EJB or Not Denver BEA User's Group Sept 2003

EJB or Not Scott Ryan Denver BEA User ’ s Group September 2003

Big Topic Little Time

References
EJB 1.0
EJB 1.1
EJB 2.0
EJB 2.1 http://java.sun.com/products/ejb/docs.html#specs
Bitter EJB - Manning Publications Co.
JBoss and AOP www.jboss.org/
Programming Weblogic EJBs

Golden Hammer or NACL

What are the Ingredients?
Stateless Session Beans
Stateful Session Beans
Entity Beans
Bean Managed
Container Managed (CMR?)
Message Driven Beans

What is in it for me?
Distributed Component Model
Pooling/Sharing
Security
Transactions
Asynchronous Behavior (MDB)

Is that the one I had before? Stateless Session Beans
Good for one Method Call
Pooled and shared for performance
Can store Instance Information
What happens with Instance Variables?

Where do put I my state? Stateful Session Beans
What is the efficient way to store state
When is the persistence done
Cluster Aware
Multiple ways to persist
Memory, Files, Database
Be careful what you store and how
Seek other ways to persist complex data

Wow Look at all I get Entity Beans
Not just a persistence mechanism
There are better ways to persist
Understand how to tune with deployment Descriptors
Persistence
Pooling
Transactions
Security

Wow Look at all I get (Continued)
Concurrency
Exclusive, Database, Optimistic, Read-only, Read Mostly
Caching Strategies
Lazy Loading
Clustering and Load Balancing
Local VS Remote

What is going on?

What is all this? CMR
Watch the depth of relationships
Leverage Concurrency, Caching, Lazy Loading but be careful
Very efficient when used correctly

How do I call you? Message Driven Beans
Very useful to control Asynchronous activity
Design to run standalone (asynchronously)
Tune the number to support the load
Handle ALL message types
Be careful what you do with exceptions
Keep it light (implementation and message size)

Who changed my bean? AOP and JBoss
Code added during run time
Horizontal extension via bytecode injection
Can I trust the implementation?
Similar to JDO implementation but on a larger scale
Possible alternative to EJBs
Selectively add functionality to POJOs

Tidbits of Knowledge
EJB ’ s have huge value when used correctly
Plan your interfaces carefully
Don ’ t write code that you can generate
Xdoclet, EJBGEN, Reverse EJBGEN
Understand what is going on under the covers
Use deployment options to tune implementation
Leverage experience of others
Remember the alternatives

Tidbits of Knowledge (cont)
Be careful when using inheritance
Understand reentrancy and Idempotency
Plan your exception handling
Understand the object lifecycles
Don ’ t spawn threads or interfere with Container code

EJB or Not Denver BEA User's Group Sept 2003

by Soaring Eagle L.L.C. on Feb 13, 2011

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EJB or Not Denver BEA User’s Group Sept 2003 — Presentation Transcript