CS520 HW2

Homework 2
CS520, Spring 2007

Due: Friday, April 20

Package all the source files of your project into a zip file using the zip Ant target you developed in Homework 1, and upload the zip file to CSNS. Note that file uploading will be disabled automatically after 11:59PM of the due date, so please turn in your work on time.

[Reading]

Hibernate Book (Java Persistence with Hibernate)

Chapter 1-6 (or corresponding chapters in Hibernate in Action). You may skip anything related to XDoclet, Annotation, JPA, and EJB.

Hibernate Documentation

Chapter 20.1.1 Customizing the schema

CSNS Source Code

DAO classes and interfaces under src/csns/model/dao
Hibernate mapping files under src/hbm

[Mailing Lists]

Mailing Lists is a new component of CSNS which you will develop in this quarter. In this assignment you are going to implement the "model" classes and database access for this component, and your design should be based on the following requirements:

Any user can create mailing lists. The user who creates a mailing list becomes the owner of the mailing list, and is automatically subscribed to the list.
A user can subscribe to any existing mailing list and become a subscriber of the mailing list.
A subscriber of a mailing list may unsubscribe from a mailing list. The owner of the mailing list can unsubscribe any subscriber of the list except him or herself.
A user can view existing mailing lists. For example:

Name	Description	Owner	Created On	# of Subscribers	Subscribe/Unsubscribe
csns-announcements	Announcements related to CSNS.	cysun	03/10/2007	20	-
cs101-s07	CS101 Spring 2007 Class Mailing List.	i0001	03/22/2007	15
j2ee-discussion	Anything related to J2EE development.	s0030	02/01/2007	30

Any subscriber of a mailing list can send messages to the mailing list. The message must be sent using CSNS, i.e. not using an external email client. The message will be mailed by CSNS to the subscribers of the mailing list, and a copy of the message will be saved in the database.
A user may view the messages sent to a mailing list. For example:

csns-announcements:

Subject	Sent by	Date
CSNS server will be down for maintenance on April 9, 2007	cysun	04/02/2007
New features added	cysun	03/10/2007

[Model] (20pt)

Create two Java classes MailingList and Message. Note that in this assignment, you do not need to implement any of the operations described above; however, you must design the classes with proper fields and methods so that these operations can be implemented later. For example, in order to send a message to the subscribers of a mailing list, the MailingList class must keep, at least, the email addresses of the subscribers. Also note that

You may need to modify existing classes, e.g. User.
MailingList and Message should be in the package csns.model.mailinglist.
MailingList must implement the interface Subscription, which defines the basic operations that all subscribable things like mailing lists, forums, and RSS feeds must support. A failed operation should throw a SubscriptionException, which is a subclass of java.lang.RuntimeException. You may add more methods to Subscription if necessary.

[Design Issues] (10pt)

Compare the pros and cons of the following three class designs:

1.	public class MailingList { List<Message> messages; // messages sent to this mailing list // other fields and methods ... ... }	public class Message { MailingList mailingList; // the mailing list to which this message was sent // other fields and methods ... ... }
2.	public class MailingList { List<Message> messages; // messages sent to this mailing list // other fields and methods ... ... }	public class Message { // other fields and methods ... ... }
3.	public class MailingList { // other fields and methods ... ... }	public class Message { MailingList mailingList; // the mailing list to which this message was sent // other fields and methods ... ... }

[Database Schema] (20pt)

Create Hibernate mapping files for MailingList and Message. Use the hbm2ddl Ant target to generate the database schema into the SQL script file db/csns.ddl. Once you are happy with the database schema, modify db/csns-create.sql accordingly.

Note that to receive full credit for this problem, you must specify proper database integrity constraints (not null, unique, foreign key etc.) in the Hibernate mapping files.

[DOA] (30pt)

Use Hibernate to implement the DAO classes for MailingList and Message. In particular, MailingListDaoImpl must implements the MailingListDao interface, and MessageDaoImpl must implements the MessageDao interface. You may add or remove methods in these interfaces base on your class design.

[Subversion]

Commit all the changes to your Subversion repository, and create a tag called cs520-hw2.