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Help is available for each task.



    Task 1

    [Modify the IDL file] First edit the IDL file. There is already a definition for the module and interface. The interface, however, does not have any way of setting a price quote of a stock. Within the interface definition, add an operation named setQuote(). It should take an in parameter of type Quote. Remember that these are IDL types, not Java types.


    The operation to add is:

    void set_quote(in Quote stock_quote);
    

    Task 2

    [Run IDL Compiler] At the command line, run the IDL compiler to generate Java code from the IDL file.
    Sun JavaIDLidltojava -fno-cpp stock.idl
    Inprise VisiBrokeridl2java stock.idl

    Task 3

    [Compile the generated Java code] Now compile the generated Java code using the standard Java compiler. Compile it in the generated StockObjects directory.

    Sun JavaIDL javac *.java
    Inprise VisiBroker vbjc *.java


    Task 4

    [Examine the generated Java files] All the files will be generated into the StockObjects directory because the IDL file defines a module StockObjects. (The purpose of each file is described in more detail in the course notes.)

    Look carefully at the file Stock.java - - this is the interface that you will have to implement.

    Task 5

    [Create "Impl" Classes] The skeleton code file we have given you, StockImpl.java has most of the implementation you will need. To finish, add a body to the method setQuote().

    Note: Be sure not to confuse the skeleton files that Magelang provides as part of out Magercises with CORBA skeleton files. The Magelang files appear as links at the beginning of the Magercise, and are files that you are to use as a starting point for coding. CORBA skeleton files are generated from IDL files, end with the name ImplBase and are used for creating classes that implement CORBA interfaces.


    An appropriate line of code to add is:
    _quote = quote;
    

    Task 6

    [Create Server Class] Now look at the file StockServer.java. This class is a java application that starts up the orb, instantiates a StockImpl instance, connects it to the ORB, and prints out a stringified reference to it.

    There is nothing for you to do except look at the file. Look carefully at each line.

    Task 7

    [Create Client Class] In the file StockClient.java, you will find code to instantiate the orb, read in a stringified reference to the remote object, and call the getQuote operation on it. Again, there is nothing for you to do except look at the file. Look carefully at each line.

    Note: Most of the Magercises are applications that have separate "server" and "client" portions. The server portions instantiate distributed objects, the client portions use them. This is not a requirement of CORBA programs, any application that is part of a CORBA environment can both instantiate and use distributed objects. The client and server pattern is used by the Magercises for convenience and consistency. Some later Magercises dispense with this convention entirely.

    Task 8

    [Compile the program] Now compile the program using the standard Java compiler.

    Sun JavaIDLjavac -classpath . *.java
    Inprise VisiBrokervbjc *.java


    Task 9

    [Run the Server program]

    The server needs to run as a separate process. In DOS/Windows, you will use the start command. In UNIX, you will use the & (ampersand).

    The Server outputs an IOR (or stringified reference) to a file and to the console for the Stock object it creates. The name of the file is passed as the first argument to the server.

    To run the server, use the normal java command. If you are using VisiBroker, you can use the vbj command instead. vbj is just like java, except it sets up the CLASSPATH variables automatically.

    Putting it all together:
    Sun JavaIDL
    java -cp . StockServer gii.ior
    Inprise VisiBroker
    vbj StockServer gii.ior


    Task 10

    [Run the Client program]

    The client reads the stringified object reference of the stock object created by your server. A file containing the stringified object reference is passed as an argument to the client.

    Sun JavaIDL java -cp . StockClient gii.ior
    Inprise VisiBroker vbj StockClient gii.ior


    Task 11

    [Kill the Server] Don't forget to kill the server.


Copyright © 1998-1999 MageLang Institute. All Rights Reserved.


[ This page was updated: 6-Dec-99 ]

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