1. 1 INTRO TO BUSINESS COMPONENTS FOR JAVA (BC4J) Matt Fierst Computer Resource Team mjfierst@crtinc.com OracleWorld 2003 - Session 36321

2. 2 Why Should I Care? Efficiency Productivity Maintainability

3. 3 Topics What is BC4J? Why use BC4J? BC4J Architecture and Components Demo - BC4J in action

4. 4 What is BC4J? Database BC4J Java Application It is a bridge from the Relational world (database) to the Object world (Java)

5. 5 What is BC4J? “Business Components for Java is JDeveloper’s programming framework for building multi-tier database applications from reusable business components.”

6. 6 What is JDeveloper? Oracle’s Java and XML development suite Language-sensitive editors Java Compiler UML modeling tool Tools, frameworks, and utilities to help write your code Built-in web server and OC4J server to help test your code Debuggers and profilers to help perfect your code Wizards and utilities to help bundle and deploy your code

7. 7 What is a Business Component? Code that implements functionality associated with an application object –Java and XML –May interact with a database –May implement business rules Encapsulates your business logic Therefore, your presentation layer is much “cleaner” Reusable Flexible deployment –Deploy to client (e.g., application, applet) –Deploy to middle tier or database (e.g., servlet, JSP, Web Service, EJB, CORBA)

8. 8 BC4J is Part of JDeveloper “Programming Framework” Wizards and tools for defining, customizing and testing components Class library and custom JSP tags for developing your applications Use any front end you wish –JSP, Struts, etc –Swing –XML Deploy on any J2EE server

9. 9 Why Use BC4J? I could just as well do it all myself! –JDBC to connect to the database –java.sql.* or SQLJ to interact with the database Besides, Java itself promotes encapsulation, reusability, etc. True, but why re-invent the wheel?

10. 10 Why use BC4J? (cont.) Wizards let you declaratively define your business components –Specify the data you want (table, column) –BC4J generates the “plumbing” to interact with that table –You can focus on implementing your application-specifics

11. 11 Why use BC4J? (cont.) Tools help you use the components –oracle.jbo: library of classes to directly interact with them –Custom tag library to use in your JSPs Tags tied to Java classes Include the tag in your JSP, class methods are automatically invoked –BC4J can also generate a JSP app for you This is NOT magic, though! Quite simplistic However, it could be a great starting point

12. 12 Why use BC4J? (cont.) Gives you the option to better divide development responsibility –Java-savvy developers can focus on components –Web-savvy developers can focus on presentation layer Easier to learn the custom tags than to learn Java BC4J handles all the database connection details for you Built-in connection pooling

13. 13 Why use BC4J? (cont.) The downside: setting up these components takes time - planning and building –Depending on the application, and how it evolves, this could be time well spent –Isolation of business logic improves maintainability Of the business logic Of the presentation layer Of the back-end database The bottom line: Is BC4J right for EVERY application? –No –But, it’s a great tool to have in your toolbox!

14. 14 BC4J Architecture Database BC4J AM Application

15. 15 BC4J Architecture (cont.) Types of Components: –Application Module (AM) Container for organizing and deploying other components Provides run-time context for defining and executing transactions Takes care of database connections Takes care of Master-Detail coordination Takes care of row locking

16. 16 BC4J Architecture (cont.) Database BC4J AM Application EO VO

17. 17 BC4J Architecture (cont.) –Entity Object (EO) Provides a wrapper for database structures Create an EO for each table, view, or stored procedure EOs contain Attributes, corresponding to columns or procedure parameters –View Object (VO) Your application’s interface to the BC4J layer Hide the complexity of the database from the application Uses SQL query to specify filtered subsets of data from one or more EO VO Attributes correspond to EO Attributes Provide cached, navigable, modifiable result sets Provide runtime dynamic linking, sorting, and filtering

18. 18 BC4J Architecture (cont.) –Association Relationships between EOs Automatically created based on Foreign Keys Manually created based on common Attributes –View Link Relationships between VOs Enforce Master-Detail filtering –Domain User-defined data types for EO and VO Attributes Define in a central location: –Validation rules –Default values –Error messages

19. 19 DEMO Our JSP application: –Uses the “scott” schema –Displays employee/department data –We want to build a page to list “worker bees” Those employees who are not managers First, we’ll try a JDBC approach Then we’ll try two BC4J approaches –Create the components, manually write a JSP –Have JDeveloper generate a JSP application for us For instructions for this demo, and code snippets, download paper - Session 36321

20. 20 To Learn More JDeveloper on-line help is a great place to start JDeveloper samples –c:\jdev\BC4J\samples OTN - sample code –http://otn.oracle.com/sample- code/products/jdev/content.html