$ ./rabbitmq-server
RabbitMQ 3.5.4. Copyright (C) 2007-2015 Pivotal Software, Inc.
## ## Licensed under the MPL. See http://www.rabbitmq.com/
## ##
########## Logs: ./../var/log/rabbitmq/rabbit@kyle-no-MacBook.log
###### ## ./../var/log/rabbitmq/rabbit@kyle-no-MacBook-sasl.log
##########
Starting broker... completed with 0 plugins.
Using RabbitMQ with Java
TweetPosted on Wednesday Aug 05, 2015 at 05:04PM in Technology
RabbitMQ is an open source message broker software made with Erlang. RabbitMQ is sponsored by Pivotal Software, Inc. in this entry, we’ll see how to launch it, publish or receive simple messages with Java client on OS X.
Installation
I’m using OS X 10.9.5. download rabbitmq-server-mac-standalone-3.5.4.tar.gz for Macs then extract it on somewhere.
Start the server
The server can be launched via execute sbin/rabbitmq-server as follows.
To shutdown, hit Ctrl+C then press a.
Next, we’ll look how to interact with the server from Java client.
Dependencies
RabbitMQ supplies the client library for Java in Maven Central. just put following dependency to your pom.xml.
<dependency> <groupId>com.rabbitmq</groupId> <artifactId>amqp-client</artifactId> <version>3.5.4</version> </dependency>
Java examples in official tutorial
There is a complete Hello World example of a publisher in https://www.rabbitmq.com/tutorials/tutorial-one-java.html . just copy and paste it to your workspace and execute it after launch the server.
Complete a consumer example is here: https://github.com/rabbitmq/rabbitmq-tutorials/blob/master/java/Recv.java . just execute it after execution of publisher is done.
The whole project can be obtained from my GitHub repository, nothing interesting here though.
Remarks
It’s very easy to use, I haven’t experienced any pitfall at all.
I wanted to interact with the server using JMS, but the JMS client needs a commercial license to download and unfortunately I don’t have one.
References
Tags: rabbitmq
Lean example of Tomcat 8 + Guice 4 + Jersey 2.19
TweetPosted on Wednesday Aug 05, 2015 at 02:36PM in Technology
Jersey is the RI of JAX-RS. in this entry, I introduce you how to use Jersey 2.19 with Guice 4 on Tomcat 8. it looks like there are some issues exist as follows but thanks to https://github.com/Squarespace/jersey2-guice , I’ve succeeded to use them anyway.
The entire project which based on Maven can be obtained from My GitHub repository.
Dependencies
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.glassfish.jersey</groupId>
<artifactId>jersey-bom</artifactId>
<version>2.19</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
</dependency>
<dependency>
<groupId>com.google.inject</groupId>
<artifactId>guice</artifactId>
<version>4.0</version>
</dependency>
<dependency>
<groupId>com.google.inject.extensions</groupId>
<artifactId>guice-servlet</artifactId>
<version>4.0</version>
</dependency>
<dependency>
<groupId>com.squarespace.jersey2-guice</groupId>
<artifactId>jersey2-guice</artifactId>
<version>0.10</version>
</dependency>
</dependencies>
web.xml
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<servlet>
<servlet-name>Jersey Web Application</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>jersey.config.server.provider.packages</param-name>
<param-value>guice.tomcat.jersey</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Jersey Web Application</servlet-name>
<url-pattern>/webapi/*</url-pattern>
</servlet-mapping>
<listener>
<listener-class>guice.tomcat.MyJerseyGuiceServletContextListener</listener-class>
</listener>
<filter>
<filter-name>guiceFilter</filter-name>
<filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>guiceFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
MyJerseyGuiceServletContextListener.java
In this example, we use the servlet context listener named JerseyGuiceServletContextListener which comes from jersey2-guice artifact as parent class.
public class MyJerseyGuiceServletContextListener extends JerseyGuiceServletContextListener {
@Override
protected List<? extends Module> modules() {
return Collections.singletonList(new ServletModule() {
@Override
protected void configureServlets() {
bind(MyService.class).to(MyServiceImpl.class);
}
});
}
}
Service class
We use very simple pair of an interface and implementation that creates a simple greeting message, which used in a past entry so omitted for simplicity.
MyResource.java
This is an simple implementation of JAX-RS resource class. placed under guice.tomcat.jersey package. the preceding service class named MyService will be injected by @javax.inject.Inject annotation.
@Path("myresource")
public class MyResource {
@Inject
private MyService myService;
@GET
@Produces(MediaType.TEXT_PLAIN)
public String getIt() {
return myService.hello("Jersey");
}
}
Test run
$ curl http://localhost:8080/webapi/myresource Hello, Jersey
Lean example of Tomcat 8 + Guice 4 + EclipseLink 2.6.0
TweetPosted on Tuesday Aug 04, 2015 at 07:26PM in Technology
I wrote a Lean example of Tomcat 8 + Guice 4 in previous entry. this time, I’ll try JPA(EclipseLink) integration with automatic transaction management.
The entire project which based on Maven can be obtained from My GitHub repository.
Prerequisites
For database connection, we’ll use a DataSource which is defined on Tomcat server. to define a Embedded Derby DataSource, This entry would help.
Dependencies
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>2.6.0</version>
</dependency>
<dependency>
<groupId>com.google.inject</groupId>
<artifactId>guice</artifactId>
<version>4.0</version>
</dependency>
<dependency>
<groupId>com.google.inject.extensions</groupId>
<artifactId>guice-servlet</artifactId>
<version>4.0</version>
</dependency>
<dependency>
<groupId>com.google.inject.extensions</groupId>
<artifactId>guice-persist</artifactId>
<version>4.0</version>
</dependency>
</dependencies>
web.xml
No changes against previous entry except addition of resource-ref element.
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<!-- taken from https://github.com/google/guice/wiki/Servlets -->
<listener>
<listener-class>guice.tomcat.MyGuiceServletConfig</listener-class>
</listener>
<filter>
<filter-name>guiceFilter</filter-name>
<filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>guiceFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<resource-ref>
<res-ref-name>jdbc/derby</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
META-INF/persistence.xml
If you don’t want to use a DataSource on Tomcat, specify the connection information in javax.persistence.jdbc.* properties instead of non-jta-data-source.
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="myJpaUnit" transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<non-jta-data-source>java:comp/env/jdbc/derby</non-jta-data-source>
<class>guice.tomcat.MyEntity</class>
<properties>
<property name="eclipselink.ddl-generation" value="drop-and-create-tables"/>
<property name="eclipselink.logging.level" value="FINE"/>
<property name="eclipselink.logging.level.sql" value="FINE"/>
</properties>
</persistence-unit>
</persistence>
MyGuiceServletConfig.java
The last two statements will take care of JPA integration.
public class MyGuiceServletConfig extends GuiceServletContextListener {
@Override
protected Injector getInjector() {
return Guice.createInjector(new ServletModule() {
@Override
protected void configureServlets() {
serve("/*").with(MyServlet.class);
bind(MyService.class).to(MyServiceImpl.class);
install(new JpaPersistModule("myJpaUnit"));
filter("/*").through(PersistFilter.class);
}
});
}
}
MyEntity.java
This is a very simple JPA entity which keeps only generated id and ts (a timestamp).
@Entity
@NamedQuery(name = "MyEntity.findAll", query = "SELECT e FROM MyEntity e ORDER BY e.id DESC")
public class MyEntity implements Serializable {
@Id
@GeneratedValue
private Long id;
@Column(nullable = false)
@Temporal(TemporalType.TIMESTAMP)
private Date ts;
... accessors are omitted
Service class
MyService.java
public interface MyService {
void save(MyEntity e);
List<MyEntity> findAll();
}
MyServiceImpl.java
Note that you need to annotate a method with @com.google.inject.persist.Transactional if you need a transaction on it.
public class MyServiceImpl implements MyService {
// Transactions doesn't start if EntityManager is directly injected via @Inject.
// I have no idea why...
// According to https://github.com/google/guice/wiki/JPA,
// "Note that if you make MyService a @Singleton, then you should inject Provider<EntityManager> instead."
@Inject
private Provider<EntityManager> emp;
@Override
// @javax.transaction.Transactional is not supported yet. https://github.com/google/guice/issues/797
@com.google.inject.persist.Transactional
public void save(MyEntity e) {
EntityManager em = emp.get();
em.persist(e);
}
@Override
public List<MyEntity> findAll() {
return emp.get().createNamedQuery("MyEntity.findAll", MyEntity.class).getResultList();
}
}
MyServlet.java
This servlet saves a MyEntity with current timestamp, then fetches all of rows and returns them to the client on every request.
@javax.inject.Singleton
public class MyServlet extends HttpServlet {
@javax.inject.Inject
private MyService myService;
@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
MyEntity myEntity = new MyEntity();
myEntity.setTs(new Date());
myService.save(myEntity);
PrintWriter writer = resp.getWriter();
writer.write("<html><body><ul>");
for(MyEntity e : myService.findAll()){
writer.write("<li>");
writer.write(e.toString());
writer.write("</li>");
}
writer.write("</ul></body></html>");
}
}
Test run
A row will be saved on every request as follows:
Tags: eclipselink guice jpa tomcat
Lean example of Tomcat 8 + Guice 4
TweetPosted on Monday Aug 03, 2015 at 06:56PM in Technology
I prefer Java EE stack usually, but I need to learn a Tomcat based stack for some reasons these days. in this entry, I introduce you a very simple example of Tomcat 8 + Guice 4 app which uses GuiceFilter and GuiceServletContextListener so that bring Guice to a Servlet based web application.
The entire project which based on Maven can be obtained from My GitHub repository.
Dependencies
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.google.inject</groupId>
<artifactId>guice</artifactId>
<version>4.0</version>
</dependency>
<dependency>
<groupId>com.google.inject.extensions</groupId>
<artifactId>guice-servlet</artifactId>
<version>4.0</version>
</dependency>
web.xml
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<listener>
<listener-class>guice.tomcat.MyGuiceServletConfig</listener-class>
</listener>
<filter>
<filter-name>guiceFilter</filter-name>
<filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>guiceFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
MyGuiceServletConfig.java
We need to declare servlet mappings and the mappings between interfaces and implementations here.
public class MyGuiceServletConfig extends GuiceServletContextListener {
@Override
protected Injector getInjector() {
return Guice.createInjector(new ServletModule() {
@Override
protected void configureServlets() {
serve("/*").with(MyServlet.class);
bind(MyService.class).to(MyServiceImpl.class);
}
});
}
}
Service class
We use a pair of a very simple implementation of a service class. it simply creates a greetings which uses an argument.
MyService.java
public interface MyService {
String hello(String name);
}
MyServiceImpl.java
public class MyServiceImpl implements MyService {
@Override
public String hello(String name) {
return "Hello, " + name;
}
}
MyServlet.java
Note that we use @javax.inject.Singleton and @javax.inject.Inject annotations, that are standardized JSR API.
@javax.inject.Singleton
public class MyServlet extends HttpServlet {
@javax.inject.Inject
private MyService myService;
@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.getWriter().write(myService.hello("Guice"));
}
}
Test run
After deployment, send a request to check the response:
$ curl http://localhost:8080 Hello, Guice
Other things/functions need to be studied
-
Transaction management
-
CDI Producer equivalent
-
AOP
-
Automatic implementation scanning/binding
