Exercise 2 - Asynchronous method call

README.md

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-quality-day-training-tasks
-==========================
+#Excersie 2: Asynchronous method call
+##Introduction
+This lesson is about following skills:
+* creating asynchronous methods in enterprise beans
+* EJB self invocation
+* concurrency
 
-Various tasks and problems to solve
+Expected result of this exercise is an EJB application which uses self invoked asynchronous method calculatePi.
+
+##Before you start, read about...
+* Asynchronous invocation: [http://docs.oracle.com/javaee/6/tutorial/doc/gkkqg.html]
+* Session Context [http://docs.oracle.com/javaee/6/api/javax/ejb/SessionContext.html#getBusinessObject(java.lang.Class)]
+
+##The exercise
+To complete this exercise you need to follow these steps:
+* Refactor calculatePi in `PiCalculator.java` to return promise (read Asynchronous invocation) instead of Object
+* Make calculatePi asynchronous
+* Annotate Session Context to be injected properly
+* In piFullCalculator use sessionContext to recover business object of class `PiCalculator.java` and assign it to the variable
+* Use business object for self invocation of asynchronous method calculatePi and pass 
+iterations as parameter (Important note: You can't invoke private functions)
+* Assign return value to existing variable piFuture
+
+Good luck !

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>pl.itcrowd.java.exercises</groupId>
+    <artifactId>java-exercises</artifactId>
+    <packaging>war</packaging>
+    <version>1.0.0-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.jboss.as.plugins</groupId>
+                <artifactId>jboss-as-maven-plugin</artifactId>
+                <version>${version.jbossas}</version>
+                <configuration>
+                    <artifactId>${project.artifactId}</artifactId>
+                    <force>true</force>
+                    <groupId>${project.groupId}</groupId>
+                    <ignoreMissingDeployment>true</ignoreMissingDeployment>
+                </configuration>
+            </plugin>
+            <plugin>
+                <artifactId>maven-war-plugin</artifactId>
+                <configuration>
+                    <failOnMissingWebXml>false</failOnMissingWebXml>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+    <dependencies>
+        <dependency>
+            <groupId>org.jboss.spec.javax.ejb</groupId>
+            <artifactId>jboss-ejb-api_3.1_spec</artifactId>
+            <version>1.0.1.Final</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>javax.annotation</groupId>
+            <artifactId>jsr250-api</artifactId>
+            <version>1.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>1.7.7</version>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.7</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.8.1</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jboss.arquillian.junit</groupId>
+            <artifactId>arquillian-junit-container</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jboss.as</groupId>
+            <artifactId>jboss-as-arquillian-container-remote</artifactId>
+            <version>7.1.1.Final</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.jboss.shrinkwrap.resolver</groupId>
+                <artifactId>shrinkwrap-resolver-bom</artifactId>
+                <version>2.2.0-beta-1</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+            <dependency>
+                <groupId>org.jboss.arquillian</groupId>
+                <artifactId>arquillian-bom</artifactId>
+                <version>1.1.5.Final</version>
+                <scope>import</scope>
+                <type>pom</type>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+    <properties>
+        <jdk.source>1.7</jdk.source>
+        <project.build.outputEncoding>UTF-8</project.build.outputEncoding>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <version.jbossas>7.1.1.Final</version.jbossas>
+    </properties>
+</project>

src/main/java/Main.java

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+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.annotation.PostConstruct;
+import javax.ejb.EJB;
+import javax.ejb.Singleton;
+import javax.ejb.Startup;
+
+@Startup
+@Singleton
+public class Main {
+
+    private Logger logger = LoggerFactory.getLogger(Main.class);
+
+    private Double adminPiResult;
+
+    @EJB
+    private PiCalculator calculator;
+
+    @PostConstruct
+    public void main() throws Exception
+    {
+        setAdminPiResult(calculator.piFullCalculator(10000000));
+        logger.info("admin pi precision: " + Double.toString(getAdminPiResult()));
+    }
+
+    public Double getAdminPiResult()
+    {
+        return adminPiResult;
+    }
+
+    public void setAdminPiResult(Double adminPiResult)
+    {
+        this.adminPiResult = adminPiResult;
+    }
+}

src/main/java/PiCalculator.java

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+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.ejb.SessionContext;
+import javax.ejb.Stateless;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+@Stateless
+public class PiCalculator {
+
+    private Logger logger = LoggerFactory.getLogger(PiCalculator.class);
+
+    private SessionContext sessionContext;
+
+    public Double piFullCalculator(int iterations) throws ExecutionException, InterruptedException
+    {
+        Long threadId = Thread.currentThread().getId();
+
+        //You are supposed to instantiate piFuture with promise from calculatePi function(you need to fix calculatePi return value)
+        final Future<Double> piFuture = null;
+        logger.info("piFullCalculator should appear before calculatePi: " + Long.toString(threadId));
+
+        final Object monitor = new Object();
+        while(!piFuture.isDone()) {
+            logger.info("Waiting...");
+            //noinspection SynchronizationOnLocalVariableOrMethodParameter
+            synchronized (monitor) {
+                monitor.wait(1000);
+            }
+        }
+
+        return piFuture.get();
+    }
+
+    private Object calculatePi(int iterations)
+    {
+        double pi = 4;
+        boolean plus = false;
+        for (int i = 3; i < iterations; i += 2) {
+            pi = plus ? (pi + 4.0 / i) : (pi - 4.0 / i);
+            plus = !plus;
+        }
+        Long threadId = Thread.currentThread().getId();
+        logger.info("calculatePi, thread id: " + Long.toString(threadId));
+        return pi;
+    }
+}

src/main/webapp/WEB-INF/jboss-ejb3.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<jboss:ejb-jar xmlns:jboss="http://www.jboss.com/xml/ns/javaee" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:security="urn:security" version="3.1"
+               impl-version="2.0">
+    <assembly-descriptor xmlns="http://java.sun.com/xml/ns/javaee">
+        <security:security>
+            <security:security-domain>exercise</security:security-domain>
+            <ejb-name>*</ejb-name>
+        </security:security>
+    </assembly-descriptor>
+</jboss:ejb-jar>
+

src/test/java/MainTest.java

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+import junit.framework.Assert;
+import org.jboss.arquillian.container.test.api.Deployment;
+import org.jboss.arquillian.junit.Arquillian;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.asset.EmptyAsset;
+import org.jboss.shrinkwrap.api.spec.WebArchive;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import javax.ejb.EJB;
+import java.io.File;
+
+@RunWith(Arquillian.class)
+public class MainTest {
+
+    @EJB
+    private Main main;
+
+    @Deployment
+    public static WebArchive createDeployment()
+    {
+        return ShrinkWrap.create(WebArchive.class)
+            .addClasses(Main.class, PiCalculator.class)
+            .addAsWebInfResource(new File("src/main/webapp/WEB-INF/jboss-ejb3.xml"))
+            .addAsWebInfResource(EmptyAsset.INSTANCE, "beans.xml");
+    }
+
+    @Test
+    public void should_calculatePi_equal() throws Exception
+    {
+        Assert.assertEquals(main.getAdminPiResult(), 3.1415924535897797d);
+    }
+}

src/test/java/PiCalculatorTest.java

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+import junit.framework.Assert;
+import org.jboss.arquillian.container.test.api.Deployment;
+import org.jboss.arquillian.junit.Arquillian;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.asset.EmptyAsset;
+import org.jboss.shrinkwrap.api.spec.WebArchive;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import javax.ejb.EJB;
+import java.io.File;
+import java.util.concurrent.Future;
+
+@RunWith(Arquillian.class)
+public class PiCalculatorTest {
+
+    @EJB
+    private PiCalculator piCalculator;
+
+    @Deployment
+    public static WebArchive createDeployment()
+    {
+        return ShrinkWrap.create(WebArchive.class)
+            .addClasses(PiCalculator.class)
+            .addAsWebInfResource(new File("src/main/webapp/WEB-INF/jboss-ejb3.xml"))
+            .addAsWebInfResource(EmptyAsset.INSTANCE, "beans.xml");
+    }
+
+    @Test
+    public void should_calculatePi_be_called_asynchronously() throws Exception
+    {
+        Assert.assertEquals(((Future) piCalculator.calculatePi(10000)).isDone(), false);
+    }
+}