Kohei Nozaki's blog 

Environment

• Commons Configuration 1.10
• WildFly 8.0.0.Final
• Oracle JDK7u51

Why go this way?

Various portable ways are available for manage configurations of the Java EE application. such as:

• Configuration table in DB
  • I guess it's not bad, but I feel that is bit tedious work to coding.
  • There's a way to use this mechanism via Commons Configuration, but I haven't tried it yet.
• Custom JNDI resources
  • I thought that it's most efficient at first, but negative points here:
    • Badness of lookup performance.
    • Editing JNDI resources is very annoying.

So sometimes I'm thinking of any better way, and I found Commons Configurations[1]. notable capabilities of Commons Configuration are:

• Simple API
• Auto-reloading and saving mechanism provided
• Support of various formats and placement styles

So I'd try it.

Prepare sample project and related resources

Create a system property

• Create a system property which specifies the path of configuration file.
• I'm using WildFly so go with jboss-cli:

[standalone@localhost:9990 /] /system-property=app.config:add(value=/Users/kyle/app.properties)
{"outcome" => "success"}
[standalone@localhost:9990 /] 

Create the properties file

• Location is same as “app.config” system property.

hoge=fuge

pom.xml

<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>org.nailedtothex</groupId>
    <artifactId>config</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
        <failOnMissingWebXml>false</failOnMissingWebXml>
    </properties>

    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>commons-configuration</groupId>
            <artifactId>commons-configuration</artifactId>
            <version>1.10</version>
        </dependency>
    </dependencies>
</project>

Create an application-scoped bean

package org.nailedtothex.config;

import javax.annotation.PostConstruct;
import javax.enterprise.context.ApplicationScoped;
import javax.inject.Named;

import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.PropertiesConfiguration;
import org.apache.commons.configuration.reloading.FileChangedReloadingStrategy;

@Named
@ApplicationScoped
public class AppConfigBean {

    private Configuration config;

    @PostConstruct
    void init() throws ConfigurationException {
        String path = System.getProperty("app.config");
        PropertiesConfiguration propConfig = new PropertiesConfiguration(path); 
        propConfig.setReloadingStrategy(new FileChangedReloadingStrategy());
        config = propConfig;
    }

    public Configuration getConfig(){
        return config;
    }
}

• If you want to read the config at startup of application, I recommend that use of @javax.ejb.Singleton and @javax.ejb.Startup[2].

Create a servlet

• Get a configuration variable from singleton bean.

package org.nailedtothex.config;

import java.io.IOException;
import java.io.PrintWriter;

import javax.inject.Inject;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = "/*")
public class HelloServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    @Inject
    private AppConfigBean bean;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        try (PrintWriter pw = response.getWriter()) {
            pw.write(bean.getConfig().getString("hoge"));
        }
    }
}

Access via browser

• It needs only very small and clean code.

Check runtime reloading

Edit app.properties:

kyle-no-MacBook:~ kyle$ echo hoge=FUGE > app.properties
kyle-no-MacBook:~ kyle$ 

Reload browser:

• I just reloaded the browser and I didn't do any other operations, but config was updated immediately.

Collaboration with CDI

• There's a way to inject properties to CDI managed bean at [2]. that must be useful.

XMLConfiguration

• XMLConfiguration is good for hierarchical configuration.
• It depended on Commons Collection so don't forget to add the dependency.

pom.xml

        <dependency>
            <groupId>commons-configuration</groupId>
            <artifactId>commons-configuration</artifactId>
            <version>1.10</version>
        </dependency>
        <dependency>
            <groupId>commons-collections</groupId>
            <artifactId>commons-collections</artifactId>
            <version>3.2.1</version>
        </dependency>

XmlTest.java

package org.nailedtothex.config;

import java.util.Iterator;
import java.util.List;

import org.apache.commons.configuration.XMLConfiguration;

public class XmlTest {

    public static void main(String[] args) throws Exception {
        XMLConfiguration config = new XMLConfiguration();
        config.load(XmlTest.class.getResourceAsStream("/config.xml"));

        String backColor = config.getString("colors.background");
        String textColor = config.getString("colors.text");
        String linkNormal = config.getString("colors.link[@normal]");
        String defColor = config.getString("colors.default");
        int rowsPerPage = config.getInt("rowsPerPage");
        List<Object> buttons = config.getList("buttons.name");

        System.out.println(backColor);
        System.out.println(textColor);
        System.out.println(linkNormal);
        System.out.println(defColor);
        System.out.println(rowsPerPage);
        System.out.println(buttons);

        System.out.println();

        Object o;
        Iterator it = config.getKeys("colors.");
        while(it.hasNext()){
            System.out.println(it.next());
        }
    }
}

config.xml

<?xml version="1.0" encoding="UTF-8"?>
<gui-definition>
  <colors>
    <background>#808080</background>
    <text>#000000</text>
    <header>#008000</header>
    <link normal="#000080" visited="#800080"/>
    <default>${colors.header}</default>
  </colors>
  <rowsPerPage>15</rowsPerPage>
  <buttons>
    <name>OK,Cancel,Help</name>
  </buttons>
  <numberFormat pattern="###\,###.##"/>
</gui-definition>

Log

#808080
#000000
#000080
#008000
15
[OK, Cancel, Help]

colors.background
colors.text
colors.header
colors.link[@normal]
colors.link[@visited]
colors.default

References

1. Commons Configuration - Java Configuration API
2. CDIでアプリケーション設定をインジェクション - 見習いプログラミング日記
3. Apache commonsが便利な件（commons-configuration編） - 都元ダイスケ IT-PRESS
4. Commons Configuration - Hierarchical configurations and XML Howto

Environment

• WireMock 1.4.3
• HttpClient 4.3.2
• Oracle JDK7u51

Why need it?

• Sometimes website scraping stops at unexpected error like socket timeout or internal server error.
• We prefer to retry several times at such occasion.
• So we have to develop some retrying mechanism, and we have to create a test and create the mock of server.
  • So in this article, I'm going to try to create the mock with WireMock.

Requirements for client

• Retry if processing fails, for 3 times.
• Retry when timeout occurred.
  • SocketTimeoutException
• Retry when server returned status code 5xx

Test cases

1. Server returns code 200 without any problems.
2. Server returns code 500 at first, then client will retry, server returns code 200.
3. Server returns code 500 forever, then client will retry 3 times and give up.
4. Server delays the response, then client will regard as timeout and retry, then server returns code 200.
5. Server delays the response forever, then client will retry 3 times and give up.

Resources

pom.xml

<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>org.nailedtothex</groupId>
    <artifactId>wiremock</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
          <groupId>org.hamcrest</groupId>
          <artifactId>hamcrest-core</artifactId>
          <version>1.3</version>
          <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.github.tomakehurst</groupId>
            <artifactId>wiremock</artifactId>
            <version>1.43</version>
            <classifier>standalone</classifier>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>*</groupId>
                    <artifactId>*</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.3.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>fluent-hc</artifactId>
            <version>4.3.2</version>
        </dependency>
    </dependencies>

</project>

RetryableHttpFetcher.java

package org.nailedtothex.wiremock;

import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpRequestRetryHandler;
import org.apache.http.client.HttpResponseException;
import org.apache.http.client.ServiceUnavailableRetryStrategy;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;

public class RetryableHttpFetcher {

    private static final Logger log = Logger.getLogger(RetryableHttpFetcher.class.getName());

    // these parameters would be better to retrieve through JNDI or any other mechanism
    private int MAX_RETRIES = 3;
    private int RETRY_INTERVAL = 1000;
    private int TIMEOUT = 500;

    private final ServiceUnavailableRetryStrategy MY_SERVICE_UNAVAILABLE_RETRY_STRATEGY = new ServiceUnavailableRetryStrategy() {
        @Override
        public boolean retryRequest(HttpResponse response, int executionCount,
                org.apache.http.protocol.HttpContext context) {

            boolean rc = response.getStatusLine().getStatusCode() >= 500 && executionCount <= MAX_RETRIES;

            log.log(Level.INFO,
                    "retryRequest(): returning={0}, statusCode={1}, executionCount={2}, maxRetries={3}, interval={4}",
                    new Object[] { rc, response.getStatusLine().getStatusCode(), executionCount, MAX_RETRIES,
                            RETRY_INTERVAL });

            return rc;
        }

        @Override
        public long getRetryInterval() {
            return RETRY_INTERVAL;
        }
    };

    private final HttpRequestRetryHandler MY_HTTP_REQUEST_RETRY_HANDLER = new HttpRequestRetryHandler() {

        @Override
        public boolean retryRequest(IOException e, int executionCount, HttpContext context) {
            log.log(Level.INFO, "retryRequest(): exception={0}, executionCount={1}, maxRetries={2}",
                    new Object[] { e.getClass(), executionCount, MAX_RETRIES });

            if (executionCount > MAX_RETRIES) {
                log.log(Level.INFO, "give up: {0}", executionCount);
                return false;
            }

            if (e instanceof java.net.SocketTimeoutException) {
                log.log(Level.INFO, "retry: {0}", e.getMessage());
                return true;
            }

            log.log(Level.INFO, "not retry: {0}", e.getMessage());
            return false;
        }
    };

    private final RequestConfig MY_REQUEST_CONFIG = RequestConfig.custom()
            .setConnectionRequestTimeout(TIMEOUT)
            .setConnectTimeout(TIMEOUT)
            .setSocketTimeout(TIMEOUT)
            .build();

    public String fetchAsString(String url) throws ClientProtocolException, IOException {

        try (CloseableHttpClient client = HttpClientBuilder.create()
                .setDefaultRequestConfig(MY_REQUEST_CONFIG)
                .setRetryHandler(MY_HTTP_REQUEST_RETRY_HANDLER)
                .setServiceUnavailableRetryStrategy(MY_SERVICE_UNAVAILABLE_RETRY_STRATEGY)
                .build()) {

            try (CloseableHttpResponse res = client.execute(new HttpGet(url))) {
                if (res.getStatusLine().getStatusCode() >= 400) {
                    throw new HttpResponseException(res.getStatusLine().getStatusCode(), res.getStatusLine()
                            .getReasonPhrase());
                }
                return EntityUtils.toString(res.getEntity());
            }
        }

    }
}

RetryableHttpFetcherTest.java

package org.nailedtothex.wiremock;

import static com.github.tomakehurst.wiremock.client.WireMock.*;
import static org.hamcrest.CoreMatchers.*;
import static org.junit.Assert.*;

import java.net.SocketTimeoutException;

import org.apache.http.client.HttpResponseException;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;

import com.github.tomakehurst.wiremock.junit.WireMockRule;
import com.github.tomakehurst.wiremock.stubbing.Scenario;

public class RetryableHttpFetcherTest {

    @Rule
    public WireMockRule wireMockRule = new WireMockRule(18089);

    private RetryableHttpFetcher instance;

    @Before
    public void init() {
        instance = new RetryableHttpFetcher();
    }

    @Test
    public void test1_ok() throws Exception {
        stubFor(get(urlEqualTo("/hoge.txt")).willReturn(
                aResponse().withStatus(200).withHeader("Content-Type", "text/plain").withBody("OK")));
        String expected = "OK";

        String actual = instance.fetchAsString("http://localhost:18089/hoge.txt");

        assertThat(actual, is(expected));
    }

    @Test
    public void test2_retryAt500() throws Exception {
        stubFor(get(urlEqualTo("/500")).inScenario("retry at 500")
                .whenScenarioStateIs(Scenario.STARTED)
                .willSetStateTo("one time requested")
                .willReturn(aResponse().withBody("error").withStatus(500)));

        stubFor(get(urlEqualTo("/500")).inScenario("retry at 500")
                .whenScenarioStateIs("one time requested")
                .willReturn(aResponse().withBody("OK").withStatus(200)));

        String actual = instance.fetchAsString("http://localhost:18089/500");

        assertThat(actual, is("OK"));
    }

    @Test(expected = HttpResponseException.class)
    public void test3_retryAt500GiveUp() throws Exception {
        stubFor(get(urlEqualTo("/500"))
                .willReturn(aResponse().withBody("500").withStatus(500)));

        instance.fetchAsString("http://localhost:18089/500");
    }

    @Test
    public void test4_retryAtTimeout() throws Exception {
        stubFor(get(urlEqualTo("/timeout")).inScenario("retrying")
                .whenScenarioStateIs(Scenario.STARTED)
                .willSetStateTo("one time requested")
                .willReturn(aResponse().withBody("error").withStatus(500).withFixedDelay(3000)));
        stubFor(get(urlEqualTo("/timeout")).inScenario("retrying")
                .whenScenarioStateIs("one time requested")
                .willReturn(aResponse().withBody("OK").withStatus(200)));

        String actual = instance.fetchAsString("http://localhost:18089/timeout");
        assertThat(actual, is("OK"));
    }

    @Test(expected = SocketTimeoutException.class)
    public void test5_retryAtTimeoutGiveUp() throws Exception {
        stubFor(get(urlEqualTo("/timeout"))
                .willReturn(aResponse().withBody("timeout").withStatus(500).withFixedDelay(Integer.MAX_VALUE)));
        instance.fetchAsString("http://localhost:18089/timeout");
    }

    @Test(expected = HttpResponseException.class)
    public void notFound() throws Exception {
        instance.fetchAsString("http://localhost:18089/NOT_FOUND");
    }
}

Test logs

• All tests were passed.

test1_ok

2 26, 2014 11:34:22 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=false, statusCode=200, executionCount=1, maxRetries=3, interval=1,000

test2_retryAt500

2 26, 2014 11:35:32 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=true, statusCode=500, executionCount=1, maxRetries=3, interval=1,000
2 26, 2014 11:35:33 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=false, statusCode=200, executionCount=2, maxRetries=3, interval=1,000

test3_retryAt500GiveUp

2 26, 2014 11:35:51 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=true, statusCode=500, executionCount=1, maxRetries=3, interval=1,000
2 26, 2014 11:35:52 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=true, statusCode=500, executionCount=2, maxRetries=3, interval=1,000
2 26, 2014 11:35:53 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=true, statusCode=500, executionCount=3, maxRetries=3, interval=1,000
2 26, 2014 11:35:54 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=false, statusCode=500, executionCount=4, maxRetries=3, interval=1,000

test4_retryAtTimeout

2 26, 2014 11:36:12 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retryRequest(): exception=class java.net.SocketTimeoutException, executionCount=1, maxRetries=3
2 26, 2014 11:36:12 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retry: Read timed out
2 26, 2014 11:36:12 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$1 retryRequest
情報: retryRequest(): returning=false, statusCode=200, executionCount=1, maxRetries=3, interval=1,000

test5_retryAtTimeoutGiveUp

2 26, 2014 11:36:39 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retryRequest(): exception=class java.net.SocketTimeoutException, executionCount=1, maxRetries=3
2 26, 2014 11:36:39 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retry: Read timed out
2 26, 2014 11:36:40 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retryRequest(): exception=class java.net.SocketTimeoutException, executionCount=2, maxRetries=3
2 26, 2014 11:36:40 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retry: Read timed out
2 26, 2014 11:36:40 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retryRequest(): exception=class java.net.SocketTimeoutException, executionCount=3, maxRetries=3
2 26, 2014 11:36:40 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retry: Read timed out
2 26, 2014 11:36:41 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: retryRequest(): exception=class java.net.SocketTimeoutException, executionCount=4, maxRetries=3
2 26, 2014 11:36:41 午前 org.nailedtothex.wiremock.RetryableHttpFetcher$2 retryRequest
情報: give up: 4

References

1. HttpClient 4 Cookbook

Environment

• jBeret 1.0.1Beta-SNAPSHOT
• WildFly 8.0.0.Final

Why need it?

• Logger injection through CDI is easy and useful, but for jBatch programming of some occasions, I guess that Job-wide Logger is better than typical class-wide logger. thus, I will try it this time.
• With CDI, we can reduce some annoying code, even related to Job Properties so I also will try to inject a job-level property to a Batchlet through Producer.

Sample project

• jBatch resources
  • jobwideproducer.xml
  • InjectBatchlet.java
• CDI resources
  • JobWideArtifactProducer.java
  • JobLogger.java
  • BaseDate.java
• Test class
  • JobWideProducerJobTest.java

How does it work?

• 2 Injections are declared in InjectBatchlet.
• Both of them will be produced by JobWideArtifactProducer.
• JobWideArtifactProducer creates:
  • a logger. the name contains job name.
  • a Date. it came from job-level property named “baseDate”.

Log

18:14:51,064 INFO  [job.jobwideproducer] (batch-batch - 3) process(): baseDate=14/02/25 0:00

Remarks

• Injection of variables such as working directory of the job may be useful too.

References

1. [Java] CDI - Slf4j Logger Producer
2. SimpleDateFormat (Java Platform SE 6)

Environment

• WildFly8.0.0.Final
• Oracle JDK7u51

Resources

pom.xml

<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>org.nailedtothex</groupId>
    <artifactId>ejbtimer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
     <packaging>ejb</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

</project>

TimerService.java

package org.nailedtothex.ejbtimer;

import javax.ejb.Schedule;
import javax.ejb.Singleton;

@Singleton
public class TimerService {

    @Schedule(second = "*/1", minute = "*", hour = "*", persistent = false)
    public void periodic() {
        System.out.println("period");
    }

    @Schedule(dayOfMonth = "25", hour = "16", minute = "10", persistent = false)
    public void schedule() {
        System.out.println("schedule");
    }
}

• Almost all of the code was taken from [1].
• There are some additional useful informations and conversations so I recommend to visit [1].
• According to [2], “persistent” attribute means whether timers that missed should fire or not during downtime of the application server.
  • Default is true.
  • I don't want many missed timers to fire at once when I launch the application server which stopped unexpectedly so I just set it false.
• Detail of specification of @Schedule here: [4]

Log

16:09:44,002 INFO  [stdout] (EJB default - 8) period
16:09:45,001 INFO  [stdout] (EJB default - 9) period
16:09:46,002 INFO  [stdout] (EJB default - 10) period
16:09:47,002 INFO  [stdout] (EJB default - 1) period
16:09:48,002 INFO  [stdout] (EJB default - 2) period
16:09:49,002 INFO  [stdout] (EJB default - 4) period
16:09:50,002 INFO  [stdout] (EJB default - 3) period
16:09:51,002 INFO  [stdout] (EJB default - 5) period
16:09:52,002 INFO  [stdout] (EJB default - 6) period
16:09:53,002 INFO  [stdout] (EJB default - 7) period
16:09:54,002 INFO  [stdout] (EJB default - 8) period
16:09:55,002 INFO  [stdout] (EJB default - 9) period
16:09:56,001 INFO  [stdout] (EJB default - 10) period
16:09:57,001 INFO  [stdout] (EJB default - 1) period
16:09:58,001 INFO  [stdout] (EJB default - 2) period
16:09:59,002 INFO  [stdout] (EJB default - 4) period
16:10:00,002 INFO  [stdout] (EJB default - 5) period
16:10:00,003 INFO  [stdout] (EJB default - 3) schedule
16:10:01,001 INFO  [stdout] (EJB default - 6) period
16:10:02,002 INFO  [stdout] (EJB default - 7) period
16:10:03,001 INFO  [stdout] (EJB default - 8) period
16:10:04,001 INFO  [stdout] (EJB default - 9) period
16:10:05,001 INFO  [stdout] (EJB default - 10) period
16:10:06,002 INFO  [stdout] (EJB default - 1) period
16:10:07,003 INFO  [stdout] (EJB default - 2) period

References

1. Simplest Possible EJB 3.1 Timer : Adam Bien's Weblog
2. ejb 3.0 - EJB3 + JEE6: What is a persistent Timer? - Stack Overflow
3. MaestroDev | Building an EJB Project
4. Schedule (Java™ EE 7 Specification APIs)

Environment

• Apache Maven 3.1.1

Common goals

clean

• Delete everything at target directory

compile

• Compile sources to class files

test

• Run JUnit test classes

package

• Make the JAR file or WAR file

install

• It does “package” goal and install the package to local repository so that other Maven project can reference it.

Execute Main class

mvn exec:java -Dexec.mainClass=org.sonatype.mavenbook.weather.Main -Dexec.args="70112"

Show dependencies

Command

mvn dependency:resolve

What will we got

[INFO] The following files have been resolved:
[INFO]    com.ibm.icu:icu4j:jar:2.6.1:compile
[INFO]    xml-apis:xml-apis:jar:1.0.b2:compile
[INFO]    xerces:xmlParserAPIs:jar:2.6.2:compile
[INFO]    oro:oro:jar:2.0.8:compile
[INFO]    log4j:log4j:jar:1.2.14:compile
[INFO]    velocity:velocity:jar:1.5:compile
[INFO]    dom4j:dom4j:jar:1.6.1:compile
[INFO]    commons-lang:commons-lang:jar:2.1:compile
[INFO]    xerces:xercesImpl:jar:2.6.2:compile
[INFO]    commons-collections:commons-collections:jar:3.1:compile
[INFO]    junit:junit:jar:3.8.1:test
[INFO]    jdom:jdom:jar:1.0:compile
[INFO]    xalan:xalan:jar:2.6.0:compile
[INFO]    jaxen:jaxen:jar:1.1.1:compile
[INFO]    commons-io:commons-io:jar:1.3.2:test
[INFO]    xom:xom:jar:1.0:compile

Show dependencies in tree style

Command

mvn dependency:tree

What will we got

[INFO] org.sonatype.mavenbook.custom:simple-weather:jar:0.8-SNAPSHOT
[INFO] +- log4j:log4j:jar:1.2.14:compile
[INFO] +- dom4j:dom4j:jar:1.6.1:compile
[INFO] |  \- xml-apis:xml-apis:jar:1.0.b2:compile
[INFO] +- jaxen:jaxen:jar:1.1.1:compile
[INFO] |  +- jdom:jdom:jar:1.0:compile
[INFO] |  +- xerces:xercesImpl:jar:2.6.2:compile
[INFO] |  \- xom:xom:jar:1.0:compile
[INFO] |     +- xerces:xmlParserAPIs:jar:2.6.2:compile
[INFO] |     +- xalan:xalan:jar:2.6.0:compile
[INFO] |     \- com.ibm.icu:icu4j:jar:2.6.1:compile
[INFO] +- velocity:velocity:jar:1.5:compile
[INFO] |  +- commons-collections:commons-collections:jar:3.1:compile
[INFO] |  +- commons-lang:commons-lang:jar:2.1:compile
[INFO] |  \- oro:oro:jar:2.0.8:compile
[INFO] +- commons-io:commons-io:jar:1.3.2:test
[INFO] \- junit:junit:jar:3.8.1:test

Verbose Output

Command

mvn install -X

What will we got

• It outputs tons of verbose information, such as why each jars are included or excluded.

How to skipping unit tests

mvn install -Dmaven.test.skip=true

Show description of a plugin

mvn help:describe -Dplugin=exec -Dfull

Create a jar with dependencies

mvn assembly:attached

• This might need additional configuration of the plugin in the pom.xml

Run Jetty and deploy the WAR

mvn jetty:run

• This might be useful for some proto-typing of servlet or jsp.
• This might need additional configuration of the plugin in the pom.xml

Project Hierarchy

• Every Maven projects can have children or its parent.
• It's useful for declare common dependencies (using dependencyManagement) or plugins (using pluginManagement).
  • Child pom.xml can omit “version” element in dependencies that are declared in dependencyManagement of the parent pom.xml

Analyze “used undeclared” or “unused declared” dependencies

mvn dependency:analyze