Is there a tutorial or a simple applet example with JSF? How do I perform a request to a Managed Bean from an applet?
Don't use a JSF managed bean. It is not suitable for this job. Use a servlet or a webservice. To exchange data, use the session scope with an unique autogenerated key which you pass as parameter to the applet beforehand. This way the data will be available to JSF as well.
JSF (and hence managed beans) executes on the server to produce HTML; An applet executes on the client's machine - so you can't just pass a reference to a managed bean to an applet.
If you just need to pass a value from a managed bean to an Applet at start time, you can use the <param> sub-element of the tag to pass this value.
If you need some kind of dynamic access to the managed bean, it's going to be a lot harder - basically, you'll need to build some kind of web service that's backed by the managed bean so that the applet can make http requests back to the server to get the values it needs.
Related
We are starting a new project using Spring MVC, and we would like to move away from annotation-driven request/url mapping. We wish to implement the following use case:
Use Case A
User enters a URL.
The request mapping handler retrieves a list of mappings (e.g. from the DB), and based on this dynamic list of mappings, it calls the relevant controller.
This is because we want to be able to do the following as well:
Use Case B
We want to load a new Controller (perhaps a new reports module) into the web app without having to redeploy or do a server restart.
We will map this new Controller to a URL and persist it somewhere (most likely the DB).
We would like the Controller to be registered in the Spring app context (managed by Spring).
We would then like to use this new Controller in the request mapping.
We've taken an initial look at the different ways we can implement this, but we are unsure of the best architecture/method to go about this route. A couple of questions:
For Use Case A, how do we implement this within the Spring MVC framework (or if it's possible)?
For Use Case B, is there a good framework or way to be able to do dynamically loading and registering of this for web applications? We've taken a cursory look at OSGI but it seems to be advisable for use in non-web applications.
For Use case A :
Instead of DB you can keep the url mappings in a property file and then use property place holder to initialize beans using xml configuration on context up. This way remaining inside the spring framework, you can avoid annotations.
For Use Case B :
Tomcat supports dynamic reloading of classes but that to of only non structural changes in class file. But this has memory leaks as well as it doesnt cleans up old instance of class loader rather it creates a new instance.
Its quite achievable using spring-mvc-router API.
Please check below link
url-action mapping & routing in Spring MVC 3.0
Here the URL can be configured to controller.method using .conf file, but this can be achievable using java configuration, and i haven't tried so far.
Also if xml configuration chosen, then check out the property 'autoReloadEnabled', but its not adviceable for production use.
Hope this helps!!!
We have an ideological problem while creating a Web Application in JSF, EJB and JPA.
Our example situation is:
Admin displays the list of users in datatable. Next, he selects user1, which leads him to new user-edition site. The issue occure if he tries to open second card or window and select user2 for simultaneous edition in the same session.
When we try to save user1 data after edition it is not possible, because it is being overwritten in Endpoint by user2.
Data storing:
Because we do not store any data in View part of our project [diagram available below], after displaying it the Managed Beans are being destroyed. Therefore in Controller part we decided to keep the currently selected user as a field in Endpoint [Stateful EJB Bean] which is constant for a session as it is held by Session Scoped Managed Bean.
We believe we should not store any Collections in Endpoint or Session Scope Managed Bean.
Problem:
Particular case is an overview of the situation. In our application we want to edit multiple entities of the same type during on session.
Question:
Where and how should we store the current selections of User/Admin, which lead to edition of that selected entity.
Storing data in view, request scoped part allowed us to control multiple entities in the same session, though we think it is not appropriate approach. But now storing it in controller part leads to limit of one entity of the same type being edited in the same session.
DIAGRAM HERE: http://i.stack.imgur.com/9PyYr.jpg
So the lesson you learned hopefully is to not use the session scope for editing data or for transferring data between pages.
What you should do here is use a GET request with merely the id of the user to be edited. Then on the edit page, use a single view scoped backing bean.
Using this pattern you do not need extra extensions. Only if you use CDI beans as backing beans would you need CODI, since the default #ViewScoped unfortunately does not work with CDI beans. CODI provides a version that does work with CDI.
But if you use JSF managed beans, follow the pattern outlined above and you'll be fine.
Since you are using a Java EE server (Glassfish 3.1) you could get advantage of using CDI which supports different scopes than JSF. There is a CDI extension called CODI which provides the so called "window scope", allowing you to scope your beans per browser window which will solve your problem. More info about the window scope can be found here.
Another option is to use IceFaces JSF library that also supports its own window scope. More info can be found here.
I wrote custom servlet in Liferay and want to know which user page calls it and know other parameters like theme. But the request's attributes and session fields are all nulls.
How to make custom servlet to receive request as if portlet does?
Thanks
P.S. I don't want to use this solution https://www.everit.biz/web/guest/blog/-/blogs/getting-current-liferay-user-in-a-standalone-webapp?_33_redirect=/web/guest/blog
which reads cookies manually. I want to do such as Liferay does, i.e. by using it's API. Is it possible?
Update 1.
I have a portlet and a servlet in one WAR. I can know who am I (logged in user) from within portlet JSP like this:
HttpServletRequest request = (HttpServletRequest)pageContext.getRequest();
ThemeDisplay themeDisplay = (ThemeDisplay)request.getAttribute(WebKeys.THEME_DISPLAY);
themeDisplay.getUser()
Now I want to do the same from a servlet. Is it possible?
I am working in eclips which deploys automatically.
You either have to mimic what Liferay does in the portlet request handling (not recommended) or, alternatively, put your servlet code into a portlet - this can be the "resource handling" of a portlet - here you get full access to the http request and can do everything yourself with regards to data types transmitted in the stream.
I'd rather recommend this as it will be significantly easier to upgrade. Portlet Resource Handler are very similar to servlets from a logical point of view. There might be other (more advisable) options, but this is what comes to my mind for this type of problem.
I have a webapp on one Glassfish server (front-end) and an EJB 3.1 app (back-end) on another Glassfish server. The webapp communicates with the EJB 3.1 via remote invocation.
I would like to pass context data (user data i.e.) without having to define it as an input parameter of each business operation.
I have one idea, but not sure it will work: use a ThreadLocal to store data, but the ThreadLocal will only be available on one server (meaning JVM) => use the InvocationContext object and create interceptor to add user data to the ContextData Map.
What do you think about it? Any other ideas are more than welcome! ;-)
UPDATE
After first answer, I googled it a little bit and found the annotation #CallerPrincipal.
How can I set this object before the remote invocation?
The container will already handle this so you don't have to code it yourself.
In your EJB, you can access the EJBContext, which has a getCallerPrincipal() method which will give you the callers identity.
I want to use the Model-View-Controller template while writing my Web App. The problem is, the Model part of the code has already been written in Swing. The Model code also must require the container to call its main method before any interaction with its servlets. So is there a way for me to specify the location of the main method in the Deployment Descriptor so that the container calls the main method and compiles the code, and then, keeps it running for the entire duration the server is running without in any way restarting or recompiling the model class in between.
Try looking into load-on-startup parameter of servlet in Deployment Descriptor (DD). Precisely, it will load that particular servlet on server start-up.
Moreover, you should read about request lifecycle, request/session/application context. And you must look into JSP (or any other popular technology) for creating V of MVC. How URL mapping works.
Main method is basically work as an entry point in our application. Whereas in web application there is no particular entry point. Or if there is you can think of a welcome page. You might also want to look into welcome-file-list parameter of DD.
Cheers.
To run initialization when a web app is loaded, you can either use the servlet's init method or a ServletContextListener. You can call the main method from either of those yourself.