SSD08 Exercise05 个人解答

 

CORBA Distributed To-Do List

Readings: Reilly and Reilly, chapter 12 JavaTM IDL Technology Documentation at http://java.sun.com/j2se/1.5/docs/guide/idl/index.html . These readings describe a variety of ways in which Java and CORBA interact, and give an introduction to using IDL and CORBA.

Background

Build a distributed to-do list using Java and CORBA. Various clients should be able to connect to a server managing various to-do list objects to query list items, add list items, delete list items, and clear to-do lists. The server should also have management functionality that allows member registration. Each to-do list item has a description, and a start time and an end time in which users must complete their items. Users should be able to add any number of items to their to-do lists.

Tasks

For this programming exercise, we will be using JavaSoft's Java IDL, which is a CORBA ORB written completely in Java. The advantages of Java's IDL are that it is free and very portable. Its disadvantage is that its functionality is minimal. However, it supports static method invocations, and it has a naming service, which is all we need for this programming exercise. The Java IDL compiler (idlj ) is packaged with the latest version of Java (1.4.2 as of the time of this writing). You may find documentation for the idlj compiler here.

Your to-do list should implement the following functionality. Each piece of functionality outlined below must be accessible from the client using the CORBA naming service. Each user's to-do list must be a separate object that is managed using CORBA.

User Registration

New users may register. New users must supply a user name and a password. If the supplied user name is already in use by some other user, print an error message. Upon successful registration, print a message stating so. A new user registration should create a new to-do list object for the user.

Adding Items

Registered users may add items to their to-do list. Each item has a start time and an end time. Parameters should include the start and end times, and a label. The user should receive a message indicating a successful addition or an error if one occurs.

Querying Items

Registered users may look up all items in their to-do list in a given interval of time. The parameters should include the start and end times of the search interval. Return a list of the entries found in the specified time range. In the list, include the start time, end time, and label of each item.

Deleting Items

Registered users may delete items from their to-do list. The parameters should uniquely identify the entry to be deleted.

Clearing Items

Registered users may clear all items from their to-do list.

Interface

Your client must be accessible via a simple console-based menu.

Implementation

To complete this assignment, you will need to manage multiple CORBA objects using the CORBA naming service. For each user that successfully registers, you must create a new to-do list and add it to the CORBA naming service. To that end, you will need to write a to-do list creator that creates to-do lists and adds them to the CORBA naming system. The to-do list creator must be also be accessible using the CORBA naming service. Therefore, if there are n to-do list system users, CORBA must manage n+1 CORBA objects — one to-do list object for each user plus the creator object. You will need to perform the following tasks to complete this assignment.

• Write a to-do list creator object that creates to-do lists upon a successful user registration and adds the to-do list objects to the CORBA naming service.
• Casting the to-do list object to a generic Java object and generating the IDL description of the interfaces.
• Write a simple CORBA client that exercises the main methods of the to-do list and to-do list creator CORBA object.
• Deploying and running the system. You should run a test involving two or more agenda objects, keeping track of the agendas of different users. The client should use the CORBA naming service to find the appropriate agenda object.

Submission

Coding Style and Documentation

You are expected to design classes in an object-oriented manner using good programming practices.

Your code must be written using Java coding conventions . Your code must be well documented and contain a README file with instructions on compiling and running each program.

The files you should turn in are listed below.

• Submit all files necessary to run your to-do list.
• A README file.

To help yourself do your best on this assessment, consult this general list of grading guidelines.