I have implemented pretty simple application, using gwt and gwt event service 1.1.1, it sends some information to the server and waits for particular event to come back.
When application is opened in one browser window, it works fine.
When it is opened in two browser windows (the same browser and the same address: localhost:port/app or ip:port/app) on one machine, only one instance of my application receives event (UI reflects changes only in one window).
When it is opened in two different browsers, but with the same addresses (for instance, both are localhost:port/app), then both browsers receive events.
When it is opened in two windows of the same browser, but with different addresses (one is localhost:port/app, second is ip:port/app), then it also receives events.
So, could somebody provide any explanation to such behavior? And if is there some kind of workaround for this problem.
Thanks in advance,
Alex.
You are using gwt event service on the server, right?
They claim to have "Only one open connection for event listening". So they actively check that one client has only one connection for sending events. They probably use web sessions to achieve this.
Since you open the same URL in the same browses in two tabs, this two tabs share the same session. There is no way around it. There are a lot of questions about this: https://stackoverflow.com/search?q=browser+tabs+session
Update:
It seems that gwt-event-service can be configured to support multiple sessions: use SessionExtendedConnectionIdGenerator
Update 2:
Use a config file like this: http://code.google.com/p/gwteventservice/source/browse/trunk/conf/eventservice.properties?r=265
Related
On my wicket page I have a link that opens a second page in another tab/new window.
Click here for second window
These windows are meant to be used in parallel (e.g. in a two-monitor-environment). But I don't want to spread out different menu entries over both screens, so I want all menu entries to stay on MyFirstPage, even if they should influence MySecondPage only.
My ultimate goal is to click a menu entry on MyFirstPage that results in displaying a new Component on MySecondPage. Is this even possible? How can I obtain a java-reference of MySecondPage inside MyFirstPage or establish some other sort of communication?
Everything I found while researching only applied to modal windows or Wicket 1.4, but MySecondPage is not modal.
Maybe wicket's event bus is an option, see: http://code.google.com/p/wicket-guide/downloads/list - Chapter 15.3 Wicket events infrastructure
You could send the event in MyFirstPage , receive it in your Session or Application and there send it to MySecondPage. Session and Application implement IEventSink: http://ci.apache.org/projects/wicket/apidocs/6.x/org/apache/wicket/event/IEventSink.html
There is WebSocket support in Wicket 6:
http://wicketinaction.com/2012/07/wicket-6-native-websockets/
Basically you need to add WebSocketBehavior to the page to make it available for messages from the server.
On the other hand, you can send messages to the server via Wicket.WebSocket.send("A message sent by the client");
I have never tired it but it sounds very promising.
We have a GWT based thick client like web application. The application is considerably large and has some initial load time.
We would like to send the users of our application e-mail messages with href links that would open up a specific asset in our application. Well this of course has the effect that clicking the link opens up the application again, reloads it which we would like to avoid. Ideally we would like the href link to just signal our application/web page somehow so that we could pick up the event in our application and react to it.
Any ideas how we should approach this or is this even possible ?
Thanks!
You need to use a GWT Hyperlink which is a widget that serves as an "internal" hyperlink. That is, it is a link to another state of the running application. When clicked, it will create a new history frame using History.newItem(java.lang.String), but without reloading the page.
If you are not already using it, information is here on GWT's History mechanism
There seems not to be any elegant solution to send an event from a link to an existing browser window. Few solutions I have encountered this far:
a) Implement a cookie polling solution for the application to poll if a cookie exists or changes. The link points to our server which just sets the cookie and this way informs the running app about the event. Some tricky handling should be implemented with some kind of 2-way protocol between the returned temporary page from server to handle the situation where the application is not (yet) running.
b) The same approach as in solution a) but use html5 local storage for communication. This way the poller is not needed as the local storage fires an event when content changes. This would be a possible solution but is not for me as we have to support older browsers without local storage support.
c) A long polling ajax or a web socket for delivering events from the server to the client. A solution but seems overkill and might require a modern browser for atleast web sockets.
We have a working web application, which has been developed with ExtJS for client side, and Struts, Spring, Hibernate for server side. now, we are considering to migrate to GXT (or may be GWT itself). The thing is I'm very new to GWT/GXT. and we are trying to decide whether we go down this road or not.
1) Until now, we have 2 domains for our web-app. one is that the application (Struts+...) have been deployed to, and the other is mainly a cookie-less custom CDN. The transfer between client and server is mostly XHR requests, sending/receiving JSON and/or JSONP. But with the new approach ahead of us, I began to understand that we are supposed to have only ONE domain, for the whole GXT application. Is it correct or I forgot to consider something here?
and if not, Is it possible that we deployed just part of the application (i.e. com.ourcompany.webapp.gxt.server.*) to the main server, and the contents that have been compiled and generated by the GWT compiler to the other CDN-like domain?
2) The other big issue we are facing is that the current application is consists of mostly 3 huge modules. One is responsible for "SignIn", the other is for "Webtop", and the third one is "Modules which each users has access to". The latter has been generated on the server due to "access rights" of each users, and obviously could be different from one user to the other.
The only thing I could find on this matter, which might be related is Code Splitting. Although I'm not totally sure if this would be the right solution for this.
We want that the application, on Start Up, checks whether user has been logged in or not. if not, loads the SignIn sets of javascript files (i.e webapp.signin.nocache.js), then after user has entered the correct username/password, unloads this signin file and loads webtop.nocache.js AND modules.nocache.js.
I would be really appreciated if you could help me out.
1) If your GWT app is loaded from a different domain than you have to face the same origin policy. You can not do a xhr to a different domain. You could use the ScriptTagProxy to get around this. But it does not feel very netural.
2) You can use CodeSplitting in order to automatically load a particular part of your application dynamically. All you have to do is to warp your splitt point into an async call.
A detailed compile report gives you a pretty good overview how well code splitting is working.
But CodeSplitting does not unload already loaded code. If its really importend to do so you have to redirect the user to another url in order to load the appropriate user depended module.
Once Javascript code has been loaded and executed its impossible to remove the code from the browsers memory.
Grettings,
Peter
I am trying to write a VPN app using VpnService. I started my app based on the sample ToyVpn. It seems to work fine but I am wondering if there is a way to get rid of the pop up dialog when I click connect. I am hoping that I could just click "connect" and it would start without having to click the "I trust this application..." check box and "Ok".
Thanks.
I don't think it's possible. They seem to be very careful about this class. If you take a look at the documentation you can see it says:
Letting applications intercept packets raises huge security concerns. A VPN application can easily break the network. Besides, two of them may conflict with each other. The system takes several actions to address these issues. Here are some key points:
User action is required to create a VPN connection. [emphasis mine]
There can be only one VPN connection running at the same time. The existing interface is deactivated when a new one is created.
A system-managed notification is shown during the lifetime of a VPN connection.
A system-managed dialog gives the information of the current VPN connection. It also provides a button to disconnect.
The network is restored automatically when the file descriptor is closed. It also covers the cases when a VPN application is crashed or killed by the system.
Since it says that user action is required to create the VPN connection, I assume they mean this is something you cannot control yourself.
I want to write a workflow application that routes a link to a document. The routing is based upon machines not users because I don't know who will ever be at a given post. For example, I have a form. It is initially filled out in location A. I now want it to go to location B and have them fill out the rest. Finally, it goes to location C where a supervisor will approve it.
None of these locations has a known user. That is I don't know who it will be. I only know that whomever it is is authorized (they are assigned to the workstation and are approved to be there.)
Will Microsoft Windows Workflow do this or do I need to build my own workflow based on SQL Server, IP Addresses, and so forth?
Also, How would the user at a workstation be notified a document had been sent to their machine?
Thanks for any help.
I think if I was approaching this problem workflow would work to do it. It is a state machine you want that has three states:
A Start
B Completing
C Approving
However workflow needs to work in one central place (trust me on this, you only want to have one workflow run time running at once, otherwise the same bit of work can be done multiple times see our questions on MSDN forum). So a central server running the workflow is the answer.
How you present this to the users can be done in multiple ways. Dave suggested using an ASP.NET site to identify the machines that are doing the work, which is probably how I would do it. However you could also write a windows forms client that would do the same thing. This would require using something like SOAP / WCF to facilitate communication between client form applications and the central workflow service. This would have the advantage that you could use a system try icon to alert the user.
You might also want to look at human workflow engines, as they are designed to do things such as this (and more), I'm most familiar with PNMsoft's Sequence
You can design a generic "routing" workflow that will cause data to go to a workstation. The easiest way to do this would be to embed the workflow in an ASP.NET application. Each workstation should visit the application with a workstation ID in the querystring:
http://myapp/default.aspx?wid=01
When the form is filled out at workstation A, the workflow running in the web app can enter it into the "work bin" of the next workstation. Anyone sitting at the computer for which the form is destined will see it appear in their list of forms to review. You can use AJAX to make it slick and auto-updating.