Raible's Wiki: CreateManager

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__Part II:__ [Creating new Managers|CreateManager] - A HowTo for creating [Business Delegates|http://java.sun.com/blueprints/corej2eepatterns/Patterns/BusinessDelegate.html] that talk to the database tier (DAOs) and the web tier (Struts Actions).

__Part II:__ [Creating new Managers|CreateManager] - A HowTo for creating Business Facades that talk to the database tier (DAOs) and handle transaction management.

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;:''This tutorial depends on __Part I:__ [Creating new DAOs and Objects in AppFuse|CreateDAO].''

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This tutorial will show you how to create a Business Delegate class (and a JUnit) to talk to the [DAO we created in Part I|CreateDAO] of this tutorial.

This tutorial will show you how to create a Business Facade class (and a JUnit Test) to talk to the [DAO we created in Part I|CreateDAO].

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In the context of [AppFuse], this is called a Manager class. It's main responsibility is converting backend data (POJOs) into front-end data (Struts ActionForms). The main reason I even use Managers, rather than just calling the DAOs directly is testability. It's nice to be able to populate a Form manually (in the test) and call the DAO to persist it, and verify the database gets the proper results. The [Business Delegate|http://java.sun.com/blueprints/corej2eepatterns/Patterns/BusinessDelegate.html] pattern from Sun says that these objects are usefull for de-coupling your presentation layer from your database layer. Managers should also be where you put any business logic for your application.

In the context of [AppFuse], this is called a Manager class. Its main responsibility is to act as a bridge between the persistence (DAO) layer and the web layer. It's also useful for de-coupling your presentation layer from your database layer (i.e. for Swing apps). Managers should also be where you put any business logic for your application.

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Let's get started on creating a new ManagerTest and Manager in AppFuse's architecture.

Let's get started by creating a new ManagerTest and Manager in AppFuse's architecture.

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* [3] Run the ManagerTest

* [3] Configure Spring for this Manager and Transactions

* [4] Run the ManagerTest

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Create a new ManagerTest to run JUnit tests on the Manager [#1]

!!Create a new ManagerTest to run JUnit tests on the Manager [#1]

In [Part I|CreateDAO], we created a Person object and PersonDao - so let's continue developing this entity. First, let's create a JUnit test for the PersonManager. Create PersonManagerTest in the test/service/**/service directory. We'll want to test the same basic methods (get, save, remove) that our DAO has.

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Create a new Manager to talk to the DAO [#2]

;:''This may seem redundant (why all the tests!), but these tests are GREAT to have 6 months down the road.''

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Run the ManagerTest [#3]

This class should extend [BaseManagerTestCase|http://raibledesigns.com/downloads/appfuse/api/org/appfuse/service/BaseManagerTestCase.java.html], which already exists in the ''service'' package. The parent class (BaseManagerTestCase) serves similar functionality as the BaseDaoTestCase.

;:%%(color: blue)''I usually copy (open → save as) an existing test (i.e. UserManagerTest.java) and find/replace [[Uu]ser with [[Pp]erson, or whatever the name of my object is.''%%

The code below is what you need for a basic JUnit test of your Manager. Unlike the DaoTest, this test uses [jMock|http://jmock.org] to isolate the Manager from its dependencies and make it a ''true'' "unit" test. This can be very helpful because it allows you to test your business logic w/o worrying about other dependencies. The code below simply sets up the Manger and its dependencies (as Mocks) for testing.

[{Java2HtmlPlugin

package org.appfuse.service;

import java.util.List;

import java.util.ArrayList;

import org.appfuse.dao.PersonDao;

import org.appfuse.model.Person;

import org.appfuse.service.impl.PersonManagerImpl;

import org.jmock.Mock;

import org.springframework.orm.ObjectRetrievalFailureException;

public class PersonManagerTest extends BaseManagerTestCase {

private final String personId = "1";

private PersonManager personManager = new PersonManagerImpl();

private Mock personDao = null;

private Person person = null;

protected void setUp() throws Exception {

super.setUp();

personDao = new Mock(PersonDao.class);

personManager.setPersonDao((PersonDao) personDao.proxy());

}

protected void tearDown() throws Exception {

super.tearDown();

personManager = null;

}

}]

Now that you have the skeleton done for this class, you need to add the meat: the test methods to make sure everything works. Here's a snippet from the [DAO Tutorial|CreateDAO] tutorial to help you understand what we're about to do.

;:''...we create methods that begin with "test" (all lower case). As long as these methods are public, have a void return type and take no arguments, they will be called by our <junit> task in our Ant build.xml file. Here's some simple tests for testing CRUD. An important thing to remember is that each method (also known as a test), should be autonomous.''

Add the following methods to your PersonManagerTest.java file:

[{Java2HtmlPlugin

public void testGetPerson() throws Exception {

// set expected behavior on dao

personDao.expects(once()).method("getPerson")

.will(returnValue(new Person()));

person = personManager.getPerson(personId);

assertTrue(person != null);

personDao.verify();

}

public void testSavePerson() throws Exception {

// set expected behavior on dao

personDao.expects(once()).method("savePerson")

.with(same(person)).isVoid();

personManager.savePerson(person);

personDao.verify();

}

public void testAddAndRemovePerson() throws Exception {

person = new Person();

// set required fields

person.setFirstName("firstName");

person.setLastName("lastName");

// set expected behavior on dao

personDao.expects(once()).method("savePerson")

.with(same(person)).isVoid();

personManager.savePerson(person);

personDao.verify();

// reset expectations

personDao.reset();

personDao.expects(once()).method("removePerson").with(eq(new Long(personId)));

personManager.removePerson(personId);

personDao.verify();

// reset expectations

personDao.reset();

// remove

Exception ex = new ObjectRetrievalFailureException(Person.class, person.getId());

personDao.expects(once()).method("removePerson").isVoid();

personDao.expects(once()).method("getPerson").will(throwException(ex));

personManager.removePerson(personId);

try {

personManager.getPerson(personId);

fail("Person with identifier '" + personId + "' found in database");

} catch (ObjectRetrievalFailureException e) {

assertNotNull(e.getMessage());

}

personDao.verify();

}

}]

This class won't compile at this point because we have not created our PersonManager interface.

;:%%(color: blue)''I think it's funny how I've followed so many patterns to allow __extendibility__ in AppFuse. In reality, on most projects I've been on - I learn so much in a year that I don't want to extend the architecture - I want to rewrite it. Hopefully by keeping AppFuse up to date with my perceived best practices, this won't happen as much. Each year will just be an upgrade to the latest AppFuse, rather than a re-write. ;-)''

!!Create a new Manager to talk to the DAO [#2]

First off, create a PersonManager.java interface in the src/service/**/service directory and specify the basic CRUD methods for any implementation classes. ''I've eliminated the JavaDocs in the class below for display purposes.'' The ''setPersonDao()'' method is not used in most cases - its just exists so the PersonManagerTest can set the DAO on the interface.

;:%%(color: blue)''As usual, I usually duplicate (open → save as) an existing file (i.e. UserManager.java).''%%

[{Java2HtmlPlugin

package org.appfuse.service;

import org.appfuse.model.Person;

import org.appfuse.dao.PersonDao;

public interface PersonManager {

public void setPersonDao(PersonDao dao);

public Person getPerson(String id);

public void savePerson(Person person);

public void removePerson(String id);

}

}]

Now let's create a PersonManagerImpl class that implements the methods in PersonManager. To do this, create a new class in src/service/**/service/impl and name it PersonManagerImpl.java. It should extend BaseManager and implement PersonManager.

[{Java2HtmlPlugin

package org.appfuse.service.impl;

import org.appfuse.model.Person;

import org.appfuse.dao.PersonDao;

import org.appfuse.service.PersonManager;

public class PersonManagerImpl extends BaseManager implements PersonManager {

private PersonDao dao;

public void setPersonDao(PersonDao dao) {

this.dao = dao;

}

public Person getPerson(String id) {

return dao.getPerson(Long.valueOf(id));

}

public void savePerson(Person person) {

dao.savePerson(person);

}

public void removePerson(String id) {

dao.removePerson(Long.valueOf(id));

}

}]

One thing to note is the {{setPersonDao()}} method. This is used by Spring to bind the PersonDao to this Manager. This is configured in the applicationContext-service.xml file. We'll get to configuring that in Step 3[3]. You should be able to compile everything now using "ant compile-service".

Now you need to edit Spring's config file for our services layer so it will know about this new Manager.

!!Configure Spring for this Manager and Transactions [#3]

To notify Spring of this our PersonManager interface and its implementation, open the src/service/**/service/applicationContext-service.xml file. Add the following to the bottom of this file.

[{Java2HtmlPlugin

</bean>

}]

This bean must have a name that ends in "Manager". This is because there is AOP advice applied at the top of this file for all *Manager beans.

{{{<aop:advisor id="managerTx" advice-ref="txAdvice" pointcut="execution(* *..service.*Manager.*(..))" order="2"/>}}} For more information on transactions with Spring, see [Spring's documentation|http://www.springframework.org/docs/reference/transaction.html].

!!Run the ManagerTest [#4]

Save all your edited files and try running __ant test-service -Dtestcase=PersonManager__.

''Yeah Baby, Yeah:''

%%(color:green)BUILD SUCCESSFUL\\

Total time: 9 seconds%%

----

The files that were modified and added to this point are [available for download|https://appfuse.dev.java.net/files/documents/1397/7484/appfuse-tutorial-managers-1.6.zip].

''Next Up:'' __Part III:__ [Creating Actions and JSPs|CreateActions] - A HowTo for creating Actions and JSPs in the AppFuse architecture.

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