As the title mentions, what is the purpose of an Application Server Application-Client?
Scouring the web, there really isn't much explanation of what an Application Client for an Application Server is and what its' purpose is for.
From what information I can glean, an application client is like a browser in that they both access an application hosted on an application server, but the application client provides a better (graphical?) interactivity? Also it creates a container that allows access to an application server's resources, or it's Java EE resources?
But I still really don't understand how it all fits together or what it is exactly.
Simplify this, the client of some a A element, is some other element, that uses the A element to do something (e.g. one class object use other to do something)
Application Client is simply other application, class or component that uses, invokes or executes methods. If you wrote some class with some methods you can use this class as a part of other class. And then the second class will be a client of the first one.
You can develop some EJB component on application server in JavaEE and you can create standalone JavaSE application which will invoke methods from your component deployed on server. And then this standalone JavaSE application is your client for your component.
... an application client is like a browser in that they both access an application hosted on an application server, but the application client provides a better (graphical?) interactivity?
Not only browsers can be client applications. In JavaEE (Enterprise Edition) you can develop components and deploy them to the application server. Components contains special classes with only business methods (i.e methods that do something concrete). You provide some interface for your developed components on application server. Thanks to this interface client applications can invoke methods in components. Your client application that can use this component through provided interface can be JavaSE application, Web Servlet, JSP or other components.
You can read section 1.3.3 Java EE Clients to get further details from below tutorial:
https://docs.oracle.com/javaee/7/JEETT.pdf
Related
I want to access to remote EJB running on Liberty Server from a swing Client like this :
Object found = new InitialContext().lookup(
"corbaloc:iiop:localhost:2809#ejb/ear/ejb.jar/package/Bean#com.package.BeanRemote);
I'm getting that error :
javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or in an application resource file: java.naming.factory.initial
at java.naming/javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:691)
at java.naming/javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:305)
at java.naming/javax.naming.InitialContext.getURLOrDefaultInitCtx(InitialContext.java:342)
at java.naming/javax.naming.InitialContext.lookup(InitialContext.java:409)
at com.package.ClassMain.main(ClassMain.java:43)
How is a connection to Liberty established?
Need help please
I'd strongly recommend you to re-architect your app to use JAX-RS (rest over http) instead of remote EJB. Just use Facade pattern and wrap your EJB as REST endpoints, and use Rest client on the Swing side.
There are several reasons:
remote EJB is almost dead technology now
http/rest is more firewall/network/container friendly
http/rest is more client agnostic - if you would later like to change your client from Swing to web/JS it will be much easier
But if you really insist, setting up remote EJB is not very simple.
The easiest would be to use Liberty Application client and run your Swing app from there.
If you cannot use that you will need to get traditional WebSphere Application Server Client, and use the client jar provided with that com.ibm.ws.ejb.thinclient_8.5.0.jar. If the client is running with a non-IBM java you will also need to add the orb jar onto the class path (com.ibm.ws.orb_8.5.0.jar).
See theses links:
how-to-set-up-thin-client-to-call-remote-ejb-on-liberty
Running the IBM Thin Client for Enterprise JavaBeans (EJB)
Using enterprise JavaBeans with remote interfaces on Liberty
So all in all, rewrite will be usually simpler and more beneficial.
I have to develop enterprise level application using Java technologies. I decided to develop client side environment with swing and server side related things using Java EE components. My planned way could be described as following
First swing client makes request to application server. And application server has business logic and it has ability to decide which way should transfer my requests. Database server has my DBs.
these technologies I willing to use.
swing for client side
servlet for HTTP request handling in application server
EJB for handling business logic in application server
Hibernate to access my DBs form EJB.
Could you tell me above architecture is compatible with JEE enterprise level system architecture?
Swing <==>Socket<==>JEE (Application) REST based <==>Hiberate (DAO)
Yes its good but.
But if your application is going to be used by different end user devices then you need to think different way of client side.
Using JNLP you can deliver your SWING client items to your end users that will give you better upgradation and later customization also possible without any intimation to your clients.
This is my points only.
I know how to make web application in technologies like jsp/servlets and applications servers.
Suppose I make some utility method for particular application say ‘A’ and its working fine no any other web or desktop application in need of this method.
Same thing I can provide such utility method via web service like Rest/Soap.
So why I need web service in this scenario, I can imagine if such service is useful for other application and we provide it as web service then its fine.
Can anyone give me some answer which clear my doubt?
Thanks
Based on Your Comment, i would like to clarify.
Web service is a concept in which you expose a utility or functionality to the world.
Any one in the world can access the same by first establishing ground rules as in SOAP via WSDL.
The Services can serve any number of requests from any application provided it sends the proper input request needed by your service.
In case you have built an application A with a utility functionality X,
Then application B,C,D and so on can access the Web Service.
All it needs is:
the URL for the Service which is exposed through network to the consuming application
The requested parameter format
and the Proper Response format.
Once this is setup, any application, not just in java, can access the service so even .Net applications or PL/SQL applications can access the Web Service Utility.
I am a little confused about the roles of a java application server and its differences from a web server.
I found many sites explaining the same difference between the two but not to my satisfaction.
So please explain me about the two following cases:-
1)App. Server and its difference with web server:
From these two links:
Difference between an application server and a servlet container?
What is the difference between application server and web server?
web server: It handles everything through http protocol by accepting requests from clients and sending
responses to them with the help of its servlet container(e.g Apache Tomcat)
App. Server: An application server supports the whole of JavaEE like JMS,JPA,RPC etc.
Now what I am confused with is that how can I use a lot of JavaEE APIs like JMS,JPA etc. with my Tomcat
by adding their jar files in my web application ?
Does that mean that if I use an appliation server I don't have to add those jar files?(I don't think so)
2)The roles of an appl. server (This is very important to me)
From Wikipedia
http://en.wikipedia.org/wiki/Application_Server
An application server provides services such as security,transaction support etc.
"The term is often used for web servers which support the JavaEE" -- It sounds like if we add the required jar files of JavaEE APIs a web server becomes an appl. server.What about it.
Now my question is how an application server performs the tasks of security control or transaction management by itself ?
E.g. in my web application using Spring framework I am providing security by using spring-security and transaction management by using #Transactional annotation and all those things you know.
So does the appl. server have anything to do with my security or transaction management or it has its own ways ?
Forgive my ignorance.
Using Spring, you're in fact embedding some kind of Java EE container inside your application. But even when using Spring, if you need JTA support (because you need distributed XA transactions), you'll need to use an additional transaction manager. If you need JMS, you'll need to install an additional JMS broker. If you need connection pooling, you'll need to use an additional connection pool. Sometimes it's as simple as adding additional jars to the classpath and properties or XML files. Sometimes it's harder.
A Java EE app server comes with everything bundled. You have less flexibility, but you don't need to install, configure and make everything work by yourself.
When you use the Java EE framework, that is a specification. So the application server, if it is Java EE compliant, needs to implement this. So once it is implemented the specification, then it will address Security,transaction etc because it is mentioned in the spec. So it is a contract. Whereas, in a web server, it will just pull out your static resource. There is no need for handling other stuff.
In case of the Spring framework, the framework knows how to handle transaction, security etc. So particularly the developer need not look into these aspects which are implemented by the Application Server in the other scenario.
how an application server performs the tasks of security control or transaction management by itself
It is rather the specification that address these issues, not the application server. So, the duty of the app server is to implement these.
So, if your application is Java EE compliant, then these areas will be addressed and the implementation would have been done by the app server.
May be this is oversimplification,
A web server is basically a HTTP server serving contents over http protocol. So a web server is simply about serving the contents over http protocol. A typical example would be Apache web server. This is simply a file server.
Now the question is where does the web server gets the contents from ? Possible sources are
Static contents (the contents like images/css etc) which are not generated on request but statically served.
Dynamic contents: Simply put, the contents to be served are generated upon the user request.
For the static contents, the web server does not need anything as it simply reads the file and serves it.
For dynamic contents, the web server might need help of additional components which will generate the contents to be served.
Here the Application Server comes into picture.
Now these additional components referred earlier, might interact with database or some other system etc.
In a web environment where your website is exposed to huge number of users (intended/unintended), you need typical services like transaction/security/concurrency etc. so that the user get expected responses and do not see inconsistencies in the behavior of the application.
An application server has inbuilt abilities to manage transaction/security/concurrency/resource management. generally these are referred as Managed services and environment offered by them is called Managed Environment where these basic services are managed by the application server and programmer does not have be bother for them.
Application Server needs web servers or we can say Web servers use Application server's services to generate dynamic contents.
For example, JBoss uses Tomcat as inbuilt web server. Whereas web logic has its own web server. Tomcat again can be called as application server (in principle) as it also offers managed environment for servlets (it manages concurrency and instance pool of servlets/JSPs ).
Coming your your example of Spring:
An Application server will come inbuilt with transaction/security etc whether you need it or not. The Spring offers a very nice way handling this. Spring has all these things BUT you use what you need. Not just these, but just a Java Web Sever like Tomcat is sufficient to build a full fledged services that needs an application server.
I want to use JavaFx as a front-end in my web-application. My question is that is it possible to bind Model object with the form which is developed with Java Fx.
I kindly request you to put some light on this issue.
Please let me know If you need more clarification regarding this
The main differences between Web front-ends (like Spring MVC) and rich clients (and RIAs like JavaFX) is that for web front-ends the server-side logic runs in the same JVM as the web framework while for rich clients the server-side logic and the client are running on 2 separate JVMs, one on the server machine and one on the client machine.
Rich clients are usually downloaded/ installed completely before the user can run it, while for web front-ends each HTML page is possibly first dynamically created and then send to the user as needed.
Since the user usually already has the complete rich client from start, only the actual data (DTOs) get sent back and forth using some kind of remote service e.g Web Services.
So this means that the JavaFX client cannot access the objects of the server (e.g. attached JPA entities). You need to wrap the data up and send it to the JavaFX client using some kind of service (see the Service Facade and DTO design patterns).
The main difference between JAVAFX and any Java EE framework is same as the difference between the swing applications and Java EE apps.
You can design applications using JAVAFX to be directly used on desktop or deployed as browser applets with the help of the Java browser plugin. But, using it as a framework for designing the front end of a Java EE application is not possible.
Read this post :
https://www.java.net//node/674176