Since EJB 3 we have embeddable EJB containers, JPA implementations can be used without an application server, there is Weld for contexts and dependency injection and so on. Since on many systems is only Tomcat available, I wonder, if Java EE could be used without an application server but with a Servlet container like Tomcat.
What would I have to do to set up an Java environment? What drawbacks do you see?
Note that Tomcat is an Application Server. That said, in October we released Apache TomEE which is Tomcat with the missing JavaEE parts added, then Java EE 6 certified using the official TCK from Oracle.
The stack evolved from what used to be simply called "OpenEJB/Tomcat", which was a useful stack with a bad name :) Commonly overlooked because of the "EJB" part, meanwhile it also delivered Transactions, JMS, WebServices and more to Tomcat. The new name is far better and now it's officially certified like JBoss or GlassFish. We're pretty excited about its future.
If I understand well, you want to use EJB3/JPA within a servlet container.
There are not only stand-alone implementations of JPA, but also embeddable EJB3 container, such as OpenEJB or Glassfish embeddable container. So nothing prevents you from starting such an embeddable container from the Servlet container to use EJB3.
(Note: I don't know all the details about transactions. In a full-blown app. server, you have JTA and a distributed transaction manager. You don't have that in a Servlet container such as Tomcat. JPA works with JTA and plain JDBC, but I don't know exactly how an embeddable container work without JTA. Still, I guess that would work given that such embeddable containers are also meant for unit-testing where I guess there is no JTA distributed transaction manager.)
Another approach would be to use Spring. Spring and EJB3 have indeed become very similar. You can start the Spring DI container within the Servlet container and benefit more or less from the same facilities as EJB3 (declarative transactions, etc.). See this post about Spring vs. EJB3.
All these technologies have become pretty modular, especially with Java EE profiles. You can use Sevlets, EJB3, JMS, JPA, even JTA somehow independently of one other. You can also create an environment where you cherry pick the ones you would like, either with Spring or with Java EE. The question is when does it stop to make sense and rather use an app. server with everything available and easily manageable. I think Servlet/EJB3/JPA is the limit, if more is needed go for an app. server.
You will generally require some kind of container, even if that container doesn't provide Java EE-related services. After all, you do need a long-lived JVM process to host the code that you're executing. Tomcat and Jetty will do the job nicely, and in addition to basic servlet services, provide a few useful extras that will be relevant, like connection pooling.
J2EE without application server was introduced years ago by me (Guy Pardon, from Atomikos), with this seminal article: http://www.onjava.com/pub/a/onjava/2006/02/08/j2ee-without-application-server.html - focused on JMS and JDBC at the time.
In general it's easy to setup thanks to Spring and Hibernate. Actually, I got inspired to do this after doing a Java EE project and being confronted with the XML hell associated with app servers and EJBs. Without application server things suddenly became a lot simpler and more testable.
If you need a Tomcat installation then can be a bit more of a hassle to configure, but recently Atomikos has introduced out-of-the-box Tomcat integration as part of its commercial offering at http://www.atomikos.com.
HTH
Related
I know that Tomcat is a web server but why it is not an application server?
Any server needs to follow some specification. What is that spec?
Is it possible for apache to make the tomcat application server?
Also I have read in a blog that the tomcat do not have some lib to act as an application server. What are those libs?
Thanks
I've heard once the following explanation I tend to agree with:
There is a spec of JEE (Java enterprise edition).
Formally you can think about it as a bunch of pdf-s describing the behavior of various technologies that comprise the JEE stack (for example: JMS, EJB, JPA, JPA, JSF, CDI and so on and so forth) as well as deployment models (EARs for example).
Implementors of Application servers have to implement all those technologies and offer interfaces that can be used by the application developers. So teams that stand behind WildFly (former JBoss), Geronimo, WebSphere, WebLogic and so on have read these specs and implemented everything in there.
Now, Tomcat didn't do that, they've only concentrated on (primarily) Servlets/JSPs. These are web technologies, so Tomcat can't be considered as an Application server that implements the whole JEE stack.
In general Tomcat (as well as Jetty, incidentally) should be more lightweight than full JEE compliant Application servers, it should start-up faster and it memory footprint should be smaller. So Tomcat/Jetty call themselves web servers.
I understand that this answer can be considered as speculation, but for me it makes a lot of sense.
Bellow is my perceive:
know that Tomcat is a web server but why it is not an application server?
Here, Application Server is specially for Java EE Server，Java EE is a huge specific collections for Enterprice Application Development，So Application Server should implement most specifics of these, while Tomcat(or Jetty) is only a Web Server(More accurately，Servlet Container)，they only implements the specific about Web(such as Servlet Spec(JSR340), JSP(JSR245)). Therefore，Application Server is stronger than Web Server，but Web Server is more lightweight and enough to satisfy most web applications.
Any server needs to follow some specification. What is that spec?
Of course，it depends on that your Server want to provide what services(functions)，these specifications can view here.
Is it possible for apache to make the tomcat application server?
I don't think apache will make tomcat to be an application server. Now, there are some popular Java EE Server: Jboss，WebLogic, etc. Not all enterprices need a heavyweight Application Server, on the contrary, most only need a lightweight Web Server。
Also I have read in a blog that the tomcat do not have some lib to act as an application server. What are those libs?
Tomcat only need care the specs about Web，and implements them.
Hope for your help.
I'm starting to learn spring and I came across one definition which says "Spring enables developers to do enterprise development without an application server".
What does this exactly mean and what's the harm in using an application server for enterprise development.
But don't developers use tomcat while developing enterprise development and isn't Tomcat an application server.
I'm confused here.
Can someone clarify the two points mentioned above.
I think what's meant by "Spring enables developers to do enterprise development without an application server", is that you don't need a full Java EE application server like JBoss, WebLocic, WebSphere ... but can do everything with a 'simple' servlet container like Tomcat.
Springframework provides services like dependency injection, declarative transaction management and others which are provided by Java Application Server for Java EE applications. The difference is that Spring based app can work standalone while Java EE app can't. It may be the reason to favor Springframework over a Java AS.
Tomcat is a servlet container which implements only Servlet and JavaServer Pages specifications, Java Application Server is supposed to support all of Java EE specifications like EJB, JMS, JPA, JTA and many others
We are currently developing a web application for college and we would like some advice from a more experienced developer.
We have a backend using Hibernate to operate on a MySQL database. Another project is the web UI that uses the API delivered by the backend (registering user, fetching data associated with certain profiles etc.). We use the JSF framework (RichFaces) for the UI. Everything is built using Maven.
The technology we can't decide on is for the communication between UI and logic modules. The first option is to use ApacheCXF to provide SOAP webservices that UI can be a client of. The second option is to use EJBs to invoke backend methods from the UI module.
What approach is more widely-used? As far as we read on the Web, using EJB is faster than SOAP webservices. On the other hand, we don't have any experience with EJBs using Tomcat (we would prefer using Tomcat since it seems to be a cheaper option, however we don't know what we would have to do in order to use EJBs with Tomcat). Additionally, working with webservices since the beginning will allow us to add support for different platforms (for example, Android).
Another aspect which we are discussing is about how should the application be deployed. The alternatives we have considered right now are:
Deploy it as a single WAR project (which would solve the problem we have about communicating the UI with the backend of our application).
Deploy two WAR projects in the same server using webservices for communication between the projects. (We have a prototype using this approach deployed on a Tomcat server)
Deploy a WAR project and EJB project.
Deploy an EAR project which would contain the references to the WAR and EJB projects. (We have a prototype using this approach deployed on a Glassfish server)
The project right now is starting, so we will only be handling a couple hundreds of users right now. However, if the project succeeds we would need to deal with a couple million of users.
Any advice would be appreciated. Thanks.
Edit: So any advice about how the project should be deployed? Is it necessary to use EAR? Is there any advantage if we deploy the project as an EAR module?
Edit 2: We found the advice we needed on this thread: Deploying java applications (Tomcat/Glassfish)
First things first. I would avoid using Web Services if there's no need for it. If you feel that you might need to call this system from external programs and platforms, then go for it. Even then, I would only use the web service interface for external integration, and still have an internal EJB implementation.
EJBs are awesome for enterprise applications. I would highly recommend that you look into that. They provide support for EJB Pooling, Transactions, Aspect oriented programming, Security, Stateful sessions, Java Messaging, JNDI etc. And you can inject them directly inside a Managed Bean (JSF). You said that you will eventually handle millions of users, so I assume that you will want your application to run as fast as possible, I don't think SOAP web services will be a good fit. Remember that SOAP web services encode messages as text, so if your application will be sending binary files etc, then you'll suffer significant performance issues.
As far as deployment goes I would go with an EAR, or a WAR for the JSF and and EAR backend. you can use Injection to pull the classes you need, even remotely, from multiple web applications and other EAR apps.
I'm not sure why you say Tomcat is Cheaper. Glassfish open source edition is a fully functioning JavaEE6 Server and its free. JBoss is also JavaEE compliant and is free. both of them are used in lots of production environments. I find glassfish to be much more user friendly, and would recommend it to EJB noobs :)
I also started with Tomcat, but now I don't use it at all. why use the servlet container only, when you can have the whole shabang? hope this helps.
we use ApacheCXF at work and its has SOAP and Restful. Reliable and relatively easy to setup. I am not sure why you want to use glassfish maybe it's preference but you can implement your projects in eclipse too. It's really that is up to you and your team and the requirements and skill sets your team may have to build and support, that a side CXF webservice+apache + eclipse with maybe two war files would be a good path.
I wouldn't use web services in this case. You can use managed beans as controllers.
Put the logic into EJBs, views into rich faces and control the flow using managed beans.
If you use maven you can generate a project with the structure of EAR (war for web module and jar for ejbs). I don't remember the name of an archetype but you can find it easily.
I've been doing Java standard edition development for awhile, and the frameworks and solutions have been fairly obvious to me (Swing for GUI, etc). I've recently begun the task of building a server for my own needs and to host a web page (things the server will be doing in addition to hosting a web page would include personal SVN hosting and integrating more web functionality into existing and future applications). For coding for only a single computer (that is, distributed computing, etc. is not really a concern)- I'm not entirely certain between Spring, Hibernate and EJB and am not very knowledgeable as to the capabilities of each. Information would be appreciated. I know Spring is an alternative to EJB, and Hibernate is an object-relational mapping library, so does EJB combine the two?
EJB3 in summary consists of 3 bean types; Message Driven Beans, Stateless/Stateful Session Beans and Entity Beans or JPA (Java Persistance Architecture). Hibernate can be used as a JPA provider, but it doesn't have to be used that way.
Spring has functionality that is roughly similar to Message Driven Beans and Stateless/Stateful session beans but it does not have an equivalent to JPA. Instead it allows you to utilize JPA or hibernate directly but if you do combine Spring with JPA you'll need an EJB container.
Another difference is that EJB is provided by 'containers' whereas spring is a framework that can be deployed into a java se application or a java servlet container web application like jetty or tomcat. Its an important distinction to make. Tomcat is not an EJB container, only a servlet container, hence if you were to only use basic tomcat, you couldn't use EJBs but you could use spring by including the required spring jar files in your web application (WEB-INF/lib). In that case you wouldn't use JPA either but you could use hibernate.
Some java servers that ARE EJB containers include weblogic, websphere, jboss, geronimo, and glassfish. Tomcat can become an EJB container if you combine it with OpenEJB.
In an application i'm developing at the moment, I'm using tomcat + openejb so I have an EJB container so I can use JPA with OpenJPA as the persistance provider. I'm using Spring MVC to do the web application development and will most likely use spring security as well down the track. I probably will also use Stateless Session EJBs as well to encapsulate business functionality but i could just as easily use Spring service/dao beans instead of statless session ejbs as well.
Its pretty confusing sometimes to work out what parts of which framework or container you should use and really comes down to either preference or using functionality in one that doesn't exist in the other or ease of use. Another consideration is memory utilization. Some of the ejb containers consume large amounts of memory just starting up with no applications running. This is one reason I ended up using tomcat + openejb. Hope this helps.
I am looking for a single sign on framework in java which supports Weblogic 10.3 and Jboss 4.2.2 and 5.1. JOSSO supports weblogic and jboss both but I am having lot of problems in weblogic (Session expiry issues, its not working on root context, different workflow for jboss and weblogic etc.). I am tired of JOSSO now. Please suggest me a stable SSO framework which works in jboss and weblogic.
What about an alternative like OpenID?
If you are able to use Spring security you can choose from several SSO options including CAS, Cloudseal and OpenId. A great benefit of Spring is that it sits at the application level (i.e. inside the WAR/EAR) and therefore eliminates many of the platform specific "gotchas" like the ones you are experiencing.
Of course if you aren't able to use Spring my solution is of little use! :)
Cloudseal includes a standard Java EE servlet filter which certainly works on JBoss (I have used it). I haven't tried it on Weblogic though.