CD Database Server (CDDB) Zachary Carter Alan Savage Diana Abbas Kyle Dorman

What Does a CDDB Server Do? Provides Internet-based access to CD database Database Provides music CD information –Artist –Track Titles –Release Date Because most music CDs do not have this information

Why Another CDDB Server? Gracenote denies non-certified music players, and only supports CDDB2 Gracenote is not free Provide a platform independent server Provide an alternative when other free databases are down

Implementation CDDB level 1 protocol –A text-based protocol TCP/IP connection MySQL and Enterprise JavaBeans (EJB) manage database OpenEJB Container

Data Flow CD Player Protocol Server MySQL Server EJB

Music Player Must Support CDDBP level 1 Client Configuration –Connect via TCP/IP to CDDB server

Server CD Player connects to multithreaded server Server instantiates a client thread Client thread sends and receives data to the CD player Client thread uses ServerProtocol to process CD player requests Client thread dies when transactions finish

ServerProtocol Implements CDDBP level 1 protocol Parses and interprets client requests Provides appropriately formatted responses Requests CD database information from EJBClient

What is an EJB? Enterprise Java Bean Server-side objects Aids in transactions between client and database Consists of methods that encapsulate business logic

EJB Architecture Three tiers: –The client (makes calls to remote EJBs) –The EJB server (where the container resides) –The database (EJB business methods directly accesses database)

EJB Container Provides support for: –Transactions –Persistence –Management of multiple instances of a given bean –Concurrent execution of many beans –Keeping track of their state Does not allow the bean to be accessed directly from the client Protects the bean from the client

EJB Analogy EJB Bean EJB Container EJB Server Operating System Applications Programs Operating System BIOS Hardware Layering in EJBs Layering in typical operating system

A High-Level View of an EJB Conversation Finding the bean Getting access to a bean Calling the bean’s methods

EJB Conversation Finding a bean: Java Naming and Directory Interface (JNDI) Access to a bean: Home Interface Calling the bean’s methods: Remote Interface Analogous to JNDI: DNS translation from symbolic names

Entity Beans Track beans and CDAlbum beans Life cycle includes: –Nonexistence –Pooled (Beans exist in the container with no identity) –Ready (Business methods can be invoked)

MySQL An opensource database Data elements are organized using primary keys generated by MySQL database SQL statements inserts data into the database using a script

Advantages of EJB’s Transaction processing Persistent storage of objects Platform independence Multitiered architecture “Write once, run anywhere”

Visions Implement higher level CDDB protocols Implement a façade pattern Index database by discid Implement search features –Artist, disc title, track name, genre Add file logging –Usage Statistics Create a server side GUI

The End! Questions?