:

idlj -pkgPrefix Widgets com.abc Widgets.idl

If you have an IDL file that includes Widgets.idl, then the -pkgPrefix flag must appear in that command also. If it does not, then your IDL file will be looking for a Widgets package rather than a com.abc.Widgets package.

If you have a number of these packages that require prefixes, then it might be easier to place them into the idl.config file described previously. Each package prefix line should be of the form: PkgPrefix.<type>=<prefix>. The line for the previous example would be PkgPrefix.Widgets=com.abc. This option does not affect the Repository ID.

DEFINE SYMBOLS BEFORE COMPILATION¶

You might need to define a symbol for compilation that is not defined within the IDL file, perhaps to include debugging code in the bindings. The command idlj -d MYDEF My.idlis equivalent to putting the line #define MYDEF inside My.idl.

PRESERVE PREEXISTING BINDINGS¶

If the Java binding files already exist, then the -keep flag keeps the compiler from overwriting them. The default is to generate all files without considering that they already exist. If you have customized those files (which you should not do unless you are very comfortable with their contents), then the -keep option is very useful. The command idlj -keep My.idl emits all client-side bindings that do not already exist.

VIEW COMPILATION PROGRESS¶

The IDL-to-Java compiler generates status messages as it progresses through its phases of execution. Use the -v option to activate the verbose mode: idlj -v My.idl.

By default the compiler does not operate in verbose mode

DISPLAY VERSION INFORMATION¶

To display the build version of the IDL-to-Java compiler, specify the -version option on the command-line: idlj -version.

Version information also appears within the bindings generated by the compiler. Any additional options appearing on the command-line are ignored.