1 / 69

Course #3036 Enterprise Java Beans

Course #3036 Enterprise Java Beans. Patrick W. McMichael Pillar Technology Group, LLC. Your Expectations. Who are you? Where are you from? What is your role? Why are you here at this tutorial? What business challenges are you hoping J2EE can help with?. My Expectations.

biana
Download Presentation

Course #3036 Enterprise Java Beans

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Course #3036Enterprise Java Beans Patrick W. McMichael Pillar Technology Group, LLC

  2. Your Expectations • Who are you? Where are you from? What is your role? • Why are you here at this tutorial? • What business challenges are you hoping J2EE can help with?

  3. My Expectations • NO head-nodding -- if in doubt, ASK! • DON’T be shy! I’m going to need your help this afternoon! • Think about how the concepts presented might be applied in your domain.

  4. Agenda • The role of the container • Bean Basics • A Closer Look… • Entity Beans • Session Beans • Message Driven Beans • Bean Info You Shouldn’t Leave Home Without • JNDI • JNDI ENC • Transactions • Exceptions • Coming Soon to a Container Near You! (EJB 2.1/3.0)

  5. eFlix Online Rental System

  6. eFlix Online Rental System

  7. 7 Primary Services (Monson-Haefel) • Concurrent access to system resources • Transaction management • Persistence • Object distribution / Location transparency • Naming / Object binding • Security • Asynchronous messaging

  8. Tell Me About It! How have your apps depended on these services?

  9. Approach #1 -- The MACHO Way “I coded my app…” • with vi • by candlelight • on the last ounce of laptop battery juice • barefoot • using a dial-up connection

  10. Approach #2: The time-to-market way

  11. How do you configure / manage these services? • Programmatically • Declaratively • UUM Example • intranet deployment • extranet deployment

  12. Questions • What’s the point of using a J2EE container? What does it buy you? • What’s the advantage of declarative configuration of an app’s behavior vs. programmatic configuration?

  13. Bean Basics EXAMPLE: The Rental Manager EJB

  14. Break That Bean Down! • RentalManagerHome • RentalManager • RentalManagerBean • Developer Written Code vs. Generated Code • javac vs. EJB Compiler

  15. WHY All These Classes? • Remember the primary services? • Example: “Going on a Date

  16. EJB Server Client EJB Container Home Stub Remote / Local Home Interface EJB Home Remote / Local Home Interface EJB Object Object Stub Bean Instance Remote / Local Interface Remote / Local Interface Client Calls to Session/Entity Beans

  17. The Special Case of the MDB Hey You!

  18. Remote vs. Local Interfaces • The expense of RMI, Serialization, etc. • Proprietary Optimizations • Planned Localization

  19. Remote vs. Local Interfaces --Delegated Calls

  20. Remote vs. Local Interfaces --Session Façade w/ Entity Beans

  21. Questions • Which parts of an EJB does a developer have to create? • What’s the point of the “egg yolk/eyeball” diagram? • What’s unique about MDB’s? • What’s the difference between remote and local interfaces? • When would you use one, the other, or both?

  22. Bean Types Entity Beans

  23. Entity Beans • Encapsulate key NOUN entities in the problem domain • eFlix Entity Bean Candidates • Persistence -- CMP vs. BMP • CMR -- introduced in EJB 2.0 • EJB QL -- also brought in by the 2.0 spec • * (shameless plug for 3138…)

  24. Entity Bean Example • TitleHome -- Local Home Interface • create methods • find methods • remove • Title -- Local “Business” Interface • getters • setters • TitleBean -- Bean Implementation Class • ejbCreate counterparts to Home Interface • lifecycle/callback method implementation • getters/setters and the abstract persistence schema

  25. Entity Bean CMR Example

  26. Entity Bean Example -- EJB QL • EJB 2.0’s EJB QL provides a non-proprietary, declarative way of mapping custom finders (i.e. not by primary key) to their implementation. • findUnitsForTitleByStatus method on TitleUnitHome • SELECT OBJECT(u) FROM TitleUnit AS u WHERE u.title.productNumber = ?1 AND u.status = ?2

  27. Entity Bean Example -- EJB QL • SELECT OBJECT(u) FROM TitleUnit AS u WHERE u.title.productNumber = ?1 AND u.status = ?2 • “TitleUnit” -- Abstract Schema Name • u -- AS clause, object usage, references • u.status -- drill down to field value • u.title.productNumber -- carry across CMR objects

  28. The Entity Bean Lifecycle

  29. Entity Beans vs. Straight JDBC • Simultaneous access to large volumes of entities -- POOL EXAMPLE -- NEED MORE OR LESS WILLING VOLUNTEERS! • Simultaneous access to same data at the same time by multiple clients (potential blocking issues) • Optimistic Concurrency • DB Schema -- stable or still in flux? • Session Façade Pattern -- clients shouldn’t know or care if entity beans JDBC, JDO, Hibernate, etc. was used.

  30. Bean Types Session Beans

  31. Session Beans • Handle things like... • business logic • workflow • Come in two varieties • Stateless • Stateful

  32. Session Beans

  33. Stateless Session Bean Lifecycle

  34. Stateful Session Bean Lifecycle

  35. Stateless Session Bean Advantages • NO Activation/Passivation • Instance Swapping between clients • fewer beans can service more clients! • Simple, Efficient Failover in a clustered environment

  36. Session Bean Example • TitleManager Home Interface • create method • TitleManager Business Interface • business methods • TitleManager Bean Class • Session Façade Pattern • locateAvailableUnit method in façade -- more specific to a business service • findUnitsForTitleByStatus method in Entity Bean Home (uses EJB QL) -- more generalized

  37. Bean Types Message Driven Beans

  38. Messaging Basics “First, a little background...”

  39. JMS Messaging in Java --Point-to-Point

  40. JMS Messaging in Java --Pub-Sub

  41. Session and Entity Beans were NOT designed to handle asynchronous processing of JMS messages. What about synchronous processing? What triggers the processing? A client call? What type of receiving would be done? Endless blocking? Timed blocking? Non-blocking? There simply were NO good options before MDBs! Before MDBs...

  42. Asynchronous -- senders/publishers of messages are decoupled from the processing of the messages. Concurrent -- container-provided, multithreaded, concurrent message consumption Automated -- No client trigger calls are needed because... MDB Message Processing

  43. Client Calls to MDBs The CONTAINER IS the client!

  44. The MDB Lifecycle

  45. Example 1a -- Publishing to a Topic Renting Out Titles -- RentalManagerBean

  46. Example 1b --An Example Subscriber Renting Out Titles -- CustomerRentalWorkOrderMDB

  47. Example 1c --Run It! onMessage -- CustomerRentalWorkOrderMDB & CustomerRentalNotificationMDB

  48. Implements MessageDrivenBean Implements MessageListener EJB 2.1 allows other options (I.e. JAXM) This is why EJB 2.0 did NOT have MessageDrivenBean extend MessageListener onMessage method (JMS) The bean pool and MDBs ejb-jar.xml ejb-borland.xml jndi-definitions.xml MDB Message Processing

  49. Questions • What are the 3 bean types? • Which was new to EJB 2.0? Why was it added? • What are the two types of session beans? • What are the peformance differences b/t stateful and stateless and why? • What’s an alternative to a Stateful session bean in a web application?

  50. Does your head hurt yet? Bean Info You Shouldn’t Leave Home Without

More Related