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These entries are created each time one of the timers expires. using software todraw qr code iso/iec18004 for asp.net web,windows application .NET CF [ 362 ]. 9 . Calendar-based EJB timer expressions The example in the pre vious section has one disadvantage: the startTimer() method in the session bean must be invoked from a client in order to start the timer. This restriction makes it difficult to have the timer start as soon as the bean is deployed. Java EE 6 introduced calendar-based EJB timer expressions.

Calendar-based expressions allow one or more methods in our session beans to be executed at a certain date and time. For example, we could configure one of our methods to be executed every night at 8:10 pm, which is exactly what our next example does..

package com.ensode.gla Software qr-codes ssfishbook.

calendarbasedtimer; import import import import java.util.logging.

Logger; javax.ejb.Stateless; javax.

ejb.LocalBean; javax.ejb.

Schedule;. @Stateless @LocalBean public class CalendarBasedTimerEjbExampleBean { private static Logger logger = Logger.getLogger( CalendarBasedTimerEjbExampleBean.class.

getName()); @Schedule(hour = "20", minute = "10") public void logMessage() { logger.info("This message was triggered at:" + System.currentTimeMillis()); } }.

As we can see in this qrcode for None example, we set the time when the method will be executed via the javax.ejb.Schedule annotation.

In this particular example, we set our method to be executed at 8:10 pm by setting the hour attribute of the @Schedule annotation to "20" and its minute attribute to "10" (the value of the hour attribute is 24 hour based, setting hour to "20" is equivalent to 8:00 pm). The @Schedule annotation has several other attributes that allow a lot of flexibility in specifying when the method should be executed. We could, for instance, have a method executed on the third Friday of every month, or on the last day of the month, and so on and so forth.

The following table lists all the attributes in the @Schedule annotation that allow us to control when the annotated method will be executed:. [ 363 ]. Enterprise JavaBeans Attribute dayOfMonth Description The day of the month. Example values "3": th e third day of the month "Last": the last day of the month "-2": two days before the end of the month "1st Tue": the first Tuesday of the month. Default value "*". dayOfWeek The day of the week Ho qr codes for None ur of the day (24 hour based) Minute of the hour Month of the year Second of the minute Timezone ID Four digit year. "3": every Wednesday "Thu": every Thursday "14": 2:00 pm "*" "0". hour minute month "10": ten minutes afte r the hour "2": February "March": March "5": five seconds after the minute "America/New York" "2010". "0" "*" "0" "" "*". second timezone year In addition to single qr bidimensional barcode for None values, most attributes accept the asterisk ("*") as a wild card, meaning that the annotated method will be executed every unit of time (every day, hour, and so on). Additionally, we can specify more than one value by separating the values with commas. For example, if we needed a method to be executed every Tuesday and Thursday, we could annotate the method as @Schedule(dayOfWeek="Tue, Thu").

We can also specify a range of values; the first value and the last value are separated by a dash (-). To execute a method from Monday through Friday, we could use @Schedule(dayOfWeek="Mon-Fri"). Additionally, we could specify that we need the method to be executed every "n" units of time (for example, every day, every two hours, every ten minutes, and so on).

To do something like this, we could use @Schedule(hour="*/12"), which would execute the method every 12 hours.. [ 364 ]. 9 . As we can see, the @Sc hedule annotation provides a lot of flexibility as how to specify when we need to get our methods executed. Plus it provides an advantage of not needing a client call to activate the scheduling. It also has the advantage of using cron-like syntax.

Therefore, developers familiar with this Unix tool will feel right at home when using this annotation.. EJB security Enterprise JavaBeans a llow us to declaratively decide which users can access their methods. For example, some methods might only be available to users in certain roles. A typical scenario is that only users with a role of administrator can add, delete, or modify other users in the system.

The following example is a slightly modified version of the DAO session bean we saw earlier in this chapter. In this version, some methods that were previously private were made public. Additionally, the session bean was modified to allow only users in certain roles to access its methods.

. package net.ensode.gla QR Code ISO/IEC18004 for None ssfishbook; import import import import import import import import import import java.

sql.Connection; java.sql.

PreparedStatement; java.sql.ResultSet; java.

sql.SQLException; javax.annotation.

Resource; javax.annotation.security.

RolesAllowed; javax.ejb.Stateless; javax.

persistence.EntityManager; javax.persistence.

PersistenceContext; javax.sql.DataSource;.

@Stateless @RolesAllow ed("appadmin") public class CustomerDaoBean implements CustomerDao { @PersistenceContext private EntityManager entityManager; @Resource(name = "jdbc/__CustomerDBPool") private DataSource dataSource; public void saveCustomer(Customer customer) { if (customer.getCustomerId() == null) [ 365 ]. Enterprise JavaBeans { Software qr bidimensional barcode saveNewCustomer(customer); } else { updateCustomer(customer); } } public Long saveNewCustomer(Customer customer) { customer.setCustomerId(getNewCustomerId()); entityManager.persist(customer); return customer.

getCustomerId(); } public void updateCustomer(Customer customer) { entityManager.merge(customer); } @RolesAllowed({ "appuser", "appadmin" }) public Customer getCustomer(Long customerId) { Customer customer; customer = entityManager.find(Customer.

class, customerId); return customer; } public void deleteCustomer(Customer customer) { entityManager.remove(customer); } private Long getNewCustomerId() { Connection connection; Long newCustomerId = null; try { connection = dataSource.getConnection(); PreparedStatement preparedStatement = connection.

prepareStatement("select max(customer_id)+1 " "as new_customer_id from customers"); ResultSet resultSet = preparedStatement.executeQuery(); if (resultSet != null && resultSet.next()) { newCustomerId = resultSet.

getLong("new_customer_id"); [ 366 ]. 9 } connection.close( ); } catch (SQLException e) { e.printStackTrace(); } return newCustomerId; } }.

As we can see, we decl QR for None are what roles have access to the methods by using the @RolesAllowed annotation. This annotation can take either a single string or an array of strings as a parameter. When a single string is used as a parameter for this annotation, only users with a role specified by the parameter can access the method.

If an array of strings is used as a parameter, users with any of the roles specified by the array"s elements can access the method. The @RolesAllowed annotation can be used to decorate an EJB class, in which case its values apply to all the methods in the EJB or to one or more methods. In this second case, its values apply only to the method the annotation is decorating.

If, like in our example, both the EJB class and one or more of its methods are decorated with the @RolesAllowed annotation, the method-level annotation takes precedence. Application roles need to be mapped to a security realm"s group name. This mapping, along with what realm to use, is set in the sun-ejb-jar.

xml deployment descriptor:. < xml version="1.0" encoding="UTF-8" > <!DOCTYPE sun-ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Application Server 9.

0 EJB 3.0//EN" "http://www.sun.

com/software/appserver/dtds/sun-ejb-jar_3_0-0.dtd"> <sun-ejb-jar> <security-role-mapping> <role-name>appuser</role-name> <group-name>appuser</group-name> </security-role-mapping> <security-role-mapping> <role-name>appadmin</role-name> <group-name>appadmin</group-name> </security-role-mapping> <enterprise-beans> <ejb> <ejb-name>CustomerDaoBean</ejb-name> <ior-security-config> [ 367 ]. Enterprise JavaBeans & Software qr bidimensional barcode lt;as-context> <auth-method>username_password</auth-method> <realm>file</realm> <required>true</required> </as-context> </ior-security-config> </ejb> </enterprise-beans> </sun-ejb-jar>. The <security-role- mapping> element of the sun-ejb-jar.xml deployment descriptor does the mapping between application roles and the security realm"s group. The value of the <role-name> sub-element must contain the application role.

This value must match the value used in the @RolesAllowed annotation. The value of the <group-name> sub-element must contain the name of the security group in the security realm used by the EJB. In the previous example, we map two application roles to the corresponding groups in the security realm.

Although in this particular example the name of the application role and the security group match, this does not need to be the case.. Automatically matching qr codes for None roles to security groups It is possible to automatically match any application roles to identically named security groups in the security realm. This can be accomplished by logging into the GlassFish web console, clicking on the Configuration node, clicking on Security, then clicking on the checkbox labeled Default Principal To Role Mapping, and saving this configuration change..

As can be seen in the example, the security realm to use for authentication is defined in the <realm> sub-element of the <as-context> element. The value of this sub-element must match the name of a valid security realm in the application server. Other sub-elements of the <as-context> element include <auth-method>, whose only valid value is username_password, and <required>, whose only valid values are true and false.

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