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Innovator 11 classiX

Enterprise JavaBeans (EJB) for JBuilder

Alexander Borschet

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Modeling and Generating Enterprise JavaBeans (EJB) for JBuilder

What is the Purpose of Connection to JBuilder?

The Innovator connection models and generates Enterprise JavaBeans (EJB) for Borland JBuilder.

What are Enterprise JavaBeans?

Enterprise JavaBeans (EJB) is a specification published by Sun Micro-systems for modeling classes for a component-based distributed architecture of business applications, among other things. You can find more information about the specifications under http://java.sun.com. EJB supports Entity Beans and Session Beans. Entity Beans are persistent and have primary keys. Instances can be identified and searched for using the primary key. If several attributes are involved in a primary key, then they are combined in an independent primary key class. Session beans are, in contrast, not persistent. They are assigned to a client process and are destroyed when the client process is ended. A Bean is not directly communicated within distributed applications. Instead, the home interface of a bean provides the methods for creating and searching instances. A bean's technical methods respond via a remote interface. EJB uses Message Driven Beans for processing messages.

Data-base

EJB Container

Stateless Session BeanStateful Session BeanMessage Driven Bean

Bean Managed Entity BeanContainer Managed Entity Bean

Data-base

Data-base

Data-base

Web Container

Browser Client

J2EEJ2EE

EJB Container in J2EE and Innovator Context

In this paper, EJB embedding occurs using the general software process of EJB applications for JBuilder favored by MID; embedding can also, how-ever, be carried out in other ways.

What is JBuilder? Borland JBuilder is a cross-platform environment for developing powerful enterprise Java applications. JBuilder accelerates EJB, Web, Web Servi-ces, XML, mobile and database application development. http://www.borland.com/jbuilder/

What is BES? Borland Enterprise Server is the standard runtime environment for all business applications for J2EE, CORBA and Web Services platforms. http://www.borland.com/bes/

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Enterprise JavaBean (EJB) Applications

EJB applications normally use business data which is stored in relational databases. Regardless of whether a new database is to be set up or a long standing one accessed, data management that prevents redundancies and consistency of business data should be ensured. This can only be achieved using a suitable database model which focuses on the normalized form structure of the data. It is virtually impossible to obtain such a database model from a pure bean class model. A conceptual and physical data model must therefore be created, which will be used as a basis for the class model of all persistent Entity Beans. Innovator Data supports the modeling of a conceptual and physical data model, based on general recognized entity relationship modeling (ERM) standards. At the same time, an extended structured entity relationship model (SERM) method (proposed by Prof. Dr. Sinz) is made available, which prevents the problem of cyclical existence dependencies of entities and illustrates existence dependencies. In connection with the generative and associative transformations between a relational and an object-oriented model (ER-OO-mapping), Innovator provides the opportunity to model redundancy-preventative data manage-ment for persistent Entity Bean objects right from the start. This is of parti-cular importance if the new application is to be installed on a pre-existing database model. This means that a wizard cannot be used to make a bean class persistent. Instead, targeted transformation needs to be applied. This is the only way to ensure that the application works on and with a consistent database which is free of redundancies. While the data model serves as the basis for persistency, the bean class model focuses on the distribution of functionalities and their re-usability in component architecture. The way in which a bean class is made persistent is left up to the Bean Container. It is here where object-relational trans-formation is used. It specifies the rules for the transformation of beans in database tables and anchors them in a container. If both bean class models and database models are created in Innovator, then this modeling information is extracted and exported to the correct directory structure in the form of Java classes, embedded in package structures, together with the default EJB deployment descriptor and a BES-specific deployment descriptor. This information is now available in Innovator perspectives, as well as other JBuilder perspectives in JBuilder.

How are EJBs Supported? Innovator supports EJBs within object-oriented modeling with the help of the UML for Java language using the component Innovator Object classiX. Innovator Object supports the modeling and generating of EJBs in line with the specifications in version 2.x with the Java EJB 2.x for Borland add-on (extra costs incurred). The declaration of classes, attributes and methods are added to the specific stereotypes and EJB element properties, which are evaluated during modeling and generating. Only the bean classes are to be modeled. The derived classes (e.g. remote/home interface and primary key class) are created using so-called engineering actions or adapted to the bean class modeling. What’s more, the respective EJB methods (ejBCreate, ejbActivate, ejbPassivate, etc.) are created in the classes.

The following bean classes are supported: Container Managed Entity Bean Bean Managed Entity Bean Stateless Session Bean Stateful Session Bean Message Driven Session Bean

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Innovator expands the Java declaration for classes, attributes and methods using additional element properties (referred to as “tagged values” in UML) and stereotypes. The values of these element properties determine which role a class, an attribute or a method has within the framework of the EJB specification. Two new class diagrams are already provided for EJB extension. A class diagram with the «Java EJB Definition Class Diagram» stereotype contains one bean class and its remote/home interfaces, as well as its primary key class (where applicable). Commands are provided in this diagram for creating EJB classes, attributes and methods. The class diagram with the «Java EJB Relationship Class Diagram» stereotype only contains bean classes. It does not, however, contain their respective interface classes. This diagram creates the relationships between EJBs. Commands are provided in this diagram for creating relationships between EJB classes. The available Java Apply EJB 2.0 Pattern engineering action assumes that the modifications made in the model will only be applied to the Entity Beans, Session Beans or Message Driven Beans. These modifications are then automatically propagated in the assigned home interface or remote interface or in the assigned primary key class. If they do not already exist, then they are created. You can create Container Managed Entity Beans using an ER-OO-mapping variant based on a data model (which you created before with the InnovatorData component) using the engineering action Create EJBs from Database Model. The engineering action configures the connection to the data model and creates the Container Managed Entity Beans according to the data model’s tables, which have been created since the last generator run. Alongside the Entity Beans, the action also creates their attributes and relationships. It does not, however, create the home/remote interfaces of these bean classes. Each EJB class or interface concerns a normal Java class with the «class» or «interface» stereotype. Generating Java code, forward, reverse or round-trip engineering treat these classes like other Java classes.

How to Proceed with Modeling and Generating EJBs

According to the software development process used here, the basis of modeling and generating of Enterprise Java Beans (EJB) for JBuilder provides, on the one hand, a UML model (obligatory with platform-specific packages for design and implementation (as a result of Java profile) and the specific EJB for JBuilder using an appropriate add-on) and, on the other hand, essentially provides an ER model which can be created using standard generation in a UML model. To model and generate Enterprise JavaBeans (EJB) for JBuilder, please follow the next steps:

Create an ER data model (e.g. reverse engineering from a pre-existing database)

Based on the UML model, configure the connection to the data model and generate the persistent Container Managed Entity Beans (CMP) from this data model

Create the bean classes in the UML class diagrams (non-persistent Session Beans and Message Driven Beans for communication)

Model relationships between beans in the UML class diagram Create local and remote references Model the beans’ attributes and methods Execute Java Apply EJB 2.x Pattern forward engineering action

to create and maintain the missing elements (e.g. home/remote interface) according to EJB specification.

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Copy the JBuilder project directory structure into Innovator packages. Determine create defaults for forward and reverse engineering Create source code using relevant engineering actions Create EJB deployment descriptor with Java Generate EJB 2.x DD for Borland engineering action

Create value object for efficient data exchange between Entity Beans and their clients

Mapping to Data Model As the CMP beans are generated from the data model in Innovator, complete information about the illustrations can be found in JBuilder. As well as model/table definitions, mapping and relations are also fully created.

Copyright © 2010 MID GmbH For questions, please contact our hotline Tel.: +49 (0)911 / 9 68 36 -22, E-mail: support@mid.de. You can also find this document along with others in the exclusive log-in download area for Innovator customer service under http://www.mid.de/support/produktinformationen/. Your MID team MID GmbH, Eibacher Hauptstr. 141, 90451 Nuremberg, Germany Tel.: +49 (0)911 / 9 68 36 -0, Fax: +49 (0)911 / 9 68 36 -10 E-mail: info@mid.de, Internet: http://www.mid.de

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