I would like to take a doubt about the container to run a "Spring Application", in my opinion one of many features who Spring Framework offer is a possibility to create application without container EE. Is right use this type of container ("WildFly", "GlassFish") with a spring project ? In my option is wrong but i'm open to listening more people.
i saw a article where the author are showing the features of Spring 4 with the WildFly, but i didn't agree, so i would like to take more opinions about this topic here.
Considering Spring Web and Web MVC you will typically use a lightweight container like Tomcat, Jetty or any other servlet container - maybe embedded like Spring Boot does.
Spring Web is designed to work without a full JEE container but will also work deployed inside one.
With Spring without JEE you have much more control about the features you use. A full appserver has a bundled feature list, you get all or none. Spring offers you to pick what you need resulting in a more slim application.
Well, first of all it is a little tricky to say that "something" is wrong or right in software development, mainly in this type of subjective question. As always, that really depends on what you need and on the EE Container that that you are using.
Let's get Widlfly as example. Since JBoss 7 (and now Wildfly) I do not think we can say that JBoss is a "heavy" Server, as it starts in just a few seconds, much faster than in the earlier versions. While it is true that Wildfly comes with a lot of services that you may not use, it is not correct to say that you get "all or none", for at least 2 reasons:
You can disable the services you do not need.
Wildfly works with the concept of lazy-loading for its services, which means that it will only load the services that are required to run a given application.
Having said that, we can not forget that Spring also uses some EE services, if you want to. So, if you need to use Spring with JMS, for example, you still need a JMS container. In this case, you can use an EE Server without needing to install additional services or you can start a JMS container in your Tomcat.
Besides the EE features, there is also the question of features related to the server, such as configurability/manageability (Web interface, CLI), HA, scalability... that really varies from server to server and I think Jboss 7/Widfly does a good work on these points.
I have Websphere 7 server, and it don't support JPA 2.0. So I can't run on WAS 7 JPA 2.0 applications.
But I'm wondering how Spring users run Hibernate on Tomcat or Jetty? This servlet-containers also (as WAS 7) doesn't support Java EE 6.
So it's mean that I can run Hibernate on WAS 7 with the same results as on the Tomcat or Jetty?.
If yes, what are benefits of using app-servers for JPA? Why all developers don't use servlet-containers instead app-servers?
Also I heard about "container-managed" stuff, that allows some additional features and functionality. So it's mean that many developers (who uses Spring on Jetty and Tomcat) don't get benefits of using container-managed features of app-servers?
P.S. I know about available Feature Pack patch for WAS 7 for JPA 2.0 support, but question not about it.
You can bring in a lot of functionality by including the appropriate jars in your WEB-INF/lib folder, but then the servlet container cannot help you in any way with the functionality, and it will most likely not be well integrated with the functionalty actually provided by the container. A typical example is bringing your own JSF 2.0 libraries.
The real advantages of using implementations in the container, is that the container can then help with clustering across multiple hosts, providing JDBC connection pools, etc.
So, you need to be more careful when including e.g. Hibernate yourself, and do all the configuration inside your own deployment, but it can be done.
You could just as well ask an exactly opposite question: "why use bare servlet containers with JPA 2 since it is included in all the Java EE 6 servers?".
Basically it boils down to either:
having a light-weight container and then a heavy application (the Spring way),
having a light-weight application and then a heavy container (the Java EE 6 way).
After years of evolution, the models of building the applications with Spring and Java EE 6 have converged to the point where sometimes you cannot really tell just by looking at a class, whether it's a Spring or a CDI bean. So the real difference is mostly in configuration.
Application servers offer a set of services "out of the box", so they are easier to use if the offered services are the ones you need. You just package and deploy your application and the thing works. Furthermore, most of the technologies are instantiated by the application server, so you avoid a lot of classloader issues.
The problem with application servers is that sometimes (quite often, actually), you need to pick and choose particular versions of particular frameworks, services, etc that are incompatible with those which the application server offers. In those cases, you usually need to fiddle with the application server, and in some cases, what you would like to do might not even be possible with your application server.
For example, Weblogic 10.x is a Java EE 5 application server and so it will offer by default JSF 1.2 and JPA 1. If you want to use something newer, you need to manually deploy some additional libraries (JSF 2.0), or patch the server (JPA 2.0).
Another example: with Glassfish 3.1 I have not been able to use Tomcat EL intead of Glassfish EL. Tomcat EL supports varargs method call while Glassfish EL does not.
That rigidness of Java EE application servers makes a lot of people prefer developing for a standalone servlet container such as Tomcat or Jetty, where you have nothing out of the box but the Servlet and JSP APIs, but you can manually put everything inside. You can also package it with your application, which is more comfortable when you are developing, but can give you problems if you deploy more than one application per container (waste of resources, classloading issues, classloader leaks, ...)
UPDATE:
There are some differences in using JPA in a SE environment (such as Tomcat) when compared to using JPA inside a Java EE container. Basically:
You have to manually manage EntityManagerFactory and EntityManager instances.
Tomcat does not do injection so #PersistenceContext annotation and similar ones do not work.
Note that some containers (such as Spring) can be configured to hide these details, so you can work exactly as if you were inside a Java EE container.
Read the JPA spec for details on running in SE environments instead of EE environments.
Regarding another libraries, in general you will find some minor differences. For example, JAX-WS requires registering a servlet and a listener for your webapp, but anything else should be identical. Usually you can search the documentation for instructions on how to run the thing inside a standalone servlet container.
There is a JPA 2.0 feature pack for WAS 7.0, which may help you.
Ok, I know this is a vague question, and I expect a vague/basic answer.
I am well versed with PHP driven MVC frameworks and how the process of serving pages works. I'm very interested in learning Java, and I figure the only way to learn it is to do it. However, after reading page after page after page, it gets more confusing as I read.
I'm running into GWT (front end), Hibernate (ORM connection?), Spring Architecture, Spring Roo (what is this?), JBoss (servelet), JPA (ORM), POJO (a style of using regular java objects with orm?), Maven?
My basic question is how do all of these fit together? I like the idea of using a framework, because it's worked well in the past with PHP. How do I use this functionality with java? Suppose I wanted to build a web application with a relational data store. How does java authenticate, initate a session, and serve pages with dynamic content? What is the process?
When responding, please don't say "stick with what you know," (as I've seen on other pages) because I'm very interested about java and I'm trying to learn.
I totally hear you - too many acronymns have propped up as Java EE has evolved.
I will try to put an explanation
Java is the language
Java EE (Java Enterprise Edition) is the general term used to encapsulate all Java technologies that help create an enterprise/web application with Java
So a typical web application with Java looks like follows:
Front End
Use JSP or JSF for server side processing and rendering (JSP and JSF
offer ability to define your UI using HTML and server side tags that
bind easily with your Java Beans) However they do tend to mix UI with
backend if not implemented correctly
you can also use plain HTML and any client side toolkits for rendering (such as jquery, dojo, extjs or flex) and fetch your data
from the Java EE server.
you can even mix the two (use a client side framework in a JSP to achieve best of both) or use a toolkit like GWT that offers client side richness with javascript with Java APIs and ease of accessing your java beans
Middle tier
Java Servlets offer the base for all server side processing with Java EE (Servlets offer session persistence, HTTP request processing, response processing) and typically offload the business processing to a model bean - which could be a POJO or spring bean.
Servlets are Java programs you write and are executed in what is called a Java EE container. Popular containers are tomcat, IBM websphere, BEA Weblogic
To help implement a good MVC architecture, there are several frameworks and tools provided on top of Servlets:
Struts2 and Spring MVC are examples of such frameworks
To make it easy to implement web services, Restlet/Jersey help with REST based web services, JAX-WS/APache Axis help with SOAP based web services
Integration with backend database/persistent store
You could use JDBC in your POJO or other model bean to access the DB using Java.
Or alternately use one of the frameworks such as Hibernate to make it easy to interface with the DB backend
Sun's petstore application is a good place to start to learn how the pieces fit together
http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-eedocs-419425.html#7522-petstore-1.1.2-oth-JPR
Build and Deployment
Ant and Maven are tools used to build your app and manage dependencies
the application gets packaged as a WAR or EAR file and can be dropped into any Java EE container to deploy it. Once it is deployed, it can be accessed using a URL
Tools like Eclipse, Netbeans, Oracle JDeveloper offer integrated IDEs to help with local deployment and testing
The good part with Java EE is that you can pick and choose the components you want to use to build your webapp.
The problem Java has is that it's fairly old and there are TONS of frameworks and packages that do similar things as other packages. At the very core, however, is the Servlet, that specifies how Java behaves as a server over the HTTP protocol.
With that basic building block, there are lots of web frameworks like Struts, and Spring MVC that build up layers of functionality by using lots of good OO development patterns, like Fiters, Delegates, Factories, MVC, etc., to allow the developer to put together an application that takes web requests as input and returns a web response as output.
Those frameworks often build on other frameworks or packages to give application developers more capabilities at different layers of the application. This includes things like ORMs (like Hibernate) to talk to relational databases, or view compositing frameworks like Tiles or Velocity to help put together an HTML page as part of the response.
There are lots of other acronyms and tools and layers that get built up around web frameworks, but essentially they are all just programming tools that have useful functionality pre-built and just need to be used.
If you are looking for a more packaged web application development framework that is more cohesive and doesn't make you feel quite as lost, you may want to take a look at Grails. It is in Groovy, but it is very close to Java in terms of the language and actually builds on top of lots of the other tools you have heard of.
Grails itself builds on the Spring and Spring MVC frameworks, as well as Hibernate, so it's using the same technologies as other more pure Java frameworks, but it abstracts the ugly details away so you don't have to worry about them unless you want to. You can then bundle in additional functionality, like authentication / security, through plugins. If you are well versed in PHP-based MVC frameworks and how they work from an architecture standpoint, you will feel right at home in a similar MVC environment like Grails or Spring MVC. The Grails User Guide is a great place to start, and the rest of the documentation is good too.
If you are new to the Java language, I would strongly suggest doing a few small applications (not web apps, just simple ones) to learn the language and get familiar with how things work. Java is very different from PHP, since PHP bundles in a lot of the base functionality into the language whereas Java has a fairly sparse language with much of the commonly used functionality coming from libraries.
Once you have a good grasp of the Java language, I would jump right to the Grails framework and I would skip all of the nitty-gritty details of servlets and ORMs and Hibernate, etc. at first because you don't need to know it all and there is so much there that it can get in the way of actually understanding things.
Then, once as you start to build out an application with Grails, you will gradually get a deeper understanding of the technology Grails is built on in order to do more complex and powerful things. Slowly, you will work your way into Spring and Hibernate and build up an understanding of how things are put together under the covers, but you can be doing real things faster since you don't have to know all of that from the beginning and can quickly make web applications in Grails the just work, especially with an understanding of the MVC architecture pattern with respect to an application responding to a web request.
Wow, not only is this an open ended question, but it could have pages and pages of answers. I worked in php ~ 7 years ago without a framework so I'll try to point you in some starting directions and compare my experience (which is outdated and sans framework!)
You need an application server just like your Apache server for your Java web app, such as Tomcat, Jboss or Glassfish. These servers handle serving dynamic content.
On top of the server you have your web frameworks which you've mentioned GWT, Spring, and Spring Roo. Spring Roo is like Rails, but in Java. GWT goes all out and and will write your html/javascript code based on your Java code.
In Spring You can define objects to be used in your forms and then when they are submitted the entire object is passed back so there is less work. I remember the days of getting a lot of $_POST[] stuff and I'm thankful not to have to do that when using spring. There is Spring Security that you can use for auth.
The web frameworks are configured to connect to the database and then there is the database abstraction ORM, Hibernate. In PHP I used EZSQL for abstraction which didn't contain nearly the amount of features Hibernate does. Hibernate has a steep learning curve, but is worth learning.
For dynamic GUI's you'll probably want to research JSP, but may be interested in learning JSF.
If I were you, I'd pick an application server, maybe tomcat, then a web framework to play around with, personally I'd go with Spring. The framework will probably have dynamic GUI examples so you'll pick up jsp/jsf. Then possibly add the ORM and a build tool to build externally from your IDE, such as Maven, Ant, or Gradle.
There are some very mature java libraries that each target a very small need in a web application. This means that many tutorials on the subject will have to pick and choose the libraries for each need. For someone just starting out from your position, this probably sucks.
Naively, then, I searched for "java full stack framework" and found: Full stack framework for Java
The benefit of a full stack framework is that you don't have to choose each component. The framework has strong (perhaps rigid) opinions on how ORM is done, how templating is done, how mapping URLs to functions or actions is done, etc.
As for your list of technologies and acronyms:
GWT - a framework from google that focuses on the front end. Poorly stated, write your front end functionality in Java and have it magically transform into javascript.
Hibernate (ORM connection?) - yep, store and load objects in your app.
Spring Architecture - Spring is pretty close to a full-stack framework, but it doesn't have as many rigid opinions on things. You can swap out templating engines, swap out ORM, etc. Not a bad framework, though. You might want to simply follow a tutorial on Spring (see below on Roo), and use the components suggested by the tutorial. Just know that you might find something else later that fills a particular niche.
Spring Roo (what is this?) - Spring Roo takes Spring and becomes opinionated (use what we say). This allows for less code on your part because it provides the code that integrates the various components. It still allows quite a bit of flexibility when you want to change something. Bonus, it comes with a nice tutorial.
JBoss (servelet) - Usually I think of JBoss as an application container. Since the Java EE spec is a bit more complicated than simple CGI--there's a lot of things that need to be set up by the web server (loading classes, loading configuration files, connecting crap together)--JBoss does that stuff. Alternatives are Tomcat or Jetty.
JPA (ORM) - Yeah, it's a common set of interfaces that the various serialization providers might implement. It might be a database, it might be something else. But the idea is that your code for storing and retrieving objects would look the same.
POJO (a style of using regular java objects with orm?) - In context, probably. "Plain Old Java Objects" are nice for any library. Sometimes a framework might require that you inherit your classes from some special class, like Model or Controller to work properly (also, HTTPServlet). This isn't good, because it restricts your own class hierarchy design and makes your own code less flexible. Consequently, things that work with POJOs are considered better.
Maven - Maven is a tool that helps manage dependencies. Without it, java has its own form of DLL hell. Library A depends on version 1.1 of Library B, but Library C depends on version 1.5 of Library B. Ohhh crap, time to read through a tutorial on classloaders. Don't worry too much, though, any tutorial on java web apps is likely to tell you exactly what you need to download and use.
The first thing I would suggest you to start with, given a knowledge of http protocol, is the JSP technology. Although you would probably use some framework like JSF2 for instance, it is important to start with JSP in order to well understand the technology and how to use it to deal with request/responses (that's my humble opinion of course).
Once you are familiar with JSP and, let's say, JSF 2.0 (you can find loads of documents on that topic) the next step is to try to connect with a data source. In Java EE technology there is a specification called JPA (Java Persistence API). JPA is just a specification for ORM (which is, roughly speaking, mapping an object java model with a set of DB tables)
Once you have your web application working with some basic pages and some operations on a DB you could enforce the security of your app introducing some security mechanisms.
this is a very good reference and start point for all of these topics and much more. It's a long path and it will take you some time. But, believe me, it's worth it!
Good luck!
I suggest you google those keywords and look for some books and tutorials.
Maven
is a tool for managing your Java projects and artifacts (JARs, WARs, etc.). I'd start learning Maven first, so that you have a foundation to create your Java projects on. It also handles your dependency management: you just specify what JARs you need in your application and Maven will download them for you.
JPA (Java Persistence API) handles the Object-Relational-Mapping of your entities. You can write POJOs (plain old Java objects) and map them to your database tables.
Hibernate is a JPA provider (i.e. implementation of JPA). Usually you don't have to deal with Hibernate that much, most of the time you can use JPA directly. You just configure the JPA provider in the persistence.xml config file.
CDI (Context and Dependency Injection) see description. CDI "wires" the components of your application together.
Springframework started as a framework to offer Dependency Injection capabilities, but today it's much more than that. The WebMVC module of spring might be interesting to you. You can write Controllers and Views (using JSP for example).
Servlet API A servlet acts like a little server, handling a HTTP request and generating the response. You can write your own servlets or use a web framework to do it's job, for example Spring's DispatcherServlet or Java Server Faces, or whatever framework.
JSP is a technology to write templates for your HTML files. JSP files are being compiled into Java classes and can contain HTML code, JSP-specific XML code and Java code.
Example:
<ul>
<c:forEach items="${countries}" var="country">
<li>${country}</li>
</c:forEach>
</ul>
renders a list of countries, where ${countries} might be a collection of country objects (or strings in this case).
JSF (Java Server Faces) is another framework for building web applications, utilizing JSP and/or XHTML for defining the views and backing beans for the backend part. I would start learning with JSP instead of JSF, it's easier to learn.
Most of the frameworks are part of the JavaEE standards portfolio. For stuff like CDI to work you need either an application server (like JBoss AS) or at least a server with a servlet container (like Apache Tomcat or Jetty) in combination with Spring.
Spring and Hibernate are not standard, but they implement many of the standard APIs nowadays.
**EDIT: ** you might also want to learn about Annotations in Java code. They are around since Java 5 and are widely used as an alternative to XML based configuration.
So my suggestion is that you start learning Maven (not necessary tho, you can also manage your project manually), then Spring and JSP to be able to create a simple web application and then JPA/Hibernate to make your data persistent.
In my opinion learning Spring is much easier than learning the whole JavaEE APIs, since Spring is quite good documented.
One of the nice things about GWT is that you'll right your client code in Java, with all of its benefits and if you have server code, that could also be in Java as well, and you could share some of the source code, even if the front-end ends up running as JavaScript.
TO build a basic Java web application, go through this tutorial as it will explain the core foundational technologies with the standard Java EE platform and how to develop something real with them.
http://netbeans.org/kb/docs/javaee/ecommerce/intro.html
It will demonstrate the standard Java web technologies such as EJBs, Servlets, JSP, JPA, and how to use Netbeans for your IDE.
Most beginner's are very overwhelmed by the thousands of different technologies and platforms out there with the Java EE framework. Java caters to a very 'open source' type of community and that means that you have ALOT of different choices and road maps on how you can build applications. This is very different from say the .NET world where everything is pretty straightforward and there's a very clean cookie cutter path.
Once you have learned these foundational basics by going through the tutorial, you will have a grasp on what the Java EE framework. Once you understand these basics, you can then start to learn about Maven or Spring and how those type of technologies can help you build better applications and you can make better and more educated decisions.
GWT - Web interface tools. Some competing technologies: Spring, JSF, Wicket
Hibernate - ORM mapping for databases. Competing technology: JPA
Spring Architecture - Web Framework. Competing technology: JSF, Wicket, GWT
Spring Roo - An MVC style flavor of Spring.
JBoss - Application hosting. Competing technologies: Glassfish, Tomcat
JPA - ORM mapping for databases. Competing technology: Hibernate
POJO - Plain old java object. Just a simple object.
Maven - Maven is a way to manage libraries or dependencies that your project uses. There's a central server that hosts many of these libraries and if you ever need to import a new one to use in your project, it's as simple as searching through the server and then copy and paste the configuration settings that they provide you into an XML document called the POM file or pom.xml
Vijay's answer above is pretty much spot on. I'll elaborate on a few points.
Most of the "fameworks" that you mention, spring, roo (which is just a way to work with spring), gwt, struts, etc. all work on top of "Java EE". Java EE is Sun (now oracle's) term for the "standard" way to work with web applications. Java EE also includes a lot of more enterprise stuff like EJBs, JMS, JMX which you won't really need to concern yourself with unless you're doing very high end stuff.
JSP is the part that will be most familiar to you coming from PHP, it's a way of embedding code inside of an HTML page.
Servlets are the middle tier, that's where database connections are created and application logic happens. As it turns out, JSPs are converted into Servlets at compile time.
All Java EE stuff runs inside of a "servlet container" or an "application server". That's the big difference between java and php. Your choices here are usually Tomcat, JBoss or Jetty.
Maven is a build system that helps you to manage 3rd party jar files (libraries) and compiles and runs your test codes. It has plugins to deploy your code to tomcat/jboss/jetty.
POJO stands for "Plain old java object". Most modern frameworks try to shield you from the complexities of what happens under the hood and let you work with "POJOS". This comes into play when working with something like spring or hibernate. You may also see the term "java bean" tossed around, that's a standard way of defining "pojos" that just sets up a convention about how to name getter/setter methods and constructors.
I would recommend getting a book on getting started with JSPs/Servlets and starting there.