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Spring has left the Building!

Veröffentlicht: Oktober 7, 2010 in Automatic Binding for Guice, Java
Schlagwörter:, , , ,

Hi,

my Name is Daniel Manzke and I’m one of the Co-Moderators of the Xing-Group for the Java User Group Berlin-Brandenburg (Germany). I’m also organizing Presentations for the Group. I’m using Java for 6-7 years and worked with Spring for 3-4 years. At the moment I’m working on the Automatic Binding of Beans, Modules, Configurations and AOP for Google Guice. #GAB

So enough about me, I justed want to tell you a short story and I want to know from you, if I’m so wrong.

Some weeks ago I wrote Adam Bien an Email and asked him if he would present all the new Stuff around Java EE 6. I really like the guy, because he is pragmatic and you can discuss with him, without the normal flame wars of Programmers. (you should visit one of his presentations!)
We agreed that the 25.01.2011 would be the perfect date and ImmobilienScout24 will allow us, to present in one of their rooms. (with Pizza and Drinks – Thanks!)

Disclaimer: This blog and my opinions have nothing to do with ImmobilienScout24 or Adam Bien. These are my personal opinions.

In a later mail Adam had the great Idea, that we could make a Side-by-Side presentation. We thought Spring would be a nice Partner. I really liked the idea to hack an Example Side-by-Side with Java EE and Spring. Why? Because Spring always wanted to replace EJBs and all the heavy Stuff of Java EE.

So I started to search a good Spring-Presenter who would like to do this hacking. And here begins the funny part!

One guy (I don’t want to blame anybody so I’ll call him Mr. S) Mr. S wrote me that he liked the idea, but this comparison of the two Stacks doesn’t make a sense for him.
He wrote me, that you can create the Presentation Example with Spring, CDI, EJB and without Java EE, because Spring is so flexible. „And you can use Xml, Annotations and all this stuff.“

Until here I could follow him a little bit, but than he begun to write me the real features and advantages of Spring.

Mr.S wrote, that we can’t compare the Stacks, we should instead show how easy it is to bring such an App into the GAE, how to integrate Caching, how to integrate Twitter and how to connect NoSQL-Databases. „Java EE has no rudiments for the needs of the Future“

At this point I started laughing for about one hour and had a lot of discussions with Friends.

Does Spring has left the Building? Are you using Spring anymore? What DI-Implementation would you choose if you would start a new Project?

For me it is clear, I’ll never use Spring again. (only if I have to) Spring is just to heavy and not lightweight anymore. They tried to implement everything and make everything better. Do they have reached their aim or do they have lost their focus?
There are needs for NoSQL and all the stuff, but not for my Customers. I don’t know if they know how to write NoSQL, but I know that they are not able to administrate it.

So there are a lot of scenarios where I’m happy that Java EE is on the best way, to get really lightweight and Adam will show us all the Core-Stuff.

I’m really glad to know, that he is not one of the Marketing Guys!

So let us discuss, if Spring is useful anymore. If Java EE is fit for the Future. I’m really interested in your thoughts!

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		<dependency>
			<groupId>de.devsurf.injection.guice.integrations</groupId>
			<artifactId>de.devsurf.injection.guice.integrations.guicyfruit</artifactId>
			<version>0.6.2-SNAPSHOT</version>
		</dependency>

This will add the JSR250Module of the GuicyFruit-Extension to your Classpath and the Scanner will find the Module, because it is marked with @GuiceModule.
So you can annotate your Classes with @PostConstruct, @PreDestroy and/or @Resource.

In my git-Repository you will also find an Example-Folder, where all Features are used. From automatic Binding of Classes, over automatic installation of Modules, to using JNDI and/or Multiple-Bindings.

I’ll show it in the next Example how to use it.

In our Example we have one Interface „Example“ 🙂 :

public interface Example {
    String sayHello(); //will be called in our Application
    void inform(); //will be called through @PostConstruct
}

Our Implementation is as easy and boring as you would expect it 🙂 :

public class ExampleImpl implements Example {  
    @PostConstruct  
    public void inform(){  
	System.out.println("inform about post construction!");  
    }  
    
    @Override  
    public String sayHello() {  
	return "yeahhh!!!";  
    }  
}

and for completeness a Module, which will be installed automatically which will bind our Interfact to the Implementation:

@GuiceModule
public class ExampleModule extends AbstractModule {   
    @Override
    protected void configure() {  
	bind(Example.class).to(ExampleImpl.class);
    }
}

You see how difficult it is? 🙂

Oh and I forgot our Application. We will use the StartupModule, which only wants to know about the ClasspathScanner-Implementation and which Packages should be scanned.
After creating an Injector, we will retrieve an Instance of our DynamicModule, which is bound to the ScannerModule.
Last but not least, this Module can be used to create a new Injector.

public static void main(String[] args) throws IOException {  
	StartupModule startupModule = StartupModule.create(VirtualClasspathReader.class, ExampleApp.class.getPackage().getName(), JSR250Module.class.getPackage().getName());  
	Injector injector = Guice.createInjector(startupModule);  
  
	Module m = Modules.combine(startupModule, injector.getInstance(DynamicModule.class));  
	injector = Guice.createInjector(m); 

	System.out.println(injector.getInstance(Example.class).sayHello());  
}

Attention: At the Moment there is something I don’t understand. When I use my original Injector to create a ChildInjector, all Interface-to-Class-Bindings work like a charm. But I install a Module, which will bind a TypeListener or something else, they are not recognized.
I’m not sure if this is a Bug or a wanted behavior. So we are only able to use GuicyFruit, if we create a new Injector with the Help of the DynamicModule.

Guicefy JNDI

If you are working a lot with JNDI and/or JavaEE you often have to work with a Context. A good description about the Use Case can be found on the GuicyFruit Wiki. I’ll only describe how you can use it with my Extension.

First of all you will need a „jndi.properties“ with the ContextFactory, our Class for the ClasspathScanner and which Packages should be scanned. (sounds familiar? :))

java.naming.factory.initial = ...integrations.guicyfruit.GuicyInitialContextFactory
guice.classpath.scanner = ...scanner.asm.VirtualClasspathReader
guice.classpath.packages = ...

After that you need to create a new Context and lookup your Instances with the help of it. The Rest is magic. 🙂 (behind the scene there is the normal automatic binding and installation of modules/beans)

public static void main(String[] args) throws Exception {  
	InitialContext context = new InitialContext();  
	Example example = (Example) context.lookup(Example.class.getName());  
  	
	System.out.println(example.sayHello());  
}

On the road to Version 1.0 I have to invest a little bit in the rocoto-Integration and further Tests/Documentation.

The work on Automatic Injection/Binding for Guice is in heaviy progress. I added the possibility to use the JSR330 and/or Google Guice Annotations.

So you can create a Named-Binding due using the @Named-Annotation. Due the fact, that the Guice-Named Annotation is not able to annotate a Class, I only support the javax.inject.Named-Annotation.
If you annotate a Class with it, it will result in

binder.bind(interface).annotatedWith(Names.named(annotation.name())).to(annotatedClass)

To declare a Singleton you can use the @Singleton of the JSR330 and/or the Google Guice-Annotation.

binder.bind(interface).to(annotatedClass).in(Scopes.SINGLETON)
/* for named resources */
binder.bind(interface).annotatedWith(Names.named(annotation.name())).to(annotatedClass).in(Scopes.SINGLETON)

After I submitted this feature, I want to release a new Version. So I added the Maven Release Plugin and tried to do „mvn release:prepare“ and „mvn release:perform“.
What a big mistake. 🙂

My Environment?

  • Windows 7
  • Github Account
  • git 1.7.x + msysgit
  • Maven 2.2.x

I faced several problems. First of all I didn’t recognize, that I don’t had the distribution section, due the fact that the most Maven Repository are only working if you have a project there, I decided to use the Sonatype Repository.
I just can recommend to every github User which needs one, get your account there!
You create a Account, create a JIRA ticket and after one Day you can upload to OSS. The big advantage is, you can stage your releases. So release your version and if your think your are done, bring it from a Stage-Level to a Release and it wil be synched to Maven Central.

Have a look at the Usage Guide

After adding a „settings.xml“ to my „~\.m2“ Folder, I also decided to encrypt it, because you have to store your Sonatype-Account Settings there.

How-to do it? Maven Encrypt Password

What I also can recommend is, that you create a Root-Project, which inherits from the Sonatype-POM. You need this step, because they already configured the plugins, which you need for you. Parent POM Settings

After this step you need to configure GPG. For releasing to Maven Central you have to sign your Releases and Snapshots. For me the easiest way was, to remove all gpg*.exe Files from my Git-Installation.
I installed a newer Version: gpg4win.
Nevertheless the easiest way (whatevery gpg you use) you should create a certificate and import it with gpg –import mycertificate.asc.
The problem with the Git gpg was, that it search for my certificates in ~\.gnupg. But I don’t have this directory. You can overwrite the directory with passing -Dgpg.homedir= when using mvn release:*.

All the problems I had are related to the Unix-Environment for Windows. Due the fact, that it uses Unix-Folder Path, but partly working with Windows-Paths Style, I had a lot of problems.

  • Not finding POMs (your pom is outside of the repository
  • StringIndexOutOfBoundsException when using the Release Plugin Version 2.0

How could I overcome these issues?
I’m working with git-bash, but the first thing I do is, type cmd. So you have your whole Environment, but working in Windows-Style.
If I’m working with git, I’m using the Bash-Style not the Windows one.
You also need the git-bash because I didn’t get it up and running to use the ssh-agent under Windows. But if you are starting the git-bash this will work, because it ask you while startup about your Passphrase. How-to start SSH-Agent

EDIT: The problems with Windows, Maven, msysgit is how you start your git-bash. Start your bash with the Help of the Windows Command. Doing it this way, the Letter is „F:“ (or whatever :)). Starting directly the git-bash it is „f:“.

EDIT 2: When using the Command Line + Git-Bash, you should change to your local drive with „F:“. The major point is the Uppercase of the Letter!!! Without it, the Maven-Release-Plugin 2.0 will fail.

Some Tips&Tricks:

  • Use -DautoVersionSubmodules=true if you have multiple Modules, but want just one Version Number

I hope my comments, can help you a little bit, while working with Maven, git/Github and Windows.

If you have questions, don’t hesitate to ask me. 🙂

On Monday I released my „Automatic Injection for Guice„, which should help to automatically create Bean bindings and install Guice Modules.
This is done, due using Implementations of Classpath Scanners. At the moment there is my own pure Implementation, which uses ASM to inspect the classes. You can also choose between the Reflections-API or a Guice Extensions which was created by Sonatype.

Reflections has the biggest advantage at the moment, because it scans the classpath in parallel if you have multiple Cores/CPUs. One Problem I figured out is, that the Binder of Guice is not threadsafe. So if you are want to use it in parallel, make sure that you synchronize it.

In the last stage, my extension added the GuiceModule- and AutoBind-Feature by default. Due the fact, that this can have bad behaviors you can now overwrite it. The „bad“ behaviors can result of multiple bindings. If you for example have an automatic installed Guice-Module which binds your class and if the class is annotated with @AutoBind, which would lead to another binding.

The default StartupModule still uses both Features. Create it like that:

StartupModule.create(VirtualClasspathReader.class, "de.devsurf", "net.java.dev.webdav.jaxrs")

StartupModule is an abstract Class, which should be used, if you want to overwrite the used Features. It therefore declares an abstract method „bindAnnotationListeners“.
To bind multiple Implementations we are using the Multibindings Extension for Guice.

So if you only want the automatic Module installation, just bind the GuiceModuleListener:

public class ExampleStartupModule extends StartupModule {
    public ExampleStartupModule(Class<? extends ClasspathScanner> scanner, String... packages) {
        super(scanner, packages);
    }

    @Override
    protected void bindAnnotationListeners() {
        Multibinder<AnnotationListener> listeners = Multibinder.newSetBinder(binder(), AnnotationListener.class);
        listeners.addBinding().to(GuiceModule.GuiceModuleListener.class);
        //listeners.addBinding().to(AutoBind.AutoBindListener.class); //used for Automatic Bean Binding
    }
}

I extended the Examples which can be found on Github Automatic Guice Injection.

Still to go:

  • Maven Release
  • JUnit Tests
  • GIN Release (if possible :)) – Research has to be done.

Today I wanted to share a new Proof-of-Concept of mine.

I’m working for an ECM company, which often faces to create new Integration for customers or in other products. Some months ago I created a http-based Interfaces for a customer. To give it a general touch, I decided to make it highly configurable, so it can be used for more projects.

This led me to the Command- and Chain of Responsibility-Pattern. I created a mechanism to configure the steps, which are taken when a new document should be archived. These Plugins (Java Classes) are annotated, so I can find them at runtime.

You ask yourself now, what does it have to do with Google Guice?

I started the project without Dependency Injection and used Reflections (http://code.google.com/p/reflections/), to scan my Classpath for my plugins. Due the fact that I have vacations and have to look after my son (15 months), I started to investigate a little bit to learn GWT and Guice.

I really like the idea of the Guice ESL to bind all my stuff, but for a project like mine where I need configurable bindings, this doesn’t fit. So I started to search for Classpath Scanners for Guice and found a project created by Sonatype.

This project did exactly what I want. It scans my classpath and informs me about Classes and its annotations. The problem was that just for scanning the footprint was to much and there were some design decisions which I don’t like.

So I created the „Guice Automatic Injection“-Project, with a small Classpath Scanner which uses ASM to load and inspect classes. I also created some interfaces, so I can use Reflections or Sonatype as a Scanner, too.

After a lot of experiments, I found my way how to do it. I created some listeners.

Number 1: Installs all Google Guice Modules, which are annotated with @GuiceModule (mehr …)