Fabio Medeiros Faria

This approach avaible with spring framework is commonly used in many applications.

Once I was using this resource, but when I set a value in an attibute of the object, this was changed of datase too, but i didn't call the layer persistence.

I think this somewhat

um tanto quanto "dangerous"... Do you think this is a good practice to use in applications?

tks Kirk by rapid response

My frequently problems are out of memory. Many files has more 50MB...

I will download the files, tks!

Some kinds of applications, such as medical, needs storage big images and videos in database.

I would like to know if there are any kind of design or architecture to provide better perfrmance and better handling of resources.

By curiosity and knowledge, I did a quick search about DataIterator of JSF and some UI components.

In the JEE6 tutorial of Oracle, I found:

The value attribute of an h:dataTable tag references the data to be included in the table. This data can take the form of any of the following:

A list of beans

An array of beans

A single bean

A javax.faces.model.DataModel object

A java.sql.ResultSet object

A javax.servlet.jsp.jstl.sql.Result object

A javax.sql.RowSet object

Extracted from: JEE 6 tutorial

As I said earlier a collection of POJOs to be only displayed will work perfectly, but if I need more interaction, such as: checkbox, rowSeleciton, and others; in these cases will be necessary build a DataModel.

At show case of primeFaces in the DataTable component is used only a simple collection, so I this mode works too: DataTable - PrimeFaces

I I observed is need, only in cases that table is handled with components, such as: check box, row select.

For simple exhibition it isnt necessary. Of course, if the collection for changed for an DataModel, it's work perfectly too.

[]s

to be more specific, see an example:

@ManagedBean @ViewScoped public class MyMB { private Long personIdSelected; private List<Person> listPersons = new ArrayList<Person>(); public Long getPersonIdSelected() { return personIdSelected; } public void setPersonIdSelected(Long personIdSelected) { this.personIdSelected = personIdSelected; } public List<Person> getListPersons() { return listPersons; } public void setListPersons(List<Person> listPersons) { this.listPersons = listPersons; }

and in your page (I'm using jsf with primefaces, but is the same for other UI components or only JSF):

<p:dataTable value="#{myMB.listPersons}" var="person"> <p:column headerText="Code"> #{person.id} </p:column> <p:column headerText="Name"> #{person.name} </p:column> <p:column headerText="down"> <p:commandLink value="Download" action="#{myMB.anyMethod}"> <f:setPropertyActionListener target="#{myMB.personIdSelected}" value="#{person.id}" /> </p:commandLink> </p:column> </p:dataTable>

Tks Tim, I agree with you!

I think the pattern DAO is perfect to maintenance the high cohesion in the code. Its simplify the use of the better practices and most efficient test tools, providing tests of the layer persistence clearly, as dbUnit, for example.

Tks for write your opinion.

I would like if you can access my simple blog, it is in portuguese, but the google translator can help you.

Hi James,

I think there are another way for you to do this. Generally when we use JSF is possible set the value directly in a property of a managed bean.

Search about the tag <f:setPropertyActionListener target="<<MB property>>" value="<<value>>">, this is efficiently.

But, in last case, if you really need put some parameters in an URL, could you use an <h:outputLink> and concatenate the parameters after correct url.

I'm adherent to use the pattern DAO as a specific layer in the application. But I have seen many discution about this question, some arguments show this pattern in nowadays isn't more necessary, because technologies as JPA are well matured.

One this discussions borned in a post with my simple blog, www.serjava.blogspot.com, and although I advocate the pattern DAO I would like to know what are you think?

[]s

I've a doubt with EJB Lite 3.1 embeddable:

I'm using EJB Lite for a app JSE; the call of EJB components are OK! The problem only appear when I try
do a connection using JTA for the database.

See
@Stateless @DataSourceDefinition(name="java:app/jdbc/estudo", databaseName="estudo", password="123456", user="postgres", className="org.postgresql.Driver", portNumber=5432, serverName="localhost") public class DataSourceCustomBean { @PersistenceContext(unitName="ExemploEJbPU") private EntityManager em;

This datasource is who provides the data-source-name for references in the persistence.xml. See the persistence.xml:

<?xml version="1.0" encoding="UTF-8"?> <persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> <persistence-unit name="ExemploEJbPU" transaction-type="JTA"> <jta-data-source>java:app/jdbc/estudo</jta-data-source> <properties> <property name="eclipselink.ddl-generation" value="update"/> </properties> </persistence-unit> </persistence>

The call this component is definied below:

EJBContainer container = EJBContainer.createEJBContainer(); InitialContext context = (InitialContext) container.getContext(); DataSourceCustom dataSource = (DataSourceCustom) context.lookup("java:global/classes/DataSourceCustomBean");

In the moment I try run the application, appear the following stack,
SEVERE: Exception while invoking class org.glassfish.persistence.jpa.JPADeployer prepare method java.lang.RuntimeException: javax.naming.NamingException: Lookup failed for 'java:app/jdbc/estudo' in SerialContext [Root exception is javax.naming.NamingException: Invocation exception: Got null ComponentInvocation ] at org.glassfish.persistence.jpa.PersistenceUnitInfoImpl.<init>(PersistenceUnitInfoImpl.java:111) at org.glassfish.persistence.jpa.PersistenceUnitLoader.loadPU(PersistenceUnitLoader.java:130) at org.glassfish.persistence.jpa.PersistenceUnitLoader.<init>(PersistenceUnitLoader.java:96) at org.glassfish.persistence.jpa.JPADeployer.prepare(JPADeployer.java:121) at com.sun.enterprise.v3.server.ApplicationLifecycle.prepareModule(ApplicationLifecycle.java:644) at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:296) at org.glassfish.kernel.embedded.EmbeddedDeployerImpl.deploy(EmbeddedDeployerImpl.java:214) at org.glassfish.kernel.embedded.EmbeddedDeployerImpl.deploy(EmbeddedDeployerImpl.java:144) at org.glassfish.ejb.embedded.EJBContainerImpl.deploy(EJBContainerImpl.java:128) at org.glassfish.ejb.embedded.EJBContainerProviderImpl.createEJBContainer(EJBContainerProviderImpl.java:120) at javax.ejb.embeddable.EJBContainer.createEJBContainer(EJBContainer.java:102) at javax.ejb.embeddable.EJBContainer.createEJBContainer(EJBContainer.java:78) at exemploejb.Main.main(Main.java:32)

Waiting for suggestions. tks