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Roadmap
• EJB model overview
• What is the EJB model?
• EJB model as a PSM model
• Mapping the EJB model
• Model elements and code generation
• EJB model elements—details
• Implementation features
• Simple scenario
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OptimalJ training section 9 - PSM: DBMS
Model 1

What is the EJB Model?
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EJB Model as a PSM Model
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OptimalJ training section 9 - PSM: DBMS
Model 2

Mapping the EJB Model
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Main Model Elements
• EJB model elements
• EJB module
• EJB data schema
• EJB data class
• EJB data association
• EJB entity component
• EJB session component
• EJB message-driven component
• EJB key class
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OptimalJ training section 9 - PSM: DBMS
Model 3

EJB Model and Code Generation
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Roadmap
• EJB model overview
• EJB model elements—details
• EJB entity component
• EJB session component
• EJB message-driven component
• EJB struct type
• EJB enum type
• JMS Message
• Implementation features
• Simple scenario
OptimalJ training section 9 - PSM: DBMS
Model 4

Entity Component
• Purpose
• Corresponds a domain class
• Object wrapper around data
• Model elements
• Business method
• Finder method
• Select method
• EJB entity component reference
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Session Component
• Purpose
• Corresponds a domain service
• Logical view of compound data
• Browsing data with the assistance of DAO
• Model elements
• Business method
• Data schemas
• State
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OptimalJ training section 9 - PSM: DBMS
Model 5

Message-driven Component
• Purpose
• Serves as a JMS message consumer
• Modeled in the EJB model – no equivalent in the domain
• Model elements
• JMS message consumption
• JMS destination type and name
• Selectors
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Other Elements in the Model
• EJB Structure
• Single unit of reusable data – set of attributes
• Maps to a Serializable Java class
• EJB Enumeration
• List of named unordered values
• JMS Message
• Meta information for message and transported data
• Associated with the EJB message-driven component
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OptimalJ training section 9 - PSM: DBMS
Model 6

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Roadmap
• EJB model overview
• EJB model elements—details
• Implementation features
• EJB implementation patterns
• EJB interfaces, relationships, and persistence
• Finder, home, and select methods
• Interaction with the EJB tier
• Messaging
• Simple scenario
EJB Implementation Patterns
• Two implementation patterns
• EJB 1.1
• EJB 2.0 (default)
• Local and Remote interfaces
• EJB persistence and relations
• Use of SQL or EJB QL
• Transactions
• Concurrency support
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OptimalJ training section 9 - PSM: DBMS
Model 7

Interaction with the EJB Layer
• Problem description:
• Clients usually require more than one value from a bean
• Set and get methods increase the number of remote calls
• Solution:
• Business Facade to limit the network traffic
• Data object collects the data in case of read
• Business Facade creates an update object for fine-grain communication
• Update object is passed back to the EJB in case of update
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Local and Remote Interfaces
• Definition
• Client views to the EJB components
• Remote: location transparency!
• Local: performance!
• Local and Remote: flexibility!
• Model elements
• Local
• Remote
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OptimalJ training section 9 - PSM: DBMS
Model 8

EJB Persistence and Relations
• EJB 1.1 defaults—CMP and BMR
• EJB 2.0 defaults—CMP and CMR
• EJB relations
• One-to-many
• One-to-one
• Many-to-many
• Model elements
• EJB references
• Relationship management
• Referred component
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EJB References
• Definition
• Element containing the relationship information
• Features
• Appear under EJB entity component
• Appear under EJB session component
• One reference for each navigable association
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OptimalJ training section 9 - PSM: DBMS
Model 9

Finder Methods
• Definition
• Queries to return one or a collection of entity beans instances
• Exposed via Home/LocalHome
• Operate on CMP and CMR fields
• Utilize SQL or EJB QL
• Properties
• whereClause
• ejbQLQuery
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Select Methods
• Definition
• Queries to return single or a collection of entity beans instances
• Queries to return CMP or CMR values
• NOT exposed via Home/LocalHome
• Operate on CMP and CMR fields
• Use EJB QL
• Properties
• ejbQLQuery
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OptimalJ training section 9 - PSM: DBMS
Model 10

Home Methods
• Definition
• Perform operations related to the EJB component
• Not specific to a bean instance
• Defined in the Home/LocalHome interface
• Property
• isHomeBusinessMethod = True
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Create and Remove Methods
• Definition
• Create method—a factory method that clients use to get a reference to an EJB object.
• Remove method—a method that a client use to release a reference to an EJB object and to free resources.
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OptimalJ training section 9 - PSM: DBMS
Model 11

Messaging in OptimalJ
• Creation of JMS messages
• Message consumption and production
• Creation of message-driven components
• Registration of JMS destinations in JBoss
• Support for durable subscribers
• Message selectors
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Message Production
• Delivered by all EJB components
• Defined used JMS destinations and factories
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OptimalJ training section 9 - PSM: DBMS
Model 12

Message Consumption
• Delivered via a model wizard
• Durable subscribers
• Guaranteed message delivery
• Reliability
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Switching EJB 2.0 and 1.1
• Add ipEjb11.jar (or ipEjb20.jar) from modules directory under OptimalJ installation
• Re-enable any disabled modules
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OptimalJ training section 9 - PSM: DBMS
Model 13

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Roadmap
• EJB model overview
• EJB model elements—details
• Implementation features
• Simple scenario
• Domain model
• EJB model
• Code model
Simple Scenario—CRM
• Customer Relationship Management (CRM) project
• A simplified real-life example
• Conduct basic customer relationship management tasks
• Monitoring range of queries on the customer database
• Viewing customer calls per customer
• Maintaining call data
• Demonstrate the functionality of the EJB model
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OptimalJ training section 9 - PSM: DBMS
Model 14

CRM—Domain Model
• CRM main elements
• Customer
• Service Agreement
• Call
• Address (structure)
• CustomerMSvc
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CRM—EJB Model
• Entity and session components
• Data schemas and key classes
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OptimalJ training section 9 - PSM: DBMS
Model 15

CRM—Code Model
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Summary
• The OptimalJ EJB model:
• Support for entity, session, and message-driven beans
• Code generated for enterprise beans conforms to EJB specifications
• Generation of deployment descriptors as prescribed by specifications
• Well-designed implementation approaches
• Extended messaging support
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OptimalJ training section 9 - PSM: DBMS
Model 16

Exercises
• Explore the EJB model
• Become familiar with the main EJB model features
• Create a finder method
• Define finder methods based on CMP and CMR fields
• Create a home and select methods
• Model a home business method, which invokes a select method
• Optional—JMS application
• Model JMS message production and consumption
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OptimalJ training section 9 - PSM: DBMS
Model 17