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| Home > Apache Geronimo v1.1 > Documentation > Apache Geronimo v1.1 - GuÃa de Usuario > Aplicaciones ejemplo > Aplicación EJB ejemplo |
Enterprise Java Beans ha sido uno de los extremos sólidos de la especificación J2EE. Como un servidor certificado J2EE 1.4, Apache Geronimo soporta EJB's extensivamente con el apoyo del Contenedor de EJB, OpenEJB. Aunque es posible usar objetos Java estándar para contener tu lógica de negocios y datos de negocio, el uso de EJBs direcciona muchos de los temas del uso de objetos Java simples, como la escalabilidad, administración del ciclo de vida y administración de estado. En este artÃculo, observarás como una aplicación inicial de base de datos se extiende y usa tanto para clientes de aplicación locales y remotos, con un fondo (back end) de Enterprise Java Beans. La aplicación usa a Apache Derby incluido como su base de datos. Emplea este artÃculo para aprender el como simplificar tu proceso de desarrollo de aplicación empresarial.
La aplicación bancaria tiene dos tipos de aplicaciones cliente, llamadas "Aplicación de Banca Remota" y "Aplicación de Banca Web". Cada cliente demuestra el cómo referirse a Enterprise Java Beans en interface remota y local, respectivamente. Ambos clientes hacen referencia a una capa de lógica de negocio común, la cual ha sido implementada con la ayuda de Session y Entity Beans. Stateless Session Beans actúan como la interfaz de servicio de negocio entre entidades de negocio y clientes de aplicación. Toda entidad de negocio de la capa de aplicación se implementa con CMP y BMP Entity Beans. Relaciones entre entidades CMP son administradas como Container Managed Relations (Relaciones Administradas por el Contenedor).
Después de la lectura de este artÃculo deberÃas ser capaz de obtener lo mejor de las caracterÃsticas EJB de Geronimo, como la definición de Enterprise Java Beans, la administración de relaciones entre ellos y la referencia a EJB's a través de distintos tipos de clientes.
Este artÃculo esta organizado con las secciones siguientes.
La implementación EJB puede variar de un distribuidor a otro. A continuación se muestra la lista principal de caracterÃsticas que soporta Apache Geronimo como un contenedor J2EE.
Como se mencionó previamente, la aplicación de Banca soporta dos tipos de clientes de aplicación negocio. El panorama de cada cliente se muestra a continuación.
Ambas aplicaciones usan una capa de servicio de negocio común. Detrás de esa capa de servicio de negocio, existen tres entidades de negocio comunes que aparecen en el dominio de la aplicación bancaria: Cuenta, Cliente y TasaDeCambio. Cada Cliente puede tener más de una Cuenta, mientras una Cuenta puede pertenecer a un solo Cliente. TasaDeCambio representa el valor de tasa dada por el banco, en relación a USD para una divisa particular.
La siguiente figura proporciona la arquitectura general de la aplicación bancaria.
La aplicación bancaria consiste en la lista siguiente de paquetes y clases.
Finalmente, la aplicación bancaria será activada como EAR en el servidor de aplicaciones. La revisión global de la estructura del contenido del archivo EAR se muestra a continuación.
|-Bank.ear
|-BankEJB.jar
|-META-INF
|- ejb-jar.xml
|- openejb-jar.xml
|-BankWeb.war
|-jsp
|- customer_info.jsp
|- customer_main.jsp
|- error.jsp
|- exchange_rates.jsp
|- index.jsp
|-WEB-INF
|- web.xml
|- geronimo-web.xml
|- classes
|-META-INF
|- application.xml
|- geronimo-application.xml
|-tranql-connector-1.2.rar
|-BankPool.xml
Primero, analizaremos como la capa de servicio de negocio de la aplicación ha sido implementada con la ayuda de EJBs. En este ambiente de aplicación, todo EJB emplea XDoclet para generar su meta-información y sus interfaces.
openejb-jar.xml define las caracterÃsticas especÃficas de EJBs sobre Geronimo. Tiene tanto información de EJB como sus relaciones. Además proporciona una liga al pool de base de datos de la aplicación. Entity Beans en la aplicación dependen de esa pool. Nota que la parte final de este archivo define una Container Managed Relation (CMR) 1-N entre los Beans Customer y Account.
<?xml version="1.0" encoding="UTF-8"?> <openejb-jar xmlns="http://www.openejb.org/xml/ns/openejb-jar-2.1"> <dep:environment xmlns:dep="http://geronimo.apache.org/xml/ns/deployment-1.1"> <dep:moduleId> <dep:groupId>default</dep:groupId> <dep:artifactId>BankEJB</dep:artifactId> <dep:version>1.0</dep:version> <dep:type>car</dep:type> </dep:moduleId> <dep:dependencies/> <dep:hidden-classes/> <dep:non-overridable-classes/> </dep:environment> <cmp-connection-factory> <resource-link>BankPool</resource-link> </cmp-connection-factory> <enterprise-beans> <session> <ejb-name>BankManagerFacadeBean</ejb-name> <jndi-name>org.apache.geronimo.samples.bank.ejb.BankManagerFacadeBean</jndi-name> <ejb-ref> <ref-name>ejb/Customer</ref-name> <ejb-link>Customer</ejb-link> </ejb-ref> <ejb-ref> <ref-name>ejb/Account</ref-name> <ejb-link>Account</ejb-link> </ejb-ref> <ejb-ref> <ref-name>ejb/ExchangeRate</ref-name> <ejb-link>ExchangeRate</ejb-link> </ejb-ref> </session> <entity> <ejb-name>Account</ejb-name> <local-jndi-name>AccountLocalEntity</local-jndi-name> <table-name>Account</table-name> <cmp-field-mapping> <cmp-field-name>accountNumber</cmp-field-name> <table-column>ACC_NO</table-column> </cmp-field-mapping> <cmp-field-mapping> <cmp-field-name>accountType</cmp-field-name> <table-column>ACC_TYPE</table-column> </cmp-field-mapping> <cmp-field-mapping> <cmp-field-name>customer</cmp-field-name> <table-column>CUSTID_FK</table-column> </cmp-field-mapping> <cmp-field-mapping> <cmp-field-name>balance</cmp-field-name> <table-column>BALANCE</table-column> </cmp-field-mapping> <resource-ref> <ref-name>jdbc/BankDataSource</ref-name> <resource-link>BankPool</resource-link> </resource-ref> </entity> <entity> <ejb-name>Customer</ejb-name> <local-jndi-name>CustomerLocalEntity</local-jndi-name> <table-name>Customer</table-name> <cmp-field-mapping> <cmp-field-name>customerId</cmp-field-name> <table-column>CUST_ID</table-column> </cmp-field-mapping> <cmp-field-mapping> <cmp-field-name>customerName</cmp-field-name> <table-column>CUST_NAME</table-column> </cmp-field-mapping> <resource-ref> <ref-name>jdbc/BankDataSource</ref-name> <resource-link>BankPool</resource-link> </resource-ref> </entity> <entity> <ejb-name>ExchangeRate</ejb-name> <local-jndi-name>ExchangeRate</local-jndi-name> <resource-ref> <ref-name>jdbc/BankDataSource</ref-name> <resource-link>BankPool</resource-link> </resource-ref> </entity> </enterprise-beans> <relationships> <ejb-relation> <ejb-relation-name>Customer-Account</ejb-relation-name> <ejb-relationship-role> <ejb-relationship-role-name>Account-to-Customer</ejb-relationship-role-name> <relationship-role-source> <ejb-name>Account</ejb-name> </relationship-role-source> <cmr-field> <cmr-field-name>customer</cmr-field-name> </cmr-field> <foreign-key-column-on-source/> <role-mapping> <cmr-field-mapping> <key-column>CUST_ID</key-column> <foreign-key-column>CUSTID_FK</foreign-key-column> </cmr-field-mapping> </role-mapping> </ejb-relationship-role> </ejb-relation> </relationships> </openejb-jar>
BankPool.xml es un archivo de configuración tÃpico de una pool de base de datos, la cual se conectará a BankDB, definida en el servidor de base de datos incluÃdo: Derby. Entity beans de la aplicación se refieren a la base de datos mediante su archivo de configuración.
<?xml version="1.0" encoding="UTF-8"?> <connector xmlns="http://geronimo.apache.org/xml/ns/j2ee/connector-1.1"> <dep:environment xmlns:dep="http://geronimo.apache.org/xml/ns/deployment-1.1"> <dep:moduleId> <dep:groupId>console.dbpool</dep:groupId> <dep:artifactId>BankPool</dep:artifactId> <dep:version>1.0</dep:version> <dep:type>rar</dep:type> </dep:moduleId> <dep:dependencies> <dep:dependency> <dep:groupId>org.apache.derby</dep:groupId> <dep:artifactId>derby</dep:artifactId> <dep:version>10.1.1.0</dep:version> <dep:type>jar</dep:type> </dep:dependency> </dep:dependencies> </dep:environment> <resourceadapter> <outbound-resourceadapter> <connection-definition> <connectionfactory-interface>javax.sql.DataSource</connectionfactory-interface> <connectiondefinition-instance> <name>BankPool</name> <config-property-setting name="Driver">org.apache.derby.jdbc.EmbeddedDriver</config-property-setting> <config-property-setting name="UserName">app</config-property-setting> <config-property-setting name="ConnectionURL">jdbc:derby:BankDB</config-property-setting> <connectionmanager> <local-transaction/> <single-pool> <max-size>10</max-size> <min-size>0</min-size> <match-one/> </single-pool> </connectionmanager> </connectiondefinition-instance> </connection-definition> </outbound-resourceadapter> </resourceadapter> </connector>
geronimo-application.xml y application.xml definen los componentes principales del EAR. La información de archivos de los componentes EJB y Web se proporcionan en estos archivos. Además, estos dos archivos XML definen el uso del pool de base de datos en esta aplicación, indicándolo mediante tranql-connector-1.2.rar y BankPool.xml.
<?xml version="1.0" encoding="UTF-8"?> <application xmlns="http://geronimo.apache.org/xml/ns/j2ee/application-1.1"> <dep:environment xmlns:dep="http://geronimo.apache.org/xml/ns/deployment-1.1"> <dep:moduleId> <dep:groupId>default</dep:groupId> <dep:artifactId>Bank</dep:artifactId> <dep:version>1.0</dep:version> <dep:type>car</dep:type> </dep:moduleId> <dep:dependencies/> <dep:hidden-classes/> <dep:non-overridable-classes/> </dep:environment> <module> <connector>tranql-connector-1.2.rar</connector> <alt-dd>BankPool.xml</alt-dd> </module> </application>
<?xml version="1.0" encoding="UTF-8"?> <application xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/application_1_4.xsd" version="1.4"> <module> <ejb>BankEJB.jar</ejb> </module> <module> <web> <web-uri>BankWeb.war</web-uri> <context-root>/Bank</context-root> </web> </module> <module> <connector>tranql-connector-1.2.rar</connector> </module> </application>
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Since Banking Web Application is a part of EAR, the BankManagerFacade Session Bean will be reffered as a local interface. Those additional configuration information required for the EJB reference can be found in the web.xml.
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4"> <welcome-file-list> <welcome-file>/jsp/index.jsp</welcome-file> </welcome-file-list> <servlet> <display-name>CustomerServiceServlet</display-name> <servlet-name>CustomerServiceServlet</servlet-name> <servlet-class>org.apache.geronimo.samples.bank.web.CustomerServiceServlet</servlet-class> </servlet> <servlet> <display-name>CommonServiceServlet</display-name> <servlet-name>CommonServiceServlet</servlet-name> <servlet-class>org.apache.geronimo.samples.bank.web.CommonServiceServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>CustomerServiceServlet</servlet-name> <url-pattern>/customer_info</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>CommonServiceServlet</servlet-name> <url-pattern>/exchange_rates</url-pattern> </servlet-mapping> <!-- To refer local EJB's --> <ejb-local-ref> <ejb-ref-name>ejb/BankManagerFacade</ejb-ref-name> <ejb-ref-type>Session</ejb-ref-type> <local-home>org.apache.geronimo.samples.bank.ejb.BankManagerFacadeHomeLocal</local-home> <local>org.apache.geronimo.samples.bank.ejb.BankManagerFacadeLocal</local> <ejb-link>BankManagerFacadeBean</ejb-link> </ejb-local-ref> </web-app>
Account Balance Modifier swing application refers the same BankManagerFacade Session bean as a remotely refer EJB. It's configuration information can be found in the bank_client.properties file.
java.naming.factory.initial=org.openejb.client.RemoteInitialContextFactory java.naming.provider.url=localhost:4201 java.naming.security.principal=system java.naming.security.credentials=manager jndi.bankManager=org.apache.geronimo.samples.bank.ejb.BankManagerFacadeBean
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Always check for the correct network information to run this application client out side of the local computer. |
The sample database that is being used to demonstrate this application is inbuilt Derby database. The name of the sample database is BankDB and it consists of three tables, CUSTOMER ,ACCOUNT and EXCHANGE_RATE. The fields for each of these tables are described below.
| Table Name | Fields |
|---|---|
| CUSTOMER | CUST_ID (PRIMARY KEY) CUST_NAME |
| ACCOUNT | ACC_NO (PRIMARY KEY) ACC_TYPE BALANCE CUSTID_FK |
| EXCHANGE_RATE | RATE_ID (PRIMARY KEY) CURRENCY RATE |
The CUSTOMER table stores the data related to the customers.It stores only the identification number and and the name. ACCOUNT table has a unique account number for identification. Account type and balance are the other information stored. CUSTID_FK is a foriegn key to the Customer table which is the owner of the Account. EXCHANGE_RATE table has a primary key of RATE_ID for an identification. Each record of EXCHANGE_RATE has CURRENCY name and RATE paid by the bank.
The tools used for developing and building the Banking applications are:
XDoclet is an open source code generation engine. It enables Attribute-Oriented Programming for java. In short, this means that you can add more significance to your code by adding meta data (attributes) to your java sources. This is done in special JavaDoc tags.
Although XDoclet originated as a tool for creating EJBs, it has evolved into a general-purpose code generation engine. XDoclet consists of a core and a constantly growing number of modules. It is fairly straight forward to write new modules if there is a need for a new kind of component.
http://xdoclet.sourceforge.net/xdoclet/index.html
Apache Derby, an Apache DB subproject, is a relational database implemented in Java. Its footprint is so small you can easily embed it in any Java-based solution. In addition to its embedded framework, Derby supports a more familiar client/server framework with the Derby Network Server.
http://db.apache.org/derby/index.html
The Eclipse IDE was used for development of the sample application. This is a very powerful and popular open source development tool. It has integration plug-ins for the Geronimo too. Eclipse can be downloaded from the following URL:
http://www.eclipse.org
Ant is a pure Java build tool. It is used for building the war files for the Inventory application. Ant can be downloaded from the following URL:
http://ant.apache.org
Download the bank application from the following link:
[Bank|^bank.zip]
After decompressing the given file, the bank directory will be created.
Configuration of the application consists of creating the database and defining the connection pool to access it.
After starting Apache Geronimo log into the console and follow the given steps to create the BankDB.
CREATE TABLE customer(
CUST_ID VARCHAR(15) PRIMARY KEY,
CUST_NAME VARCHAR(40)
);
CREATE TABLE account(
ACC_NO VARCHAR(15) PRIMARY KEY,
ACC_TYPE VARCHAR(10),
BALANCE DOUBLE,
CUSTID_FK VARCHAR(15),
FOREIGN KEY (CUSTID_FK) REFERENCES customer
);
CREATE TABLE exchange_rate(
RATE_ID VARCHAR(10) PRIMARY KEY,
CURRENCY VARCHAR(10),
RATE DOUBLE
);
INSERT INTO customer(CUST_ID,CUST_NAME) VALUES('12345','Lasantha Ranaweera');
INSERT INTO account(ACC_NO,ACC_TYPE,BALANCE,CUSTID_FK) VALUES('1234567890','Savings',1005.35,'12345');
INSERT INTO account(ACC_NO,ACC_TYPE,BALANCE,CUSTID_FK) VALUES('2345678901','Current',999.95,'12345');
INSERT INTO exchange_rate(RATE_ID,CURRENCY,RATE) VALUES('001','EURO',0.812);
INSERT INTO exchange_rate(RATE_ID,CURRENCY,RATE) VALUES('002','YEN',111.15);
INSERT INTO exchange_rate(RATE_ID,CURRENCY,RATE) VALUES('003','SLR',99.18);
Bank application comes with an Ant script to help users to build from source code. It has to be properly configured before using it to build from source code. build.properties file in the config directory has to modify according to your enviroment. Set the correct paths to the xdoclet.home and geronimo.home directories.
Also set the correct network information in the bank_client.properties file, which is going to reffered by remote application client.
| This build script depends on XDoclet version 1.2.3 and Geronimo 1.1. |
Use a command prompt to navigate into the bank directory and just give ant command to build. It will create the Bank.ear and bankclient.jar under the bank/releases folder. Also note it will create a lib folder with a list of jar files reffered by the client application. Now, you are ready to deploy bank application in the Geronimo Application server.
Deploying sample application is pretty straight forward as we are going to use the Geronimo Console.
Core business application logic of the banking application is shared between two different clients. Testing of each client is given below.
To test the sample web application open a browser and type http://localhost:8080/Bank. It will forward you to the index page of banking application which has direct links to the view customer and exchange rate information. To view the list of account information of each customer, provide a relavant customer id in the DB. Exchange rate page will display list of all currencies in the exchange rate table.
Unable to render embedded object: File (banking_web_app.gif) not found.
Banking remote application client can be run by issuing the java -jar bankclient.jar in a command prompt. Use an existing account number in the database to view it's balance. Modification of account balance can be done by providing a numeric value to the balance field and using the Update button.
Unable to render embedded object: File (banking_remote_app.gif) not found.
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Always consider that the lib folder inside releases are a part of this client application.Check your Operating Sytem's security configuration when you connect from a remote machine. |
This article has shown you how to use the EJB features of the Apache Geronimo. It has provided step-by-step instructions to build an application, deploy and run it to elaborate those features.
Following are some of the highlights of the article.
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